Improving Thermodynamic Stability of nano-LiMn 2 O 4 for Li-Ion Battery Cathode
Improving Thermodynamic Stability of nano-LiMn 2 O 4 for Li-Ion Battery Cathode
复制标题
提高锂离子电池正极纳米LiMn 2 O 4 的热力学稳定性
DOI：
10.1021/acs.chemmater.0c04305
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发表时间：
2021
影响因子：
8.6
通讯作者：
Castro, Ricardo H.
中科院分区：
文献类型：
--
作者：
Nakajima, Kimiko;Souza, Flavio L.;Freitas, Andre L.;Thron, Andrew;Castro, Ricardo H.
纳米材料在阴极应用中可以表现出更好的电化学性能，但其固有的高表面积会导致非常规的不稳定性，导致有限数量的电池循环后容量下降。这是因为它们的高表面反应性，这使得它们更容易受到诸如晶粒生长、烧结、溶解和相变等现象的影响。热力学上，这些可以归因于增加的贡献的界面结晶的系统的总自由能。锂基材料界面热力学实验数据的缺乏阻碍了减轻这种降解机制的策略。在这项研究中，界面能的LiMn 2 O 4纳米粒子直接测量的第一次使用量热法，并探讨了使用掺杂剂（钪）的表面和晶界能的操纵的可能性。我们发现，未掺杂的LiMn 2 O 4纳米粒子的表面能为0.85 J/m2，这是显着低于LiCoO 2。此外，钪的引入进一步降低了LiMn 2 O 4的表面能，导致对粗化的稳定性和对水的反应性得到改善，这可能会导致电池应用中更稳定的阴极材料。
Nanomaterials can exhibit improved electrochemical performance in cathode applications, but their inherently high surface areas cause unconventional instability, leading to capacity fading after a limited number of battery cycles. This is because of their high surface reactivity, which makes them more susceptible to phenomena such as grain growth, sintering, solubilization, and phase transformations. Thermodynamically, these can be attributed to an increased contribution of interfacial enthalpies to the total free energy of the system. The lack of experimental data on the interfacial thermodynamics of lithium-based materials has hindered strategies to mitigate such degradation mechanisms. In this study, interfacial energies of LiMn2O4nanoparticles were directly measured for the first time using calorimetry, and the possibility of thermodynamically manipulating both surface and grain boundary energies using a dopant (scandium) was explored. We show that undoped LiMn2O4nanoparticles have a surface energy of 0.85 J/m2, which is significantly lower than that of LiCoO2. Moreover, introducing scandium further lowered the LiMn2O4surface energy, leading to a demonstrated improved stability against coarsening and reactivity to water, which can potentially result in more stable cathode materials for battery applications.