To achieve fast ion transport of engineered electrolyte and ultra-high rate of defected Nb16W5O55-based anode

Abstract

The maximum output power and minimum charge time of a lithium-ion battery depend on ion transport and electron transport. The electron conduction/ion diffusion within the electrochemically active materials and the ion mobility of the electrolyte usually represent the fundamental limits of the battery charge and discharge rates. Nb16W5O55 is notable for its exceptional lithium-ion mobility and high electronic conductivity, making it a popular choice for fast-charging anode materials. However, the lithium-ion diffusion capability of the electrolyte is also crucial in determining the overall fast-charging performance of the battery. This can be a limiting factor for Nb16W5O55-based batteries. This work delves into the impact of electrolyte composition on fast-charging performance by examining the electrochemical properties of electrolytes with varying concentrations, in conjunction with molecular dynamics simulation. Specifically, increasing the concentration of LiTFSI salt alters the solvation structure of lithium ions due to the increasing coordination numbers of TFSI− and Li+, which hampers lithium-ion diffusion. Additionally, low-concentration electrolytes struggle with rapid mass transfer due to fewer lithium-ion carriers, limiting ultra-high-rate performance. To address these challenges, the solvation structure of the electrolyte was optimized, leading to enhanced fast-charging and discharging performance.