Si/CrSi2 Alloy Anodes Synthesized by a High-Energy Ball-Milling Method for Lithium-Ion Batteries: Microstructure, Electrochemistry, and Carbon Coating

This work successfully introduced the different ratiosof metallicCr into micrometer Si bulk via a high-energy ball-milling method tosynthesize nanostructured Si/CrSi2 alloy anodes with enhancedelectrochemical performance in lithium-ion batteries (LIBs). Thisstudy demonstrated that the in situ-formed CrSi2 couldeffectively suppress the generation of crystalline Li3.75Si in the lithiation process, dilute Si's volume expansion,and improve electronic conductivity. Concretely, Si85Cr15 displayed an outstanding reversible volumetric capacityof & SIM;1400 A h & BULL;L-1 and 100-cycle capacityretention at 0.2 C of 90.1% with an average Coulombic efficiency of99.46%. Moreover, another advantage of Si85Cr15 is good compatibility with the carbon-coating treatment at 800 & DEG;Cby virtue of the reinforced thermal stability derived from a highmelting point of CrSi2. The homogeneous distribution ofSi and metal silicide crystallites was better maintained in Si85Cr15@c-PDA compared to our previously annealedSi-Cu3Si-NiSi2 alloys at the sametemperature. Correspondingly, the cycle stability and rate capabilityof Si85Cr15@c-PDA were further improved witha capacity retention of 93.1/90.6% at 0.2/0.5 C (100/200 cycles) and40% at 2 C, respectively. The excellent electrochemical performanceindicates that Si/CrSi2 alloys may be prospective candidatesas compositions in the carbon-coated anode materials for industrializedLIBs.