Carbon-coated SnOx anchored on phosphorus-doped carbon framework as high performance anode of lithium-ion batteries

Abstract

SnO2 has been recognized as one of the most potential anodes of lithium-ion batteries due to its high theoretical specific capacity, low cost, simple synthetic method, and environmental friendliness. However, the application of SnO2 is hindered owing to its huge volume expansion (∼300 %) and poor electronic conductivity. In this work, carbon-coated SnOx containing some SnO anchored on the phosphorus-doped carbon framework (SnOx/C–P@C) has been fabricated via a novel, simple and green precipitation route using phytic acid as the complexing agent, carbon and phosphorus sources, and glucose as the second carbon source. Phosphorus-doped carbon framework in situ forms via calcining phytic acid at a high temperature. Phosphorus doping can further enhance the electronic conductivity of carbon. The carbon framework can provide sufficient buffer space to make the SnOx particles have good dispersion. The carbon layer from glucose can prevent the direct contact between SnOx and the electrolyte to decrease the side reactions and then reinforce the structure of SnOx/C–P@C. The synergistic effect of the double carbon effectively controls the volume expansion, enhances the electronic conductivity and diffusion coefficient of Li+ ions as well as capacitive contribution ratio, and reduces the charge transfer resistance of SnOx/C–P@C. The SnOx/C–P@C-0.5 sample with the carbon content of 25.8 wt% exhibits outstanding electrochemical performance. At 0.1 A g−1, the discharge specific capacity of 776.2 mAh g−1 can be reached after 100 cycles. At 0.5 A g−1, 555.5 mAh g−1 is still delivered after 200 cycles. Moreover, the sample shows good potential practical applications in the LiNi0.5Mn1.5O4//SnOx/C–P@C-0.5 full cell. 687.9, 597.1, 510.1, 434.8 and 595.6 mAh g−1 are retained for the full cell at 0.1, 0.2, 0.5, 1 and 0.1 C, respectively. The full cell cycling for 200 cycles at 0.5 C can still light up the light-emitting diode (LED) bulbs.