Development of Yolk-Shell Si@void@C Anode for High Performance Lithium-Ion Batteries

Abstract

The quest for high-performance anodes for lithium-ion batteries (LIBs) has prompted extensive research into silicon (Si)-based materials, due to Si's remarkable theoretical capacity (~4200 mAhg-1). However, the practical use of silicon anodes has been impeded by significant volume expansion during lithiation, resulting in rapid capacity loss and structural deterioration. To tackle these significant obstacles, we present the design and synthesis of Si@void@C yolk-shell structured composite where surfactant stabilized and pH modulated SiNPs are carefully coated with Stöber silica and resorcinol-formaldehyde (RF) resin at room temperature. The synthesis combines controlled silica templating and subsequent carbon coating via sol-gel followed by pyrolysis under Ar and careful etching of the intermediate layer from Si@SiO2@C double core-shell which leads to the formation of Si@void@C yolk-shell architecture. This architecture consists of a SiNPs core, a tunable nanoscale void space, and a durable carbon shell coating, all designed to accommodate significant volume fluctuations and preserve electrical connectivity during extended charge-discharge cycles. The Si@void@C nanoparticles improve the electrolyte infiltration, ionic diffusion length, and electrochemical reaction kinetics of silicon anode. The Si@void@C anode demonstrates an average discharge capacity of ~453 mAhg-1 and charge capacity of ~449 mAhg-1 after 200 cycles at a 0.1 Ag-1 with a coulombic efficiency of ~99.65%. The anode architecture demonstrates superior rate performance due to additional void space between the silicon core and polymeric carbon coating preventing structural collapse during cycling.