High-Capacity NASICON-Type Na<sub>3</sub>V<sub>1.8</sub>Cr<sub>0.2</sub>(PO<sub>4</sub>)<sub>3</sub> Cathode for High-Performance Sodium-Ion Batteries
Jiawen Hu, Zixing Chen, Wenhao Ye, Qianqian Liang, Xinwei Li, Xu Li, Changsheng Ding, Yanfeng Gao
Abstract
Na 3 V 2 (PO 4 ) 3 (NVP) has been deemed a promising cathode material for sodium-ion batteries (SIBs). However, the low sodium-ion diffusion kinetics and inferior electronic conductivity of NVP are two major bottlenecks facing its practical application. Realizing multielectron redox reactions in NVP by a doping strategy is very efficient to enhance electronic conductivity and specific capacity, as well as ensuring structural stability of NVP. In this work, Cr-doped NVP, Na 3 V 2– x Cr x (PO 4 ) 3 (0 ≤ x ≤ 0.6), is prepared by a sol–gel method, and its electrochemical performance is fully investigated. The optimized Cr-doping content is x = 0.2, and the V 4+ /V 5+ redox couple is activated under higher voltage by Cr doping, which results in the Na 3 V 1.8 Cr 0.2 (PO 4 ) 3 (NVCP-2) cathode delivering a high reversible capacity of 221.6 mAh g –1 at 0.1 C and high-rate capability with a reversible capacity of 120.0 mAh g –1 at 20 C in 1.0–4.3 V. Moreover, the NVCP-2 also shows an improved discharge capacity of 103.6 mAh g –1 at 0.1 C and cycling stability compared with bare NVP in 2.4–4.3 V. Furthermore, the NVCP-2 cathode also exhibits excellent electrochemical performance in a NVCP-2||Na 3 Zr 2 Si 2 PO 12 ||Na solid-state battery. This work demonstrates that the NVCP-2 cathode has substantial potential for application in high-performance SIBs.