Enhancing electrochemical properties of PNb9O25 anodes at elevated temperature via surface modification by nitrogen-doped carbon

Abstract

Improving the performance of electrode materials is a crucial step for enhancing the intrinsic safety of batteries, especially during high operating temperature and rapid charge/discharge processes. The aggravation of side reactions caused by electro-thermal behaviors especially at high operating temperature is the main factor causing the instability of surface structure. In this work, we focus on the titanium-free, coarse-grained PNb9O25 (PNO) anode and enhance its electrochemical performance at an elevated temperature of 45 °C using a nitrogen-doped carbon (N-C) surface modification strategy. The homogeneous N-C passivation layer provides favorable electronic conductivity and fast Li+ diffusion kinetics, significantly reducing chemical reactivity and improving the interfacial charge transfer capability. As a result, PNO@N-C demonstrates exceptional high-rate capacity retention (249 mAh g–1 at 0.1 A g–1 and 173 mAh g–1 at 6 A g–1 under 45 °C) and superior cycling stability, maintaining a high capacity of 147 mAh g–1 after 1000 rapid charging cycles at a current density of 4 A g–1 (∼20 C, 45 °C). This approach provides a practical strategy for further development of electrode materials for high-rate lithium-ion batteries operating at high temperatures.