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Op imized The mal T ea men o Li hium-Ion Ba e y
Componen s as a Basis o Sus ainable Py ome allu gy
Anna P ažano á,* Jan Koˇcí, JonášUˇ iˇcᡠ, Dominik Pilnaj, Daniel-Ioan S oe, and Vacla Knap
The escala ing global demand o li hium-ion ba e ies necessi-
a es e icien and sus ainable end-o -li e managemen . Majo
ecycling ou es such as py ome allu gy and hyd ome allu gy
o e p omising pa hs o me al eco e y, bu hei e iciency
o en depends on he p e ea men o spen ba e ies.
Howe e , op imizing low- empe a u e p e ea men o comple e
o ganic emo al while p ese ing ac i e ma e ial in eg i y
emains challenging. This s udy in es iga ed he mal decompo-
si ion and su ace changes o key ba e y componen s—li hium
nickel manganese cobal oxide (NMC622) ca hode, g aphi e
anode, and polyme ic sepa a o — om 100 o 800 °C, ocusing
on he 400–650 °C indus ial in e al. Ma e ial esponses we e
cha ac e ized using he mo-g a ime ic analysis coupled wi h
mass spec ome y, iso he mal mass loss, and scanning elec on
mic oscopy wi h ene gy-dispe si e X- ay spec oscopy. A 500 °C
ea men was iden i ied as op imal, enabling comple e o ganic
ca bon emo al wi hin 1 h wi hou comp omising he NMC spinel
s uc u e o cu en collec o deg ada ion. This p ecise con ol
educes ene gy consump ion and mi iga es haza dous gas elease,
enhancing en i onmen al sus ainabili y and p o iding a p ac ical,
scalable, and cos -e ec i e s a egy o imp o ing ba e y ecy-
cling. These indings help o de ine he pa ame e s o e icien
elec oac i e ma e ial sepa a ion. This wo k ad ances he unde -
s anding o low- empe a u e he mal p e ea men o ba e y
ecycling, suppo ing a ci cula economy o c i ical ma e ials.
1. In oduc ion
The escala ing global demand o li hium-ion ba e ies (LIBs),
especially in elec ic ehicles (EVs), necessi a es e icien and sus-
ainable end-o -li e (EOL) managemen s a egies.
[1,2]
In pa allel,
g owing en i onmen al conce ns and he limi ed a ailabili y o
c i ical aw ma e ials such as li hium, cobal , and nickel unde -
sco e he impo ance o de eloping ci cula economy solu ions
ha suppo esou ce secu i y and indus ial esilience.
[3,4]
Rega dless o he inal me allu gical eco e y ou e, he ecy-
cling o spen LIBs ypically begins wi h a se ies o p e ea men
s eps, among which he mal ea men is c i ical o handling he
o ganic componen s
[5–7]
This s ep is ounda ional o bo h majo
ecycling pa hways. Fo hyd ome allu gical p ocesses, a con-
olled low- empe a u e ea men ( ypically up o 800 °C) is
employed o decompose he o ganic binde s (e.g., poly inylidene
luo ide - PVDF) and polyme ic sepa a o s. This libe a es he
ac i e ma e ials om he cu en collec o s, making hem acces-
sible o e icien downs eam chemical leaching
[8–10]
Fo py o-
me allu gical p ocesses, his low- empe a u e s age se es a
simila pu pose o emo ing ola ile and lammable o ganic
ma e ials o ensu e sa e and mo e s able ope a ion o he sub-
sequen high- empe a u e smel ing (1500–1800 °C) o me al
eco e y.
[11,12]
I should be no ed, howe e , ha some indus ial
py ome allu gical ope a ions pe o m di ec smel ing o ba e y
packs wi hou a sepa a e low- empe a u e p e ea men
s ep.
[13,14]
Ou wo k ocuses on op imizing he sepa a e, low-
empe a u e p e ea men , as his app oach o e s be e con ol
o e o ganic deg ada ion and p ese es he in eg i y o ac i e
ma e ials, enhancing he e iciency and sus ainabili y o he o e -
all ecycling chain.
The i s s age condi ions he in e nal elec ode–sepa a o
assembly and mi iga es sa e y haza ds om esidual elec oly es
and lammable ma e ials.
[15]
This s ep is o en decoupled om
me allu gical eco e y o con ol o ganic deg ada ion be e , p e-
se e ac i e ma e ials’in eg i y, and acili a e delamina ion o
downs eam eco e y. Howe e , decomposi ion in ol es o e lap-
ping eac ions wi h speci ic onse empe a u es, equi ing p ecise
p ocess con ol. Among a ious chemis ies, li hium nickel man-
ganese cobal oxide (NMC) is widely s udied due o i s p e alence
in high-ene gy cells and complex he mochemical beha io .
