A Novel NASICON‑Type   Na3.5MnCr0.5Ti0.5(PO4)3 Nanofber with Multi‑electron Reaction for High‑Performance Sodium‑Ion Batteries

Abstract:Sodium superionic conductors (NASICONs) show signifcant promise for application in the development of cathodes for sodium-ion batteries (SIBs). However, it remains a major challenge to develop the desired multi-electron reaction cathode with a high specifc capacity and energy density. Herein, we report a novel NASICON-type   Na3.5MnCr0.5Ti0.5(PO4)3 cathode obtained by combining electrospinning and stepwise sintering processes. This cathode exhibits a high discharge capacity of 160.4 mAh   g−1 and operates at a considerable medium voltage of 3.2 V. The   Na3.5MnCr0.5Ti0.5(PO4)3 cathode undergoes a multi-electron redox reaction involving the C r3+/4+ (4.40/4.31 V vs. Na/Na+),   Mn3+/4+ (4.18/4.03 V), M n2+/3+ (3.74/3.41 V), and   Ti3+/4+ (2.04/2.14 V) redox couples. This redox reaction enables a three-electron transfer during the N a+ intercalation/de-intercalation processes. As a result, the N a3.5MnCr0.5Ti0.5(PO4)3 demonstrates a signifcant enhancement in energy density, surpassing other recently reported SIB cathodes. The highly reversible structure evolution and small volume changes during cycling were demonstrated with in-situ X-ray difraction, ensuring outstanding cyclability with 77% capacity retention after 500 cycles. Furthermore, a NMCTP@C//Sb@C full battery was fabricated, which delivered a high energy density of 421 Wh   kg−1 and exhibited good cyclability with 75.7% capacity retention after 100 cycles. The rational design of composition regulation with multi-metal ion substitution holds the potential to unlock new possibilities in achieving high-performance SIBs.

Ting Zhu, Wei Liu, Xiaobin Liao, Mengyao Wang, Hao Fan, Zihe Wei, Congcong Cai, Liyan Yang, Mufang Li, Dong Wang, Ping Hu, Xuanpeng Wang . A Novel NASICON‑Type   Na3.5MnCr0.5Ti0.5(PO4)3 Nanofber with Multi‑electron Reaction for High‑Performance Sodium‑Ion Batteries. Advanced Fiber Materials. (2024).