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NASICON-type Na3.5V1.5Mn0.5(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. [ABSTRACT FROM AUTHOR]

Na 4 Fe 3 (PO 4) 2 P 2 O 7 (NFPP) has been developed as the most promising polyanion cathode for sodium-ion batteries due to its excellent electrochemical performance, high safety properties, and environmental friendliness. However, the electrochemically inactive impurity (m-NaFePO 4) will inevitably generate during synthesis process, which decreases the practical capacity of NFPP significantly. In this paper, a novel Na 3.6 Fe 2.6 (PO 4) 1.6 P 2 O 7 cathode material with excellent performance is successfully exploited by optimizing sodium-iron ratio to reduce the formation of impurity phases. In a series of as-prepared materials with sodium-iron ratio between 1.33–1.50, Na 3.6 Fe 2.6 (PO 4) 1.6 P 2 O 7 exhibits the highest discharge specific capacity (110.3 mAh g−1 at 0.1C), best rate capability (84.4 mAh g−1 at 30 C) and cycle performance (78.2 % capacity retention after 3000 cycles at 20 C). Furthermore, 20 Kg of the Na 3.6 Fe 2.6 (PO 4) 1.6 P 2 O 7 cathode material is prepared by spray drying method, which has been successfully applied in sodium-ion pouch cells (12 Ah) with a commercial hard carbon as the anode materials. The assembled pouch cells display excellent cycle performance (82.4 % capacity retention after 2000 cycles at 1 C), rate capability (88 % capacity retention at 30 C) and low-temperature performance (74 % capacity retention at −40 °C). [Display omitted] • High performance Na 3.6 Fe 2.6 (PO 4) 1.6 P 2 O 7 was prepared by optimizing sodium-iron ratio. • The kilogram-scale Na 3.6 Fe 2.6 (PO 4) 1.6 P 2 O 7 was prepared and assembled into pouch cell. • The Na 3.6 Fe 2.6 (PO 4) 1.6 P 2 O 7 //HC pouch cell with excellent comprehensive performance. [ABSTRACT FROM AUTHOR]