[16]
Indus ially, ex e nal casings (polyme -lamina ed aluminum (Al)
A. P ažano á, J. Koˇcí, J. Uˇ iˇcᡠ, D. Pilnaj, V. Knap
Depa men o Elec o echnology
Facul y o Elec ical Enginee ing
Czech Technical Uni e si y in P ague
P ague 16000, Czech Republic
E-mail: [email p o ec ed]
J. Koˇcí
Depa men o Glass and Ce amics
Uni e si y o Chemis y and Technology P ague
Technická 5, 166 28 P ague, Czech Republic
J. Uˇ iˇcáˇ
Depa men o Polyme s
Uni e si y o Chemis y and Technology P ague
16628 P ague, Czech Republic
D.-I. S oe
Depa men o Ene gy
Aalbo g Uni e si y
Aalbo g 9220, Denma k
© 2025 The Au ho (s). ChemSusChem published by Wiley-VCH GmbH. This is
an open access a icle unde he e ms o he C ea i e Commons A ibu ion
License, which pe mi s use, dis ibu ion and ep oduc ion in any medium,
p o ided he o iginal wo k is p ope ly ci ed.
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o nickel) a e emo ed be o e he mal ea men , so esea ch
ocuses on he in e nal s ack: ca hode, anode, and sepa a o .
[15,17]
NMC ca hodes a e gene ally he mally s able ela i e o
o ganic compounds, bu hei beha io depends on deli hia ion
and esidual binde s o sal s.
[18]
While he spinel s uc u e may
pe sis up o 800 °C,
[19]
side eac ions in ol ing li hium sal s
(e.g., li hium hexa luo ophospha e, LiPF
6
; li hium luo ide, LiF; li h-
ium ca bona e, Li
2
CO
3
) can lead o he elease o ca bon dioxide
(CO
2
) o hyd ogen luo ide (HF) and phospho us-con aining
gases.
[20,21]
Fu he mo e, he Al cu en collec o , wi h a mel ing
poin o ≈660 °C, may mel and encapsula e ac i e ma e ial i em-
pe a u es exceed his h eshold,
[22,23]
comp omising downs eam
sepa a ion and ma e ial quali y.
[12,24,25]
The e o e, p ecise empe -
a u e con ol is c i ical o emo e o ganic compounds while p e-
se ing ca hode in eg i y.
[26]
G aphi e anodes exhibi high he mal s abili y unde ine
a mosphe es bu oxidize in ai abo e ≈500 °C, esul ing in signi i-
can CO
2
elease and mass loss.
[27]
Comple e combus ion ypically
occu s be ween 600 and 700 °C, depending on oxygen con en in
he a mosphe e, hea ing a e, and su ace a ea
[27–29]
Residual su -
ace compounds, such as li hium alkyl ca bona es o Li
2
CO
3
, o ig-
ina ing om solid elec oly e in e phase laye deg ada ion, may
also a ec he oxida ion pa hway and ini ia e ea lie
decomposi ion.
[30]
Polyme ic sepa a o s, ypically made o polye hylene (PE) o
polyp opylene (PP), begin o deg ade below 200 °C. This in ol es
ini ial mel ing ollowed by decomposi ion in o hyd oca bon
species
[31–33]
Poly inylidene luo ide (PVDF), commonly used as
a binde , decomposes be ween 350 and 500 °C, eleasing HF,
wa e , and low-molecula -weigh agmen s.
[34]
Abo e 500 °C,
emaining esidues a e mos ly con e ed in o s able ino ganic
phases; o example, alumina-coa ed sepa a o s may yield alumi-
num oxide (Al
2
O
3
) a e ea men .
[33]
Gi en he complexi y o mul icomponen ba e y a chi ec u es,
mos s udies on low- empe a u e py ome allu gical p e ea men
ha e ocused on achie ing e icien o ganic emo al while p ese -
ing aluable ma e ials, as bo h a e essen ial o scalable LIB
ecycling
[35–38]
The mal exposu e be ween 500 and 600 °C is widely
ega ded as a c i ical s ep o decomposing polyme ic binde s and
e apo a ing elec oly e esidues, he eby imp o ing he e iciency
o mechanical comminu ion and downs eam me al eco e y.
[37]
Howe e , empe a u es abo e 600 °C can lead o he emb i le-
men o mel ing o Al oils, complica ing hei sepa a ion. In pa al-
lel, ele a ed empe a u es also p omo e he ca bo he mic
educ ion o ac i e ma e ials, such as LiCoO
2
, which begins decom-
posing a ound 700 °C and a ec s bo h mass loss and li hium eco -
e y yields. Al hough e iews o p e ea men s a egies con i m
ha calcina ion be ween 150 and 650 °C e icien ly emo es con-
duc i e ca bon and o ganic compounds, educing binde adhesion
and enhancing sepa abili y, hey also emphasize challenges
ela ed o high ene gy demands and he elease o haza dous
gases, including oxic luo ina ed species.
[35,37]
While se e al s ud-
ies ha e explo ed high- empe a u e py ome allu gy, a comp ehen-
si e insigh in o low- empe a u e p e ea men e ec s on ca hode
and sepa a o in eg i y emains limi ed. The e o e, a de ailed,
componen -speci ic unde s anding o he mal deg ada ion,
pa icula ly how con olled hea ing in luences he s uc u e, su -
ace chemis y, and sepa abili y o indi idual ac i e ma e ials
and polyme ic sepa a o s, is c ucial o he de elopmen o
ene gy-e icien , scalable ecycling p ocesses. Such p ocesses mus
no only ensu e e ec i e o ganic emo al bu also minimize
unwan ed side eac ions and p ese e ma e ial unc ionali y.
