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首页> 外文期刊>Advanced Functional Materials >Sodium-Ion Batteries: Building Effective Layered Cathode Materials with Long-Term Cycling by Modifying the Surface via Sodium Phosphate
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Sodium-Ion Batteries: Building Effective Layered Cathode Materials with Long-Term Cycling by Modifying the Surface via Sodium Phosphate

机译：钠离子电池：通过磷酸钠修饰表面来构建具有长期循环作用的有效分层阴极材料

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Surface stabilization of cathode materials is urgent for guaranteeing long-term cyclability, and is important in Na cells where a corrosive Na-based electrolyte is used. The surface of P2-type layered Na-2/3[Ni1/3Mn2/3]O-2 is modified with ionic, conducting sodium phosphate (NaPO3) nanolayers, approximate to 10 nm in thickness, via melt-impregnation at 300 degrees C; the nanolayers are autogenously formed from the reaction of NH4H2PO4 with surface sodium residues. Although the material suffers from a large anisotropic change in the c-axis due to transformation from the P2 to O2 phase above 4 V versus Na+/Na, the NaPO3-coated Na-2/3[Ni1/3Mn2/3]O-2/hard carbon full cell exhibits excellent capacity retention for 300 cycles, with 73% retention. The surface NaPO3 nanolayers positively impact the cell performance by scavenging HF and H2O in the electrolyte, leading to less formation of byproducts on the surface of the cathodes, which lowers the cell resistance, as evidenced by X-ray photoelectron spectroscopy and time-of-flight secondary-ion mass spectroscopy. Time-resolved in situ high-temperature X-ray diffraction study reveals that the NaPO3 coating layer is delayed for decomposition to Mn3O4, thereby suppressing oxygen release in the highly desodiated state, enabling delay of exothermic decomposition. The findings presented herein are applicable to the development of high-voltage cathode materials for sodium batteries.
机译：阴极材料的表面稳定化对于保证长期可循环性非常重要，并且在使用腐蚀性Na基电解质的Na电池中非常重要。 P2型层状Na-2 / 3 [Ni1 / 3Mn2 / 3] O-2的表面经过300摄氏度的熔融浸渍，经离子导电磷酸钠（NaPO3）纳米层改性，厚度约10 nm。 ;纳米层是由NH4H2PO4与表面钠残基的反应自生形成的。尽管该材料由于相对于Na + / Na从4 V以上从P2转变为O2相而在c轴上遭受较大的各向异性变化，但涂有NaPO3的Na-2 / 3 [Ni1 / 3Mn2 / 3] O-2 /硬碳全电池在300次循环中表现出出色的容量保持率，保留率达73％。 X射线光电子能谱和时间分析证明，表面NaPO3纳米层通过清除电解质中的HF和H2O积极地影响电池性能，从而导致在阴极表面上形成较少的副产物，从而降低了电池电阻。飞行二次离子质谱时间分辨的原位高温X射线衍射研究表明，NaPO3涂层被延迟分解为Mn3O4，从而抑制了高度脱氧状态下的氧气释放，从而使得放热分解得以延迟。本文介绍的发现适用于钠电池高压阴极材料的开发。

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