Moderate Solvation Structure Design Endows Long Cycling of 5 V-Class Fast-Charging Lithium-Ion Batteries
Ruilin He, Tong Zhang, Fangzheng Liu, Junhao Li, Jiachun Wu, Xueping Xiao, Xiaoqi Wu, Jun Wang, Yan Li, Fangfang Pan, Yonghong Deng, Guangzhao Zhang
Abstract
LiNi 0.5 Mn 1.5 O 4 (LNMO) cathode attracts great attention due to its low cost, good air stability, and three-dimensional lithium-diffusion channels. However, the operation voltage of LNMO (∼5 V vs Li + /Li) exceeds the oxidative limitation of most electrolytes, hindering the application of LNMO batteries. Fluorinated carbonate-based electrolytes can partially solve the oxidation challenge, but excessive viscosity and poor solvation ability cause the sluggish transport of Li + . Here we report a moderate solvation electrolyte design using 2,2,2-trifluoroethyl acetate (EA3F) as the main solvent to stabilize LNMO cathodes under fast charging conditions. EA3F not only shows moderate Li + coordination that can promote fast desolvation, but also facilitates the formation of thin and robust interphases at cathode/anode electrodes. Consequently, the 1.4 Ah graphite||LNMO pouch cells with this electrolyte can achieve 80% capacity retention over 1200 cycles at 1 C and release ∼90% capacity retention at a rate of 4 C (9.4 mA cm –2 ).