[38,39]
While se e al s udies ha e explo ed high- empe a u e py o-
me allu gy, a comp ehensi e insigh in o low- empe a u e p e-
ea men e ec s on ca hode and sepa a o in eg i y emains
limi ed. The e o e, he p ima y aim o his wo k is o sys ema i-
cally in es iga e he he mal deg ada ion and su ace e olu ion
o indi idual c i ical componen s— he NMC622 ca hode, g aph-
i e anode, and polyme ic sepa a o — o iden i y an op imal p e-
ea men empe a u e. The no el y o his s udy lies in i s
in eg a ed analy ical app oach. We combine dynamic analysis
ia he mog a ime ic analysis coupled wi h mass spec ome y,
s a ic iso he mal mass loss s udies, and de ailed su ace cha ac-
e iza ion using scanning elec on mic oscopy wi h ene gy-
dispe si e X- ay spec oscopy. This allows us o b idge he gap
be ween simple mass loss, and a deepe unde s anding o
how con olled hea ing in luences he s uc u al in eg i y, su ace
chemis y, and sepa abili y o ma e ials. By de ining a p ecise,
ene gy-e icien empe a u e (500 °C) ha ensu es comple e
o ganic emo al while p ese ing he aluable ino ganic compo-
nen s, his wo k p o ides p ac ical, ounda ional da a o design-
ing and scaling up sus ainable p e ea men p ocesses applicable
o any subsequen me allu gical eco e y, wi h a pa icula ocus
on i s ole as a basis o sus ainable py ome allu gy.
2. Expe imen al Sec ion
2.1. Ma e ial
The LIB pouch cells used in his s udy possess a nominal ol age
o 3.65 V and a a ed capaci y o 78 Ah. These cells we e p e i-
ously cha ac e ized in ou p e ious wo k by P ažano á e al.
[40]
Each cell comp ises 36 s acked laye s comp ising NMC622 ca h-
ode ma e ials, whe e he numbe s indica e he mola a io o
Ni:Mn:Co, a polyme sepa a o , and g aphi e-based anode laye s.
The elec oly e consis s o LiPF
6
in an o ganic sol en , and he
en i e assembly was encapsula ed in a lexible polyme –
aluminum lamina ed pouch.
The module was sou ced om an elec ic ehicle a i s EOL,
ep esen ing a ealis ic eeds ock o ecycling. I had a nominal
ol age o 29.36 V and a o al ene gy capaci y o 6.85 kWh. While
he p ecise S a e o Heal h (SOH) was no de e mined, i was
assumed o be in he ypical 70%–80% ange o an EOL ba e y.
C i ically, o sa e y easons, be o e disassembly, he module was
deeply discha ged o ≈0 V. This p ocess subjec s he cell compo-
nen s o ha sh condi ions known o induce u he i e e sible
deg ada ion, hus posi ioning ou samples as a challenging
bu ep esen a i e case o he mal ea men . I could be pos u-
la ed ha a p ocess p o en e ec i e on his deg aded ma e ial
will be equally o mo e success ul on less deg aded ba e ies
(highe SOH). To access he in e nal cells, he module’s casing
ChemSusChem 2025,00, e202501753 (2 o 12) © 2025 The Au ho (s). ChemSusChem published by Wiley-VCH GmbH
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was ca e ully milled open, and he adhesi e bonding was
weakened by applying alcohol o acili a e hei sepa a ion.
Subsequen ly, he cells we e manually ex ac ed om he opened
module. The open s uc u e o he module, indi idual ba e y
cells, hei opening p ocedu e, and specimen p epa a ion and
cha ac e iza ion a e shown in Figu e 1.
2.2. Me hods
2.2.1. Specimen P epa a ion
A se o samples consis ing o he ac i e ma e ial coa ed on i s
na i e cu en collec o was p epa ed o analysis. This con igu-
a ion was in en ionally main ained because a p ima y objec i e
o he s udy is o op imize a he mal p ocess ha acili a es he
sepa a ion (delamina ion) o he ac i e ma e ial om he oil by
decomposing he binde . Analyzing he isola ed powde wi hou
he oil would he e o e no align wi h he s udy’s p ac ical,
ecycling-o ien ed goals. To ensu e s a is ical alidi y and ep o-
ducibili y, all measu emen s we e conduc ed in i e independen
eplica es. The ba e y cell was ca e ully disassembled using a
ce amic kni e, and indi idual componen s, speci ically he ca h-
ode enclosed wi hin he sepa a o pouch and he anode, we e
isola ed. All p ocedu es we e conduc ed inside a labo a o y ume
hood.
Following disassembly, as desc ibed in Figu e 1, in ac elec-
odes and he sepa a o laye s we e p ed ied a ambien empe -
a u e o e apo a e he ca bona es. The p ed ied laye s we e
subsequen ly sec ioned in o 25 25 mm squa e samples using
a p ecision pape cu e . A e wa ds, he sec ions we e d ied a
60 °C un il no u he dec eases in mass we e obse ed (app oxi-
ma ely 1 week). The inal samples we e weighed in po celain c u-
cibles using an analy ical balance.
