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Molecular Level Investigations on Electrode/Electrolyte Interfacial Reactions in Localized High Concentration Electrolytes


EMSL Project ID
50610

Abstract

The objective of this proposal is to understand the interfacial reactions and processes occurring at the electrode/electrolyte in localized high concentration electrolytes (LHCEs) for various energy storage systems including rechargeable metal batteries and metal-ion batteries. Since the use of the high concentration electrolytes (HCEs) in lithium (Li) batteries was first reported in 2003, the studies on HCEs in various types of battery chemistries and systems have been reported in an increasing number especially from 2013. The HCEs, normally with the salt concentration over 3 M (mole/liter), have unique properties over conventional diluted electrolytes with a salt concentration of about 1 M and allow the batteries to perform much better than conventional diluted electrolytes. However, the mechanisms behind the enhanced behaviors have not been well understood. On the other hand, the high salt concentration also causes some other issues in the battery systems, such as high cost, poor wettability to separator and thick electrodes, poor low-temperature performance, and so on. Since 2017, we at PNNL proposed a new type of electrolytes called LHCEs by adding a second solvent as diluent to the HCEs. This diluent solvent can well mix with the primary solvent that has good solvation capability with the salt cation, but the diluent solvent has no or limited solvation to the salt cation, thus the total salt concentration of the final electrolyte can be largely reduced from 4 M to about 1.2-1.6 M, the wettability issue of the electrolyte to separator and electrodes has also been significantly improved, and more importantly the unique properties of the high salt concentration are reserved locally and the battery performance also has been maintained or even improved. However, the mechanisms have not been investigated much and need to be studied intensively and comprehensively from macroscopic to microcosmic and even molecular level, and also from electrolytes to electrode/electrolyte (including cathode/electrolyte and anode/electrolyte) interface reactions and processes. All of the researches are leveraged with the strong capabilities in PNNL including energy storage materials, characterizations and computational calculations/simulations.

Project Details

Start Date
2018-11-01
End Date
2019-09-30
Status
Closed

Team

Principal Investigator

Wu Xu
Institution
Pacific Northwest National Laboratory

Team Members

Xia Cao
Institution
Pacific Northwest National Laboratory

Xiaodi Ren
Institution
University of Science and Technology of China, Chinese Academy of Sciences

Bin Liu
Institution
Pacific Northwest National Laboratory

Xiaolin Li
Institution
Pacific Northwest National Laboratory

Jiguang Zhang
Institution
Pacific Northwest National Laboratory

Donghai Mei
Institution
Tiangong University