A novel kilogram-scale preparation method of the Na3.5V1.5Mn0.5(PO4)3 cathode material with excellent performance for sodium-ion pouch cells

Abstract

NASICON-type Na_3.5V_1.5Mn_0.5(PO₄)₃ (NVMP) has been developed as a promising cathode material for sodium-ion batteries (SIBs). However, low-cost, environmentally friendly industrialization of NVMP is still limited. In this study, a nitrogen-doped carbon coated NVMP cathode material with enhanced conductivity as well as excellent rate performance was obtained by the suspensoid quick-drying method. Due to the advantage of the suspensoid quick-drying method, the mass prepared cathode material has fewer impurities, a more complete crystal structure, a more uniform carbon coating effect and better processing performance, which is conducive to improving the electrochemical performance and processability of the cathode, enhancing the cycling life and the energy density of the battery. Consequently, the electrochemical results show that compared with NVMP-2 obtained by the solid-state method, the as-prepared NVMP-1 cathode (more than 3 kg) exhibits an excellent rate performance of 80.2 mA h g⁻¹ at 50C and an impressive capacity retention of 77.8% after 8000 cycles at 10C. DFT computations indicated that substituting V³⁺ with Mn²⁺ can enhance the crystal structure stability and electron conductivity. In addition, the assembled pouch cells display excellent low-temperature performance and cycling performance along with superior safety, which are much better than those of lithium-ion batteries (LIBs), suggesting that the NASICON-based pouch cells lay a foundation for the large-scale application of sodium-ion batteries.