Paraffin Wax Protecting 3D Non-Dendritic Lithium for Backside-Plated Lithium Metal Anode

Abstract Trapping Li into three-dimensional (3D) conductive host to construct 3D-Li is an effective strategy to suppress the growth of Li dendrites. However, the increased contact area between 3D-Li and electrolyte unavoidably induces more side reactions to further deteriorate the electrochemical performance of lithium metal batteries (LMBs). Herein, we use low-cost paraffin wax (PW) as the conformal protection layer of 3D non-dendritic Li (PW@3D-Li) to improve the cycling stability and safety of LMB via backside plating configuration. During the first charging process, PW overlayer serves as an ionic/electronic insulator to protect 3D-Li from the frontal attack of Li+ ions originating from the cathode, which have to travel over its edge and backside deposit in the interior and bottom of 3D host. During subsequent cycles, the plating and stripping of Li are confined beneath the PW protection layer to mitigate the corrosion of electrolyte and depress the formation of Li dendrites and “dead Li”. Attributing to these advantages, the symmetric PW@3D-Li battery exhibits long cycling life (1050 cycles) and low voltage hysteresis (289 mV at 20 mA cm−2). Additionally, the PW@3D-Li‖Li(Ni1/3Mn1/3Co1/3)O2 battery also exhibits excellent rate capability. Overall, this study offers new fundamental insights for the design of stable and safe LMBs.