Tang Wei, Duan Jidong, Xie Jianlong, Qian Yan, Li Jing, Zhang Yu
School of Life Science and Engineering, Southwest University of Science and Technology, Mianyang 621010, Sichuan, China.
State Key Laboratory of Environmentally-Friendly Energy Materials, School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010, China.
ACS Appl Mater Interfaces. 2021 Apr 14;13(14):16407-16417. doi: 10.1021/acsami.1c02020. Epub 2021 Mar 31.
Lithium-rich layered oxide (LLO) cathode materials are considered to be one of the most promising next-generation candidates of cathode materials for lithium-ion batteries due to their high specific capacity. However, some inherent defects of LLOs hinder their practical application due to the oxygen loss and structure collapse resulting from intrinsic anion and cation redox reactions, such as poor cycle stability, sluggish Li kinetics, and voltage decay. Herein, we put forward a facile synergistic strategy to respond to these shortcomings of LLOs via dual-site doping with cerium (Ce) and boron (B) ions. The doped Ce ions occupy the octahedral sites, which not only enlarge the cell volume but also stabilize the layered framework and introduce abundant oxygen vacancies for LLOs, while B ions occupy the tetrahedral sites in the lattice, which block the migration path of transition metal (TM) ions and reduce the oxygen loss using the strong B-O bond. Based on this dual-site doping effect, after 100 cycles at 1 C, the dual-site doped materials exhibit excellent structural stability with a capacity retention of 91.15% ( 75.12%) and also greatly suppress the voltage decay in LLOs with a voltage retention of 93.60% ( 87.83%).
富锂层状氧化物（LLO）正极材料因其高比容量而被认为是锂离子电池下一代最有前途的正极材料候选者之一。然而，LLO的一些固有缺陷阻碍了它们的实际应用，这是由于本征阴离子和阳离子氧化还原反应导致的氧损失和结构坍塌，例如循环稳定性差、锂动力学迟缓以及电压衰减。在此，我们提出一种简便的协同策略，通过铈（Ce）和硼（B）离子的双位点掺杂来应对LLO的这些缺点。掺杂的Ce离子占据八面体位置，这不仅扩大了晶胞体积，还稳定了层状结构，并为LLO引入了大量氧空位，而B离子占据晶格中的四面体位置，利用强B-O键阻断过渡金属（TM）离子的迁移路径并减少氧损失。基于这种双位点掺杂效应，在1 C下循环100次后，双位点掺杂材料表现出优异的结构稳定性，容量保持率为91.15%（75.12%），并且还极大地抑制了LLO中的电压衰减，电压保持率为93.60%（87.83%）。
