SiOx@Si-graphite microspheres for high-stable anode of lithium-ion batteries

• The conductive carbon network enhances the structural stability of the material. • SiOx@Si structure is beneficial to alleviate Si volume expansion. • Stable structure enables excellent cycling stability of materials. The practical application of silicon (Si) anode with high theoretical capacity has not yet satisfied the commercial requirements of lithium-ion batteries (LIBs) due to serious degradation electrochemical properties arising from large volume expansion and deteriorated electrode architecture during cycling. Co-utilization of Si and graphite has become a commercially feasible method for realizing high-energy LIBs. Herein, we have synthesized a nitrogen-doped Si-graphite composite microspheres enhanced by three-dimensional carbon network by spray drying method. The three-dimensional network carbon structure generated by sodium alginate carbonization can further enhance the structural stability of the material and be favorable to the rapid transfer of electrons. The Si particle surface is partial converted into silicon oxide (SiO x ) phase during sodium alginate carbonation process, which is beneficial to restrain the volume expansion effect of Si and enhance the electrochemical performance of the material. The fabricated SiO x @Si-graphite composite microspheres enhanced by three-dimensional carbon network is prospective for practical application in high-performance LIBs.