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Vol. 18 (2026)

Interfacial Evolution and Accelerated Aging Mechanism for LiFePO4/Graphite Pouch Batteries Under Multi-Step Indirect Activation

https://doi.org/10.1007/s40820-025-01971-2
Yun Liu
School of Materials Science and Engineering, Beijing Key Laboratory of Environmental Science and Engineering, Beijing Institute of Technology, Beijing 100081, People’s Republic of China
Jinyang Dong
School of Materials Science and Engineering, Beijing Key Laboratory of Environmental Science and Engineering, Beijing Institute of Technology, Beijing 100081, People’s Republic of China
Jialong Zhou
School of Materials Science and Engineering, Beijing Key Laboratory of Environmental Science and Engineering, Beijing Institute of Technology, Beijing 100081, People’s Republic of China
Yibiao Guan
China Electric Power Research Institute, Haidian District, Beijing 100192, People’s Republic of China
Yimin Wei
21C Innovation Laboratory, Contemporary Amperex Technology Co., Ningde 352100, People’s Republic of China
Jiayu Zhao
School of Materials Science and Engineering, Beijing Key Laboratory of Environmental Science and Engineering, Beijing Institute of Technology, Beijing 100081, People’s Republic of China
Jinding Liang
21C Innovation Laboratory, Contemporary Amperex Technology Co., Ningde 352100, People’s Republic of China
Xixiu Shi
21C Innovation Laboratory, Contemporary Amperex Technology Co., Ningde 352100, People’s Republic of China
Kang Yan
Chongqing Innovation Center, Beijing Institute of Technology, Chongqing 401120, People’s Republic of China
Yun Lu
School of Materials Science and Engineering, Beijing Key Laboratory of Environmental Science and Engineering, Beijing Institute of Technology, Beijing 100081, People’s Republic of China
Ning Li
School of Materials Science and Engineering, Beijing Key Laboratory of Environmental Science and Engineering, Beijing Institute of Technology, Beijing 100081, People’s Republic of China
Yuefeng Su
School of Materials Science and Engineering, Beijing Key Laboratory of Environmental Science and Engineering, Beijing Institute of Technology, Beijing 100081, People’s Republic of China
Feng Wu
Chongqing Innovation Center, Beijing Institute of Technology, Chongqing 401120, People’s Republic of China
Lai Chen
School of Materials Science and Engineering, Beijing Key Laboratory of Environmental Science and Engineering, Beijing Institute of Technology, Beijing 100081, People’s Republic of China

Corresponding Author: Lai Chen

chenlai144@sina.com

Nano-Micro Letters, Vol. 18 (2026), Article Number: 136

Abstract

The dissolution of iron from the cathode and electrode/electrolyte interface (EEI) during long cycles significantly accelerates the aging process of LiFePO4 (LFP)/graphite batteries; there is a lack of systematic understanding of the spatial distribution of the EEI interface layer and the dissolve of Fe ions, especially in terms of the mechanism of the cathode–electrolyte interphase (CEI), solid electrolyte interphase (SEI), and iron dissolution. In this study, aged cells were subjected to continuous activation with constant current and multi-step segmented indirect activation (IA) and analyzed for capacity fade, impedance growth, and active Li+ mass loss at the EEI and nanoscale levels. The interaction between dissolved Fe2+ and the EEI in LFP/graphite pouch batteries was proposed and verified. The findings indicate that during IA process, the electric field facilitates the migration of solvated ions toward the electrodes, while simultaneously inhibiting the formation of organic species such as ROCO2Li. The SEI primarily consists of a mixture of organic and inorganic small molecules, forming a continuous and uniform film on the electrode surface. This study demonstrates that IA favors the formation of a uniform EEI and offers constructive insights for advancing accelerated lifetime prediction strategies in lithium-ion batteries.


Highlights:
1 Quantifying the aging mechanisms and their evolution patterns during battery aging is crucial for enabling renewable energy.
2 The uniform electrode/electrolyte interface (EEI) film on the electrode surface has an important impact on the energy density, cycling performance and power density of the battery.
3 Multi-step segmented indirect activation strategy promotes the formation of uniform EEI and suppresses iron dissolved in the electrolyte.

Keywords

Accelerated aging Electrode/electrolyte interface Multi-step segmented indirect activation EEI film Dissolve of Fe ions
Liu, Yun, Jinyang Dong, Jialong Zhou, Yibiao Guan, Yimin Wei, Jiayu Zhao, Jinding Liang, Xixiu Shi, Kang Yan, Yun Lu, Ning Li, Yuefeng Su, Feng Wu, and Lai Chen. 2026. “Interfacial Evolution and Accelerated Aging Mechanism for LiFePO4/Graphite Pouch Batteries Under Multi-Step Indirect Activation”. Nano-Micro Letters 18 (January):136. https://doi.org/10.1007/s40820-025-01971-2.
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