A forestry waste-derived lithium ion capacitor: Sustainable, high-power energy storage

A forestry waste-derived lithium ion capacitor: Sustainable, high-power energy storage Jon Rodriguez-Romero, Idoia Ruiz de Larramendi * , Eider Goikolea ** Departamento de Química Org´ anica e Inorg´ anica, Facultad de Ciencia y Tecnología, Universidad Del País Vasco (UPV/EHU), Barrio Sarriena S/n, 48940, Leioa, Spain HIGHLIGHTS •Lithium-ion capacitor using Pinus Radiata-derived biomass electrodes is presented. •Hard carbon anode achieves 112 mAh g⁻ 1 at 10C without expensive additives. •The system delivers 105 Wh kg⁻ 1 at 700 W kg⁻ 1 and retains 60 % capacity after 10,000 cycles. •Biomass-based LIC offers a sustainable and cost-effective energy storage solution. ARTICLE INFO Keywords: Lithium-ion capacitor Hard carbon Activated carbon Biomass-derived carbon ABSTRACT In order to fill the demand for efficient and sustainable energy storage, hybrid systems combining batteries and supercapacitors are being explored. Lithium-ion capacitors (LICs), which leverage advances in electrical doublelayer capacitors (EDLCs) and lithium-ion batteries (LIBs), are particularly promising. In this study, we present a LIC using electrodes derived from Pinus Radiata biomass. The negative electrode, made of a hard carbon, achieves high capacity values (up to 112 mAh g⁻ 1 at 10C) without complex doping procedures, the use of expensive additives or complex processing. The positive capacitive electrode utilizes an activated carbon derived from the same hard carbon, which has a high specific surface area of 2399 m 2 g −1 . The proposed system exhibits an energy density of up to 105 Wh kg⁻ 1 at 700 W kg⁻ 1 , retaining 60 % capacity after 10,000 cycles at 10C. By utilizing locally accessible biomass, this approach offers a cost-effective and sustainable alternative to conventional LICs, with further optimization potential. This research highlights the potential of biomass-derived materials in developing high-power, eco-friendly, and affordable energy storage systems. 1. Introduction The exponential energy demand in modern society necessitates sustainable energy solutions that do not contribute to global warming, but the sporadic character of renewable renewable energies poses challenges to make the leap to a more sustainable future [1]. Energy storage systems play a crucial role to bridge the gap between energy production and energy consumption [2,3]. Today’s leading energy storage systems are lithium-ion batteries (LIBs) and supercapacitors (SCs). The differences in these devices lie in their operating mechanisms. While LICs are based on reversible electrochemical reactions in the bulk of the active material, typical SCs form an electrical double layer on the interface of the electrodes by electrostatic adsorption of charges [4]. LICs enjoy a wide potential window, provide high energies (150–200 Wh kg −1 ) and present a very low self-discharge rate [5]. SCs, on the other hand, provide a high power output (5–15 kW kg −1 ) and compared to batteries, their cycle life is orders of magnitude longer. Nevertheless, each finds its limitation in the strength of the other: LIBs suffer from sluggish kinetics in the Li + diffusion across electrode materials, and a much reduced cycle life due to the degradation of their materials during cycling [6,7]. SCs, on the other hand, present limited specific energy, due to their relatively low operating voltage. In addition, they self-discharge after a short period of disuse [8,9]. These properties make them complementary technologies, with batteries being preferred for high-energy applications, while SCs are needed when high power and fast charge/discharges are required. The * Corresponding author. ** Corresponding author. E-mail addresses: [email protected] (I. Ruiz de Larramendi), [email protected] (E. Goikolea). Contents lists available at ScienceDirect Journal of Power Sources journal homepage: www.elsevier.com/locate/jpowsour https://doi.org/10.1016/j.jpowsour.2024.235961 Received 5 September 2024; Received in revised form 15 November 2024; Accepted 26 November 2024 Journal of Power Sources 629 (2025) 235961 Available online 4 December 2024 0378-7753/© 2024 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC license ( http://creativecommons.org/licenses/bync/4.0/ ). system that effectively combines electrodes of these two technologies is known as a Li-ion capacitor (LIC), and has emerged as a promising source of high energy and high power with a long cycle life. Combining the benefits of both devices opens doors to applications that were previously only achievable by oversized SCs and LIBs. In fact, some LICs have already been commercialized and proven to be an affordable option for stationary applications like windmills and electromobility applications such as trams and electric buses [10]. The selection of active materials and cell design significantly impacts the success of any hybrid