(352g) Silicon Carbide As a Protective Layer to Stabilize Si-Based Anode By Inhibiting the Chemical Reaction

Yu, C., Tsinghua University
Wei, F., Tsinghua University
Zhang, C., Tsinghua University
Chen, X., Tsinghua University
The poor cycle performance of the silicon based (Si-based) anode hindered its practical application. Here, a fresh and fundamental mechanism was proposed to interpret the rapid capacity decay of Si-based materials. Silicon could chemically react with LiPF6 and generate Li2SiF6 aggregations constantly during cycling process. What’s worse, nano carbon coated on the silicon acted as a catalyst to accelerate such detrimental reaction. By taking advantages of high strength and toughness of silicon carbide (SiC), SiC layer was rationally introduced between inner silicon and outer carbon to inhibit the chemical formation reaction of Li2SiF6. The side reaction rate reduced significantly attributed to the increased activation energy of such reaction. The Si@SiC@C maintained a specific capacity of 980 mAh g-1 at the current density of 1 A g-1 after 800 cycles with the initial Coulombic efficiency over 88.5%.