The specimens we e classi ied in o h ee g oups acco ding o
hei unc ional ole wi hin he cell: ca hode, anode, and sepa a-
o . In addi ion, a ou h e e ence g oup was p epa ed, consis ing
o he ca hode laye co e ed by a sepa a o on bo h sides, o con-
ol po en ial in e acial e ec s. This con igu a ion de ia es om
he s anda d a chi ec u e, in which sepa a o s on bo h sides yp-
ically enclose he ca hode. Fi e independen eplica es we e
measu ed o each sample ca ego y o ensu e s a is ical alidi y.
Fo he he mal deg ada ion analyzes, ci cula samples wi h
a diame e o 5 mm we e punched om an unopened ba e y
cell using a manual punche . These specimens comp ised he
en i e c oss-sec ion o he ba e y cell, including spinel, sepa a-
o , and g aphi e laye s, and a e he eina e e e ed o as “c oss-
sec ion samples.”In addi ion o he ull c oss-sec ion samples,
a sepa a e specimen o ca hode, anode, and he ca hode wi h
a wo-sided sepa a o was explici ly p epa ed o TGA-MS
measu emen s.
Figu e 1. O e iew o he expe imen al wo k low: opening o he ba e y module, ex ac ion and disassembly o pouch cells, p epa a ion o specimens o
ba e y ma e ials, and subsequen mo phological and elemen al analyzes (SEM; ene gy-dispe si e X- ay spec oscopy, EDS) ollowed by he mal analyzes
( he mog a ime ic analysis, TGA; he mog a ime ic analysis coupled wi h mass spec ome y, TGA-MS).
ChemSusChem 2025,00, e202501753 (3 o 12) © 2025 The Au ho (s). ChemSusChem published by Wiley-VCH GmbH
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2.2.2. Ma e ial Cha ac e iza ion Me hods
2.2.2.1. The mog a ime ic Analysis
The mal deg ada ion in dynamic mode was assessed using a
he mog a ime ic analyze (Disco e y TGA550 Au o Ad anced,
TA Ins umen s, USA). A c oss-sec ion specimen, including all
elec ochemically ac i e laye s wi h a weigh o ≈25 mg, was
subjec ed o hea ing om oom empe a u e (24 °C) o 1000 °C
a a cons an hea ing a e o 10 °C min
1
in an ai a mosphe e
wi h a low a e o 65 mL min
1
.
2.2.2.2. The mog a ime ic Analysis –Mass Spec ome y
The chemical composi ion o deg ada ion p oduc s was in es-
iga ed using coupled TGA-MS. The ollowing sample ypes we e
analyzed: c oss-sec ion, anode, ca hode, and ca hode wi h
one-sided sepa a o . Measu emen s we e pe o med on a
TG-DTA Se sys E olu ion sys em (Se a am, F ance) coupled o
an OmniS a quad upole mass spec ome e (P ei e Vacuum,
Ge many).
Be o e he mal ea men , all samples we e s abilized a 30 °C
o 30 min. Subsequen ly, he samples we e hea ed in an ai
a mosphe e a a cons an hea ing a e o 10 °C min
1
. A e
he hea ing and he mog a ime ic da a acquisi ion we e com-
ple ed, he samples we e allowed o cool unde ambien condi-
ions, while mass spec ome ic da a acquisi ion con inued o an
addi ional 50 min. Mass spec a we e eco ded up o 150 m z
1
(mass- o-cha ge a io) wi h a esolu ion o 1 m z
1
; each spec um
was acqui ed o e 8 s, co esponding o a dwell ime o 53 milli-
seconds pe m/z uni . The da a ob ained om TGA and MS we e
synch onously aligned, p ocessed, anno a ed, and isualized
using O iginP o so wa e. Rep esen a i e ions co esponding o
speci ic compounds o chemical g oups we e selec ed based
on he NIST17 lib a y o elec on ioniza ion spec a.
2.2.2.3. S a ic The mal Mass Loss Analysis
Samples we e placed in a CLASIC labo a o y u nace wi h a on -
opening design o s a ic he mog a ime ic measu emen s.
Hea ing was pe o med a 5 °C min
1
o a ge empe a u es o
100, 200, 300, 400, 500, 600, 700, and 800 °C, each ollowed by
a 1h iso he mal hold, hen cooled o oom empe a u e by na u al
con ec ion o e nigh . The ela i ely high hea ing a e and sho
exposu e ime we e chosen o educe he equi ed ime o e ec-
i ely ob ain he s udied ma e ials, which co esponds o he
s udy’s objec i es and he economic demands o indus ial
use. This app oach is ele an o py ome allu gical p e ea men
in ba e y ecycling, whe e ene gy e iciency and ime op imiza-
ion a e c i ical. Tempe a u es we e selec ed o iden i y he mini-
mum e ec i e ecycling h eshold unde economic cons ain s,
ocusing in de ail on he 400 o 650 °C ange, wi h measu emen s
a 400, 450, 500, 550, 600, and 650 °C.
A e cooling o ambien empe a u e unde na u al condi-
ions, g a ime ic measu emen s we e pe o med using a
calib a ed KERN analy ical balance o e alua e mass loss esul ing
om he mal exposu e. Each sample ype was measu ed in i e
independen eplica es, and he mass was eco ded o ou deci-
mal places o ensu e high p ecision. This me hodology enabled a
comp ehensi e assessmen o he mally induced mass changes,
enhancing unde s anding o ma e ial decomposi ion beha io
ac oss a ious empe a u e condi ions.
