Solid electrolyte interphase layer formation on mesophase graphite electrodes with different electrolytes studied by small‐angle neutron scattering

Abstract

Relative solid electrolyte interphase (SEI) film thickness investigation on graphite electrodes after the first charge state in the lithium-ion battery was successfully demonstrated by the ex-situ small-angle neutron scattering technique. Here, for both the mesophase graphite powder (MGP) and the finemesophase graphite powder (FMGP) anodes, with two different particle sizes was analyzed precisely by the Guinier-Porod model. The data revealed a stable, maximum (tens of nm) bi-layer SEI film formed on MGP anode in ethylene-carbonate/dimethyl-carbonate (EC/DMC) at a capacity of 50 mAh/g and sluggish above 100 mAhg-1. The SEI formed on FMGP with and without 3 wt% fluoroethylene-carbonate additive in EC/DMC showed the relative thickness greater than that only in ethylene-carbonate/diethyl-carbonate. Lithiation initiated the rapid SEI formation on the graphite surface and achieved a maximum thickness in the cell potential ≤0.2 V, and became thinner when the graphite particle expanded after Li + intercalation. It was observed that the SEI thickness influenced the electrolytes and additives, which might ultimately impact battery performance. Our preliminary results make evident that smallangle neutron scattering could be employed to better understand the complex microstructure solid electrolyte interphase formation and its accurate thickness, on a mesophase graphite anode.

Rapid Interfacial Exchange of Li Ions Dictates High Coulombic Efficiency in Li Metal Anodes

“…12,17,20,21,[41][42][43][44] It is well-established that electrolyte formulation can be leveraged to tune Li deposition morphologies, 13,15,24,45,46 likely by altering SEI composition and arrangement. Claims that a thinner, more homogeneous SEI is correlated with smooth Li deposition and high CE are ubiquitous in the literature, 13,15,[47][48][49][50][51][52][53][54][55][56][57][58] likely due to the fact that uncontrolled SEI growth can hinder Li transport to the underlying electrode. However, recent reports indicate that the SEI formed in high performance LiTFSI/LiNO3 salt mixtures in ether-based solvents is actually thicker than the SEI on Li metal compared to LiTFSI alone.…”

Rapid Interfacial Exchange of Li Ions Dictates High Coulombic Efficiency in Li Metal Anodes

“…12,17,20,21,[41][42][43][44] It is well-established that electrolyte formulation can be leveraged to tune Li deposition morphologies, 13,15,24,45,46 likely by altering SEI composition and arrangement. Claims that a thinner, more homogeneous SEI is correlated with smooth Li deposition and high CE are ubiquitous in the literature, 13,15,[47][48][49][50][51][52][53][54][55][56][57][58] likely due to the fact that uncontrolled SEI growth can hinder Li transport to the underlying electrode. However, recent reports indicate that the SEI formed in high performance LiTFSI/LiNO3 salt mixtures in ether-based solvents is actually thicker than the SEI on Li metal compared to LiTFSI alone.…”

Synthesis, mechanical, thermal, and electrical characterization of graphite–epoxy composites

“…[ 23–25 ] Among all carbon fillers, the graphite component is a more versatile filler due to its mass production and low‐cost advantages. [ 26,27 ] Its excellent physical properties, particularly the high thermal and electrical conductivities, make it an attractive candidate to improve the physical properties of an epoxy. The graphite is one of the allotropes of carbon with its atoms arranged in a hexagonal structure and its composites can be prepared with the polypropylene, polystyrene, epoxy polymer matrix, and others.…”