Tracking Structural Evolution in Lithium-ion Batteries via In-Operando Scanning Electron Microscopy

Tracking structural evolution in lithium-ion batteries via operando scanning electron microscopy Ondˇ rej Klvaˇ c a,b,* , David Trochta a,b , Libor Nov´ ak a , Peter Priecel a , Manuel Bornh¨ offt a , Tom´ aˇ s Kazda b , Zhao Liu c,d,** a Thermo Fisher Scientic Brno, Vlastimila Pecha 12, 627 00 Brno, Czech Republic b Department of Electrical and Electronic Technology, Faculty of Electrical Engineering and Communication, Brno University of Technology, Technick´ a 10, 616 00 Brno, Czech Republic c Thermo Fisher Scientic, 5350 NE Dawson Creek Dr, Hillsboro, OR, 97124, USA d Materials Science and Engineering Department, University of Washington, Seattle, WA, 98195, USA ARTICLE INFO Keywords: Li-ion batteries Operando SEM Structural evolution Battery R&D and manufacturing ABSTRACT The comprehensive understanding of structural-performance correlation of lithium-ion batteries is paramount for optimizing their performance, safety, and longevity, which are critical for applications such as portable electronics, electric vehicles, and renewable energy storage systems. Scanning Electron Microscopy (SEM) is instrumental in the examination of lithium-ion batteries, offering high-resolution imaging and detailed insights into the battery microstructure and morphology. Operando SEM analyses are invaluable as they provide precise descriptions of the dynamic phenomena and structural temporal evolution within the battery. However, the application of SEM for operando analyses is hindered by the challenges in the preparation of samples that can deliver practical electrochemical performance within the SEM environment. In this manuscript, we introduce an operando SEM workow that enables high-resolution analysis of structural evolution in lithium-ion batteries from electrode level to particle level. The efcacy of this system and workow is demonstrated on lithium nickel manganese cobalt oxide (NMC) and lithium titanium oxide (LTO) battery cells revealing electrode expansion and contraction, as well as grain cracking. Additionally, a graphite-lithium metal system is analyzed, where expansion and cracking of graphite grains were observed. The study delineates a procedure enabling the investigation from entire electrodes change at hundreds of micron level or even larger cell components to submicron changes at the granular level, applicable across various chemistries. We propose that this workow can offer valuable insights for both fundamental research at the materials development level and cell structure optimization in manufacturing environments. 1. Introduction With advancements in the technology eld, decarbonization efforts, and ecological demands, the need for advanced electrochemical power sources is increasing. However, large-scale production faces challenges connected with limited raw materials resources, rising costs, and environmental impacts. Taking lithium-ion battery manufacturing as an example, the process aims to produce cells that achieve high energy density, long lifespan, enhanced safety, and low cost, all while maintaining consistent quality [1]. Achieving this goal relies on multiple critical factors, including cost-driven fundamental research for materials and process innovation, a robust and resilient supply chain, as well as advanced metrology and characterization capabilities [2,3]. Recently, as battery designs have grown increasingly complex across multiple length scales to push the boundaries of performance, metrology techniques that offer deep insights into physical, chemical, and electrochemical processes at these scales have become critical [4]. They are essential not only for advancing research and development (R&D) but also for ensuring effective quality control and failure analysis within manufacturing environments. Among all metrology techniques, in-situ/operando imaging techniques offer insights into the kinetics of processes and mechanisms * Corresponding author at: Thermo Fisher Scientic Brno, Vlastimila Pecha 15; 627 00 Brno, Czech Republic. ** Corresponding author at: Thermo Fisher Scientic, 5350 NE Dawson Creek Dr, Hillsboro, OR 97124, USA. E-mail addresses: ondrej.klvac@thermosher.com (O. Klvaˇ c), zhao.liu@thermosher.com (Z. Liu). Contents lists available at ScienceDirect Energy Storage Materials journal homepage: www.elsevier.com/locate/ensm https://doi.org/10.1016/j.ensm.2025.104516 Received 2 May 2025; Received in revised form 7 July 2025; Accepted 2 August 2025 Energy Storage Materials 81 (2025) 104516 Available online 5 August 2025 2405-8297/© 2025 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license ( http://creativecommons.org/licenses/by/4.0/ ). occurring within a battery during operation by probe structure and chemical information in real time [5–9]. Unlike ex-situ or post-mortem methods, where the structural and chemical information may have been impacted by sample handling or intrinsic cell relaxation process, operando techniques enable the precise identication of structural and chemical states at the moment of occurrence, leading to a clearer understanding of its underlying mechanism [6,7]. Techniques with various probes, including electron, X-ray, optical, infrared, and ultrasound are nowadays applied in the battery eld [10–16]. Since each probe provides a distinct imaging resolution, they collectively deliver information across multiple length scales, enabling t-for-purpose solutions to meet the metrology needs in battery R&D and manufacturing. In general, electron probes and X-ray probes offer structural analysis from atomic level to cell level with focus covering both R&D and manufacturing [8, 17–20], while the optical, infrared, and ultrasound probes are applied mainly on the length scale from electrode level up to pack level with focus and application potential for battery quality control and failure analysis in manufacturing [21–26]. As the highest-resolution probes, electron probes are utilized in transmission electron microscopy (TEM) or scanning electron microscopy (SEM), including focused ion beam scanning electron microscopy (FIB-SEM), to observe structural evolution during battery reactions in real time with resolution down to atomic scale. TEM offers higher resolution that enables detailed insight into reaction process within electrode particles, at the interface, or within the electrolyte, such as lithiation/de-lithiation study [27–32] or solid-liquid interface reactions analysis [33,34]. Because of the limited volume of the materials and deep level of details TEM can access, it is commonly considered as a powerful tool for fundamental electrochemical processes and mechanism understanding, making it well-suited for basic research [35]. Compared to TEM, SEM offers the capability to access a much