A "tug-of-war" effect tunes Li-ion transport and enhances the rate capability of lithium metal batteries

Han Zhang; Ziqi Zeng; Mengchuang Liu; Fenfen Ma; Mingsheng Qin; Xinlan Wang; Yuanke Wu; Sheng Lei; Shijie Cheng; Jia Xie

doi:10.1039/d2sc06620c

A "tug-of-war" effect tunes Li-ion transport and enhances the rate capability of lithium metal batteries

Chem Sci. 2023 Feb 7;14(10):2745-2754. doi: 10.1039/d2sc06620c. eCollection 2023 Mar 8.

Authors

Han Zhang^{1

2}, Ziqi Zeng¹, Mengchuang Liu¹, Fenfen Ma³, Mingsheng Qin^{1

2}, Xinlan Wang^{1

2}, Yuanke Wu^{1

2}, Sheng Lei^{1

2}, Shijie Cheng¹, Jia Xie¹

Affiliations

¹ State Key Laboratory of Advanced Electromagnetic Engineering and Technology, School of Electrical and Electronic Engineering, Huazhong University of Science and Technology Wuhan 430074 Hubei China xiejia@hust.edu.cn ziqizeng@hust.edu.cn.
² State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology Wuhan 430074 Hubei China.
³ GuSu Laboratory of Materials Suzhou 215123 Jiangsu China.

Abstract

"Solvent-in-salt" electrolytes (high-concentration electrolytes (HCEs)) and diluted high-concentration electrolytes (DHCEs) show great promise for reviving secondary lithium metal batteries (LMBs). However, the inherently sluggish Li⁺ transport of such electrolytes limits the high-rate capability of LMBs for practical conditions. Here, we discovered a "tug-of-war" effect in a multilayer solvation sheath that promoted the rate capability of LMBs; the pulling force of solvent-nonsolvent interactions competed with the compressive force of Li⁺-nonsolvent interactions. By elaborately manipulating the pulling and compressive effects, the interaction between Li⁺ and the solvent was weakened, leading to a loosened solvation sheath. Thereby, the developed electrolytes enabled a high Li⁺ transference number (0.65) and a Li (50 μm)‖NCM712 (4 mA h cm^-2) full cell exhibited long-term cycling stability (160 cycles; 80% capacity retention) at a high rate of 0.33C (1.32 mA cm^-2). Notably, Li (50 μm)‖LiFePO₄ (LFP; 17.4 mg cm^-2) cells with a designed electrolyte reached a capacity retention of 80% after 1450 cycles at a rate of 0.66C. An 6 Ah Li‖LFP pouch cell (over 250 W h kg^-1) showed excellent cycling stability (130 cycles, 96% capacity retention) under practical conditions. This design concept for an electrolyte provides a promising path to build high-energy-density and high-rate LMBs.