Stable Electrode/Electrolyte Interface for High-Voltage NCM 523 Cathode Constructed by Synergistic Positive and Passive Approaches,ACS Applied Materials & Interfaces

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Stable Electrode/Electrolyte Interface for High-Voltage NCM 523 Cathode Constructed by Synergistic Positive and Passive Approaches
ACS Applied Materials & Interfaces ( IF 8.3 ) Pub Date : 2021-11-19 , DOI: 10.1021/acsami.1c15690
Xiaotang Shi _{1,

2} , Tianle Zheng _{1,

3} , Jianwei Xiong _{1,

4} , Bingying Zhu _{1,

4} , Ya-Jun Cheng ₁ , Yonggao Xia _{1,

5}

Affiliation

Increasing the working voltage of lithium-ion batteries (LIBs) is an efficient way to increase energy density. However, high voltage triggers excessive electrolyte decomposition at the electrode–electrolyte interfaces, where the electrochemical performance such as cyclic stability and rate capability is seriously deteriorated. A new synergistic positive and passive approach is proposed in this work to construct a stable electrode–electrolyte interface at high voltage. As a positive approach, inorganic lithium sulfide salt (Li₂S) is used as an electrolyte additive to build a stable cathode electrolyte interface (CEI) at the LiNi_0.5Co_0.2Mn_0.3O₂ (NCM523) cathode surface. In a passive way, acetonitrile (AN) is applied as a solvent additive to suppress oxidative decomposition of a carbonate electrolyte via preferential solvation with a lithium ion. Because of the synergistic interaction between the positive and passive approaches, the cyclic stabilities of NCM523/Li cells improved with a tiny amount of Li₂S (0.01 mg mL^–1) and AN (0.5 vol %). The capacity retention increased to 80.74% after 200 cycles compared to the cells with the blank electrolyte (67.98%) and AN-containing electrolyte (75.8%). What is more, the capacity retention of the NCM523/graphite full cell is increased from 65 to 81% with the addition of the same amount of Li₂S and AN after 180 cycles. The mechanism is revealed on the basis of the theoretical calculations and various characterizations. The products derived from the preferential adsorption and oxidation of Li₂S on the surface of NCM523 effectively increase the content of inorganic ingredients. However, the presence of AN prevents oxidation of the solvent. This study provides new principle guiding studies on a high-voltage lithium-ion battery with excellent electrochemical performance.

中文翻译：

由协同正负方法构建的高压 NCM 523 阴极的稳定电极/电解质界面

提高锂离子电池（LIBs）的工作电压是提高能量密度的有效途径。然而，高电压会引发电极-电解质界面处的过度电解质分解，从而严重降低循环稳定性和倍率性能等电化学性能。在这项工作中提出了一种新的协同正被动方法，以在高压下构建稳定的电极 - 电解质界面。作为一种积极的方法，无机硫化锂盐 (Li ₂ S) 用作电解质添加剂，以在 LiNi _0.5 Co _0.2 Mn _0.3 O ₂处构建稳定的阴极电解质界面 (CEI)(NCM523) 阴极表面。以一种被动的方式，乙腈 (AN) 被用作溶剂添加剂，通过与锂离子的优先溶剂化来抑制碳酸盐电解质的氧化分解。由于正和被动方法之间的协同相互作用，NCM523/Li 电池的循环稳定性随着少量 Li ₂ S (0.01 mg mL ^–1 ) 和 AN (0.5 vol %) 的加入而提高。与使用空白电解质 (67.98%) 和含 AN 电解质 (75.8%) 的电池相比，200 次循环后的容量保持率增加至 80.74%。更重要的是，NCM523/石墨全电池的容量保持率从65%提高到81%，加入等量的Li ₂180 次循环后的 S 和 AN。该机制是在理论计算和各种表征的基础上揭示的。NCM523表面的Li ₂ S优先吸附氧化得到的产物有效地增加了无机成分的含量。然而，AN 的存在可防止溶剂氧化。该研究为具有优异电化学性能的高压锂离子电池的研究提供了新的原理指导。

更新日期：2021-12-08

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