F and N Rich Solid Electrolyte for Stable All‐Solid‐State Battery
Hongli Wan, Jiaxun Zhang, Jiale Xia, Xiao Ji, Xinzi He, Sufu Liu, Chunsheng Wang
Abstract
Abstract The instability of sulfide solid electrolytes to Li anode and high‐voltage LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811) cathodes limits the cyclic performance of all‐solid‐state lithium battery (ASSLB). Herein, the stability of Li 6 PS 5 Cl against Li anode is enhanced by mixing a small amount (0.32 wt%) of CuF 2 ‐LiNO 3 (CL) into Li 6 PS 5 Cl electrolyte layer to in‐situ form a mixed‐conductive‐lithiophobic and self‐healing LiF‐Li 3 N‐Cu solid electrolyte interphase (SEI) at Li 6 PS 5 Cl‐CL/Li interface. The critical current density (CCD) of Li 6 PS 5 Cl‐CuF 2 ‐LiNO 3 increases to 1.4 mA cm –2 /1.4 mAh cm –2 at room temperature, which is much higher than that of pristine Li 6 PS 5 Cl (0.4 mA cm –2 /0.4 mAh cm –2 ) even though mixing 0.32 wt% CL into Li 6 PS 5 Cl slightly reduces the ionic conductivity from 2.9 × 10 –3 to 1.5 × 10 –3 S cm –1 . The compatibility of Li 6 PS 5 Cl‐CL electrolyte to single‐crystalline NMC811 (S‐NMC811) is further enhanced by adding a small amount (0.02 wt%) of AlF 3 into Li 6 PS 5 Cl‐CL forming Li 6 PS 5 Cl‐CuF 2 ‐LiNO 3 ‐AlF 3 (Li 6 PS 5 Cl‐CLA) as a cathode electrolyte and by doing Cl – on S‐NMC811 (Cl@S‐NMC811) surface. The Cl@S‐NMC811‐Li 6 PS 5 Cl‐CLA|Li 6 PS 5 Cl‐CL|Li cells with areal capacity of 2.55 mAh cm ‐2 achieve a capacity retention of 69.4% after 100 cycles at 1C (1C = 200 mAh g ‐1 ). Adding a small amount of SEI and cathode/electrolyte interphase (CEI) former into the sulfide electrolytes with minimal reduction (48.3%) of ionic conductivity is an effective method to enhance the performance of ASSLB.