You Ya, Celio Hugo, Li Jianyu, Dolocan Andrei, Manthiram Arumugam
Materials Science and Engineering Program and Texas Materials Institute, The University of Texas at Austin, Austin, TX, 78712, USA.
Angew Chem Int Ed Engl. 2018 May 28;57(22):6480-6485. doi: 10.1002/anie.201801533. Epub 2018 Apr 25.
High-Ni layered oxides are promising next-generation cathodes for lithium-ion batteries owing to their high capacity and lower cost. However, as the Ni content increases over 70 %, they have a high dynamic affinity towards moisture and CO in ambient air, primarily reacting to form LiOH, Li CO , and LiHCO on the surface, which is commonly termed "residual lithium". Air exposure occurs after synthesis as it is common practice to handle and store them under ambient conditions. The air exposure leads to significant performance losses, and hampers the electrode fabrication, impeding their practical viability. Herein, we show that substituting a small amount of Al for Ni in the crystal lattice notably improves the chemical stability against air by limiting the formation of LiOH, Li CO , LiHCO , and NiO in the near-surface region. The Al-doped high-Ni oxides display a high capacity retention with excellent rate capability and cycling stability after being exposed to air for 30 days.
高镍层状氧化物因其高容量和低成本而有望成为下一代锂离子电池的阴极材料。然而，当镍含量超过70%时，它们对环境空气中的水分和一氧化碳具有很高的动态亲和力，主要反应是在表面形成LiOH、Li₂CO₃和LiHCO₃，这通常被称为“残余锂”。合成后会发生空气暴露，因为在环境条件下处理和储存它们是常见的做法。空气暴露会导致显著的性能损失，并阻碍电极制造，从而妨碍它们的实际可行性。在此，我们表明，在晶格中用少量铝替代镍，通过限制近表面区域LiOH、Li₂CO₃、LiHCO₃和NiO的形成，显著提高了对空气的化学稳定性。掺杂铝的高镍氧化物在暴露于空气中30天后仍具有高容量保持率、优异的倍率性能和循环稳定性。
