Stabilizing the Deep Sodiation Process in Layered Sodium Manganese Cathodes by Anchoring Boron Ions

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Abstract
Advanced high‐energy‐density sodium‐ion batteries (SIBs) are inseparable from cathode materials with high specific capacities. Layered manganese‐rich oxides (NaxMnO2, 0.6 ≤ x ≤1) are promising cathode materials owing to their ease of intercalation and extraction of a considerable amount of sodium ions. However, lattice interactions, especially electrostatic repulsive forces and anisotropic stresses, are usually caused by deep desodiatin/sodiation process, resulting in intragranular cracks and capacity degradation in SIBs. Here, boron ions are introduced into the layered structure to build up B─O─Mn bonds. The regulated electronic structure in Na0.637B0.038MnO2 (B‐NMO) materials inhibits the deformation of MnO6 octahedra, which finally achieves a gentle structural transition during the deep sodiation process. B‐NMO electrode exhibits a high capacity (141 mAh g–1) at 1 C with a capacity retention of 81% after 100 cycles. Therefore, anchoring boron to manganese‐rich materials inhibits the detrimental structural evolution of deep sodiation and can be used to obtain excellent cathode materials for SIBs.
Funding Information
  • National Key Research and Development Program of China (2020YFA0406203)
  • National Natural Science Foundation of China (22175018)
  • U.S. Department of Energy (DE‐AC02‐06CH11357)

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