A Bifunctional Shear-Thickened Composite Electrolyte Toward High-Safety Lithium Metal Batteries

Lithium metal batteries (LMBs) are limited in practical applications due to safety issues resulting from uncontrolled dendrite growth and mechanical abuse. Herein, a bifunctional gel shear-thickened electrolyte (STE) is developed to simultaneously prevent lithium dendrite growth and improve impact protection by dispersing hydroxyl-rich fumed silica in a conventional liquid electrolyte (LE). STE in Li||Cu cells enabled a lower overpotential for Li deposition compared to that using LE. Li|STE|Li cells stably cycled 1200 h, while Li|LE|Li cells only survived for 200 h, which is attributed to STE promoting the formation of the stable inorganic-rich SEI. Li|STE|LFP full cells achieved capacity retention of 77% after 200 cycles, much higher than LE-containing cells (54%@200 cycles). In addition, the superior protection performance of STE-containing pouch cells is verified by in-situ monitoring with digital image correlation technology and theoretical analysis with finite element simulation. Compared with the pouch cell without STE, the maximum principal strain and plastic strain of the STE-containing pouch cell are reduced by 80% and 62.5%, respectively, which benefits from the non-Newtonian fluid behavior of STE under impact loading. This work confirmed the great potential of the bifunctional gel electrolyte for enhancing the electrochemical performance and safety of LMBs.