2.2.2.4. Scanning Elec on Mic oscopy
Following he mal exposu e, he samples we e subjec ed o s uc-
u al and composi ional analyzes o assess changes induced by
hea ea men . SEM was employed o examine modi ica ions
in su ace mo phology using a TESCAN VEGA 3 LMU scanning
elec on mic oscope. Imaging was conduc ed a an accele a ing
ol age o 20 kV, a wo king dis ance o 15 mm, and a beam in en-
si y o 15 nA, u ilizing bo h seconda y and backsca e ed elec-
ons a a magni ica ion o 2000 .
To complemen he mo phological in es iga ion, EDS was
pe o med o de e mine al e a ions in elemen al composi ion.
Measu emen s we e conduc ed using an OXFORD Ins umen s
INCA 350 EDS analyze , enabling p ecise chemical mic oanalysis
o he obse ed samples. Da a we e p ocessed using AZ ec so -
wa e ( e sion 4.4), wi h composi ion measu emen s aken o e an
a ea o 0.005 mm
2
, yielding an accu acy o 0.1 % o each mea-
su ed poin . Mic o-X- ay elemen al mapping was also ca ied ou
o isualize he spa ial dis ibu ion o elemen s ac oss he sample
su ace.
3. Resul s and Discussion
3.1. Dynamic The mal Deg ada ion Analysis
The he mal deg ada ion o he c oss-sec ion sample in an ai
a mosphe e is a complex p ocess in ol ing mul iple decomposi-
ion s eps. While esidual weigh a a gi en empe a u e is obse -
able, a s a ic he mal weigh loss es on a la ge scale was also
pe o med due o he dynamic na u e o he measu emen and
he small sample size. The dis inc decomposi ion s eps a e isible
in he empe a u e-weigh de i a i e cu e shown in Figu e 2a.
The i s signi ican weigh loss, cha ac e ized by a peak a ound
120 °C, is ollowed by a double peak wi h maxima a ound 250 °C
and 350 °C. A u he small weigh loss peak was obse ed a ound
450 °C. The mos in ensi e weigh loss occu ed be ween 550 and
750 °C. High- empe a u e weigh loss (abo e 900 °C) was also
obse ed, which migh be connec ed o luo ine elease, as
desc ibed in wo k by Ross e al.
[41]
While TGA p o ides aluable insigh in o he he mal deg a-
da ion beha io o ma e ials, i is insu icien o iden i y decom-
posi ion p oduc s. The e o e, TGA-MS was used o de ec and
iden i y e ol ed gases. The esul s in Figu e 2b include he
TGA empe a u e p o ile, ollowed by he weigh loss cu e
and i s i s de i a i e in he second ow. The subsequen ows
display MS signal in ensi ies o selec ed mass- o-cha ge (m/z)
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a ios: 15, 18, 20, 29, and 44, chosen o hei ele ance o deg a-
da ion pa hways and e ol ed moie ies. Ion 15 co esponds o he
me hyl moie y, 18 o wa e , 20 o HF ( hough i may also a ise
om wa e con aining he
18
O iso ope), 29 o e hyl, o myl, o ca -
bon monoxide, and 44 o CO
2
. Wa e , HF, and CO
2
we e selec ed
as indica i e deg ada ion p oduc s o he PVDF binde .
[41,42]
HF
also o igina es om he he mal b eakdown o he LiPF
6
elec o-
ly e. Me hyl and e hyl g oups a e ypically associa ed wi h ca bon-
a e-based elec oly e sol en s o wi h he he mal deg ada ion o
he PE sepa a o . Addi ionally, CO
2
is a known oxida i e deg ada-
ion p oduc o g aphi e. Howe e , due o he mass spec ome ic
esolu ion o 1 m z
1
uni , coelu ing o o e lapping signals om
o he agmen s canno be excluded. Fo he same eason, CO
was omi ed om in e p e a ion as i s nominal mass is he same
as N
2
in he ca ie gas.
Decomposi ion o he c oss-sec ion sample is i s indica ed
by he eme gence o peaks o me hyl and e hyl g oups a ound
120 °C, associa ed wi h he e apo a ion o ca bona e-based sol-
en s, mos likely dime hyl o die hyl ca bona e and me hyl e hyl
ca bona e. A b oad signal ange o me hyl, wa e , hyd ogen luo-
ide, and e hyl be ween 225 and 450 °C e lec s he decomposi-
ion o li hium alkyl ca bona es.
[43]
The wa e signal appea s as a
double , wi h a second local maximum a ≈375 °C, co esponding
o he he mal deg ada ion o he PE sepa a o . This is accompanied
by ion 15, indica ing CH
3
moie ies eleased du ing he clea age o
PE chains. Wa e peak ails ex ending up o 530 °C a e likely a ib-
u ed o he decomposi ion o he PVDF binde . A empe a u es
exceeding 500 °C, a b oad CO
2
signal is obse ed, co esponding
o he he mo-oxida i e deg ada ion o he g aphi e anode.
Simila TGA–MS measu emen s we e pe o med on indi idual
anode, ca hode, and ca hode-wi h-sepa a o samples. The
ob ained p o iles exhibi ed compa able ends wi h sample-
speci ic a ia ions; he c oss-sec ion sample p o ile (see Figu e 2b),
howe e , p o ides a ep esen a i e o e iew and se es as he
p ima y e e ence o in e p e a ion.
