Adjusting Li+ Solvation Structures via Dipole–Dipole Interaction to Construct Inorganic-Rich Interphase for High-Performance Li Metal Batteries,Small

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Adjusting Li+ Solvation Structures via Dipole–Dipole Interaction to Construct Inorganic-Rich Interphase for High-Performance Li Metal Batteries
Small ( IF 13.0 ) Pub Date : 2024-01-02 , DOI: 10.1002/smll.202308995
Chuan Wang ₁ , Sheng Liu ₁ , Haoyang Xu ₁ , Xinxiang Wang ₁ , Guilei Tian ₁ , Fengxia Fan ₁ , Pengfei Liu ₁ , Shuhan Wang ₁ , Chenrui Zeng ₁ , Chaozhu Shu ₁

Affiliation

Practical applications of lithium metal batteries are limited by unstable solid electrolyte interphase (SEI) and uncontrollable dendrite Li deposition. Regulating the solvation structure of Li⁺ via modifying electrolyte components enables optimizing the structure of the SEI and realizing dendrite-free Li deposition. In this work, it is found that the ionic–dipole interactions between the electron-deficient B atoms in lithium oxalyldifluoro borate (LiDFOB) and the O atoms in the DME solvent molecule can weaken the interaction between the DME molecule and Li⁺, accelerating the desolvation of Li⁺. On this basis, the ionic–dipole interactions facilitate the entry of abundant anions into the inner solvation sheath of Li⁺, which promotes the formation of inorganic-rich SEI. In addition, the interaction between DFOB⁻ and DME molecules reduces the highest occupied molecular orbital energy level of DME molecules in electrolytes, which improves the oxidative stability of the electrolytes system. As a result, the Li||Li cells in LiDFOB-containing electrolytes exhibit an excellent cyclability of over 1800 h with a low overpotential of 18.2 mV, and the Li||LiFePO₄ full cells display a high-capacity retention of 93.4% after 100 cycles with a high Coulombic efficiency of 99.3%.

中文翻译：

通过偶极-偶极相互作用调整Li+溶剂化结构构建高性能锂金属电池的富无机界面相

锂金属电池的实际应用受到不稳定的固体电解质界面（SEI）和不可控的枝晶锂沉积的限制。通过改变电解质成分来调节Li ⁺的溶剂化结构，可以优化SEI的结构并实现无枝晶的锂沉积。本工作发现草酰基二氟硼酸锂（LiDFOB）中的缺电子B原子与DME溶剂分子中的O原子之间的离子偶极相互作用可以减弱DME分子与Li ⁺之间的相互作用，加速Li ⁺的去溶剂化。在此基础上，离子-偶极相互作用促进丰富的阴离子进入Li ⁺的内部溶剂化鞘，从而促进富含无机物的SEI的形成。此外，DFOB ^-与DME分子之间的相互作用降低了电解质中DME分子的最高占据分子轨道能级，从而提高了电解质体系的氧化稳定性。结果，含LiDFOB电解质中的Li||Li电池表现出超过1800小时的优异循环性能以及18.2 mV的低过电位，并且Li||LiFePO ₄全电池在使用后表现出93.4%的高容量保持率。 100 次循环，库仑效率高达 99.3%。

更新日期：2024-01-02

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