Dual Substitution Strategy in Co-Free Layered Cathode Materials for Superior Lithium Ion Batteries.
Dual Substitution Strategy in Co-Free Layered Cathode Materials for Superior Lithium Ion Batteries.
复制标题
DOI：
10.1021/acsami.1c01221
复制
发表时间：
2021-04
影响因子：
9.5
通讯作者：
Guofeng Jia;Faqiang Li;Jue Wang;Suqin Liu;Yuliang Yang
中科院分区：
文献类型：
--
作者：
Guofeng Jia;Faqiang Li;Jue Wang;Suqin Liu;Yuliang Yang
通过分别用Na和Al部分取代Li和Ni，将双取代策略引入到无Co层状材料LiNi 0.5Mn 0.5O2中，以获得用于锂离子电池的上级正极材料。Na+离子在锂层中起到“支柱”和“阳离子屏障”的作用，而Al 3+离子在稳定结构和晶格氧方面起到辅助作用，以提高电化学性能和安全性。晶格氧的稳定性来自于Ni和O之间的结合能，由于Ni离子的高价态，沿着晶体结构中较强的Al-O键以及Na+离子在高电荷时的“阳离子阻挡”效应，使得Ni和O之间的结合能较大。更稳定的晶格氧减少循环中的阳离子无序，并且Li层中的Na+挤压过渡金属从LiM 2（M =金属）层到Li层的路径，通过抑制电化学驱动的阳离子无序来稳定层状晶体结构。此外，Na-Al双取代的阴极显示出较小的体积变化，产生更稳定的结构。本研究揭示了Na-Al双取代对无Co层状正极材料的放电容量、中点电位和循环稳定性的影响，这对锂离子电池的发展至关重要。
A dual substitution strategy is introduced to Co-free layered material LiNi0.5Mn0.5O2 by partially replacing Li and Ni with Na and Al, respectively, to achieve a superior cathode material for lithium ion batteries. Na+ ion functions as a "pillar" and a " cationic barrier" in the lithium layer while Al3+ ion plays an auxiliary role in stabilizing structure and lattice oxygen to improve the electrochemical performance and safety. The stability of lattice oxygen comes from the binding energy between the Ni and O, which is larger due to higher valences of Ni ions, along with a stronger Al-O bond in the crystal structure and the "cationic barrier" effect of Na+ ion at the high-charge. The more stable lattice oxygen reduces the cation disorder in cycling, and Na+ in the Li layer squeezes the pathway of the transition metal from the LiM2 (M = metal) layer to the Li layer, stabilizing the layered crystal structure by inhibiting the electrochemical-driven cation disorder. Moreover, the cathode with Na-Al dual-substitution displays a smaller volume change, yielding a more stable structure. This study unravels the influence of Na-Al dual-substitution on the discharge capacity, midpoint potential, and cyclic stability of Co-free layered cathode materials, which is crucial for the development of lithium ion batteries.