Ni-rich layered ternary cathodes are promising candidates thanks to their low toxic Co-content and high energy density (∼800 Wh/kg). However, a critical challenge in developing Ni-rich cathodes is to improve cyclic stability, especially under high voltage (>4.3 V), which directly affects the performance and lifespan of the battery. In this study, niobium-doped strontium titanate (Nb-STO) is successfully synthesized via a facile solvothermal method and used as a surface modification layer onto the LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) cathode. The results exhibited that the Nb-STO modification significantly improved the cycling stability of the cathode material even under high-voltage (4.5 V) operational conditions. In particular, the best sample in our work could provide a high discharge capacity of ∼190 mAh/g after 100 cycles under 1 C with capacity retention over 84% in the voltage range of 3.0–4.5 V, superior to the pristine NCM811 (∼61%) and pure STO modified STO-811-600 (∼76%) samples under the same conditions. The improved electrochemical performance and stability of NCM811 under high voltage should be attributed to not only preventing the dissolution of the transition metals, further reducing the electrolyte’s degradation by the end of charge, but also alleviating the internal resistance growth from uncontrollable cathode–electrolyte interface (CEI) evolution. These findings suggest that the as-synthesized STO with an optimized Nb-doping ratio could be a promising candidate for stabilizing Ni-rich cathode materials to facilitate the widespread commercialization of Ni-rich cathodes in modern LIBs.

中文翻译：

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通过简易溶剂热合成铌掺杂钛酸锶稳定富镍阴极的高压性能


富镍层状三元阴极由于其低毒性钴含量和高能量密度（∼800 Wh/kg）而成为有前途的候选者。然而，开发富镍正极的一个关键挑战是提高循环稳定性，特别是在高电压（>4.3 V）下，这直接影响电池的性能和寿命。在本研究中，通过简单的溶剂热方法成功合成了铌掺杂钛酸锶（Nb-STO），并将其用作LiNi _0.8 Co _0.1 Mn _0.1 O ₂ (NCM811) 阴极。结果表明，即使在高电压（4.5 V）工作条件下，Nb-STO 改性也显着提高了正极材料的循环稳定性。特别是，我们工作中最好的样品在 1 C 下循环 100 次后可提供~190 mAh/g 的高放电容量，在 3.0-4.5 V 电压范围内容量保持率超过 84%，优于原始 NCM811（~ 61%) 和纯 STO 修饰的 STO-811-600 (∼76%) 样品在相同条件下。 NCM811在高电压下电化学性能和稳定性的提高不仅可以防止过渡金属的溶解，进一步减少充电结束时电解质的降解，还可以减轻由于不可控的正极-电解质界面而导致的内阻增长。 CEI）的演变。这些发现表明，具有优化铌掺杂比的合成STO可能是稳定富镍正极材料的有前途的候选者，以促进富镍正极在现代锂离子电池中的广泛商业化。