Electrochemical performance and thermal stability analysis of LiNixCoyMnzO2 cathode based on a composite safety electrolyte

Lihua Jiang; Qingsong Wang; Jinhua Sun

doi:10.1016/j.jhazmat.2018.03.015

Electrochemical performance and thermal stability analysis of LiNi_xCo_yMn_zO₂ cathode based on a composite safety electrolyte

J Hazard Mater. 2018 Jun 5:351:260-269. doi: 10.1016/j.jhazmat.2018.03.015. Epub 2018 Mar 10.

Authors

Lihua Jiang¹, Qingsong Wang², Jinhua Sun¹

Affiliations

¹ State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei 230026, China.
² State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei 230026, China; CAS Key Laboratory of Materials for Energy Conversion, University of Science and Technology of China, Hefei 230026, China. Electronic address: pinew@ustc.edu.cn.

PMID: 29550560
DOI: 10.1016/j.jhazmat.2018.03.015

Abstract

LiNi_xCo_yMn_zO₂ (NCM) cathode material with high energy density is one of the best choices for power batteries. But the safety issue also becomes more prominent with higher nickel content. The improvement of thermal stability by material modification is often complex and limited. In this study, a composite safety electrolyte additive consisting of perfluoro-2-methyl-3-pentanone, N, N-Dimethylacetamide (and fluorocarbon surfactant is proved to be effective and simple in improving the thermal stability of NCM materials. Electrochemical compatibility of composite safety electrolyte with various NCM materials is investigated. Uniform interface film, lower impedance and polarization for NCM (622) cycled in composite safety electrolyte are proved to be the main reasons to ensure good cycle performance. Homemade pouch cells (NCM (622)/C) are used to verify the effectiveness for practical application, accelerating rate calorimeter and nail penetration test shows a slower temperature rise and delay of thermal runaway. For heating experiment, no fire appears for pouch cell with composite safety electrolyte. Thus, this composite safety electrolyte is effective to improve the safety of lithium ion batteries with NCM materials.(.

Keywords: Composite safety electrolyte; High energy density; LiNixCoyMnzO(2)(NCM); Lithium ion battery safety; Thermal stability.