Details

Autor(en) / Beteiligte

• Gu, Zhen‐Yi
• Guo, Jin‐Zhi
• Zhao, Xin‐Xin
• Wang, Xiao‐Tong
• Xie, Dan
• Sun, Zhong‐Hui
• Zhao, Chen‐De
• Liang, Hao‐Jie
• Li, Wen‐Hao
• Wu, Xing‐Long

Titel

High‐ionicity fluorophosphate lattice via aliovalent substitution as advanced cathode materials in sodium‐ion batteries

Ist Teil von

• InfoMat, 2021-06, Vol.3 (6), p.694-704

Ort / Verlag

Melbourne: John Wiley & Sons, Inc

Erscheinungsjahr

2021

Link zum Volltext

Quelle

Wiley Online Library - AutoHoldings Journals

Beschreibungen/Notizen

• As a cathode for sodium‐ion batteries (SIBs), Na3V2(PO4)2F3 (NVPF) with 3D open framework is a promising candidate due to its high working voltage and large theoretical capacity. However, the severe capacity degradation and poor rate capability hinder its practical applications. The present study demonstrated the optimization of Na‐storage performance of NVPF via delicate lattice modulation. Aliovalent substitution of V3+ at Na+ in NVPF induces the generation of electronic defects and expansion of Na+‐migration channels, resulting in the enhancement in electronic conductivity and acceleration of Na+‐migration kinetics. It is disclosed that the formed stronger NaO bonds with high ionicity than VO bonds lead to the significant increase in structural stability and ionicity in the Na+‐substituted NVPF (NVPF‐Nax). The aforementioned effects of Na+ substitution achieve the unprecedented electrochemical performance in the optimized Na3.14V1.93Na0.07(PO4)2F3 (NVPF‐Na0.07). As a result, NVPF‐Na0.07 delivers a high‐rate capability (77.5 mAh g−1 at 20 C) and ultralong cycle life (only 0.027% capacity decay per cycle over 1000 cycles at 10 C). Sodium‐ion full cells are designed using NVPF‐Na0.07 as cathode and Se@reduced graphene oxide as anode. The full cells exhibit excellent wide‐temperature electrochemical performance from −25 to 25°C with an outstanding rate capability (96.3 mAh g−1 at 20 C). Furthermore, it delivered an excellent cycling performance over 300 cycles with a capacity retention exceeding 90% at 0.5 C under different temperatures. This study demonstrates a feasible strategy for the development of advanced cathode materials with excellent electrochemical properties to achieve high‐efficiency energy storage. An advanced Na3.14V1.93Na0.07(PO4)2F3 cathode with high ionicity and excellent energy‐storage performance is prepared via aliovalent substitution of V3+ at Na+ sites. It exhibits the higher structural stability and improved electron/ion‐transport kinetics than the pristine Na3V2(PO4)2F3 owing to the stronger NaO and VO bonds, thereby extending the cycle life of NASICON cathode materials.