Affiliation:
1. College of Chemistry Xiangtan University Xiangtan 411105 China
2. School of Science Hunan University of Technology and Business Changsha 410205 China
3. National Local Joint Engineering Laboratory for Key Materials of New Energy Storage Battery National Base for International Science & Technology Cooperation Key Laboratory of Environmentally Friendly Chemistry and Application of Ministry of Education Xiangtan 411105 China
Abstract
AbstractNa0.67Ni0.33Mn0.67O2 (NNMO) is one of the most promising cathodes for Sodium‐ion batteries. However, due to undesired P2−O2 phase transition at high voltage during Na+ extraction, its cyclic stability and coulomb efficiency are greatly adversely affected. Herein, electrochemically active Fe3+ ions substituted Na0.67Ni0.23Fe0.1Mn0.67O2 samples were prepared by both sol‐gel method (NNFMO‐SG) and solid phase method (NNFMO‐SP). It has been found that Fe substitution can suppress P2−O2 phase transition with a stable P2 phase during charging and discharging. Additionally, it also suppresses Na+/vacancy ordering, expands the slab‐spacing of the structure and improves the reversibility of the redox of anions. Owing to the combined advantages, NNFMO‐SG material exhibits the enhanced rate capability (70.1 mAh/g at 1000 mA/g) and excellent cycling stability (75.3 % capacity retention after 100 cycles at 200 mA/g).
Funder
National Natural Science Foundation of China