| Affiliation: | 1. Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals, Key Laboratory of Green Chemical Media and Reactions Ministry of Education, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan, 453007 China;2. Department of Materials Science and Engineering, Shenzhen Key Laboratory of Interfacial Science and Engineering of Materials, Guangdong-Hong Kong-Macao Joint Laboratory for Photonic-Thermal-Electrical Energy Materials and Devices, Southern University of Science and Technology, Shenzhen, Guangdong, 518055 China Department of Materials Engineering, KU Leuven, Leuven, 3001 Belgium;3. Department of Materials Science and Engineering, Shenzhen Key Laboratory of Interfacial Science and Engineering of Materials, Guangdong-Hong Kong-Macao Joint Laboratory for Photonic-Thermal-Electrical Energy Materials and Devices, Southern University of Science and Technology, Shenzhen, Guangdong, 518055 China;4. Department of Mechanical and Energy Engineering, Key Laboratory of Energy Conversion and Storage Technologies, Southern University of Science and Technology, Shenzhen, Guangdong, 518055 China |
| Abstract: | Manganese-based Na superionic conductors (NASICONs) Na4MnCr(PO4)3 with three-electron reaction are attractive cathode materials for sodium-ion batteries. However, the irreversible distortion of Mn local structure leads to sluggish electrode kinetics, voltage hysteresis, and poor cycling stability. Here, SiO4 is introduced to substitute PO4 to modulate the local environment of Mn to activate the redox activity and stabilize the reversibility of Na4MnCr(PO4)2.9(SiO4)0.1 (NMCP-Si). A combined experimental and theoretical investigation have been undertaken to reveal the evolution of electronic structures and Na storage properties associated with SiO4 substitution. The NMCP-Si exhibits much-enhanced rate capability and cycling stability, being attributed to the unique Jahn-Teller distortion (Mn3+) that facilitates sodium de/insertion kinetics by optimizing the Na ion diffusion channels. This work addresses the challenge of stabilizing the structure of Mn-based NASICONs and represents a breakthrough in understanding how to improve the Na+ conductivity by regulating local structure. |
