As the demand for high-energy batteries to power electric vehicles continues to grow, Ni-rich cathode materials have emerged as promising candidates due to their high capacity. However, these materials are prone to rapid degradation under increased voltages, posing significant challenges for their long-term stability and safety. In this study, we investigate the effects of tantalum (Ta) doping on the performance and stability of LiNi_0.80Mn_0.1Co_0.1O₂ (NMC811) cathode materials. Using a combined theoretical and experimental approach, we employ density functional theory (DFT) and cluster expansion models to analyze the electronic structure and oxygen vacancy formation enthalpy in Ta-doped NMC811. Experimental validation is conducted using cycling and gas measurements via on-line electrochemical mass spectrometry (OEMS) on in-house synthesized cathode active materials. Both theoretical and experimental approaches show an improvement in oxygen binding due to tantalum doping, with the DFT results highlighting the impact of Ni⁴⁺ concentration on the proximity of the vacancy. Our results suggest that Ta doping inhibits the formation of oxygen vacancy-induced side phases, reducing cracking and enhancing the longevity and safety of Ni-rich cathodes.

中文翻译：

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通过 Ta 掺杂增强富镍正极材料的稳定性和性能：理论与实验相结合的研究


随着电动汽车对高能电池的需求不断增长，富镍正极材料因其高容量而成为有前途的候选材料。然而，这些材料在电压增加的情况下容易快速降解，对其长期稳定性和安全性构成重大挑战。在本研究中，我们研究了钽 （Ta） 掺杂对 LiNi_0.80Mn_0.1Co_0.1O₂ （NMC811） 正极材料的性能和稳定性的影响。采用理论和实验相结合的方法，我们采用密度泛函理论 （DFT） 和团簇展开模型来分析 Ta 掺杂 NMC811 中的电子结构和氧空位形成焓。通过在线电化学质谱 （OEMS） 对内部合成的阴极活性材料进行循环和气体测量，进行实验验证。理论和实验方法都表明，由于钽掺杂，氧结合得到改善，DFT 结果突出了 Ni⁴⁺ 浓度对空位接近度的影响。我们的结果表明，Ta 掺杂抑制了氧空位诱导的侧相的形成，减少了开裂并提高了富镍阴极的寿命和安全性。