larger area and volume — from electrode level to individual particles — while maintaining capability to monitor nanometer-sized features. This enables the study of phenomena such as particle and electrode structural evolution and dendrite formation under practical operation conditions possible, making the knowledge gained through operando SEM valuable for both battery R&D as well as manufacturing applications. To date, irrespective of the battery chemistry under investigation, three major operando SEM design approaches have been developed, each accompanied by inherent constraints that limit their learning for broader applicability [36–46]. The single-particle analysis approach enables detailed structural characterization within an individual particle to elucidate degradation mechanisms; however, it lacks sufcient statistical representation to fully capture the behavior of real battery operation [36,37,46]. The liquid electrochemical cell design or the customized cell with active materials deposited on the mesh provide enough statistics and electrochemical performance close to a practical cell, while the image resolution can be compromised due to cell design ooded by electrolyte as well as the requirement for a long working distance in SEM. In addition, only the surface of the electrode could be investigated, which lacks information about other components, such as current collectors and separators [38–41]. The cell design with cross-section view geometry offers opportunities to observe structural evolution across multiple layers. However, this conguration faces challenges in preparing high-quality cross-sections for optimal SEM imaging (e.g. mechanical polishing results in surface artifacts or delamination), while direct FIB trenching on rough surfaces may restrict the eld of view, limiting the ability to obtain sufcient statistical data [42–45]. To enable operando SEM be effectively contributing knowledge for both battery R&D and manufacturing environment, it shall satisfy several criteria: (i) the set up provides access to large area and volumes with multiple components for representative analysis, (ii) optimal surface with minimized defect allows for high resolution imaging for detailed structural analysis, (iii) the sample transfer or handling process to SEM needs to be under inert gas protection or vacuum to avoid risk of contamination and degradation by exposure to air or moisture, (iv) electrochemical performance is comparable with the real battery cell [47]. The challenges of preparing a smooth surface with minimized artifacts can be addressed via broad ion beam (BIB) polishing method, which is commonly used in battery post-mortem analysis [48,49]. As shown in Fig. 1(a) and (b), the BIB method prepares high quality cross-section with the region of interest at hundreds of micron width for ex-situ SEM imaging. Although particle cracking can be identied when comparing the electrode before and after cycling, information may be lost as the samples are not identical. In this study, by integrating BIB sample preparation with operando bias SEM testing, we present an operando SEM workow that enables high-resolution analysis to track structural evolution in lithium-ion batteries from electrode level to particle level (Fig. 1(c)). Two electrode pairs, namely lithium nickel manganese cobalt oxide–lithium titanium oxide (NMC-LTO) and graphite –lithium metal (Gr-Li) pairs, were selected to investigate the structural evolution of NMC and graphite during electrochemical cycling. For electrolyte selection, factors such as electrochemical stability, ionic kinetics, and vacuum compatibility need to be considered. Conventional carbonate-based electrolytes (e.g., EC:DMC with LiPF₆) are inherently incompatible with high-vacuum conditions, thereby restricting their use in current operando SEM workows. Moreover, they typically induce the formation of chemically unstable, heterogeneous organic/inorganic interphases that are prone to degradation [50], thereby complicating the correlation between electrochemical performance loss and microstructural observations. In contrast, the ionic liquids (ILs), specically pyrrolidinium-based ILs such as Pyr13-TFSI and Pyr13-FSI, promote the formation of predominantly inorganic solid-electrolyte interphase (SEI) and cathode-electrolyte interphase (CEI) layers with enhanced chemical and mechanical robustness [51], ensuring that observed degradation phenomena at the electrode or particle level are more directly attributable to intrinsic electrochemical processes. While the relatively high viscosity and reduced ionic conductivity of ILs may impede Li⁺ transport and contribute to increased polarization, they also serve to moderate (de)lithiation kinetics. Such moderate kinetics reduce stress accumulation and mitigate the formation of concentration gradients within active materials, thereby enhancing the spatial and temporal resolution of structural evolution under operando SEM [52]. Furthermore, the non-volatile nature of these ILs maintains stable electrochemical environments during SEM operation, minimizing electrolyte-induced imaging artifacts and facilitating more accurate attribution of morphological changes to fundamental material behavior [53]. Therefore, to enable the demonstration of the operando SEM workow for investigating electrode microstructural dynamics, pyrrolidinium-based ILs were chosen as electrolytes for integration into both battery systems. The observed structural evolution is correlated with electrochemical mechanisms to elucidate degradation pathways and material behavior under operational conditions. 2. Materials and experimental methods 2. Materials Commercially available electrode sheets from CustomCells were used in this study. Cathode was made of NMC111 coated on an aluminum current collector to pair with anode that was made of LTO coated on an aluminum current collector. The NMC cathode composed of NMC111, PVDF binder, and conductive carbon was formulated in a weight ratio of 86:7:7. Graphite was coated on a current copper collector to pair with Li-metal. The capacity of the electrodes is specied in the datasheet as 1 mAh/cm². Metallic lithium (99.9 %; Sigma-Aldrich) was used as the counter electrode in Gr–Li metal study. A Whatman GF/C glass ber lter with a thickness of 260 µm was used as the separator. Different ILs electrolytes were used to test NMC-LTO and Gr-Li system. For NMC - LTO systems, an ILs electrolyte was prepared using a mixture of 1-methyl-1-propylpyrrolidinium bis(triuoromethylsulfonyl) imide (Pyr13-TFSI, >99 %; Sigma-Aldrich) and lithium bis O. Klvaˇ c et al. Energy Storage Materials 81 (2025) 104516 2 (triuoromethanesulfonyl)imide salt (LiTFSI, >99 %; Sigma-Aldrich) at a concentration of 0.5 M. For Gr-Li system, mixture of LiTFSI: 1-propyl1-methylpyrrolidinium bis(uorosulfonyl)imide (Pyr13-FSI), 1:9 mol (Solvionic >99.5 %) was used. 2.2. Cells assembly and operando SEM setup Fig. S1 shows the electrochemical cell preparation workow. To prepare for the cell assembly, electrode pieces with approximately 5 mm x 8 mm in size were rst cut from the electrode sheets with scissors. The electrode of interest (NMC and graphite) was then moved to Thermo Scientic CleanMill BIB polisher to prepare a cross-section using Ar ion beam. For the NMC electrode, 16 kV and 3.5 mA (anode current) were used for one hour; for the graphite electrode, 10 kV and 3.5 mA (anode current) were used for 1.5 h. Sample rocking +/- 40◦was used to reduce curtaining artifact. The resulting area size of the completely polished region was about 500 µm in width (Fig. S1(a)). Similar methods can be used to prepare a cross-section of either electrode individually or the whole cell at once. A slightly larger piece of approximately 7 mm x 12 mm was cut from the separator with a razor blade. The electrode of interest was then aligned together with counter electrode and separator. It has been found to be advisable to place the electrode of interest to be a few micrometers above the separator to avoid ooding the region and electrode of interest with ILs electrolyte during the operando SEM experiment (Fig. S1(b)). The alignment and mechanical xation were done in a customized clamping tool. It contains two clamping plates, which can be pressed together using a screw. In addition to mechanical clamping, these plates also serve as an electrical contact to the pins on the edge of the clamping tool (Fig. S2). The pre-prepared cell was then transferred to the Ar-lled glovebox. The specimen was left in the glovebox antechamber for several hours under vacuum to dry all parts of the system before subsequent application of the electrolyte. The electrolyte was applied to the separator edges with a pipette until the cell was soaked properly (Fig. S1(c)). The Fig. 1. Comparison of SEM analysis between ex-situ and operando analysis. Ex-situ SEM analysis of NMC cathode cross-section prepared via BIB polishing. It is not possible to examine the same region and its changes over time to directly compare (a) pristine and (b) cycled electrode due to the destructive nature of this analysis. (c) Operando SEM analysis of selected NMC grain cross-section at different charging stages to show continuous structural evolution – observation of crack evolution during rst formation cycle. Fig. 2. Schematic of operando SEM setup. O. Klvaˇ c et al. Energy Storage Materials 81 (2025) 104516 3 prepared cell was then transferred to the SEM chamber in the Ar atmosphere using the Thermo Scientic CleanConnect Sample Transfer System (Fig. S1(d)) to perform operando testing in SEM (Fig. S1(e)). Fig. 2 shows the schematic of operando SEM analysis setup. In the SEM chamber, a stage with the contact pins was pre-installed, into which the pins on the clamping tool t when inserted (Fig. S2). These pins are wired through a vacuum feedthrough to a potentiostat outside the SEM chamber. A BioLogic SP-150 potentiostat was used for electrochemical measurements. The capacity of the system was estimated based on the electrode size, considering the datasheet value of 1 mAh/cm 2 . The description of the potentiostat settings and cycling protocol for each sample is provided in the results and discussion section. 2.3. Operando SEM imaging and data processing Thermo Scientic Quattro ESEM was utilized to perform operando SEM imaging. An automated control script (Thermo Scientic AutoScript 4 Software) was developed to manage SEM magnication and stage movements, enabling the imaging of multiple areas with different horizontal eld width (HFW) that provided both detailed and overview SEM images during battery cycling. The acquired images were then correlated with specic points on the electrochemical curve based on the data from potentiostat. By combing these images, a video was generated where the current frame is indicated by a cursor (red cross, Fig. 2) on the curve. Further image analysis was conducted using Thermo Scientic Phenom ParticleMetric particle analysis software and Python script automatic edge detection for structural quantication. For electrode structural analysis, electrode boundaries (edges) were detected using Python script to track the whole electrode thickness changes. Changes are expressed as percentages relative to the initial image taken at the start of the measurement. For NMC particle structural evolution analysis, the Thermo Scientic Avizo software identies grain boundaries and calculates the area of each grain based on the actual SEM magnication. The real size of the particles and cracks can be calculated from the known eld of view of SEM images. 3. Results and discussion 3.1. Operando study of structural evolution at electrode level The NMC-LTO battery was prepared as described in Section 2.2 and connected to a potentiostat within SEM as shown in Fig. 2. After two initial formation cycles conducted at 0.1C in a potential window of 1.3 – 2.8 V, 15 min rest phase, the battery was further cycled in constant current followed by constant voltage (CCCV) mode at 1.0C with 5 min rest phase, and imaged. Notably, the cycling continued at the potential window of 0.8 – 3.3 V to accelerate and amplify the structural changes on NMC electrode for evaluation. The thickness of the electrode was continuously measured during cycling (Fig. 3, corresponding video to record the full cycling process can be found in Video S1). The results show NMC electrode thickness oscillated with the charge/discharge process, namely expansion during battery charging (NMC electrode delithiation) and contraction during battery discharging (NMC electrode lithiation) (Fig. 3(a)). Interestingly, after expansion during the battery charging phase, the electrode does not return to its original thickness during battery discharging. Instead, it gradually expands with each subsequent cycle, leading to irreversible expansion in the electrode. In the rst cycle, the thickness was approximately 37.9 μ m in the battery charged state and 37.0 μ m in the discharged state. By the end of the 13th cycle, these values increased to 39.8 μ m and 39.1 μ m (Fig. 3(C)), respectively. Previous studies have shown that the changes in electrode thickness during cycling cannot be simply derived from the volumetric changes of the unit cell of the active materials [50]. For instance, in NMC cathodes, the PVDF binder significantly contributes to irreversible electrode expansion, owing to its plastic deformation behavior and weak van der Waals interactions with the active material [51]. Acting as a structural skeleton, it provides Fig. 3. Operando tracking structural evolution at electrode scale; (a) Charge and discharge curve vs. thickness change over the cycling process; SEM