Encasing Prelithiated Silicon Species in the Graphite Scaffold: An Enabling Anode Design for the Highly Reversible, Energy-Dense Cell Model.

Abstract

Si anodes suffer from poor cycling efficiency because of the pulverization induced by volume expansion, lithium trapping in Li-Si alloys, and unfavorable interfacial side reactions with the electrolyte; the comprehensive consideration of the Si anode design is required for their practical deployment. In this article, we develop a cabbage-inspired graphite scaffold to accommodate the volume expansion of silicon particles in interplanar spacing. With further interfacial modification and prelithiation processing, the Si@G/C anode with an areal capacity of 4.4 mA h cm-2 delivers highly reversible cycling at 0.5 C (Coulombic efficiency of 99.9%) and a mitigated volume expansion of 23%. Furthermore, we scale up the synthetic strategy by producing 10 kg of the Si@G/C composite in the pilot line and pair this anode with a LiNi0.8Co0.1Mn0.1O2 cathode in a 1 A h pouch-type cell. The full-cell prototype realizes a robust cyclability over 500 cycles (88% capacity retention) and an energy density of 301.3 W h kg-1 at 0.5 C. Considering the scalable fabrication protocol, holistic electrode formulation design, and harmony integration of key metrics evaluated both in half-cell and full-cell tests, the reversible cycling of the prelithiated silicon species in the graphite scaffold of the composite could enable feasible use of the composite anode in high-energy density lithium batteries.