One-Pot Aqueous Spray Drying of Hierarchical Na3V2(PO4)3 (NVP) Particles for High-Performance Sodium-Ion Batteries

Sodium-ion batteries (NIBs) have been recognized as a promising alternative to lithium-ion batteries (LIBs), especially for stationary large-scale applications that favor inexpensive storage over high energy density, as their cathode materials don’t require scarce and expensive elements such as Li, Co, and Ni. 1,2 Na 3 V 2 (PO 4 ) 3 (NVP) offers high ionic conductivity and long term stability due to its sodium super ionic conductor (NASICON) structure 3 . However, it suffers from poor electronic conductivity and requires energy-intensive synthesis routes 4 . Spray drying has recently become a common energy-effective route but requires organic solvents 5 or complex carbon additives 6 . In this study, a more efficient and sustainable aqueous spray-drying method is presented to synthesize carbon-coated NVP by using L-ascorbic acid as a carbon source. Additionally, the role of conductive additives is explored in low-carbon samples. NVP sodium-ion half cells showed very high reversible capacity (114.7 mAh g -1 at 0.2C), high rate capability (80.8% capacity retention at 30C), and long cycling performance (93.8% capacity retention after 5000 cycles at 10C). The exceptional cycle life makes it a promising candidate for grid level energy storage. Furthermore, if configured without an intercalation anode material, the "host-free" NVP cells hold the promise to substitute the widely used LiFePO 4 batteries for EV applications 7 . References (1) Liu, J. Addressing the Grand Challenges in Energy Storage. Advanced Functional Materials . February 25, 2013, pp 924–928. https://doi.org/10.1002/adfm.201203058. (2) Schneider, S. F.; Bauer, C.; Novák, P.; Berg, E. J. A Modeling Framework to Assess Specific Energy, Costs and Environmental Impacts of Li-Ion and Na-Ion Batteries. Sustain Energy Fuels 2019, 3 (11), 3061–3070. https://doi.org/10.1039/c9se00427k. (3) Zhang, X.; Rui, X.; Chen, D.; Tan, H.; Yang, D.; Huang, S.; Yu, Y. Na 3 V 2 (PO 4 ) 3 : An Advanced Cathode for Sodium-Ion Batteries. Nanoscale . Royal Society of Chemistry February 14, 2019, pp 2556–2576. https://doi.org/10.1039/c8nr09391a. (4) Tang, X.; Ding, H.; Teng, J.; Zhao, H.; Li, J.; Zhang, K. Green and Scalable Synthesis of Na3V2(PO4)3 Cathode and the Study on the Failure Mechanism of Sodium-Ion Batteries. ACS Appl Energy Mater 2023, 6 (16), 8443–8454. https://doi.org/10.1021/acsaem.3c01195. (5) Pi, Y.; Gan, Z.; Li, Z.; Ruan, Y.; Pei, C.; Yu, H.; Han, K.; Ge, Y.; An, Q.; Mai, L. Methanol-Derived High-Performance Na3V2(PO4)3/C: From Kilogram-Scale Synthesis to Pouch Cell Safety Detection. Nanoscale 2020, 12 (41), 21165–21171. https://doi.org/10.1039/d0nr04884d. (6) Zhang, J.; Fang, Y.; Xiao, L.; Qian, J.; Cao, Y.; Ai, X.; Yang, H. Graphene-Scaffolded Na3V2(PO4)3 Microsphere Cathode with High Rate Capability and Cycling Stability for Sodium Ion Batteries. ACS Appl Mater Interfaces 2017, 9 (8), 7177–7184. https://doi.org/10.1021/acsami.6b16000. (7) Ma, B.; Lee, Y.; Bai, P. Dynamic Interfacial Stability Confirmed by Microscopic Optical Operando Experiments Enables High-Retention-Rate Anode-Free Na Metal Full Cells. Advanced Science 2021, 8 (12). https://doi.org/10.1002/advs.202005006. Figure 1