images of NMC cathode during the cycling between 0.8 – 3.3.V; Electrode thickness comparison between the (b) beginning of the experiment and (c) after 13 cycles. O. Klvaˇ c et al. Energy Storage Materials 81 (2025) 104516 4 mechanical stability and holds the active material particles together. During battery cycling, the binder matrix experiences plastic deformation driven by mechanical stresses, which originate from intergranular expansion during the lithiation phase and microcrack propagation within NMC secondary particles during delithiation. Unlike hydrogen-bonded or covalently crosslinked binders, the weak interaction with the active materials and lack of strong retroactive forces result in electrode not fully recovering to its original structure and therefore leading to irreversible expansion of the electrode or even delamination over multiple cycles [52,53]. In addition, the electrode porosity and particle rearrangement also contribute to the observed thickness evolution [54]. The electrode porosity allows local accommodation of stress and permits permanent displacement of particles under binder deformation. As the binder plastically yields, additional voids formed during contraction are not always closed in the following cycles, especially when the binder fails to recover its original shape. This creates a net volume gain per cycle, even if the active material itself returns to its previous lattice state. Overall, the changes of electrode thickness can be attributed to the synergic interaction among binder composition, mechanical properties, active materials unit cell volume changes, and electrode porosity. The operando experimental data shows that the changes in the materials structure within the electrode, including the behavior of the binders, have a signicant impact on the electrode’s performance, and need to be considered when designing and optimizing battery electrode architecture. Understanding and measuring electrode expansion during cycling Fig. 4. Operando tracking structural evolution at particle level with selected NMC particles. (a) voltage curve of the cell and the corresponding grain size changes of Particle A and B; (b) SEM images of Particle A and (c) Particle B for two delithiation/lithiation cycles. O. Klvaˇ c et al. Energy Storage Materials 81 (2025) 104516 5 can enhance knowledge for optimizing manufacturing processes and battery development. It is worth noting that the current operando SEM workow does not directly measure mechanical properties or isolate the binder’s role in degradation. A more comprehensive understanding could be achieved by integrating in-situ mechanical characterization techniques, such as nanoindentation or AFM-based mechanical mapping, which enable direct assessment of local stiffness variations, plastic deformation, and fracture behavior within the electrode composite, particularly in binder-enriched regions [55,56] Complementary approaches, such as Raman spectroscopy, could also help identify chemical or structural changes in the binder during cycling [57,58]. It is expected that the combination of real-time monitoring on structural tracking with in-situ mechanical testing and complementary techniques such as Raman spectroscopy can allow for in-depth understanding the role of binder in the electrode, where the learning can support structural design and process optimization to ensure higher quality and more reliable batteries manufacturing. 3.2. Operando study of structural evolution at particle level When tracking structural evolution at particle level, imaging was performed during rst two formation cycles conducted at 0.1C in a standard potential window of 1.3 – 2.8 V. Cycling was conducted in CC mode with 15 min rest phase. Fig. 4(a) illustrates the voltage curve of the cell and the corresponding grain size changes. Points associated with signicant size changes were selected from the curves and marked with lines, corresponding to the SEM images of Particle A (Fig. 4(b)) and Particle B (Fig. 4(c)). The location of Particle A and Particle B within the electrode are shown in Fig. S3 with Video S2 recording the process of 2 full cycles. Images labeled as "start" represent the initial snapshot at the beginning of the experiment, while images labeled as “end” represent the nal snapshot (not marked by lines in the graph). Observations indicate that at the onset of the rst lithiation (rst NMC delithiation), particle shrinkage occurs in both observed cases. Approximately halfway through the NMC delithiation plateau, the particles reach their minimum size. Prior to reaching the minimum (images A1, B1), no signicant changes in grain integrity were observed compared to the "start" images. Subsequently, the behavior of the particles diverges. Image A2, taken shortly after the minimum size, shows the initiation of crack formation, which results in an increase in size. This behavior is consistent with previously described observations of NMC 811 particles [59]. The growth of particle A reaches a maximum upon completion of the NMC delithiation cycle (image A3), expanding beyond its original size. At this point, the cracks are fully formed, and the particle is mostly expanded. In contrast, particle B remains practically constant in size after reaching the minimum. Images B2 and B3 indicate minimal crack formation and propagation compared to particle A. During the rst NMC lithiation cycle, a shrinkage of particle A was observed together with signicant disappearance of most cracks (images A5). Particle B visibly grew until the end of the rst NMC lithiation cycle, with a concurrent disappearance of cracks (images B4, B5). During the second delithiation/lithiation cycle, particle A size remained nearly unchanged. The graph suggests the sign of potential initial shrinkage in delithiation followed by expansion in the lithiation process. However, the well-developed cracks in the rst cycle compensate for the size change due to the delithiation/lithiation process, making the size change insignicant compared to rst cycle. Particle B, during the second cycle, mimics the behavior of the rst cycle. It shrinks in the rst half and then returns back to original size until the end. The size changes are smaller than rst cycle also due to the compensation from developed cracks. In the second lithiation cycle, both particles exhibit a retraction of cracks (images "end"). The observations suggest that synergized effects of two phenomena are responsible for volumetric changes in particles: lithiation and delithiation process, and particle cracking. The lithiation and delithiation process results in primary particles shrinkage and expansion due to the expulsion and insertion of lithium ions from and to their structure. However, signicant cracking can lead to an increase in size during delithiation while mitigating the particle