原位合成Si/(SiO+Ag)复合负极材料及电化学性能

In-situ mechanochemical synthesis of Si/ (SiO + Ag)composite anodes and electrochemical property evaluation

摘要:

开发一种机械化学原位固相反应合成硅基复合材料,该方法通过球磨过量微米Si和Ag₂O,使其在球磨破碎过程中原位形成SiO和Ag颗粒并附着在基体Si上,简记Si/(SiO+Ag),并以沥青为碳源采用高温煅烧制备碳包覆硅基复合材料Si/(SiO+Ag)-C。这两种复合材料都展现出良好的倍率性能,在低电流密度(0.12 A/g)下分别表现出1422和1039 mA h/g的可逆比容量,而在高电流密度(2.4 A/g)下仍能获得672和393 mA h/g的可逆比容量；当电流密度再次恢复到0.12 A/g时,可逆容量可恢复到1329 和961 mA h/g。相比之下,碳包覆硅基复合材料表现出更好的循环稳定性,经80次循环后容量仍然稳定在943 mA h/g以上。这种突出的倍率性能归因于硅基颗粒细化及原位形成纳米Ag颗粒导电特性,而循环稳定性的提高与原位形成SiO和包覆碳构成的双相缓冲结构有关。

Abstract:

A mechanochemical in-situ solid-state reaction synthesis method for Si-based composites was developed. This method involves milling excess micron-Si and Ag2O to form SiO and Ag particles in-situ and adhere to the matrix Si during the ball-milling crushing process (abbreviated as Si/( SiO + Ag )). Carbon-coated Si-based composites Si/( SiO + Ag ) - C were prepared using asphalt as a carbon source by high-temperature calcination. Both of these composites exhibit excellent rate performance, exhibiting reversible specific capacities of 1422 and 1039 mA h/g at low current density (0.12 A/g), respectively, while 672 and 393 mA h/g can still be obtained at high current density (2.4 A/g); When the current density is restored to 0.12 A/g again, the reversible capacity can be restored to 1329 and 961 mA h/g. In contrast, Si/(SiO + Ag ) - C exhibit better cycle stability, and their capacity remains stable above 943mA h/g after 80 cycles. This outstanding rate performance is attributed to the refinement of Si-based particles and the electrical conductivity of in situ-formed nano-Ag particles, while the improvement in cycle stability is related to the dual-phase buffer structure composed of in situ-formed SiO and coated carbon.