Computational Design of Cation-Disordered Li3Ta2O5 with Fast Ion Diffusion Dynamics and Rich Redox Chemistry for a High-Rate Li-Ion Battery Anode Material

Disordered rock salt transition-metal oxides have emerged recently as promising electrodes for Li-ion batteries (LIBs). However, only two disordered rock salt (DRX) materials, Li3V2O5 and Li3Nb2O5, have been studied as anodes so far, leaving numerous DRX compounds with vast compositions and exotic battery-related performance unexplored. Here, based on theoretical analyses and calculations, we propose a Ta pentoxide-based DRX anode with rich electrochemical properties, where the thermodynamic stability, average voltage, energy density, redox chemistry, and cation mobility are studied. Our results show that DRXLi3Ta2O5 can cycle three Li ions at an average voltage of 1.27 V, which is higher than that of DRX-Li3V2O5 (0.73 V) but lower than that of DRX-Li3Nb2O5 (1.76 V), falling in the optimal range for the high rate performance. More importantly, DRX-Li3Ta2O5 exhibits a superhigh volumetric capacity of 1336 mAh cm-3, which surpasses that of graphite, Li4Ti5O12, and DRX-Li3V2O5. Meanwhile, the unique geometry of DRX-Li3Ta2O5 allows Li+ to diffuse rapidly through channels with low diffusion energy barriers, and Ta2O5 is electronically activated by inserting Li+ into the available octahedral sites with enhanced orbital overlapping. Our work expands the family of DRX anode materials with new features.

Automated summary

Based on theoretical analysis and calculations, researchers propose a Ta pentoxide-based disordered rock salt (DRX) anode with rich electrochemical properties. The DRX-Li3Ta2O5 material exhibits high average voltage, superhigh volumetric capacity, and enhanced orbital overlapping, making it a promising candidate for Li-ion batteries. This work expands the family of DRX anode materials with new features.