further increase during lithiation process. Table S1 summarizes the quantitative analysis of particle cracking and particle size for both particles at the corresponding cycling stage during which SEM images were acquired, providing quantitative validation for the proposed degradation mechanism. In the case of particle A, large cracks formation resulted in expansion beyond its original size. Particle B exhibited minimal cracking and therefore size follows delithiation/lithiation process more closely. The incomplete recovery to its original size may result from capacity loss during cycling, where a portion of lithium is not returned to the original structure. Furthermore, it appears that once a particle has cracked, volumetric changes are more likely absorbed as the expansion/contraction of cracks rather than overall growth and contraction. This is observable in particle A. Particle B, which contains only minor cracks, shows more signicant overall size changes along cycling. These observed phenomena may inuence electrode design in manufacturing process, particularly design of the binder structure, porosity, size, and spatial distribution of the active material grains. A more exible binder could potentially allow the particle to shrink with less cracking. Additionally, it is worth considering whether long-term cycling, which leads to the growth of the SEI layer, could cause "working" cracks to become clogged, potentially leading to the formation of new cracks. 3.3. In operando structural analysis in Gr-Li system The operando SEM setup was also performed on Gr-Li system to prove its broader applicability in different battery systems. Observation was performed during rst three formation cycles conducted at 0.1C in a potential window of 0.01 – 2.50 V. Cycling was conducted in CC mode with 10 min rest phase, without the CV phase. Volumetric changes of the particles and their cracking were observed at six selected points corresponding to different stages of lithiation and delithiation, as well as at the beginning and end of the cycling process. The resulting data are depicted in Fig. 5 (also see Video S3 for the recording of the electrochemical cycling process of Gr-Li system). The stability and robustness of the operando SEM workow was proved based on the minimal capacity loss during the cycles with comparable charge/discharge behavior with standard Gr-Li battery. Although cracks and volumetric changes were present, their impact on the overall electrode performance was negligible, demonstrating system resilient of structural changes during the initial cycles. 3.4. Method applicability and future directions The workow presented in this study offers high-resolution insight into the morphological evolution from electrode level to particle level under near operational conditions. These insights can inform optimization during R&D and pilot-scale production, facilitating more effective scaling to high-volume manufacturing conditions. While this approach enables direct visualization of degradation mechanisms with spatial and temporal precision, it is important to dene its scope of applicability and acknowledge current limitations, particularly regarding manufacturing relevance, complementary analytical techniques and statistical signicance. This workow is fully compatible with both full-cell and half-cell congurations, allowing exible investigation of a wide range of battery chemistries, including solid-state batteries. However, given that the proposed workow is fundamentally based on SEM technology, it is not directly compatible with in-line or high-throughput metrology systems commonly utilized in manufacturing settings for real-time feedback and process optimization. Its value to battery manufacturing lies in the mechanistic insights obtained from observing structural evolution of the battery sample during operando cycling. By visualizing irreversible O. Klvaˇ c et al. Energy Storage Materials 81 (2025) 104516 6 changes such as electrode expansion, particle cracking, or current collector detachment, it provides valuable information on how materials selection and cell design parameters, including binder formulation, porosity, and coating thickness, inuence mechanical stability and electrochemical performance. Furthermore, the workow is compatible with analytical techniques in SEM, such as energy-dispersive X-ray spectroscopy (EDS) and electron backscatter diffraction (EBSD), which provide compositional and crystallographic information for more in-depth mechanistic understanding. For example, in this study, the cracks tend to form in the center of the particles, which is consistent with previous studies [60,61]. More mechanistic understanding could be achieved by the integration of analytical capability such as EBSD to understand the correlation between grain structure and cracking pathway. However, it is important to note that implementing these techniques in an operando framework also introduces specic challenges. EDS and EBSD typically require higher beam currents, longer acquisition times, and higher accelerating voltages, which increase chances of beam-induced damage, resolution loss, or sample contamination, particularly when working with sensitive battery materials. While continuous real-time mapping with EDS or EBSD is impractical under operando cycling conditions, targeted measurements can be performed at selected stages of cycling, for example during rest phases or after dened cycling steps. In such cases, spatial or temporal resolution must be traded for additional compositional or structural information. Finally, although two particles with high-resolution images are selected and discussed, they are selected as the representative particles screening from around 30 particles from the full electrode shown in Fig. S3. Further statistical signicance can be achieved by applying the operando SEM workow in a wider electrode (sub mm) with more particles to investigate (Fig. S4). However, different imaging strategies need to be developed to enable both high resolution for accuracy and a large eld of view for statistics. Additionally, the cycling rate must be optimized to align with imaging throughput, ensuring that structural changes remain negligible during the acquisition of large eld-of-view images. 