Single-Phase Ternary Compounds with a Disordered Lattice and Liquid Metal Phase for High-Performance Li-Ion Battery...

Si is considered as the promising anode materials for lithium-ion batteries (LIBs) owing to their high capacities of 4200 mAh g^-1 and natural abundancy. However, severe electrode pulverization and poor electronic and Li-ionic conductivities hinder their practical applications. To resolve the afore-mentioned problems, we first demonstrate a cation-mixed disordered lattice and unique Li storage mechanism of single-phase ternary GaSiP₂ compound, where the liquid metallic Ga and highly reactive P are incorporated into Si through a ball milling method. As confirmed by experimental and theoretical analyses, the introduced Ga and P enables to achieve the stronger resistance against volume variation and metallic conductivity, respectively, while the cation-mixed lattice provides the faster Li-ionic diffusion capability than those of the parent GaP and Si phases. The resulting GaSiP₂ electrodes delivered the high specific capacity of 1615 mAh g^-1 and high initial Coulombic efficiency of 91%, while the graphite-modified GaSiP₂ (GaSiP₂@C) achieved 83% of capacity retention after 900 cycles and high-rate capacity of 800 at 10,000 mA g^-1. Furthermore, the LiNi_0.8Co_0.1Mn_0.1O₂//GaSiP₂@C full cells achieved the high specific capacity of 1049 mAh g^-1 after 100 cycles, paving a way for the rational design of high-performance LIB anode materials.