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

• The reduced graphene oxide (rGO)/Li-Al-LDH composite nanosheets by hydrothermal method. • This kind of rGO/Li-Al-LDH nanosheets layer is expected to improve the wettability of liquid electrolytes and thermal stability. • The rGO/Li-Al-LDH@PP composite separator exhibits enhanced lithium-ion transport property. • The rGO/Li-Al-LDH@PP composite separator can be applied in Li||LiFePO 4 half cells. 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 polypropylene (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||LiFePO 4 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. [Display omitted] The functional coat is a superior strategy to optimize the interface among the electrode, separator, and liquid electrolyte. In our study, we have synthesized reduced graphene oxide (rGO)/Li-Al-LDH composite nanosheets by hydrothermal method. Li-Al-LDH possesses plenty of octahedral vacancies and abundant lithium-ion diffusion pathways. Meanwhile, rGO with a graphitic-like structure is able to disperse the concentration of electrons at the sharp point when lithium dendrites arise. The prepared rGO/Li-Al-LDH@PP composite separator exhibits increased lithium-ion transference number (0.39) and enhanced ionic conductivity (0.74 mS cm−1) when compared with bare PP separator. The cell has excellent cycle performance. The discharge capacity of the Li||LiFePO 4 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%. At the same time, it also improves the rate performance and Coulomb efficiency of the cell. [ABSTRACT FROM AUTHOR]