4. Conclusion In this study, we present an operando SEM workow for investigating battery structural evolution, which integrates high-quality electrode cross-section preparation using a broad ion beam polisher, inert sample transfer to a glovebox, and SEM imaging, followed by semiautomated imaging and quantitative structural analysis. It satises four major criteria identied as critical for adopting this technology for both battery R&D and manufacturing. In electrode structural tracking study, expansion of the whole NMC electrode during cell charging (NMC delithiation) and contraction during cell discharging (NMC lithiation) were observed. The results suggest that the binder plays a key role in electrode level structural changes in addition to changes in the crystallographic structure of the active material. For particle level structural tracking, two factors that determine size changes were observed – delithiation/lithiation and cracking. The cracks are developed from delithiation process. Subsequent size changes associated with different lithiation levels manifested primarily as expansion and contraction of cracks within the particles, rather than as external bulk deformation. Finally, Gr-Li system was used to verify that the functionality of the operando SEM workow can be applied to broader battery systems with a different chemical composition. In particular, its potential application to lithium metal systems holds promise for advancing next-generation battery development. The results also showed expansion and cracking of graphite particles during lithiation and contraction during delithiation. In conclusion, the presented method enables a deeper understanding of battery cycling processes, providing insights that can drive the optimization of performance and lifetime. It is important to note that, Fig. 5. Operando structural analysis in Gr-Li system, the cracking (indicated by yellow arrow) and expansion were observed during cycling. O. Klvaˇ c et al. Energy Storage Materials 81 (2025) 104516 7 although ILs electrolytes are used to demonstrate its capability in Li-ion battery, this method is also applicable to next-gen battery development, such as solid-state battery and Li-metal batteries, which can facilitate innovation and research into new materials, ultimately contributing to the development of more advanced battery systems. CRediT authorship contribution statement Ondˇ rej Klvaˇ c: Writing – original draft, Software, Methodology, Investigation, Visualization. David Trochta: Writing – original draft, Visualization, Validation, Software, Methodology, Investigation. Libor Nov´ ak: Writing – original draft, Resources, Project administration, Methodology, Funding acquisition. Peter Priecel: Writing – review & editing, Validation. Manuel Bornh¨ offt: Software, Formal analysis. Tom´ aˇ s Kazda: Writing – review & editing, Supervision, Methodology, Investigation, Funding acquisition. Zhao Liu: Writing – original draft, Supervision, Writing – review & editing. Declaration of competing interest The authors declare the following nancial interests/personal relationships which may be considered as potential competing interests: This work was conducted as part of a collaboration between Thermo Fisher Scientic and Brno University of Technology under the National Competence Centre (NCK) project. Several authors are employees of Thermo Fisher Scientic, a provider of electron microscopy solutions. The workow presented in this publication may be further developed into a commercial product in the future. The remaining authors, who are not afliated with Thermo Fisher Scientic, declare no known competing nancial interests or personal relationships that could have inuenced the research reported in this paper. Declaration of generative AI and AI-assisted technologies in the writing process During the preparation of this work the authors used GPT-4o (OpenAI), NotebookLM (Google), and DeepL Translate in order to enhance text quality, x grammar errors, and improve readability. After using these tools, the authors reviewed and edited the content as needed and took full responsibility for the content of the published article. Acknowledgements This work was supported by the project The Energy Conversion and Storage (Project no CZ.02.01.01/00/22_008/0004617), funded under the Excellent Research call of the Johannes Amos Comenius Programme. Additional support was provided by the Brno University of Technology through the specic graduate research grant FEKT-S-23-8286 and also was conanced by the Technology Agency of the Czech Republic within the Center of Electron and Photonic Optics programme TN02000020. The authors also acknowledge funding from the European Union’s Horizon Europe research and innovation programme under grant agreement no 101192848 (FULL-MAP). Supplementary materials Supplementary material associated with this article can be found, in the online version, at doi:10.1016/j.ensm.2025.104516. Data availability Data will be made available on request. References [1] V. Etacheri, R. Marom, R. Elazari, G. Salitra, D. Aurbach, Challenges in the development of advanced Li-ion batteries: a review, Energy Environ. Sci. 4 (2011), https://doi.org/10.1039/c1ee01598b. [2] J. Xiao, X. Cao, B. Gridley, W. Golden, Y. Ji, S. Johnson, D. Lu, F. Lin, J. Liu, Y. Liu, Z. Liu, H.N. Ramesh, F. Shi, J. Schrooten, M.J. Sims, S. Sun, Y. Shao, A. Vaisman, J. Yang, M.S. Whittingham, From mining to manufacturing: scientic challenges and opportunities behind battery production, Chem. Rev. (2025), https://doi.org/ 10.1021/acs.chemrev.4c00980. [3] J. Xiao, F. Shi, T. Glossmann, C. Burnett, Z. Liu, From laboratory innovations to materials manufacturing for lithium-based batteries, Nat. Energy 8 (2023), https:// doi.org/10.1038/s41560-023-01221-y. [4] X. Liu, L. Zhang, H. Yu, J. Wang, J. Li, K. Yang, Y. Zhao, H. Wang, B. Wu, N. P. Brandon, S. Yang, Bridging multiscale characterization technologies and digital modeling to evaluate lithium battery full lifecycle, Adv. Energy Mater. 12 (2022), https://doi.org/10.1002/aenm.202200889. [5] H. Yang, P. Tang, N. Piao, J. Li, X. Shan, K. Tai, J. Tan, H.-M. Cheng, F. Li, In-situ imaging techniques for advanced battery development, Mater. Today 57 (2022) 279–294, https://doi.org/10.1016/j.mattod.2022.05.021. [6] D. Liu, Z. Shadike, R. Lin, K. Qian, H. Li, K. Li, S. Wang, Q. Yu, M. Liu, S. Ganapathy, X. Qin, Q. Yang, M. Wagemaker, F. Kang, X. Yang, B. Li, Review of recent development of In situ/operando characterization techniques for lithium battery research, Adv. Mater. (2019) 31, https://doi.org/10.1002/ adma.201806620. [7] P.P.R.M.L. Harks, F.M. Mulder, P.H.L. Notten, In situ methods for Li-ion battery research: a review of recent developments, J. Power Source. 288 (2015) 92–105, https://doi.org/10.1016/j.jpowsour.2015.04.084. [8] S.-M. Bak, Z. Shadike, R. Lin, X. Yu, X.-Q. Yang, In situ/operando synchrotronbased X-ray techniques for lithium-ion battery research, NPG Asia Mater. 10 (2018) 563–580, https://doi.org/10.1038/s41427-018-0056-z. [9] M. Pin, J. Choi, J.H. Chang, A.S. Schenk, J. Han, S. Wacławek, Y. Kim, J.Y. Cheong, In situ X-ray based analysis of anode materials for lithium-ion batteries: current status and future implications, Energy Storage Mater. 73 (2024), https://doi.org/ 10.1016/j.ensm.2024.103798. [10] G. Qian, S. Kuppan, A. Gallo, J. Zhou, Z. Liu, Y. Liu, From in-situ experimentation to in-line metrology: advanced imaging characterization for battery research and manufacturing, Energy Storage Mater. 