rGO/Li-Al-LDH composite nanosheets modified commercial polypropylene (PP) separator to suppress lithium dendrites for lithium metal battery

Lithium metal batteries (LMBs) with ultra-high theoretical energy density are a prospective candidate to replace current lithium-ion batteries (LIBs). However, there are still two non-negligible problems of lithium dendrites and the volume expansion effect of LMBs. In this study, reduced graphene oxide (rGO)/Li-Al-LDH composite nanosheets were firstly prepared via a hydrothermal method and then vacuum filtered onto commercial poly-propylene (PP) separator. This kind of rGO/Li-Al-LDH nanosheets layer is expected to improve the wettability of liquid electrolytes and thermal stability. Furthermore, rich-Li-Al LDH can promote more ionic carriers and channels, which exhibits higher-efficiency lithium-ion transport properties. Meanwhile, rGO with a graphitic-like structure is able to disperse the concentration of electrons at the sharp point when lithium dendrites arise. As a result, the discharge capacity of the Li||LiFePO4 cells based on the rGO/Li-Al-LDH@PP separator is still 1.852 mAh after 250 cycles and the capacity decay rate is just 4.24%. It is demonstrated that a feasible and effective strategy for the modified separator can enhance the electrochemical performance of LMBs.