Unlocking the Crucial Role of Oxygen Vacancies on the Low‐Temperature Li‐Ion Storage

Abstract Designing crystal structures that enable fast Li‐ion transport is essential for achieving high performance in oxide electrodes for low‐temperature lithium‐ion batteries (LT‐LIBs), especially for micron‐scale particles. The introduction of point defects is considered to be effective for accelerating local Li‐ion transport at room temperature, but due to the discontinuity of point defects, the enhancement at low temperatures remains to be verified. Besides, the understanding of defect impact at low temperatures is quite limited. In this study, a micron‐scale vanadium pentoxide (V₂O₅) cathode with abundant oxygen vacancies in bulk phase is successfully synthesized. Such crystal structure tends to form continuous and fast Li‐ion transport channels, facilitating deep lithiation at ultralow temperatures with exceptional rate capability and impressive capacitance retention (74% at −40 °C and 54% at −50 °C). Remarkably, an empirical relationship between oxygen vacancies and low‐temperature Li‐ion storage in micron‐scale oxides is uncovered. Specifically, the degree of lithiation exhibits two distinct trends depending on temperature: a linear increase in response to oxygen vacancy concentration above −40 °C, and an exponential increase below this threshold. The insights gained here highlight the crucial role of high concentrations of point defects at ultralow temperatures, providing a direction for tackling critical challenges of low‐temperature battery technologies.