device, allowing to fully exploit their potential. Among the extensively researched LIC configurations, one combines a carbonate electrolyte and a LIB anode coupled with an electric doublelayer capacitor type (EDLC-type) positive electrode. In this approach, Li + ions intercalate/deintercalate in the bulk of the anode material, while the counterion of the electrolyte is adsorbed/desorbed on the surface of the activated carbon [11,12]. Since ion intercalation is a slow process compared to ion electrosorption, it is necessary to determine a correct mass balance between the electrodes to help balance the kinetics within the system. Otherwise, the energy and power densities of the asymmetric system could be compromised [13]. LICs are intended to fill the energy-to-power gap between batteries and supercapacitors, so excellent high power performance is expected. That is why not all LIB anode materials are suitable for LICs. Conversion/alloying anodes, such as metal nitrides/oxides/sulfides and Si/Sn based materials, for example, suffer from low conductivity and a noticeable volume change when cycling, which usually results in high capacities but poor performances at high rates [14–16]. On the other hand, intercalation anodes, such as carbonaceous materials, Li 4 Ti 5 O 12 or LTO and Nb 2 O 5 , show better cycling stability and power density [17–19]. Although the latter are a less attractive option as their Li + intercalation/deintercalation potential is higher than that of carbonaceous materials, resulting in lower energy and power densities in a full cell. There are multiple methods for improving the materials’ conductivity, as well as to mitigate volume warping. These strategies include heteroatom doping, introducing lattice defects, nanostructuring the material, or forming composites with more conductive materials [20–22]. However, these approaches may not be as attractive to the industry due to their complexity or high cost [23]. On the other hand, carbonaceous materials offer an excellent option for this application. Their structural stability and low intercalation potential allow not only a long cycle life at high power values, but also acceptable energy densities [24,25]. For that reason dual carbon - LICs (DC-LICs) have had a great exposure in this area. These hybrid systems typically employ a nanostructured carbonaceous positive electrode, and a carbon-based material capable of intercalating Li + as anode. Graphite is the market leader for negative electrodes in both LICs and LIBs. However, its excellent performance is overshadowed by its limited accessibility [11]. Graphite is classified as a critical raw material (CRM), and can be either mined or synthesized. Unfortunately, both production methods have severe environmental impacts. The high temperatures needed for the synthesis and the chemical reactions involved in the purification when mining contribute to adverse effect. Moreover, the situation is expected to worsen because of the increasing need for graphite in the energy storage industry [10]. The most popular alternatives to graphite include hard carbons (HCs), soft carbons (SCs), graphene, carbon nanotubes (CNTs), and graphdiyne. Hard and soft carbons are typically derived from carbonrich materials through thermal pyrolysis. Due to the interlayer crosslinking of the predecessors, HCs are mostly composed of randomly scattered, curved graphitic sheets that are incapable of restructuring into graphite, not even at temperatures as high as 3000 ◦C [26,27]. Notably, within the minuscule graphite-like portions of HCs, the disordered structure permits Li + insertion on each side of the graphene sheets, potentially resulting in increased capacity [28]. In contrast, soft carbons show greater crystallinity, due to their more semi-graphitic regions. This structure enables soft carbons to exhibit greater ionic diffusion rates [29]. Both HCs and soft carbons show a larger interlayer distance and increased interface surface, outperforming graphite in terms of cyclability and stability at high powers. Consequently, they are acknowledged as promising anode materials for future metal-ion systems [30,31]. Unfortunately, because of their irregular structure and numerous defects, their electrical conductivity remains lower than that of graphite. Still, one useful approach to get over this problem is producing composites employing low dimensional nanocarbons or conductive polymers [32,33]. Nanosized carbons, including graphene, CNTs, and graphdiyne, are considered promising anodic materials for both LIBs and LICs because of their unique structural, mechanical, and electrical properties [34–36]. While these materials offer advantages such as tunable interlayer spacing, they also face challenges related to their low volumetric capacity, high cost and complex synthesis [37]. Some of these nano-carbons possess high specific surface areas (SSAs), and thus, they have also been explored as positive capacitive