Microstructure engineering of Ni-rich layered cathodes is crucial for mitigating mechanical degradation induced by anisotropic strain during Li-ion (de)intercalation. While the orientation of primary particles has been extensively controlled using high-valence dopants during calcination, the critical role of the hydroxide precursor in synthesizing radially aligned Ni-rich cathodes, along with the requirements for precursor characteristics, has been overlooked. Here, we present a method for precisely tailoring Ni-rich cathodes with superior radially aligned microstructure by combining strategic precipitation regulation and calcination tuning. Through stepwise control of ammonia concentration and pH during precipitation, elongated primary particles with appropriate size along [001] are promoted, facilitating the formation of radially aligned particles in the precursor. This approach enables the synthesis of LiNi0.94Co0.02Mn0.04O2 cathodes with exceptional radially aligned microstructure across a wide range of calcination temperature. Benefiting from the size-refined and radially aligned particles, as well as high crystallinity, the cathode derived from the tailored hydroxide precursor exhibit a high discharge capacity of 230 mAh g−1 at 0.05 C and 186 mAh g−1 at 5 C, with superb capacity retention of 95.6 % after 100 cycles at 1 C and 25 ℃ in half cell and 93.2 % after 1000 cycles at 1 C and 30 ℃ in full cell.

中文翻译：

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精确调控富镍正极颗粒取向，具有超长循环寿命


富镍层状阴极的微观结构工程对于减轻锂离子嵌入（脱嵌）过程中各向异性应变引起的机械退化至关重要。虽然在煅烧过程中使用高价掺杂剂广泛控制初级颗粒的取向，但氢氧化物前体在合成径向排列的富镍阴极中的关键作用以及对前体特性的要求却被忽视了。在这里，我们提出了一种通过结合策略性沉淀调节和煅烧调节来精确定制具有优异的径向排列微观结构的富镍阴极的方法。通过在沉淀过程中逐步控制氨浓度和pH值，促进了沿[001]方向拉长的具有适当尺寸的初级颗粒，从而促进前体中径向排列颗粒的形成。这种方法能够合成 LiNi0.94Co0.02Mn0.04O2 阴极，在很宽的煅烧温度范围内具有出色的径向排列微观结构。得益于尺寸细化和径向排列的颗粒以及高结晶度，由定制的氢氧化物前体衍生的正极表现出在 0.05 C 下 230 mAh g−1 和 5 C 下 186 mAh g−1 的高放电容量，半电池在 1 C 和 25 ℃ 下循环 100 次后容量保持率为 95.6%，全电池在 1 C 和 30 ℃ 下循环 1000 次后容量保持率为 93.2%。