The anode sample exhibi ed b oad peaks o wa e , hyd ogen
luo ide, me hyl, and e hyl g oups cen e ed a ound 350 °C, p i-
ma ily om decomposing li hium alkyl ca bona es.
[43]
The ailing
o wa e and hyd ogen luo ide signals, absen o me hyl and
e hyl ions, is likely associa ed wi h he deg ada ion o he
PVDF polyme ic binde , simila ly o wha was obse ed o he
c oss-sec ion sample. The elease o ca bon dioxide, a ibu ed
o he he mo-oxida i e deg ada ion o g aphi e, began a ound
500 °C. As p is ine g aphi e is known o i s high he mal s abili y,
he obse ed shi sugges s ha deg ada ion du ing ba e y ope -
a ion may educe his s abili y.
Figu e 2. The mal deg ada ion analysis o he c oss-sec ion sample: a) TGA p o ile showing sample weigh loss (black) and i s empe a u e de i a i e (blue).
b) Coupled TGA–MS analysis p esen ing he same he mal p o ile and mass spec ome ic signals o selec ed deg ada ion p oduc s.
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The ca hode and ca hode-wi h-sepa a o samples displayed
beha io wi h no able di e ences om he c oss-sec ion and
anode specimens. In he ca hode-wi h-sepa a o sample, he
signals o me hyl and e hyl g oups appea ed as dis inc dou-
ble s, wi h lowe - empe a u e peaks (a ound 200 °C) a ibu ed
o PE deg ada ion. These peaks we e less p ominen in he
c oss-sec ion da a, likely due o hei ela i ely low in ensi y
and o e lap wi h he end o ca bona es e apo a ion. Fo he
same sample, he wa e and ca bon dioxide in ensi ies peaked
a ound 375 °C and we e no iceably ele a ed, sugges ing ongo-
ing deg ada ion o he PE sepa a o . Bo h ca hode-based meas-
u emen s exhibi ed b oad ca bon dioxide peaks a ound 325 °C
and 550 °C, e en wi hou g aphi e. These obse a ions indica e
ha complex eac ions may occu wi hin he ca hode laye s.
[44]
A oiding ca hode exposu e o empe a u es abo e 500 °C is
ecommended o minimize hese undesi able decomposi ion
p ocesses.
3.2. S a ic The mal Mass Loss Analysis
Unde s anding indi idual LIB componen s’ he mal decomposi-
ion beha io and esidual mass is c ucial o designing e icien
and sa e ecycling p ocesses. The e o e, hei he mal deg ada-
ion pa e ns we e assessed by moni o ing mass loss a e con-
olled hea ing s eps. Figu e 3 illus a es he componen s’
comp ehensi e mass loss p o iles ac oss a b oad empe a u e
ange (0–800 °C). An ini ial mino mass loss, obse ed in all
samples below 100 °C, is p ima ily a ibu ed o he e apo a ion
o esidual elec oly e. Following his, signi ican he mal
deg ada ion o o ganic componen s commences in he sepa a o ,
p edominan ly e idenced by mass loss be ween 100 and 300 °C.
This empe a u e window ep esen s he p ima y he mal deg a-
da ion o he sepa a o ’s polyme ma ix. While he polyme
(e.g., polye hylene) decomposes a hese lowe empe a u es,
he sepa a o ’s alumina coa ing emains he mally s able
h oughou he en i e p ocess. By ≈500 °C, hese o ganic cons i -
uen s we e almos en i ely decomposed, al hough mino esidues
o decomposi ion p oduc s pe sis ed, as con i med in s udies by
Mouse e al.
[45]
and Sadeghi and Res uccia.
[46]
The anode exhibi s minimal mass loss up o ≈500 °C, a e
which a sha p and subs an ial mass loss is obse ed, indica i e
o he decomposi ion o i s o ganic binde s and esidual
ca bonaceous ma e ials. Con e sely, he ca hode and he ca h-
ode wi h sepa a o demons a e high in insic he mal s abili y,
wi h low mass loss eco ded ac oss he 100–800 °C ange.
Quan i a i e analysis o hese mass loss p o iles p o ides c i i-
cal insigh s in o op imal he mal p e ea men s a egies o LIB
ecycling. The p onounced mass loss e en s obse ed a speci ic
empe a u es co ela e s ongly wi h unde lying decomposi ion
p ocesses wi hin he ba e y componen s. A empe a u e o
≈500 °C was iden i ied as an op imal uppe limi o p ese ing
ma e ial in eg i y and enabling e icien mechanical sepa a ion;
his empe a u e balance is c ucial o ene gy-e icien p ocessing
and educing po en ial haza dous emissions. A his poin , he
sepa a o is ans o med mainly in o e ac o y Al
2
O
3
, which
may acili a e a ge ed su ace unc ionaliza ion, and enhances
he e iciency o downs eam me al eco e y by minimizing
impu i ies.