electrodes in LICs. However, activated carbons (ACs) remain the most popular choice due to their well-established fabrication process, low cost and high SSA [23]. Typically ACs are obtained from the chemical activation of a carbonaceous precursor at high temperatures, using activating agents like KOH, H 3 PO 4 , or H 2 O. In our current study, the AC is derived from the same biomass precursor used to obtain the HC. Most types of biomass are usually readily available, and when carbonized, the product tends to retain the morphology and microstructure of the source material [38–41]. In the study reported here the biomass comes from a local forest industry in the northern region of Biscay, Spain. Specifically, it consists of the fraction of Pinus Radiata that the company discards due to its small size (<6 cm), making it easily and continuously obtainable in abundant quantities. This work aims to exploit this material for the development of a high-energy, high-power LIC, while maintaining accessibility and production cost-effectiveness. To achieve this, the full cell was built using electrode materials that do not relay on the use of expensive additives, high pyrolysis temperatures, or additional preparation steps. 2. Materials and methods 2.1. Preparation of active materials The biomass used in this study originates from a local forestry company, Biotermiak S.L., located in the Basque Country, in the north of Spain. The raw material consists of Pinus Radiata particles discarded by the company. Therefore, by repurposing this material, this research adds value without contributing to deforestation. The preparation and first pyrolysis of the sample was reported by J. Solar et al. [42,43] The initial preparation involved sieving the woody biomass into particles ranging from 0.5 to 2 mm. Subsequently, the pyrolysis was carried out in a continuous screw reactor, with four temperature zones: 300, 500, 700 and 700 ◦C (in that order). This process yielded a HC that was used as the active material of the negative electrode. For the preparation of the AC, a tubular furnace was used under a N 2 flow. The previously prepared HC served as the precursor, which was pyrolyzed at 700 ◦C for 2 h, an then mixed with KOH in a 1:4 mass ratio. The resulting carbon was washed with HCl and distilled water, followed by overnight drying at 80 ◦C. Finally, the material was ball-milled using a SPEX 8000D mixer/mill. 2.2. Materials characterization X-ray diffraction (XRD) spectra of both active materials were obtained in a Panalytical X’Pert PRO instrument between 5 and 70◦θ with Cu K α radiation. The morphology of both samples was also examined by scanning electron microscopy (SEM) employing a JEOL JSM-7000F. N 2 adsorption/desorption measurements were carried out at 77 K on a J. Rodriguez-Romero et al. Journal of Power Sources 629 (2025) 235961 2 Quantachrome AutosorbIQ, and estimated values of the specific surface (SSA) of the samples were calculated by applying the Brunauer-EmmettTeller theory (BET). Prior to analysis, degasification was performed at 200 ◦C for 12 h, under a vacuum of 10 −4 bar. Finally, Raman spectroscopy was carried out on both carbons using a Renishaw inVia spectrometer with 514 nm Ar + laser, acquiring 4 scans in the 1000 to 2000 cm −1 range. 2.3. Electrochemical characterization The electrode composition followed a 8:1:1 mass ratio of the active material (the HC or the AC), Super P C65 (carbon black) and poly (vynildifluoride) (PVDF), respectively. Slurries for each electrode type were prepared in N-methyl pyrrolidone (NMP) and cast onto copper foil (for HC) and aluminium foil (for AC). After drying the laminates overnight at 80 ◦C, they were cut into 12.7 mm diameter circles. The electrode mass loading ranged from 1 to 3 mg per electrode. The assembly of cells took place in an argon-filled glove box (MBraun) with a water and oxygen content of less than 0.1 ppm. The electrolyte solution used was 1 M LiPF 6 in a 1:1 vol mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC) (Solvionic). The electrochemical performance tests of both HC and full cells were carried out in three-electrode PAT-Cells (EL-Cell®). ACs were tested in three electrode Swagelok-type cells with oversized self-standing counter electrodes made from commercial AC (Norit DLC Super 30, SSA 1600 m 2 g −1 ). Metallic lithium served as the reference electrode, and porous glass microfiber discs (Whatman GF/A) were used as separators. For half-cells, galvanostatic charge/discharges (GA) were performed. The AC was tested at current densities of 0,1, 0,5, 1, 2, 5, 10, 15 and 20 A g AM −1 between 2.0 and 4.2 V vs. Li + /Li, while the HC was tested at C/10, C/5, C/2, C, 2C, 5C, 10C, 20C, 50C and 100C (C =372 mAh g −1 ) between 2.0 and 0.005 V. Additionally, cyclic voltammetry tests (CVs) were conducted at 5 mV s −1 to explore the maximum safe cut off potential of the AC. The final HC//AC full cell system was tested with 1:1 and 1:2 (HC