An electrode-level prelithiation of SiO anodes with organolithium compounds for lithium-ion batteries

Silicon monoxide (SiO) is considered an attractive alternative to conventional graphite anodes due to its high specific capacity and good cycling performance. However, it suffers from low initial Coulombic efficiency (ICE) due to a large irreversible capacity and large volume change during cycling. Both deficiencies hinder the commercial use of SiO anodes. A new organolithium compound (Li−9,9-dimethyl-9H-fluorene−tetrahydrofuran) with lower redox potential is reported to prelithiate a SiO-based anode. An SEI layer is formed during prelithiation and a controllable amount of reversible lithium is preloaded into the SiO electrode. The ICE of a prelithiated SiO-based electrode in half-cell format is increased greatly to ~90.7%. When matched with a LiNi_0·6Co_0·2Mn_0·2O₂ cathode, the full cell with the prelithiated SiO/G anode exhibits a much improved ICE in comparison with the pristine one (87.1% vs. 61.1%). This facile prelithiation method is proved to be a practical solution for the commercial application of SiO-based materials.