73 (2024), https://doi.org/10.1016/j. ensm.2024.103819. [11] M. Golozar, R. Gauvin, K. Zaghib, In situ and In operando techniques to study Liion and solid-State batteries: micro to atomic level, Inorgan. (Basel) (2021) 9, https://doi.org/10.3390/inorganics9110085. [12] W. Du, R.E. Owen, A. Jnawali, T.P. Neville, F. Iacoviello, Z. Zhang, S. Liatard, D.J. L. Brett, P.R. Shearing, In-situ X-ray tomographic imaging study of gas and structural evolution in a commercial Li-ion pouch cell, J. Power Source. 520 (2022), https://doi.org/10.1016/j.jpowsour.2021.230818. [13] P. Blazek, P. Westenberger, S. Erker, A. Brinek, T. Zikmund, D. Rettenwander, N. P. Wagner, J. Keckes, J. Kaiser, T. Kazda, P. Vyroubal, M. Macak, J. Todt, Axially and radially inhomogeneous swelling in commercial 18650 Li-ion battery cells, J. Energy Storage. 52 (2022), https://doi.org/10.1016/j.est.2022.104563. [14] L. Willenberg, P. Dechent, G. Fuchs, M. Teuber, M. Eckert, M. Graff, N. Kürten, D. U. Sauer, E. Figgemeier, The development of jelly roll deformation in 18650 lithium-ion batteries at low State of charge, J. Electrochem. Soc. 167 (2020), https://doi.org/10.1149/1945-7111/aba96d. [15] P. Pietsch, V. Wood, X-ray tomography for lithium ion battery research: a practical guide, Annu. Rev. Mater. Res. 47 (2017) 451–479, https://doi.org/10.1146/ annurev-matsci-070616-123957. [16] Z. Stravova, O. Klvac, J. Bana, B. Anothumakkool, T. Zikmund, P. Blazek, J. Kaiser, T. Kazda, Comprehensive study of rapid capacity fade in prismatic Li-ion cells with exible packaging, Sci. Rep. 14 (2024), https://doi.org/10.1038/s41598-02477673-3. [17] S. Zhou, K. Liu, Y. Ying, L. Chen, G. Meng, Q. Zheng, S.-G. Sun, H.-G. Liao, Perspective of operando/in situ scanning electron microscope in rechargeable batteries, Curr. Opin. Electrochem. 41 (2023), https://doi.org/10.1016/j. coelec.2023.101374. [18] A. Pfrang, A. Kersys, A. Kriston, D.U. Sauer, C. Rahe, S. K¨ abitz, E. Figgemeier, Geometrical inhomogeneities as cause of mechanical failure in commercial 18650 lithium ion cells, J. Electrochem. Soc. 166 (2019) A3745–A3752, https://doi.org/ 10.1149/2.0551914jes. [19] O.O. Taiwo, D.P. Finegan, J.M. Paz-Garcia, D.S. Eastwood, A.J. Bodey, C. Rau, S. A. Hall, D.J.L. Brett, P.D. Lee, P.R. Shearing, Investigating the evolving microstructure of lithium metal electrodes in 3D using X-ray computed tomography, Phys. Chem. Chem. Phys. 19 (2017) 22111–22120, https://doi.org/ 10.1039/C7CP02872E. [20] J. Gonzalez, K. Sun, M. Huang, J. Lambros, S. Dillon, I. Chasiotis, Three dimensional studies of particle failure in silicon based composite electrodes for lithium ion batteries, J. Power Source. 269 (2014) 334–343, https://doi.org/ 10.1016/j.jpowsour.2014.07.001. [21] A. Schoo, R. Moschner, J. Hülsmann, A. Kwade, Coating defects of lithium-ion battery electrodes and their inline detection and tracking, Batteries 9 (2023), https://doi.org/10.3390/batteries9020111. [22] S. Wang, K. Li, Y. Tian, J. Wang, Y. Wu, S. Ji, Infrared imaging investigation of temperature uctuation and spatial distribution for a large laminated lithium–ion power battery, Appl. Therm. Eng. 152 (2019) 204–214, https://doi.org/10.1016/j. applthermaleng.2019.02.096. O. Klvaˇ c et al. Energy Storage Materials 81 (2025) 104516 8 [23] Z. Deng, Z. Huang, Y. Shen, Y. Huang, H. Ding, A. Luscombe, M. Johnson, J. E. Harlow, R. Gauthier, J.R. Dahn, Ultrasonic scanning to observe wetting and “unwetting” in Li-ion pouch cells, Joule 4 (2020) 2017–2029, https://doi.org/ 10.1016/j.joule.2020.07.014. [24] C. Hogrefe, T. Waldmann, M.B. Molinero, L. Wildner, P. Axmann, M. WohlfahrtMehrens, Cross-sectional In situ optical microscopy with simultaneous electrochemical measurements for lithium-ion full cells, J. Electrochem. Soc. 169 (2022), https://doi.org/10.1149/1945-7111/ac6c57. [25] J. Steiger, D. Kramer, R. M¨ onig, Mechanisms of dendritic growth investigated by in situ light microscopy during electrodeposition and dissolution of lithium, J. Power Source. 261 (2014) 112–119, https://doi.org/10.1016/j.jpowsour.2014.03.029. [26] H. Li, S. Guo, H. Zhou, In-situ/operando characterization techniques in lithium-ion batteries and beyond, J. Energy Chem. 59 (2021) 191–211, https://doi.org/ 10.1016/j.jechem.2020.11.020. [27] M.T. McDowell, S.W. Lee, J.T. Harris, B.A. Korgel, C. Wang, W.D. Nix, Y. Cui, In situ TEM of two-phase lithiation of amorphous silicon nanospheres, Nano. Lett. 13 (2013) 758–764, https://doi.org/10.1021/nl3044508. [28] J.M. Yuk, H.K. Seo, J.W. Choi, J.Y. Lee, Anisotropic lithiation onset in silicon nanoparticle anode revealed by in situ graphene liquid cell electron microscopy, ACS Nano 8 (2014) 7478–7485, https://doi.org/10.1021/nn502779n. [29] S.-W. Lee, D.-H. Jang, J.-B. Yoon, Y.-H. Cho, Y.-S. Lee, D.-H. Kim, W.-S. Kim, W.- S. Yoon, Crystal structure changes of LiNi 0.5 Co 0.2 Mn 0.3 O 2 cathode materials during the rst charge investigated by in situ XRD, J. Electrochem. Sci. Technol. 3 (2012) 29–34, https://doi.org/10.5229/JECST.2012.3.1.29. [30] H. Asayesh-Ardakani, W. Yao, Y. Yuan, A. Nie, K. Amine, J. Lu, R. ShahbazianYassar, In situ TEM investigation of ZnO nanowires during sodiation and lithiation cycling, Small Method. 1 (2017), https://doi.org/10.1002/smtd.201700202. [31] X.H. Liu, L.Q. Zhang, L. Zhong, Y. Liu, H. Zheng, J.W. Wang, J.-H. Cho, S.A. Dayeh, S.T. Picraux, J.P. Sullivan, S.X. Mao, Z.Z. Ye, J.Y. Huang, Ultrafast electrochemical lithiation of individual Si nanowire anodes, Nano Lett. 11 (2011) 2251–2258, https://doi.org/10.1021/nl200412p. [32] J.Y. Huang, L. Zhong, C.M. Wang, J.P. Sullivan, W. Xu, L.Q. Zhang, S.X. Mao, N. S. Hudak, X.H. Liu, A. Subramanian, H. Fan, L. Qi, A. Kushima, J. Li, In situ observation of the electrochemical lithiation of a single SnO 2 nanowire electrode, Science 330 (1979) (2010) 1515–1520, https://doi.org/10.1126/science.1195628. [33] Q. Zhang, Z. Song, X. Sun, Y. Liu, J. Wan, S.B. Betzler, Q. Zheng, J. Shangguan, K. C. Bustillo, P. Ercius, P. Narang, Y. Huang, H. Zheng, Atomic dynamics of electried solid–liquid interfaces in liquid-cell TEM, Nature 630 (2024) 643–647, https://doi.org/10.1038/s41586-024-07479-w. [34] Z. Zeng, W.-I. Liang, H.-G. Liao, H.L. Xin, Y.-H. Chu, H. Zheng, Visualization of electrode–Electrolyte interfaces in LiPF 6 /EC/DEC electrolyte for lithium ion batteries via in situ TEM, Nano. Lett. 14 (2014) 1745–1750, https://doi.org/ 10.1021/nl403922u. [35] D. Cheng, J. Hong, D. Lee, S.-Y. Lee, H. Zheng, In situ TEM characterization of battery materials, Chem. Rev. 125 (2025) 1840–1896, https://doi.org/10.1021/ acs.chemrev.4c00507. [36] X. Zhou, T. Li, Y. Cui, Y. Fu, Y. Liu, L. Zhu, Situ focused ion beam scanning electron microscope study of microstructural evolution of single tin particle anode for Li-ion batteries, ACS Appl. Mater. Interface. 