TiO2 coated Si/C interconnected microsphere with stable framework and interface for high-rate lithium storage

Si is considered as the most promising anode material for lithium ion batteries (LIBs) because of the high specific capacity (3579 mAh g−1). However, the huge volume changes (>300%) causes structural cracking and unstable solid state electrolyte (SEI) film, leading to fast capacity fading. Herein, TiO2 coated Si/C-interconnected microsphere (Si/C@TiO2) with dual-protection is designed and fabricated via a two-step procedure. In this composite, the inner flexible carbon and outer rigid TiO2 layer work together to maintain the structural integrity, stabilize the SEI film, and enhance the conductivity of the anode composite. As a result, the obtained Si/C@TiO2 composite delivers a reversible capacity of 1077.3 mA h g−1 at 0.2 A g−1 after 100 cycles, capacity retention of 58.4% at even 10 A g−1, and improved coulombic efficiency. In addition, a full cell consisted of Si/C@TiO2 anode and LiCoO2 cathode exhibits a reversible capacity of 1048 mAh g−1 at 0.2 A g−1 and 820 mAh g−1 at 1.5 A g−1 based on the anode active material with a working potential beyond 3.1 V.