Liu Meng, Jiang Yang, Qin Yinping, Feng Zhijie, Wang Deyu, Guo Bingkun
Materials Genome Institute of Shanghai University, Shanghai 200444, China.
Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China.
ACS Appl Mater Interfaces. 2021 Nov 24;13(46):55072-55079. doi: 10.1021/acsami.1c16482. Epub 2021 Nov 11.
Surficial residual LiOH and/or LiCO on Ni-rich cathodes arouse troubles for their practical applications, such as slurry gelling and durability degrading. To assure acceptable performance, the strategy of "washing and heat treatment" is generally utilized to remove them in industry, which is unavoidable to generate plenty of wastewater. In this work, we investigated the mechanism of slurry gelling caused by residual lithium on Ni-rich materials and then proposed a simple and efficient method to convert the detrimental residual lithium to the useful surface layer of LiF or LiBOB at 220 °C without water washing. As a result, the basicity of modified samples is lowered to 11.48 and 11.60 from 12.05 of the pristine, respectively. Owing to the beneficial effect of the surface layer, the treated samples deliver a discharge capacity of 189.5 and 187.9 mA h g and retain 84.1 and 82.8% of the initial capacity under 1 C after 300 cycles, which is much better than that of the untreated material (57.8%). The comprehensive performances of the modified samples in this work are very close to those of the material treated with the industrial method, demonstrating the advantage of this strategy to further reduce the cost of material production.
富镍阴极上的表面残留LiOH和/或LiCO给其实际应用带来了麻烦，比如浆料胶凝和耐久性下降。为确保性能可接受，工业上通常采用“洗涤和热处理”策略来去除它们，但这不可避免地会产生大量废水。在这项工作中，我们研究了富镍材料上残留锂导致浆料胶凝的机理，然后提出了一种简单有效的方法，即在220℃下无需水洗就能将有害的残留锂转化为有用的LiF或LiBOB表面层。结果，改性样品的碱度分别从原始样品的12.05降至11.48和11.60。由于表面层的有益作用，处理后的样品在1C下300次循环后放电容量分别为189.5和187.9 mA h g，保留了初始容量的84.1%和82.8%，这比未处理材料（57.8%）要好得多。这项工作中改性样品的综合性能与采用工业方法处理的材料非常接近，证明了该策略在进一步降低材料生产成本方面的优势。