fixed :AC) mass ratios, performing GAs at various C-rates (C/5, C/2, C, 2C, 5C, 10C, 20C and 50C) based on the active material of the anode. To assess long-term stability, 10,000 GA cycles were carried out at 10C for selected mass ratios. Each measurement was repeated multiple times to ensure accurate performance assessment. Before any full cell testing, the HC was pre-conditioned with 5 cycles at C/10 vs. metallic Li, followed by resting at 0.1 V. On the other hand, the AC was initially charged from open circuit voltage (OCV) to 4.2 V vs. Li + /Li. 3. Results and discussion 3.1. Physicochemical characterization of active materials SEM images reveal distinct morphological differences between the two carbons, as depicted in Fig. 1. Notable, the HC presents shapes that appear to stem from the retention of the microstructure inherent in the vegetal precursor. In addition, the chemical activation process introduces defects, cracks and micropores in the carbon matrix. In fact, in the AC there is no evidence of the primary structures of the precursor, but rather agglomerated structures of irregularly shaped and sized particles. To gain a better understanding of the porosity and surface area changes, it was determined from N 2 gas adsorption/desorption measurements that the BET SSA increased from 4.5 m 2 g −1 in the HC to 2399 m 2 g −1 in the AC (Fig. 2a, b). The elevated SSA observed in the AC is consistent with the isotherm profile, which exhibits a type I shape specific to microporous materials, and the significant gas adsorption at low relative pressures suggests the presence of an extensive microporous structure, as reported by other authors [44–48]. The pore size distribution indicates a significant porosity with sizes ranging between 0.5 and 1 nm, calculated applying the 2D-NLDFT theory to the AC isotherm (inset in Fig. 2b). In the XRD patterns of the two carbons (Fig. 2c, d) a prominent broad maximum around 43◦corresponds to the (100) reflection (JCPDF No. 75–1621). This feature is common in low-graphitized and highly disordered carbons [24]. Additionally, the (002) reflection appears as a broad peak at ~23◦, particularly noticeable in the HC. This may be due to the lower crystallinity of the AC sample after the activation process. As for the Raman spectra (inset in Fig. 2c, d), both samples exhibit the characteristic G (~1580 cm −1 ) and D (~1340 cm −1 ) bands of graphite, which are related to the in-plane C-C vibrations and to the Fig. 1. SEM images of HC (a,c), and AC (b,d). J. Rodriguez-Romero et al. Journal of Power Sources 629 (2025) 235961 3 presence of defects in graphitic layers, respectively [49,50]. The intensity ratio (I D /I G ) for HC is 1.08, while for AC, it is 1.13. This discrepancy indicates higher disorder in the activated sample, but also confirms the presence of graphitic carbon even after activation. 3.2. Half cell electrochemical characterization The half-cell electrochemical characterization is summarized in Fig. 3. Prior to the GA charge/discharge measurements on the AC, CV Fig. 2. N 2 adsorption/desorption isotherms of HC (a) and AC (b). Pore size distribution of AC is shown as an inset in b). XRD and Raman plots HC (c) and AC (d). Fig. 3. a) CVs of AC running in different windows from 2-4.2 V to 2–4.8 V at 5 mV s −1 . b) Profiles of the GA curves of HC running from C/10 to 100C vs metallic Li. c) Capacity comparison of AC and HC at different current densities. d) Capacity values extracted from the measurement from b). J. Rodriguez-Romero et al. Journal of Power Sources 629 (2025) 235961 4 measurements were performed to determine the upper limit of its working potential window (Fig. 3a). Below 4.2 V the behaviour is purely capacitive, as can be deduced from the square shape of the recorded curve. However, extending the cycling window to 4.4 V reveals a small bump between 3.0 and 4.0 V a pronounced deviation from the rectangular shape in the upper and lower cut off voltages. This deformation indicates redox activity in the system, and it is further accentuated by widening the window up to 4.6 and 4.8 V. This is typically associated with electrolyte decomposition, commonly observed at potentials exceeding 4.2 V. At potentials exceeding 4 V vs. Li + /Li, solvents such as ethylene carbonate (EC) and propylene carbonate (PC) oxidize to CO 2 and alkylene oxide derivatives [51,52]. This reaction can occur as a side reaction with the functional groups of the activated carbon and any residual moisture trapped within the pores. Since these irreversible reactions are considered parasitic, leading to gas evolution, pore-blocking products, and other parasitic reactions, such as hydrogen fluoride (HF) generation [53–55], the upper cut-off voltage has been set to 4.2V vs. Li + /Li. After defining the potential window of the AC between 2.0 and 4.2 V, GAs were performed to obtain the capacity values shown in Fig. 3c. The GA profiles and the capacities at each C-rate (9th cycle) for