Due to its high specific capacity and low cost, high-nickel layered oxide LiNiCoO has found promising application as the cathode materials for lithium-ion batteries. However, the crystallographic instability induced by Li/Ni anti-site exchange, the interfacial parasitic reactions and the microcracking caused by internal stress jointly contribute to the mechano-chemical failure of LiNiCoO, leading to its fast capacity decay and high thermal stability concern. In this regard, a Mg/Ta dual-site doping strategy was proposed for LiNiCoO, for which Mg was doped in situ during the synthesis of cathode precursor, while Ta ions were incorporated after the precursor synthesis. This novel synthesis approach leads to unique dual-site occupations of Mg and Ta in the 3a and 3b crystallographic sites respectively. The Mg ions residing in 3a site can function as pillar ions by preventing the Li/Ni anti-site exchange and inhibiting layered to rock-salt phase transition. The Ta ions occupying 3b site not only leads to the expanded lithium layer spacing but also creates interfacial protection and well-ordered microstructure in LiNiCoO. Consequently, the dual-site-doped LiNiCoO outperforms the pristine and single-site-doped samples. For instance, its full cell shows a greatly enhanced cycling stability from 57.3 % to 90.5 % after 300 cycles at 1C/1C and well improved thermal stability from 205.2 °C to 225.6 °C, compared to the pristine sample. This Mg/Ta dual-site doping strategy provides a facile and practical way to improve the electrochemical and thermal performances of high-nickel layered cathode material LiNiCoO.

中文翻译：

---

高镍层状正极材料LiNi0.9Co0.1O2的Mg/Ta双位点掺杂可延长循环时间并提高热稳定性

由于其高比容量和低成本，高镍层状氧化物LiNiCoO作为锂离子电池正极材料具有广阔的应用前景。然而，Li/Ni反位交换引起的晶体不稳定性、界面寄生反应和内应力引起的微裂纹共同导致LiNiCoO的机械化学失效，导致其容量快速衰减和热稳定性高。为此，针对LiNiCoO提出了Mg/Ta双位点掺杂策略，即在阴极前驱体合成过程中原位掺杂Mg，而在前驱体合成后掺入Ta离子。这种新颖的合成方法导致 Mg 和 Ta 分别占据 3a 和 3b 晶体位点的独特双位点。位于3a位点的Mg离子可以通过阻止Li/Ni反位点交换并抑制层状到岩盐相变而起到柱离子的作用。 Ta离子占据3b位不仅导致锂层间距扩大，而且在LiNiCoO中产生界面保护和有序的微观结构。因此，双位点掺杂的 LiNiCoO 优于原始样品和单位点掺杂的样品。例如，与原始样品相比，其全电池在 1C/1C 下循环 300 次后，循环稳定性显着提高，从 57.3% 提高到 90.5%，热稳定性从 205.2 °C 提高到 225.6 °C。这种Mg/Ta双位点掺杂策略为提高高镍层状正极材料LiNiCoO的电化学和热性能提供了一种简便实用的方法。