Long-lifespan thin Li anode achieved by dead Li rejuvenation and Li dendrite suppression for all-solid-state lithium batteries

Abstract

Solid polymer electrolytes (SPEs) are considered to be one of the most promising systems applied in all-solid-state lithium metal batteries (ASSLMBs) on account of their chemical and electrochemical robustness, mechanical stability, cost-effective and scalable manufacturing techniques. Lately, significant endeavors have been directed towards mitigating the formation of the Li dendrite in SPE-based ASSLMBs, while research on the inactive lithium in the forms of the solid-electrolyte interface has been rarely reported. Herein, a bi-functional GaI3 additive is developed for in-situ generating Li3Ga alloy for suppressing Li dendrite growth, as well as I3− in recovering dead lithium. Relying on the density functional theory (DFT) results, the Li atom prefers to deposit on the Li3Ga surface and then guide uniform Li deposition, while the I3 species features a relatively lower lowest unoccupied molecular orbital (LUMO) energy level (-2.12 eV), meaning a higher electron affinity, which is beneficial for reviving inactive lithium to counterbalance the loss of lithium. As a result, in comparison to cells employing pure PEGDME-based electrolytes, the Li-Li symmetric cells utilizing GaI3-containing solid-state electrolyte exhibited a cycling life nearly 30 times longer at a current density/capacity of 0.2 mA/cm2, 0.2 mAh/cm2. The full batteries of LFP//1%GaI3-SPE//40 μm Li delivered a noteworthy capacity retention of 82% after 1300 cycles at a rate of 1 C.