Supercritical CO2‐Assisted SiOx/Carbon Multi‐Layer Coating on Si Anode for Lithium‐Ion Batteries

Abstract Supercritical CO 2 (SCCO 2 ), characterized by gas‐like diffusivity, low surface tension, and excellent mass transfer properties, is applied to create a SiO x /carbon multi‐layer coating on Si particles. Interaction of SCCO 2 with Si produces a continuous SiO x layer, which can buffer Si volume change during lithiation/delithiation. In addition, a conformal carbon film is deposited around the Si@SiO x core. Compared to the carbon film produced via a conventional wet‐chemical method, the SCCO 2 ‐deposited carbon has significantly fewer oxygen‐containing functional groups and thus higher electronic conductivity. Three types of carbon precursors, namely, glucose, sucrose, and citric acid, in the SCCO 2 syntheses are compared. An eco‐friendly, cost‐effective, and scalable SCCO 2 process is thus developed for the single‐step production of a unique Si@SiO x @C anode for Li‐ion batteries. The sample prepared using the glucose precursor shows the highest tap density, the lowest charge transfer resistance, and the best Li + transport kinetics among the electrodes, resulting in a high specific capacity of 918 mAh g −1 at 5 A g −1 . After 300 charge–discharge cycles, the electrode retains its integrity and the accumulation of the solid electrolyte interphase is low. The great potential of the proposed SCCO 2 synthesis and composite anode for Li‐ion battery applications is demonstrated.