Ageing and CEI formation mechanisms in porous carbon positive electrode in sodium-ion capacitors
Abstract
This work reports on the ageing and cathode electrolyte interphase (CEI) formation mechanism of porous carbons (PCs) positive electrode in sodium ion capacitors (SICs) operating in 1 M NaPF 6 in EC:DMC(1:1) electrolyte. Three salt-templated PCs with different textures and graphitization degree were used and compared to commercial activated carbon (Kynol). The PCs electrodes were subjected to voltage hold at 4.5 V and analyzed via various complementary postmortem techniques. The ageing study revealed that the performance loss is due to a combined textural, structural and surface chemistry changes. The synthesized salt-templated carbon materials showed discharge capacity between 96 and 149 mAh g -1 , exceeding that of commercial Kynol (77 mAh g -1 ). The highest capacity retention during floating (~18 h) was observed for LiNaCl-T and Kynol, attributed to a combination of high graphitization degree and low surface chemistry. Operando electrochemical dilatometry revealed that capacity retention of aged electrodes is more strongly affected by Na + solvation in the voltage range of 1.5-2.8 V, than by desolvated PF - 6 ion operating at 2.8-4.5 V. Postmortem analysis showed that aged electrodes suffer from porosity blockage, structural changes, and increase in oxygen functionalities, resulting in capacity fade and electronic conductivity loss. In-situ XPS revealed that the CEI layer stabilizes within few electrochemical cycles, while prolonged floating leads to CEI layer dissolution of the organic component and fracture of the inorganic component, which significantly increases the resistance of the PCs electrode. A mechanism of degradation of electrode is proposed along with some solutions to extend the PCs electrode's cycle life.
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BibTeX
@article{adeniji2026ageing,
title = {{Ageing and CEI formation mechanisms in porous carbon positive electrode in sodium-ion capacitors}},
author = {Ademola Adeniji and Adrian Beda and Philippe Fioux and Krzysztof Fic and Camélia Matei Ghimbeu},
journal = {Chemical Engineering Journal},
year = {2026},
month = oct,
doi = {10.1016/j.cej.2026.182328},
url = {https://hal.science/hal-05780145v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Ageing and CEI formation mechanisms in porous carbon positive electrode in sodium-ion capacitors
AU - Ademola Adeniji
AU - Adrian Beda
AU - Philippe Fioux
AU - Krzysztof Fic
AU - Camélia Matei Ghimbeu
PY - 2026
DA - 2026/10/06
JO - Chemical Engineering Journal
DO - 10.1016/j.cej.2026.182328
UR - https://hal.science/hal-05780145v1
AB - This work reports on the ageing and cathode electrolyte interphase (CEI) formation mechanism of porous carbons (PCs) positive electrode in sodium ion capacitors (SICs) operating in 1 M NaPF 6 in EC:DMC(1:1) electrolyte. Three salt-templated PCs with different textures and graphitization degree were used and compared to commercial activated carbon (Kynol). The PCs electrodes were subjected to voltage hold at 4.5 V and analyzed via various complementary postmortem techniques. The ageing study revealed that the performance loss is due to a combined textural, structural and surface chemistry changes. The synthesized salt-templated carbon materials showed discharge capacity between 96 and 149 mAh g -1 , exceeding that of commercial Kynol (77 mAh g -1 ). The highest capacity retention during floating (~18 h) was observed for LiNaCl-T and Kynol, attributed to a combination of high graphitization degree and low surface chemistry. Operando electrochemical dilatometry revealed that capacity retention of aged electrodes is more strongly affected by Na + solvation in the voltage range of 1.5-2.8 V, than by desolvated PF - 6 ion operating at 2.8-4.5 V. Postmortem analysis showed that aged electrodes suffer from porosity blockage, structural changes, and increase in oxygen functionalities, resulting in capacity fade and electronic conductivity loss. In-situ XPS revealed that the CEI layer stabilizes within few electrochemical cycles, while prolonged floating leads to CEI layer dissolution of the organic component and fracture of the inorganic component, which significantly increases the resistance of the PCs electrode. A mechanism of degradation of electrode is proposed along with some solutions to extend the PCs electrode's cycle life.
SN - 1385-8947
ER -