Electronic structure influences on the formation of the solid electrolyte interphase,Energy & Environmental Science

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Electronic structure influences on the formation of the solid electrolyte interphase
Energy & Environmental Science ( IF 32.4 ) Pub Date : 2020-10-14 , DOI: 10.1039/d0ee01825b
Weixin Song _{1,

2,

3} , Elena Stein Scholtis _{1,

2,

3} , Peter C. Sherrell _{1,

2,

3,

4,

5} , Deana K. H. Tsang _{1,

2,

3} , Jonathan Ngiam _{1,

2,

3} , Johannes Lischner _{1,

2,

3} , Sarah Fearn _{1,

2,

3} , Victoria Bemmer _{1,

2,

3} , Cecilia Mattevi _{1,

2,

3} , Norbert Klein _{1,

2,

3} , Fang Xie _{1,

2,

3} , D. Jason Riley _{1,

2,

3}

Affiliation

The solid electrolyte interphase (SEI) is critical for lithium-ion batteries (LIBs). Understanding and control over how the SEI is formed is therefore essential to develop LIBs with improved coulombic efficiency, lifetime and capacity. Previous research has focused on how variations in electrolyte chemistry and charging conditions can manipulate the SEI, yet there remains a fundamental lack of understanding surrounding the formation mechanism of the SEI. Specifically, there is minimal research on how the electrode material itself influences the formation of the SEI. Herein, chemically equivalent yet electronically distinct mono-, bi- and multi-layered graphene are used as LIB anodes. The formation of the SEI is probed with respect to kinetics, mechanism, morphology, and composition. SEI films on monolayer graphene contain high amounts of decomposition products from the salt (LiPF₆) while on multilayer graphene, the films contain a large proportion of organic products. The basal plane of SEI films contains more organic species in the side close to the electrode than close to the electrolyte because of the intrinsic charge transfer between the solvents and graphitic anodes. We demonstrate that the composition of SEI films is tunable by modifying the reduction capability of the anode relative to the electrolyte where high reduction kinetics promotes LiPF₆ decomposition; low reduction kinetics leads to more solvent decomposition and sluggish phase change during SEI deposition. This work provides fundamental insights into the influence of electrode electronic structure on SEI formation, and provides future directions to improve LIBs.

中文翻译：

电子结构对固体电解质界面形成的影响

固态电解质中间相（SEI）对于锂离子电池（LIB）至关重要。因此，了解和控制SEI的形成方式对于开发具有改进的库仑效率，寿命和容量的LIB至关重要。先前的研究集中在电解质化学性质和充电条件的变化如何影响SEI方面，但是仍然缺乏对SEI形成机理的基本了解。具体而言，关于电极材料本身如何影响SEI形成的研究很少。在本文中，将化学等效但电子上不同的单层，双层和多层石墨烯用作LIB阳极。从动力学，机理，形态和组成方面探讨了SEI的形成。₆）当在多层石墨烯上时，薄膜包含很大比例的有机产物。由于溶剂和石墨阳极之间的固有电荷转移，SEI膜的基面在靠近电极的一侧比靠近电解质的一侧包含更多的有机物质。我们证明，通过改变阳极相对于电解质的还原能力，可以调节SEI膜的组成，其中高还原动力学促进LiPF₆分解。低还原动力学会导致SEI沉积过程中更多的溶剂分解和缓慢的相变。这项工作为电极电子结构对SEI形成的影响提供了基本的见识，并为改进LIBs提供了未来的方向。

更新日期：2020-11-03

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