Abstract
The demands for sustainable energy systems underscores the importance in developing sodium-ion batteries (NIBs) with earth abundant raw materials, enhanced energy density, prolonged lifespan, and reduced cost. Among potential candidates for such advancements, intercalation-type layered transition metal oxide (LTMO) positive electrode materials are attractive due to their notable high theoretical specific capacity and tunable chemistry. However, LTMO electrodes are often subjected to anisotropic changes during cycling. Repeated anisotropic changes cause host structure strain, eventually leading to material degradation. Regulating the electrostatic interactions is generally perceived to be a viable approach for structure stabilization in layered oxides during cycling, but conventional synthesis approaches have been unable to tame the effect. Here, we demonstrate negligible anisotropic changes in layered P2-type Na0.67Ni0.33Mn0.67O2 through regulation of electrostatic repulsion realized by modulation of transition metal ions occupancy. The electrode exhibits a capacity retention of 83.3% in 100 cycles between 2 - 4.3 V, which is significantly better than the 36.9% retention of the pristine sample. Our study emphasizes the highly correlated nature of the redox mechanism that deserves the attention and is critical for high-energy batteries.
Published Version
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