Optimizing the composition of LiFSI-based electrolytes by a method combining simplex with normalization

Hongli Lu; Shuangwei Zeng; Dongni Zhao; Jie Wang; Yin Quan; Fei Xu; Faqiang Li; Shiyou Li

doi:10.1039/d1ra05156c

Optimizing the composition of LiFSI-based electrolytes by a method combining simplex with normalization

RSC Adv. 2021 Jul 29;11(42):26102-26109. doi: 10.1039/d1ra05156c. eCollection 2021 Jul 27.

Authors

Hongli Lu^{1

2}, Shuangwei Zeng^{1

2}, Dongni Zhao^{1

2}, Jie Wang^{1

2}, Yin Quan^{1

2}, Fei Xu^{1

2}, Faqiang Li³, Shiyou Li^{1

2}

Affiliations

¹ School of Petrochemical Technology, Lanzhou University of Technology Lanzhou 730050 P. R. China lishiyoulw@163.com +86-931-7823001 +86-931-7823125.
² Gansu Engineering Laboratory of Electrolyte Material for Lithium-ion Battery Lanzhou 730050 P. R. China.
³ School of Materials Science and Engineering, Linyi University Linyi Shandong 276005 P. R. China.

Abstract

The optimizing method of electrolyte formulation is always vital for the development of high-performance lithium-ion batteries. Traditional optimization methods are mainly aimed at the optimization of the electrolyte composition type, and less attention is paid to the optimization of the composition proportion in a certain electrolyte formulation. In this paper, in order to balance the relationship between aluminum (Al) foil corrosion inhibition and battery electrochemical performance, the electrolyte system LiFSI_0.6-LiBOB_0.4-EC/DEC/EMC (1 : 1 : 1, by volume) was optimized by combining the simplex method, normalization and electrochemical testing. A lithium iron phosphate (LiFePO₄) cathode with the optimized electrolyte of LiFSI_0.53-LiBOB_0.35-EC/DEC/EMC (1.3 : 1.5 : 1.5) delivers a high capacity (143.1 mA h g^-1 at 0.5C) and remarkable cycle life (94.9% retention after 100 cycles) at 45 °C. The outstanding performance is attributed to the composition of the cathode electrolyte interphase (CEI) containing the solid and dense LiF, AlF₃, B₂O₃ and Li₂CO₃. This provides a new method and idea for future electrolyte formulation optimization.