Investigation of self-discharge properties and a new concept of open-circuit voltage drop rate in lithium-ion batteries

• Published in: Journal of solid state electrochemistry 2022, Vol.26 (1), p.163-170
• Main Authors: Shan, Haipeng, Cao, Hui, Xu, Xing, Xiao, Teng, Hou, Guangya, Cao, Huazhen, Tang, Yiping, Zheng, Guoqu
• Format: Article
• Language: English
• Subjects: Analytical Chemistry; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Condensed Matter Physics; Discharge; Electrochemistry; Energy Storage; Free energy; Graphite; Lithium; Lithium-ion batteries; Open circuit voltage; Original Paper; Physical Chemistry; Rechargeable batteries; Sheaths; Solvation; State of charge; Voltage drop
• ISSN: 1432-8488; 1433-0768
• DOI: 10.1007/s10008-021-05049-y

In this work the self-discharge characteristics are evaluated through resting OCV (open-circuit voltage)-SOC (state-of-charge) hysteresis and storage aging behavior for pouch NCM|graphite lithium-ion battery. A weak peak is found on the OCV-SOC curve of incremental capacity and differential voltage analysis. A low free-energy complex model involving the formation of an absorbed electron-lithium-ion solvation sheath on the graphite surface is proposal for this weak reaction. The electrons are shared between the graphite and electrolyte via lithium-ion. Results of batteries aging tests reveal a strong linear relation of OCV vs. square-root of time, where the dissociation of complex is considered as the mechanism. The dependency of the square-root of time demonstrates that a new concept of voltage drop rate (mV h −1/2 ) is more feasible by reducing the influence of OCV checking time from 120% to 26%.