Correlation between lithium-ion accessibility to the electrolyte–active material interface and low-temperature electrochemical performance

Highlights: • Correlation between Li⁺ accessibility & low-temperature performance was investigated. • HG, which has in-plane defects, was employed for fabrication of LTO/HG composites. • As introducing in-plane defects, low-temperature performance increased markedly. • LTO/HG showed excellent low-temperature electrochemical performance. -- Abstract: With continuous growth in the demand for energy storage, batteries are increasingly required to operate under extreme environmental conditions, including low temperatures. In this study, we systematically investigate the correlation between lithium-ion accessibility to the electrolyte–active material interface and the low-temperature electrochemical properties of electrode materials. Holey graphene with different number densities of in-plane defects on the graphene basal plane is synthesized and employed for the synthesis of Li₄Ti₅O₁₂/holey graphene composites. The electrochemical performances of the Li₄Ti₅O₁₂/holey graphene composites are evaluated at operating temperatures of –25 to 50 °C. As the number density of in-plane defects in the holey graphene increased, the polarization decreased and the apparent lithium-ion diffusion coefficient increased at operating temperatures of –25, 0, and 25 °C, resulting in improved low-temperature electrochemical performance. Based on the comparative analysis of the electrochemical properties of the Li₄Ti₅O₁₂/holey graphene composites, the introduction of in-plane defects in the carbon layer is an effective strategy for improving the low-temperature electrochemical performance of electrode materials. The results suggest that the lithium-ion accessibility to the electrolyte–active material interface becomes more important to the electrochemical properties at low operating temperatures.