Multi-Contact Carbon Encapsulation Enables Breaking the Stability–Transport Trade-Off in Si Anodes

Abstract Silicon (Si) is a promising anode material for lithium-ion batteries but suffers from severe volume fluctuation and unstable interfacial chemistry. Carbon coating is widely employed to stabilize the Si material, yet core–shell structures lack sufficient buffer space, whereas yolk–shell counterparts often provide limited ion-transport pathways. Here, an architecture that simultaneously integrates structural tolerance and fast Li+ transport is realized by constructing a micro-sized carbon capsule-encapsulated porous Si (pSi@EC) composite via an in situ templating strategy. The engineered void effectively accommodates the volume expansion of pSi and dissipates lithiation-induced stress, while multiple electrical contact channels between the pSi framework and carbon capsule enable homogeneous Li+ transport and accelerated reaction kinetics. Benefiting from these synergistic features, the pSi@EC anode delivers a high capacity of 1472.5 mAh g–1 at 5.0 A g–1 and retains 1411.2 mAh g–1 after 900 cycles at 1.0 A g–1. Finite element analysis further reveals a 58.44% reduction in lithiation stress and a 33.34% increase in average Li+ concentration compared with conformal carbon-coated porous Si (pSi@CC) composite. This work provides a robust encapsulation strategy that achieves a favorable balance among structural stability, interfacial robustness, and ion-transport kinetics, offering a promising blueprint for the development of high-performance Si/C anodes.