A Hybrid LiCl/Li_xSn Conductive Interlayer to Unlock the Potential of Solid‐State Lithium Metal Batteries

Abstract

Li1.3Al0.3Ti1.7(PO4)3 (LATP) electrolyte has a great potential for application in solid‐state lithium metal batteries. However, due to the poor interfacial contact and thermodynamic instability between LATP and Li metal, a series of interfacial problems, such as high interfacial resistance, undesirable interfacial reaction and dendrite growth are deeply criticized. Herein, a hybrid LiCl/LixSn conductive interlayer is constructed through an in situ electrochemical reaction of SnCl4 with Li metal to effectively improve the compatibility and stability of the Li/LATP interface. LiCl with both electronic insulation and high ionic conductivity can provide fast Li+ diffusion channel, block electron injection, avoid side reactions, and effectively inhibit dendrite growth. LixSn can reduce interfacial impedance, eliminate local electric field concentration, and significantly improve interfacial wettability. Under the protection of LiCl/LixSn hybrid interlayer, the initial resistance of the symmetric battery is reduced from 1066.3 to 133.6 Ω cm−2, achieving a high critical current density of 1.4 mA cm−2. At 0.1 mA cm−2/0.1 mAh cm−2 and 0.2 mA cm−2/0.2 mAh cm−2, the symmetric battery can cycle stably for more than 4000 h at 25 °C. Moreover, the full battery displays a high capacity retention ratio of 90.4% after 420 cycles at 0.5 C.