A Disordered Rock Salt Anode for Long-Lived All-Vanadium Sodium-Ion Battery
Haichen Lin, Zishen Wang, Oliver Solares, Steven Huber, Jan Hofmann, Simon Danitz, Wei-Tao Peng, Ke Zhou, Ping-Che Lee, Haodong Liu, Zeyu Hui, Runze Liu, Mengchen Liu, Wei Tang, Junlin Wu, Zheng Chen, Karena W. Chapman, Shyue Ping Ong, Ping Liu
Rechargeable batteries wherein both the cathode and the anode are vanadium-based phases are promising grid-energy storage candidates, offering long cycle life and easy recycling. However, their system-level energy density must be improved to lower their footprint and operating costs. In this work, an all-vanadium sodium-ion battery that uses a new disordered rock salt (DRS) anode, Na3V2O5 (DRS-NVO), is proposed. For DRS-NVO, ≈2 Na+ ions can be reversibly cycled at ≈0.7 V versus Na/Na+. Structural characterization by X-ray diffraction and pair distribution function (PDF) analysis reveal increased local distortions during Na+ insertion but the overall DRS structure is maintained. The material shows exceptional stability and rate capability, achieving 10 000 cycles in half-cell tests at rates of up to 20 C. Molecular dynamics simulations produce voltage profiles and ion diffusivities in good agreement with experimental results. Pairing the DRS-NVO anode with a Na3V2(PO4)3 (NVP) cathode yields a cell (NVO|NVP) voltage of 2.7 V, with symmetric voltage profiles and an energy efficiency >93%. This all-vanadium sodium-ion battery exhibits excellent cycling stability, retaining 80% of its capacity after 3 000 cycles. Levelized cost-of-storage (LCOS) evaluations based on a cell design model confirm the cost-effectiveness, positioning NVO|NVP as a competitive grid-scale energy storage solution.