11 (2019) 1733–1738, https://doi.org/ 10.1021/acsami.8b13981. [37] D.J. Miller, C. Proff, J.G. Wen, D.P. Abraham, J. Bare˜ no, Observation of microstructural evolution in Li battery cathode oxide particles by In situ electron microscopy, Adv. Energy Mater. 3 (2013) 1098–1103, https://doi.org/10.1002/ aenm.201300015. [38] C.-Y. Chen, T. Sano, T. Tsuda, K. Ui, Y. Oshima, M. Yamagata, M. Ishikawa, M. Haruta, T. Doi, M. Inaba, S. Kuwabata, situ scanning electron microscopy of silicon anode reactions in lithium-ion batteries during charge/discharge processes, Sci. Rep. 6 (2016), https://doi.org/10.1038/srep36153. [39] T. Tsuda, K. Hosoya, T. Sano, S. Kuwabata, In-situ scanning electron microscope observation of electrode reactions related to battery material, Electrochim. Acta 319 (2019) 158–163, https://doi.org/10.1016/j.electacta.2019.06.165. [40] D. Chen, S. Indris, M. Schulz, B. Gamer, R. M¨ onig, In situ scanning electron microscopy on lithium-ion battery electrodes using an ionic liquid, J. Power Source. 196 (2011) 6382–6387, https://doi.org/10.1016/j.jpowsour.2011.04.009. [41] G. Rong, X. Zhang, W. Zhao, Y. Qiu, M. Liu, F. Ye, Y. Xu, J. Chen, Y. Hou, W. Li, W. Duan, Y. Zhang, Liquid-phase electrochemical scanning electron microscopy for In situ investigation of lithium dendrite growth and dissolution, Adv. Mater. 29 (2017), https://doi.org/10.1002/adma.201606187. [42] S. Kaboli, H. Demers, A. Paolella, A. Darwiche, M. Dontigny, D. Cl´ ement, A. Guer, M.L. Trudeau, J.B. Goodenough, K. Zaghib, Behavior of solid electrolyte in Lipolymer battery with NMC cathode via in-situ scanning electron microscopy, Nano Lett. 20 (2020) 1607–1613, https://doi.org/10.1021/acs.nanolett.9b04452. [43] P. Hovington, M. Dontigny, A. Guer, J. Trottier, M. Lagac´ e, A. Mauger, C. M. Julien, K. Zaghib, In situ scanning electron microscope study and microstructural evolution of nano silicon anode for high energy Li-ion batteries, J. Power Source. 248 (2014) 457–464, https://doi.org/10.1016/j. jpowsour.2013.09.069. [44] F. Orsini, A. Du Pasquier, B. Beaudoin, J.M. Tarascon, M. Trentin, N. Langenhuizen, E. De Beer, P. Notten, In situ Scanning electron microscopy (SEM) observation of interfaces within plastic lithium batteries, J. Power Source. 76 (1998) 19–29, https://doi.org/10.1016/S0378-7753(98)00128-1. [45] P. Perrenot, P. Bayle-Guillemaud, P.-H. Jouneau, A. Boulineau, C. Villevieille, Operando focused ion beam–Scanning electron microscope (FIB-SEM) revealing microstructural and morphological evolution in a solid-State battery, ACS Energy Lett. 9 (2024) 3835–3840, https://doi.org/10.1021/acsenergylett.4c01750. [46] L. Novak, P. Glajc, O. Klvac, Battery in situ electrical testing in FIB-SEM, Microsc. Microanaly. 28 (2022) 834–835, https://doi.org/10.1017/S1431927622003737. [47] K.K. Neelisetty, J. Stetina, J. Vondruˇ ska, M. Trenz, T. Kazda, M. Hrouzek, P. Wandrol, Transfer of lithium foil under inert conditions using CleanConnect inert gas transfer system, Microsc. Microanaly. 27 (2021) 2508–2509, https://doi. org/10.1017/S1431927621008941. [48] T. Waldmann, A. Iturrondobeitia, M. Kasper, N. Ghanbari, F. Aguesse, E. Bekaert, L. Daniel, S. Genies, I.J. Gordon, M.W. L¨ oble, E. De Vito, M. Wohlfahrt-Mehrens, Review—post-mortem analysis of aged lithium-ion batteries: disassembly methodology and physico-chemical analysis techniques, J. Electrochem. Soc. 163 (2016) A2149–A2164, https://doi.org/10.1149/2.1211609jes. [49] W. Hauffe, S. Menzel, T. G¨ obel, Advantages of broad ion beam (BIB) processing compared with focused ion beam (FIB) technology for 3D investigation of heterogeneous solids, Microsc. Microanaly. 9 (2003) 148–149, https://doi.org/ 10.1017/S1431927603016106. [50] F.B. Spingler, S. Kücher, R. Phillips, E. Moyassari, A. Jossen, Electrochemically stable In situ dilatometry of NMC, NCA and graphite electrodes for lithium-ion cells compared to XRD measurements, J. Electrochem. Soc. 168 (2021), https://doi.org/ 10.1149/1945-7111/abf262. [51] M. Srivastava, A. Kumar M.R., K. Zaghib, Binders for Li-ion battery technologies and beyond: a comprehensive review, Batteries 10 (2024) 268, https://doi.org/ 10.3390/batteries10080268. [52] J.M. Foster, X. Huang, M. Jiang, S.J. Chapman, B. Protas, G. Richardson, Causes of binder damage in porous battery electrodes and strategies to prevent it, J. Power Source. 350 (2017) 140–151, https://doi.org/10.1016/j.jpowsour.2017.03.035. [53] D.-H. Yoon, M. Marinaro, P. Axmann, M. Wohlfahrt-Mehrens, Study of the binder inuence on expansion/contraction behavior of silicon alloy negative electrodes for lithium-ion batteries, J. Electrochem. Soc. 167 (2020) 160537, https://doi.org/ 10.1149/1945-7111/abcf4f. [54] T. Beuse, M. Fingerle, C. Wagner, M. Winter, M. B¨ orner, Comprehensive insights into the porosity of lithium-ion battery electrodes: a comparative study on positive electrodes based on LiNi0.6Mn0.2Co0.2O2 (NMC622), Batteries 7 (2021) 70, https://doi.org/10.3390/batteries7040070. [55] L.S. de Vasconcelos, N. Sharma, R. Xu, K. Zhao, In-situ nanoindentation measurement of local mechanical behavior of a Li-ion battery cathode in liquid electrolyte, Exp. Mech. 59 (2019) 337–347, https://doi.org/10.1007/s11340-01800451-6. [56] H. Sakai, Y. Taniguchi, K. Uosaki, T. Masuda, Quantitative cross-sectional mapping of nanomechanical properties of composite lms for lithium ion batteries using bimodal mode atomic force microscopy, J. Power Source. 413 (2019) 29–33, https://doi.org/10.1016/j.jpowsour.2018.12.003. [57] B. Beccard, S.N. Karavadra, S. Dahal, Lithium-ion battery manufacturing and Quality control: raman spectroscopy, an analytical technique of choice, Spectroscopy (2022) 46–53, https://doi.org/10.56530/spectroscopy.sx2271c5. [58] V. Stancovski, S. Badilescu, In situ Raman spectroscopic–electrochemical studies of lithium-ion battery materials: a historical overview, J. Appl. Electrochem. 44 (2014) 23–43, https://doi.org/10.1007/s10800-013-0628-0. [59] S.S. Shishvan, N.A. Fleck, R.M. McMeeking, V.S. Deshpande, Cracking and associated volumetric expansion of NMC811 secondary particles, J. Power Source. 588 (2023), https://doi.org/10.1016/j.jpowsour.2023.233745. [60] X. Zhu, Y. Chen, H. Chen, W. Luan, The diffusion induced stress and cracking behaviour of primary particle for Li-ion battery electrode, Int. J. Mech. Sci. 178 (2020) 105608, https://doi.org/10.1016/j.ijmecsci.2020.105608. [61] H.C.W. Parks, A.M. Boyce, A. Wade, T.M.M. Heenan, C. Tan, E. Martínez-Pa˜ neda, P.R. Shearing, D.J.L. Brett, R. Jervis, Direct observations of electrochemically induced intergranular cracking in polycrystalline NMC811 particles, J. Mater. Chem. A. Mater. 11 (2023) 21322–21332, https://doi.org/10.1039/D3TA03057A. O. Klvaˇ c et al. Energy Storage Materials 81 (2025) 104516 9