Self-limiting lithium deposition enabled by synergistic surface chemical and structural engineering of Li metal anodes

Abstract

Li metal is considered an ideal anode for the next-generation rechargeable batteries due to the high specific capacity and ultralow redox potential. However, the growth of Li dendrites severely impedes its application. In this study, a structural Li anode is constructed by decorating the copper phosphide nanowires modified copper mesh (PCM) on Li surface. A self-limiting Li deposition with dendrite-free feature is achieved based on the rational surface chemical and structural engineering of the Li anode. On the one hand, the meshed PCM layer as well as its lithiated species performs excellent lithiophilicity and favorable electron/ion conductivity, effectively reducing the Li nucleation barrier and redistributing the electric field and Li+ flux. This promotes a preferential and uniform Li deposition. On the other hand, the suitable combination between PCM and Li not only ensures excellent electrical contact for fast charge transfer, but also establishes a well-balanced structure with abundant active sites and large space for Li nucleation and deposition. Moreover, the meshed surface structure effectively accommodates the volume change of Li during plating/stripping. And the multiplied compressive stress between the PCM and separator greatly suppresses Li growth in vertical direction and promotes a dense Li morphology. Consequently, a self-limiting and highly reversible Li plating/stripping along the horizontal direction is achieved, even at a high areal capacity of 10 mA h cm–2. The Li deposition preferentially occurs on the PCM skeleton and gradually expands horizontally into the meshed space, without obvious formation of Li dendrites. The symmetrical cells show excellent cycling stability for over 1700 h with a low overpotential (13.1 mV at 1500 h) at 1 mA cm–2. Furthermore, the cells paired with LiNi0.6Co0.2Mn0.2O2 cathode also show excellent cycling stability for over 450 cycles.