Air sensitivity of electrode materials in Li/Na ion batteries: Issues and strategies

Abstract With the development of electrode materials in lithium ion batteries—upgrading from LiCoO₂ and LiFePO₄ to Ni‐rich layered oxides, and the shifting of battery systems from high cost lithium ion to low cost sodium ion technology, the air sensitivity of the electrode materials has become an increasingly important issue in both production and application. Furthermore, the air sensitivity of electrode materials must be carefully considered throughout nearly all stages of their life, including material design, synthesis, production, storage, packaging, transportation, and battery assembly. Therefore, a fundamental understanding of the air degradation mechanism of electrode materials and the exploration of new methods to enhance their air stability are of great significance for the development of batteries with better performance. Herein, we provide a review of the issues related to air exposure of electrode materials in Li/Na ion batteries, including factors related to air sensitivity, degradation mechanisms, and recent progress in improving their air stability. The merits and existing challenges of different strategies are presented, and a rational design perspective as well as general principles for evaluating air stability are proposed.image