Tin asymmetric membranes for high capacity sodium ion battery anodes

Sodium-ion batteries have attracted tremendous research attention as promising candidates for next generation energy storage systems due to low-cost and high abundancy. However, comparing to current Li-ion battery technology, limitations on the anode side seriously hinder the cell performance since sodium does not easily intercalate into graphite materials. Here, tin nanoparticles embedded in various asymmetric membrane structures were developed to leverage the high capacity of tin (847 mA h g⁻¹ based on Na₁₅Sn₄) and accommodate the significant volume expansion for long cycle life. It was demonstrated 762 mA h g⁻¹ reversible capacity at 50 mA g⁻¹ and stable cycling performance over 100 cycles with 92.1% capacity retention at 100 mA g⁻¹ can be achieved for the tin asymmetric membrane electrode synthesized using polysulfone and tin tert-butoxide precursor.