Preparation of SiOx@TiO2@N-doped carbon composite using chitin as carbon precursor for high-performance lithium storage

SiO x is regarded as a promising anode material for the next-generation lithium-ion batteries (LIBs) because of its high theoretical capacity. In order to relieve the volume variation and enhance the electronic and ionic conductivity , a SiO x @TiO 2 @N-doped carbon (NC) composite is prepared using biopolymer chitin as carbon precursor. The TiO 2 coating layer shields the SiO x in the alkaline chitin solution, enabling the homogeneous and stable dispersion of the SiO x during the synthesis process. After emulsion, freeze-drying, and carbonization, the SiO x @TiO 2 @NC composite is obtained. The dual-confinement of TiO 2 and NC effectively buffers the volume variation of SiO x and enhances the electronic/ionic conductivity. The enhanced structural integrity and conductivity guarantee the superior rate capability and the stable long-term cyclability of the SiO x @TiO 2 @NC composite. After 650 cycles at 0.5 and 1 A g −1 , SiO x @TiO 2 @NC maintains reversible capacities of 633 and 540 mA h g −1 , showing capacity retentions of 92.3% and 96.9%, respectively. After 100 cycles at 0.5 C, the assembled SiO x @TiO 2 @NC//LiFePO 4 full cells can retain a discharge capacity of 121 mA h g −1 , maintaining 90% of the third capacity. This work provides a chance for the industrial application of biopolymer chitin in LIBs, and may alleviate the pressure of environmental protection.