Guiding uniform lithium deposition via three-dimensional gradient MXene/ZIF-8 structure for high-performance and dendrite-free lithium metal anodes

The development of lithium-metal batteries has been severely hindered by dendritic lithium dendrites and volume changes. Three-dimensional gradient and two-dimensional lithophilic materials have been shown to improve the electrochemical performance of lithium metal anodes significantly. In this paper, we have exploited the chemical interaction between MXene and ZIF-8 to develop a gradient structure consisting of MXene, MXene/ZIF-8, and MXene+ZIF-8 by in situ growth. In this gradient structure, with the gradual increase of interlayer conductivity, lithium ions can be deposited preferentially and uniformly at the bottom of the conductive bottom during lithium plating, overcoming many deposition problems at the top of 3D structures. It enhanced the electrochemical performances of lithium anodes including a coulombic efficiency of 99 % over 800 cycles at 0.5 mA cm ⁻² and 99 % over 500 cycles at 1 mAh cm ⁻², a long cycling life up to 800 h at 1 mA cm ⁻² and 1 mAh cm ⁻². The MXene/pt-Li||LiFePO ₄ cells exhibited a stable cycling performance with a capacity retention of 94 % after 800 cycles.