| Affiliation: | 1. School of Materials Science and Engineering, North University of China, Taiyuan, 030051 China
Institute of Advanced Energy Materials and Systems, North University of China, Taiyuan, 030051 China;2. School of Electronics and Information Engineering, Sichuan University, Chengdu, 610065 China;3. School of Materials Science and Engineering, North University of China, Taiyuan, 030051 China;4. College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan, 030024 China;5. Institute of Advanced Energy Materials and Systems, North University of China, Taiyuan, 030051 China |
| Abstract: | Na3V2(PO4)3 is regarded as a promising candidate for sodium ion batteries. Nevertheless, the poor electronic conductivity, low capacities, and unstable structure limit its further investigations. Herein, a new type of Fe/Mn/Co co-substituted Na3V2(PO4)3 with nitrogen-doped carbon coating (NFMC) by a facile sol-gel route is synthesized. The introduced elements feature in both crystal bulk and carbon coating layer. Suitable heteroatom substitution activates more effective Na+ to participate in electrochemical process and reinforce the structure. An extra high voltage platform at 3.8 V resulting from the multi-element synergy (Mn2+/Mn3+/Mn4+; Co2+/Co3+; V4+/V5+) is stably and reversibly existed in NFMC to supply added capacities, which is investigated by quantum physics calculations. The high flux paths for Na+ migration and spin quantum state distribution in NFMC are demonstrated by molar magneton calculation. Significantly, the generated polyatomic coordination environment of M? N? C (M = Fe/Co/Mn) in carbon layer is first proposed. The most optimized combination structures are obtained from 69 possible structures and demonstrated by X-ray absorption spectroscopy. The superior electrochemical performance is precisely forecasted by innovative deep learning. Predicted values with high precision are obtained based on a small number of operating data, extremely short development period, and provide real-time status references for safer use. |
