Fabrication\nof SnO₂ Asymmetric Membranes\nfor High Performance Lithium Battery Anode

Abstract

Alloy electrode material like tin\ndioxide (SnO₂) possesses\nmuch higher specific capacity as compared to commercial graphite anode\nin lithium ion battery (783 vs 372 mAh g^–1). However,\nthe huge volume change (260%) of SnO₂-based anode during\nthe alloying and dealloying process can cause significant electrode\npulverization and rapid capacity loss. Herein we report the synthesis\nof SnO₂ asymmetric membranes via a unique combination of\nphase inversion and sol–gel chemistry to overcome this big\nchallenge. The SnO₂ asymmetric membrane electrode demonstrates\na specific capacity of 500 mAh g^–1 based on the\noverall electrode mass at a current density of 280 mA g^–1 (∼0.5C) with >96% capacity retention after 400 cycles.\nWhen\nthe current density is increased from 28 to 560 mA g^–1, its overall capacity is only reduced by 36%. Such an outstanding\nrate and cycling performance is attributed to the existence of networking\nporous structure in the membrane that can provide high electrical\nconductivity, multiple diffusion channels, and free volumes for electrode\nexpansion. The carbonization temperature has a dramatic impact on\nthe electrode performance. Membranes carbonized at 500 °C show\nan excellent cycling performance, whereas the capacity of the membrane\ncarbonized at 800 °C decreases by 51% in 100 cycles. Such a drastic\ndifference in cycle life is caused by the reduction of small SnO₂ NPs (∼3.9 nm) into large metallic tin spheres (∼40\nnm) at 800 °C. This is the first original report on using asymmetric\nmembrane structure to stabilize an SnO₂-based lithium ion\nbattery anode with an excellent electrochemical performance.