Dictating the interfacial stability of nickel-rich LiNi0.90Co0.05Mn0.05O2 via a diazacyclo electrolyte additive - 2-Fluoropyrazine

Xiaozhen Zhang; Gaopan Liu; Ke Zhou; Yong Cheng; Tianpeng Jiao; Lin Huang; Yue Zou; Ming-Sheng Wang; Yong Yang; Jianming Zheng

doi:10.1016/j.jcis.2022.03.089

Dictating the interfacial stability of nickel-rich LiNi_0.90Co_0.05Mn_0.05O₂ via a diazacyclo electrolyte additive - 2-Fluoropyrazine

J Colloid Interface Sci. 2022 Jul 15:618:431-441. doi: 10.1016/j.jcis.2022.03.089. Epub 2022 Mar 24.

Authors

Affiliations

¹ State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China.
² State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China; State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Materials, Xiamen University, Xiamen 361005, China.
³ State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Materials, Xiamen University, Xiamen 361005, China.
⁴ State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China. Electronic address: zhengjm@xmu.edu.cn.

PMID: 35364544
DOI: 10.1016/j.jcis.2022.03.089

Abstract

Nickel-rich (Ni-rich) cathode materials, LiNi_xCo_yMn_zO₂ (NCM, x ≥ 0.9, x + y + z = 1) hold great promise for developing high energy density lithium ion batteries especially for vehicle electrification. However, the practical application of Ni-rich cathode materials is still suffered from fast structural and interfacial degradation, and the resulted capacity decay. In this study, a diazacyclo type electrolyte additive, 2-fluoropyrazine (2-FP), was explored for the first time to boost the interfacial stabilization of single crystal LiNi_0.90Co_0.05Mn_0.05O₂ (NCM90) cathode. The capacity retention of the NCM90 is evidently promoted from 72.3% to 82.1% after 200 cycles at 1C (180 mA g^-1) when adding 0.2% 2-FP into the electrolyte. The improvement of the electrochemical performance is ascribed to the generation of a compact and homogeneous cathode electrolyte interphase (CEI) film through ring-opening electrochemical polymerization of 2-FP upon the NCM90 electrode particles. This enhanced CEI layer benefits the suppression of the decomposition of LiPF₆ electrolyte and the dissolution of the transition metals (Co and Mn), thus preventing the detrimental side reactions between the NCM90 electrode and the electrolyte.

Keywords: 2-Fluoropyrazine (2-FP); Cathode electrolyte interphase (CEI); Electrolyte additive; LiNi(0.90)Co(0.05)Mn(0.05)O(2); Lithium-ion batteries.