Enhanced Interfacial Stability of a LiNi0.9Co0.05Mn0.05O2 Cathode by a Diboron Additive,ACS Applied Energy Materials

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Enhanced Interfacial Stability of a LiNi0.9Co0.05Mn0.05O2 Cathode by a Diboron Additive
ACS Applied Energy Materials ( IF 5.4 ) Pub Date : 2021-09-22 , DOI: 10.1021/acsaem.1c01977
Yue Zou ₁ , Gaopan Liu ₁ , Ke Zhou ₁ , Jing Zhang ₁ , Tianpeng Jiao ₁ , Xiaozhen Zhang ₁ , Yong Yang _{1,

2,

3} , Jianming Zheng ₁

Affiliation

Ni-rich LiNi_xCo_yMn_zO₂ (NCM, x_Ni ≥ 0.9) layered materials are appealing cathode candidates for future-generation higher-energy-density lithium-ion batteries (LIBs). However, structural and interfacial instability of Ni-rich cathodes needs to be addressed prior to the large-scale deployment in electric vehicles. Herein, a diboron electrolyte additive 5,5,5′,5′-tetramethyl-2,2′-bi-1,3,2-dioxaborinane (TBDB) is proposed for constructing a stable LiNi_0.9Co_0.05Mn_0.05O₂ (NCM90)/electrolyte interface, thus improving the long-term cycle life and rate capability of an NCM90 cathode. Using an optimized 0.3% TBDB-containing electrolyte, the NCM90 cathode shows a capacity retention up to 84.3% after 200 cycles at 1C at a charge cutoff of 4.4 V, much superior over 70.1% when using the baseline electrolyte. The obvious performance improvement could be explained by the fact that TBDB with higher highest occupied molecular orbital (HOMO) energy is preferentially oxidized before electrolyte solvents, through boron–boron bond cleavage, generating a compact, thin, and protective cathode electrolyte interphase (CEI) layer on the cathode electrode. As a result, the electrolyte decomposition is effectively restrained with fewer poorly conducting byproducts being accumulated, which significantly enhances the interfacial stability and redox reaction kinetics of a Ni-rich NCM90 cathode.

中文翻译：

通过二硼添加剂增强 LiNi0.9Co0.05Mn0.05O2 阴极的界面稳定性

富镍 LiNi _x Co _y Mn _z O ₂ (NCM, x _Ni ≥ 0.9) 层状材料是下一代高能量密度锂离子电池 (LIB) 的有吸引力的阴极候选材料。然而，在电动汽车大规模部署之前，需要解决富镍正极的结构和界面不稳定性。在此，提出了一种二硼电解质添加剂 5,5,5',5'-四甲基-2,2'-bi-1,3,2-二氧硼烷 (TBDB) 用于构建稳定的 LiNi _0.9 Co _0.05 Mn _0.05 O ₂(NCM90)/电解质界面，从而提高 NCM90 阴极的长期循环寿命和倍率性能。使用优化的含 0.3% TBDB 的电解液，NCM90 正极在 1C 和 4.4 V 的充电截止电压下循环 200 次后显示出高达 84.3% 的容量保持率，比使用基线电解液时的 70.1% 优越得多。显着的性能改进可以解释为具有较高最高占据分子轨道 (HOMO) 能量的 TBDB 在电解质溶剂之前优先氧化，通过硼 - 硼键断裂，产生致密、薄且保护性的阴极电解质中间相 (CEI)层上的阴极电极。结果，电解液分解得到有效抑制，并且积累的不良导电副产物更少，

更新日期：2021-10-25

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