Open AccessEditors’ Choice—Quantification of the Impact of Chemo-Mechanical Degradation on the Performance and Cycling Stability of NCM-Based Cathodes in Solid-State Li-Ion Batteries
Author(s) -
Gioele Conforto,
Raffael Rueß,
Daniel Schröder,
Enrico Trevisanello,
Roberto Fantin,
Felix H. Richter,
Jürgen Janek
Publication year - 2021
Publication title -
journal of the electrochemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.258
H-Index - 271
eISSN - 1945-7111
pISSN - 0013-4651
DOI - 10.1149/1945-7111/ac13d2
Subject(s) - cathode , state of charge , electrochemistry , materials science , lithium (medication) , degradation (telecommunications) , battery (electricity) , diffusion , electrolyte , fading , composite number , ion , chemical engineering , composite material , chemistry , electrical engineering , power (physics) , electrode , thermodynamics , medicine , physics , channel (broadcasting) , engineering , organic chemistry , endocrinology
The use of solid electrolytes in lithium batteries promises to increase their power and energy density, but several challenges still need to be overcome. One critical issue is capacity-fading, commonly ascribed to various degradation reactions in the composite cathode. Chemical, electrochemical as well as chemo-mechanical effects are discussed to be the cause, yet no clear understanding of the mechanism of capacity fading is established. In this work, a model is proposed to interpret the low-frequency impedance of the cathode in terms of lithium diffusion within an ensemble of LiNi 1− x−y Co x Mn y O 2 (NCM) cathode active material particles with different particle sizes. Additionally, an electrochemical technique is developed to determine the electrochemically active mass in the cathode, based on the estimation of the state-of-charge via open circuit potential-relaxation. Tracking the length of lithium diffusion pathways and active mass over 40 charge-discharge cycles demonstrates that the chemo-mechanical evolution in the composite cathode is the major cause for cell capacity fading. Finally, it is shown that single-crystalline NCM is far more robust against chemo-mechanical degradation compared to polycrystalline NCM and can maintain a high cycling stability.