[33,40]
Figu e 3. S a ic he mal mass loss analysis o li hium-ion ba e y cell componen s (ca hode, anode, sepa a o , and ca hode wi h sepa a o ) om 0–800 °C,
illus a ing hei dis inc he mal s abili ies and highligh ing key decomposi ion and p ocessing empe a u e anges wi h s anda d de ia ion e o ba s. No e
ha da a poin s o he ca hode wi h sepa a o sample a 450, 550, and 650 °C a e linea ly in e pola ed o isual end con inui y.
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By de ining a p ecise empe a u e o 500 °C o py ome allu -
gical p e ea men , his s udy o e s a signi ican ad an age o e
p ocesses ope a ing a highe empe a u es. Compa ed o con-
en ional py olysis me hods ha o en equi e empe a u es o
700 °C o highe o comple e o ganic emo al,
[40]
ou indings
sugges a subs an ial po en ial o ene gy sa ings and educed
p ocessing ime. This app oach no only educes ene gy con-
sump ion bu also mi iga es he isk o cu en collec o mel ing
and o he side eac ions ha comp omise ma e ial quali y,
he eby p o iding a mo e e icien and sus ainable pa hway
o ba e y ecycling.
To u he cha ac e ize he p ecise he mal beha io o key
componen s wi hin he mos c i ical ange o py ome allu gical
p e ea men ,
[45,47]
mass loss obse a ions we e ocused wi hin
he 400 o 650 °C empe a u e ange. This window speci ically
cap u es he onse and p og ession o signi ican mass loss om
he anode and he inal s ages o sepa a o deg ada ion, which
a e c ucial o de ining op imal p e ea men condi ions. I is
impo an o no e ha o he ’Ca hode wi h sepa a o ’sample,
da a poin s a 450, 550, and 650 °C we e no expe imen ally
de e mined, and i s end line in Figu e 3 is linea ly in e pola ed
o isual con inui y. Con e sely, exposu e o highe empe a-
u es be ween 600 and 800 °C led o oxida ion and s uc u al deg-
ada ion o me allic componen s, pa icula ly he Al cu en
collec o in NMC ca hodes. This deg ada ion was ound o educe
ma e ial eco e y e iciency and comp omise he quali y o eco -
e ed ac ions.
3.3. Mo phological and Elemen al Composi ion Changes
Analysis
Building upon he insigh s om he mal mass loss analysis, u -
he in es iga ion was conduc ed in o he s uc u al and compo-
si ional s abili y o he ca hode ma e ials. In line wi h he
ecycling objec i es ha p io i ize he eco e y o aluable me als
ound p ima ily in ba e y ca hodes,
[38,48]
he mally exposed ca h-
ode samples we e analyzed o examine hei mo phological and
s uc u al changes using SEM and EDS. Figu e 4 illus a es he
ep esen a i e ini ial condi ion o he d ied ca hode be o e he -
mal ea men , along wi h elemen al maps depic ing bo h he
baseline s a e and he s a e a e exposu e o he highes
empe a u e achie ed (800 °C). This app oach was employed o
e alua e he su ace composi ion o he ca hode and o ack he
composi ional changes esul ing om hea ea men ac oss a
empe a u e ange o 100 o 800 °C, wi h inc emen s o 100 °C.
The comp ehensi e esul s o all exposed ca hode samples
a e p o ided in Figu e 5.
The indings om SEM imaging con i med p ese a ion o he
spinel s uc u e and pa icle mo phology o he in es iga ed
NMC laye e en a e exposu e o empe a u es up o 800 °C, indi-
ca ing i s excep ional he mal s abili y. Howe e , a c i ical obse -
a ion was he onse o mel ing o he Al cu en collec o a
700 °C. This mel ing e en signi ican ly comp omises he in eg i y
o he su ounding elec oac i e ma e ial by causing delamina-
ion and po en ial encapsula ion, he eby diminishing he quali y
o he eco e ed NMC spinel and inc easing he complexi y o
subsequen pu i ica ion. The ul ima e objec i e o he he mal
ea men p ocess is o achie e a empe a u e egime ha main-
ains he o iginal p ope ies o he aluable elec oac i e ma e i-
als while e ec i ely emo ing all o ganic componen s and
acili a ing hei subsequen sepa a ion om cu en collec o s,
suppo ing high- alue ma e ial eco e y.
Complemen ing he mo phological obse a ions, de ailed
elemen al analysis o he he mally ea ed ca hode su aces
was pe o med using EDS. The s udy p ima ily ocused on key
elec oac i e elemen s (Ni, Mn, Co) and acking changes in ca -
bon and luo ine esidues, as p esen ed in Figu e 6. Beyond hese
p ima y a ge s, a ious o he elemen s o igina ing om auxilia y
ba e y ma e ials we e also iden i ied. The de ec ed Al signal is
a ibu ed p ima ily o Al
2
O
3
esidues om he sepa a o ,
[33]
which
con amina e he ca hode su ace du ing disassembly and han-
dling. A mino con ibu ion om he unde lying Al cu en collec-
o oil is also possible in a eas whe e he ac i e ma e ial coa ing
is po ous o hin. In con as , Cu was no de ec ed, which is
expec ed as i is he cu en collec o o he anode, and his anal-
ysis ocused exclusi ely on he ca hode. Phospho us (P) was iden-
i ied as a esidue om he decomposi ion o he LiPF
6
elec oly e
sal .
