The invention provides a composite negative
electrode, a preparation method thereof and an all-
solid-state
lithium battery, and belongs to the technical field of all-
solid-state
lithium ion batteries. The composite negative
electrode provided by the invention comprises a negative
electrode material and a
nano silicon coating arranged on the surface of the negative
electrode material, and the negative
electrode material is one or more of Al, Sn, Ge, In, Mg and Ag. The negative
electrode material in the composite negative electrode provided by the invention can avoid serious
side reaction between the negative electrode and a
sulfide solid electrolyte interface, reduce the risk of
lithium dendrites at the interface, and ensure the electrochemical performance of the all-solid-state
lithium battery; the nano-
silicon coating forms a Li-Si
alloy layer after the first lithiation, and has high
lithium ion conduction characteristic and lower Young modulus, so that good interface contact is formed between the composite negative electrode and a solid
electrolyte, a high-diffusivity
transmission channel and stable dynamic guarantee are provided for the reversible lithiation / lithium removal process of the composite negative electrode, and the composite negative electrode can be applied to the
lithium ion battery. And the electrochemical performance of the all-solid-state
lithium battery is further improved.