Morphology Control and Na+ Doping toward High-Performance Li-Rich Layered Cathode Materials for Lithium-Ion Batteries,ACS Sustainable Chemistry & Engineering

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Morphology Control and Na+ Doping toward High-Performance Li-Rich Layered Cathode Materials for Lithium-Ion Batteries
ACS Sustainable Chemistry & Engineering ( IF 7.1 ) Pub Date : 2020-12-28 , DOI: 10.1021/acssuschemeng.0c06595
Qian Wang ₁ , Wei He ₁ , Laisen Wang ₁ , Shuai Li ₁ , Hongfei Zheng ₁ , Qun Liu ₁ , Yuxin Cai ₁ , Jie Lin ₁ , Qingshui Xie ₁ , Dong-Liang Peng ₁

Affiliation

The lithium-rich manganese (LRM)-based cathode materials are always subjected to poor rate capacity and terrible voltage fading. Herein, sodium citrate as a chelating agent is introduced to synthesize LRM cathode materials with high structure stability by the solvothermal method to solve the abovementioned issues. Sodium citrate can effectively control the morphology of cathode materials with a small size of primary particles, which can prevent the side reaction between the active materials and electrolyte and benefit Li⁺ diffusion. Meanwhile, the hydroxyl groups in sodium citrate can alter the crystal growth thermodynamics and thereby induce the formation of the active {010} planes under the solvothermal condition, which facilitates the formation of a good layered structure, so that the electrochemical reaction kinetics and rate performance are facilitated dramatically. Furthermore, benefitting from the doping of Na⁺, the structure of the cathode material does not collapse during repeated charge–discharge cycles, so that voltage stability is enhanced greatly. Consequently, at a current density of 5 C after cycling 200 times, the reversible capacity of the designed LRM cathode is 166 mA h g^–1 with a high capacity retention of 90.1%, and the median voltage remains at 3.21 V with a voltage retention of 91.4%. The median voltage could remain as high as 3.37 V with a very high voltage retention of 94.1% even at 10 C after 200 cycles. This study proposes a novel strategy that utilizes the synergistic modification of morphology design and Na⁺ doping to increase the lithium storage performance of LRM cathode materials.

中文翻译：

锂离子电池高性能锂富层状正极材料的形貌控制和Na ⁺掺杂

富锂锰（LRM）基正极材料始终承受不良的倍率容量和可怕的电压衰减。在本文中，引入柠檬酸钠作为螯合剂以通过溶剂热法合成具有高结构稳定性的LRM正极材料以解决上述问题。柠檬酸钠可以有效地控制一次粒子尺寸较小的正极材料的形貌，从而可以防止活性材料与电解质之间的副反应，并有利于Li ⁺扩散。同时，柠檬酸钠中的羟基可以改变晶体生长的热力学，从而在溶剂热条件下诱导活性的{010}面的形成，从而促进了良好的层状结构的形成，从而使电化学反应动力学和速率性能提高。大大方便了。此外，得益于Na ⁺的掺杂，阴极材料的结构在反复的充放电循环中不会崩溃，因此电压稳定性得到了大大提高。因此，经过200次循环后，在5 C的电流密度下，设计的LRM阴极的可逆容量为166 mA hg ^–1高容量保持率达90.1％，中位电压保持在3.21 V，电压保持率达91.4％。即使在200个循环后的10 C下，中值电压也可以保持高达3.37 V的高电压保持率，达到94.1％。这项研究提出了一种新的策略，该策略利用形态设计和Na ⁺掺杂的协同修饰来提高LRM阴极材料的锂存储性能。

更新日期：2021-01-11

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