the HC halfcell testing are depicted in Fig. 3b and Fig. 3d, respectively. Fig. 3b shows that the HC recorded a sloping curve profile in its entire potential range. The absence of a distinct plateau is common, especially in HCs produced at lower temperatures. In fact, this type of materials enables fast ion/electron transfer and exhibits lower polarisation at high currents, making them promising candidates for high-rate applications [56]. While the mechanism behind Li storage in HCs remains debated, many authors associate the sloping region from the curve with Li intercalation and the plateau with pore filling [57–62]. Fig. 3d also highlights the high irreversibility of the HC during initial cycles, with up to 50 % capacity loss in the first cycle. This behaviour is typical of HCs, and is associated with growth of the solid electrolyte interphase (SEI). Carbons with more defects, heteroatoms and functional groups exhibit higher initial irreversibility. Interestingly, these characteristics tend to predominate in carbons synthesized at lower temperatures, however, they can also be beneficial and increase the reversible capacity, so they can be considered a double-edged sword [63–65]. The mass ratio of negative and positive electrodes is a crucial aspect when attempting to balance the kinetics of both electrodes. Estimating the target current for the entire cell operation is important to determine an optimum mass balance. As can be seen in Fig. 3c, at 7.5 A g −1 both electrodes show similar capacity. At that current density the discharge time of the anode is 36 s while the discharge time of the AC falls between 26 and 53 s (at 5 and 10 A g −1 , respectively). Therefore, to balance the charges stored in each electrode, and at the same time match the kinetics of both, a 1:1 mass balance of the electrodes is estimated to be adequate. However, a full-cell utilizing electrodes in a 1:2 mass ratio (HC:AC) was also built to better understand the effect of the electrode mass balance in the system, especially at lower currents, where an oversized AC electrode could help match the capacities of the electrodes. 3.3. Full cell electrochemical characterization First, the 1:1 HC//AC system was evaluated between 1.5 and 4.2 V. Since the anode is particularly sensitive to high currents, we decided to test the hybrid full cell at current rates corresponding to the C-rates of the anode. However, all capacities shown hereafter are calculated with the masses of both active materials. Fig. 4 shows that under these conditions the positive electrode reaches potentials of approximately 4.5 V vs. Li + /Li, which could adversely impact the lifetime of the device due to the electrolyte decomposition (see Fig. 3a). To address this issue, the potential window was narrowed to 1.5–4.0 V, after which, in addition to achieving higher capacities at high rates the AC did not exceed the 4.2 V potential value. In addition to reducing the cell voltage, we also explored the strategy Fig. 4. (top) Performance of full cells from C/10 to 100C (calculated with the anode). (Bottom): Electrode window visualization during the c-rate testing. J. Rodriguez-Romero et al. Journal of Power Sources 629 (2025) 235961 5 of increasing the AC mass loading up to a 1:2 ratio. This increases the capacity of the electrode preventing the AC from exceeding the safe potential limit set in Fig. 3a. This approach narrow the cut-off potential to 4.3 V vs. Li + /Li, a safer value than that obtained with a 1:1 mass ratio at the same cell voltage. Although both strategies could sacrifice energy density -either by limiting the potential window or by increasing the total mass of the system-they enhance the capacity of the initial 1:1 1.5–4.2 V system, especially at medium/high rates. This optimization process has facilitated the observation of the impact of the electrode mass-ratio on the potential windows of each electrode. The capacitive electrode reached unsafe potential values due to the application of an excessive cell voltage, which was effectively mitigated by increasing the mass of the AC. Controlling the AC potential window against overcharging, either by reducing the cell voltage or increasing its relative mass, has helped to achieve higher capacities at higher current densities. Comparing the 1:1 1.5–4 V and 1:2 1.5–4.2 V systems, both achieved similar results, with the latter exhibiting slightly higher capacities at low rates. The results in terms of power and energy can be seen in the Ragone plot from Fig. 5. The 1:1 HC//AC system achieved an energy density of 111 Wh kg −1 at 51 W kg −1 . In contrast, the 1:2 system exhibited higher energies at this low power levels, reaching 124 Wh kg −1 at 35 W kg −1 . However, at higher rates the 1:1 system slightly outperformed its counterpart, delivering 52 Wh kg −1 at 24.4 kW kg −1 compared to 42 Wh kg −1 at 33.3 kW kg −1 . Both converged at ca. 6 kW kg −1 maintaining a similar performance up to 75 Wh kg −1 . We also investigated the long-term behaviour of each system. Both systems underwent to 10,000 cycles at 10C (relative to the anode). The choice of this current was made based on the profiles observed in Fig. 4. At higher rates such as 50C and 100C the anode exceeded 0.0 V vs Li + / Li, raising concerns about lithium plating and dendrite formation [62]. Moreover, the discharge times of 56 s for the 1:1 system and 90 s for the 1:2 system -both close to 1 min-, suggest that they can operate within the application target regime of a LIC, i.e. bridging the gap between LIBs and EDLCs. Fig. 6 shows the capacity retention obtained in the cyclability tests. The 1:1 cell outperformed its counterpart in terms of capacity retention after 10,000 cycles. The cell with a 1:1 mass balance retained 70 % of its initial capacity after 5000 cycles and up to 60 % in 10,000. In contrast, the cell with a higher voltage and a 1:2 mass ratio did not perform as well. This clearly favours the first system. Notably, the most significant difference occurred in the first 800 cycles, where the worst-performing cell lost 28 % of its initial capacity compared to 10 % of its counterpart. Subsequently, both systems showed relatively linear trends, achieving 50 % and 60 % of capacity retention, respectively. Regarding the behaviour of each electrode, neither of the AC electrodes in the two cells exceeded the potential of 4.3 V at any point, suggesting that there has been no discernible electrolyte degradation linked to the capacity decrease. As the cycles progress, both systems exhibit a shift in electrode utilization: less reliance on the positive electrode and increased use of the negative electrode. Although this tendency is present in both systems, it is more noticeable in the 1:2 cell, which also shows greater capacity fluctuations. The observed shift in the 1:2 system may be attributed to the HC exceeding 0.0 V in its initial cycles, which may have initiated an increase in Li plating, a loss of Li + from the electrolyte, and a subsequent gradual inaccessibility of the pathway to active sites [66]. This would also explain the premature loss of retention observed in the 1:2 system. Ultimatelly, the aim of the text in hand is to harness the reliablility of one unique local biomass source as the mainstay for a dual-carbon LIC. The initial capacity in the 1:1 cell were 29 mAh g −1 and 27 mAh g −1 in its 1:2 homologue. Given their similar initial capacity, and the superior capacity retention of the 1:1 system, it is concluded that the 1:1 1.5–4.0 V system is the most promising among the proposed configurations. In essence, the ultimate goal of the text in hand is to present a specific biomass source as the fundamental cornerstone for the development of a dual carbon LIC. Lines have been drawn towards the path of a competitive complete cell still leaving room for further exploration to fully comprehend the degradation mechanisms of each electrode under different mass balances. 4. Conclusions In summary, a Li-ion capacitor (LIC) was successfully developed using a hard carbon (HC) electrode and an activated carbon (AC) electrode both prepared from the same readily available biomass source. This study prioritised an energetically efficient electrode preparation, avoiding costly and unsustainable processes. Therefore, the synthesis temperatures did not exceed 700 ◦C, and the use of expensive additives was refrained. The resulting materials exhibit excellent qualities for a high rate capability device. Specifically, HC electrodes achieved 112 mAh g −1 at 10C, while AC electrodes achieved 71 mAh g −1 at 10 A g −1 . For the full cell, the cell tension and electrode mass ratios were studied to optimise the performance of each electrode and prevent issues like lithium plating or electrolyte decomposition. The best performing full cell used 1:1 mass ratio and operated in a cell voltage of 1.5–4.0 V. This system achieved energy density values of 111 Wh kg −1 at 51 W kg −1 and 52 Wh kg −1 at 24.4 kW kg −1 . Furthermore, it demonstrated a capacity retention of 70 % after 5000 cycles and 60 % after 10,000 cycles at 10C (calculated relative to the anode). This study contributes to addressing the current limitations of energy storage systems from a sustainable and cost-effective perspective, opening up possibilities for high-power technologies. CRediT authorship contribution statement Jon Rodriguez-Romero: Writing – original draft, Investigation, Formal analysis, Data curation. Idoia Ruiz de Larramendi: Writing – review & editing, Supervision, Methodology, Funding acquisition. Eider Goikolea: Writing – review & editing, Supervision, Methodology, Funding acquisition, Conceptualization. Funding sources This work was supported by Gobierno Vasco/Eusko Jaurlaritza (project IT1546-22) and project PID2023-151153OB-I00 funded by MICIU/AEI/10.13039/501100011033/FEDER, UE and project Fig. 5. 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