▎ 摘　　要

NOVELTY - Multilayer composite tin foil cathode for sodium-ion secondary batteries, comprises N layers of tin foil, where the upper surface or lower surface of the (N-1)-th layer of tin foil is coated with conductive carbon-based material, and N ≥ 5. USE - Multi-layer composite tin foil cathode sodium ion secondary battery. ADVANTAGE - The method of multi-layer composite tin foil cathode eliminates complex processes e.g. mixing and coating, as well as aluminum current collectors, resulting in an 80% reduction in production costs. The method is simple, feasible, and cost-effective, with promising industrial prospects. Moreover, the use of the lightweight and high specific capacity multi-layer composite tin foil cathode not only reduces the weight of sodium-ion batteries but also saves over 35% of space, which can be used to increase the areal capacity (thickness) of the cathode, thus effectively improving the mass/volume energy density of sodium-ion batteries. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: A preparation method of multi-layer; and A sodium ion secondary battery