[20,21]
Fu he mo e, ungs en (W). The p esence o W, de ec ed
a ≈1 w %, is a ibu ed o ungs en oxide (WO
3
). WO
3
is com-
monly used by ba e y manu ac u e s as a su ace coa ing o s a-
bilizing agen o NMC ac i e ma e ials, pa icula ly o Ni- ich
chemis ies such as he NMC622 in ou s udy.
[49,50]
This p o ec i e
Figu e 4. Illus a ion o a) SEM measu emen s o he un ea ed ca hode sample using seconda y elec ons imaging - le , backsca e ed elec ons
imaging - igh ; b) EDS mapping o he un ea ed ca hode sample (T0) compa ed o he he mally ea ed ca hode sample a 800 °C (T800).
’T’deno es he speci ic empe a u e a which he analysis was pe o med.
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laye is known o enhance s uc u al s abili y and limi deg ada-
ion om side eac ions wi h he elec oly e, he eby imp o ing
he ba e y’s ope a ional li espan and sa e y
[51–53]
The amoun
de ec ed by ou su ace-sensi i e EDS analysis is consis en wi h
le els epo ed o such unc ional coa ings. Thei iden i ica ion
p o ided insigh s in o po en ial con amina ion sou ces and he
comple eness o o ganic emo al ollowing he mal ea men .
I is impo an o cla i y ha Cu was no de ec ed, as i is he cu -
en collec o o he anode, while his analysis ocused exclu-
si ely on he ca hode. The de ec ed Al signal is a ibu ed
p ima ily o Al
2
O
3
esidues om he sepa a o , which con ami-
na e he ca hode su ace du ing disassembly and handling. A
mino con ibu ion om he unde lying Al cu en collec o oil
is also possible in a eas whe e he ac i e ma e ial coa ing is
po ous o hin.
A c i ical composi ional shi was obse ed a ≈400 °C, man-
i es ing as a subs an ial educ ion in o ganic ca bon and luo ine
con en . These changes led o a ela i e inc ease in NMC me al
con en (Ni, Mn, Co) due o he elimina ion o o ganic compo-
nen s, as e iden om he g aphs showing a signi ican inc ease
in he ela i e yield o a ge elemen s om 400 °C. No ably, a
500 °C, he ca bon signal was absen , con i ming comple e
emo al o he o ganic ma ix wi hou obse able deg ada ion
o he NMC phase. Fu he in es iga ion in o na owe empe a-
u e in e als e ealed ha esidual ca bon was ully combus ed
e en a 450 °C wi h 1 h o exposu e. Howe e , comple e luo ine
emo al was only achie ed a highe empe a u es, ≈700 °C, indi-
ca ing he p esence o mo e he mally s able luo ine-con aining
compounds a 500 °C. The pe sis ence o hese luo ides a 500 °C
is a c i ical conside a ion, as hey can complica e subsequen
hyd ome allu gical leaching and may con ibu e o equipmen
co osion o lowe inal p oduc pu i y. Rega ding o he elemen s,
esidual P om he elec oly e emained unchanged, while oxy-
gen showed an opposi e end, g owing a he highes
Figu e 5. Illus a ion o SEM measu emen s o he ca hode sample ac oss a empe a u e ange o 100–800 °C, wi h inc emen s o 100 °C, using seconda y
elec ons imaging - le , backsca e ed elec ons imaging - igh . ‘T’deno es he speci ic empe a u e a which he analysis was pe o med.
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empe a u es due o high- empe a u e oxida ion. Among he
iden i ied con aminan s, only e ac o y Al
2
O
3
and WO
3
pe sis ed
h oughou he en i e hea ea men . Despi e he incomple e
luo ine emo al a 500 °C, his empe a u e was ea i med as
op imal o py ome allu gical p e ea men , as i e ec i ely com-
bines ex ensi e o ganic pu i ica ion (especially ca bon emo al)
wi h excellen p ese a ion o he elec oac i e ma e ial s uc u e
be o e signi ican cu en collec o deg ada ion.
The sys ema ic analysis o elec ode ma e ials subjec ed o
high- empe a u e exposu e o 1 h ac oss a ange o empe a-
u es om 100 o 800 °C, explici ly ocusing on NMC ca hodes,
g aphi e anodes, and polyme ic sepa a o s, has yielded aluable
insigh s in o hei he mal beha io . The mos signi ican changes
in mass and composi ion we e consis en ly obse ed be ween
400 and 650 °C. This comp ehensi e in es iga ion unde sco es
he sui abili y o high- empe a u e py ome allu gical app oaches
o eco e ing and ecycling elec oac i e ma e ials om spen
ba e ies.
A 100 °C, elec ode ma e ials unde go ho ough d ying o a
cons an mass. Subsequen hea ing o 200 °C ini ia es he oxida-
ion and b owning o PE wi hin he sepa a o , alongside he
decomposi ion o PVDF binde . A 300 °C, he oxida ion o he
Figu e 6. EDS analysis o ca hode su ace composi ion a e he mal exposu e a selec ed empe a u es: a) ull ange om 0 o 800 °C in 100 °C inc emen s;
b) de ailed ange om 400 o 650 °C in 50 °C inc emen s. ‘T’indica es he speci ic empe a u e a which each sample was analyzed.
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