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

Yang, Tingting; Li, Qiang; Liu, Zhengbo; Li, Tianyi; Wiaderek, Kamila M; Liu, Yingxia; Yin, Zijia; Lan, Si et al. · Adv Mater · 2024

basic_science · Level V

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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 (Na<sub>x</sub>MnO<sub>2</sub>, 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 Na<sub>0.637</sub>B<sub>0.038</sub>MnO<sub>2</sub> (B-NMO) materials inhibits the deformation of MnO<sub>6</sub> octahedra, which finally achieves a gentle structural transition during the deep sodiation process. B-NMO electrode exhibits a high capacity (141 mAh g<sup>-1</sup>) 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.