Influence of NCM Particle Cracking on Kinetics of Lithium-Ion Batteries with Liquid or Solid Electrolyte
Influence of NCM Particle Cracking on Kinetics of Lithium-Ion Batteries with Liquid or Solid Electrolyte
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DOI：
10.1149/1945-7111/ab9a2c
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发表时间：
2020-06-17
影响因子：
3.9
通讯作者：
Janek, Juergen
中科院分区：
文献类型：
--
作者：
Ruess, Raffael;Schweidler, Simon;Janek, Juergen
在液体电解质型锂离子电池中，富镍NCM（Li1+x(Ni1-y-zCoyMnz)(1)-xO(2)）作为正极活性材料具有高放电容量和良好的材料利用率，而尽管过去在提高固体电解质的电导率和稳定性方面做出了努力，但固态电池的性能较差。在这项工作中，我们通过研究 NCM-811 作为典型富镍材料的锂传输动力学，确定了造成这种差异的主要原因。在电池半电池的第一次充电过程中，裂纹形成并被分布在 NCM 二次颗粒内的液体电解质填充。通过增加电化学活性表面积和减小有效颗粒尺寸，极大地改善了锂化学扩散和电荷转移动力学。由于固体电解质的机械刚性，固态电池不会受到这些裂纹的影响。因此，二次粒子破裂改善了液体电解质中NCM的初始充电和放电动力学，同时降低了固体电解质中的相应动力学。考虑到这些动力学限制，通过结合恒电流和恒电位放电，我们发现，以 LiNi0.8Co0.1Mn0.1O2 作为正极活性材料和 Li6PS5Cl 作为固体电解质的固态电池半电池在放电容量约为 173 mAh g(NCM)(-1) 时可以达到约 89% 的库伦效率。 (C) 2020 作者。由 IOP Publishing Limited 代表电化学会出版。
In liquid electrolyte-type lithium-ion batteries, Nickel-rich NCM (Li1+x(Ni1-y-zCoyMnz)(1)-xO(2)) as cathode active material allows for high discharge capacities and good material utilization, while solid-state batteries perform worse despite the past efforts in improving solid electrolyte conductivity and stability. In this work, we identify major reasons for this discrepancy by investigating the lithium transport kinetics in NCM-811 as typical Ni-rich material. During the first charge of battery half-cells, cracks form and are filled by the liquid electrolyte distributing inside the secondary particles of NCM. This drastically improves both the lithium chemical diffusion and charge transfer kinetics by increasing the electrochemically active surface area and reducing the effective particle size. Solid-state batteries are not affected by these cracks because of the mechanical rigidity of solid electrolytes. Hence, secondary particle cracking improves the initial charge and discharge kinetics of NCM in liquid electrolytes, while it degrades the corresponding kinetics in solid electrolytes. Accounting for these kinetic limitations by combining galvanostatic and potentiostatic discharge, we show that Coulombic efficiencies of about 89% at discharge capacities of about 173 mAh g(NCM)(-1) can be reached in solid-state battery half-cells with LiNi0.8Co0.1Mn0.1O2 as cathode active material and Li6PS5Cl as solid electrolyte. (C) 2020 The Author(s). Published on behalf of The Electrochemical Society by IOP Publishing Limited.