“Three in one” 3D mixed skeleton design enables dendrite-free Li metal batteries

Abstract

The practical application of Li metal batteries (LMBs) has been impeded by the uncontrolled dendrite growth and unstable solid electrolyte interphase (SEI). Herein, a “three in one” 3D mixed skeleton consisting of a MoS₂ heterostructure on nitrogen-doped carbon (h-MoS₂-NC) with an artificial SEI layer formed in situ is designed for stabilizing the Li metal anodes (LMAs). Remarkably, the h-MoS₂-NC provides abundant lithophilic sites to guide the uniform Li deposition with a low nucleation barrier within the 3D skeleton. Meanwhile, the inorganic-rich SEI layer formed by the conversion reaction between h-MoS₂-NC and Li⁺ exhibits a high ionic conductivity, which facilitated fast Li⁺ transfer and improved the stability of the electrode interface. Moreover, the 2D nanosheets with heterostructures in the 3D skeletons can enhance electronic conductivity to homogenize the electric field distribution and simultaneously provide enough space to alleviate the volume expansion. Consequently, the Li@h-MoS₂-NC delivers a long lifespan of 2500 h with a small overpotential (9 mV) at 1 mA cm⁻² and 1 mA h cm⁻². Meanwhile, a full cell constructed by pairing the Li@h-MoS₂-NC anode with an NCM111 cathode exhibits an improved rate capability and a high capacity retention of 80.8% after 200 cycles at 1 C. The construction of the “three in one” 3D mixed ion/electron-conducting skeletons provides new insights into the design approaches for high-performance LMBs.