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Synthesis of Ionic Liquid Based Electrolytes, Assembly of Li-ion Batteries, and Measurements of Performance at High Temperature
Published on: December 20, 2016
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High-Energy-Density Lithium Metal Batteries with Impressive Li+ Transport Dynamic and Wide-Temperature Performance
Ran Han1,2, Zhicheng Wang3, Dan Huang3
1School of Materials Science and Engineering, Shanghai University, Shanghai, 200444, China.
Small (Weinheim an Der Bergstrasse, Germany)
|March 15, 2023
Summary
A novel electrolyte using lithium difluoro(oxalato)borate in ethyl acetate with fluorocarbonate enhances lithium metal battery performance. This formulation improves low-temperature operation and cycling stability for high-energy-density batteries.
Area of Science:
- Electrochemistry
- Materials Science
- Energy Storage
Background:
- High-energy-density lithium metal batteries (LMBs) with Ni-rich cathodes and Li-metal anodes are crucial for advanced applications.
- Commercial carbonate electrolytes face challenges like poor cycling stability, Li dendrite growth, cathode cracking, and limited low-temperature performance (below -40°C).
- Improving Li+ transport dynamics and interfacial stability is essential for overcoming these limitations.
Purpose of the Study:
- To design a novel electrolyte for stable and high-performance LMBs, particularly at low temperatures.
- To address the limitations of conventional carbonate electrolytes in Ni-rich cathode and Li-metal anode systems.
- To enhance interfacial stability between the electrolyte and battery electrodes.
Main Methods:
- Development of a new electrolyte formulation: 2.4 m lithium difluoro(oxalato)borate (LiDFOB) in ethyl acetate (EA) with 20 wt% fluorocarbonate (FEC), termed 2.4m-DEF.
- Investigation of electrolyte properties, including Li+ transport dynamics, freezing point, viscosity, and dielectric constant.
- Electrochemical testing of LiNi0.9Co0.05Mn0.05O2 (NCM90)/Li LMBs using the developed electrolyte at various temperatures and rates.
Main Results:
- The 2.4m-DEF electrolyte exhibits excellent Li+ transport due to the properties of the ethyl acetate solvent.
- A stable solid electrolyte interface (SEI) is formed on the electrodes, attributed to the decomposition of DFOB- anions and FEC.
- NCM90/Li LMBs with 2.4m-DEF show high rate capability (184 mAh g-1 at 30C) and stable cycling (93.7% retention after 200 cycles at 20C).
- Remarkable ultra-low-temperature performance is achieved: 173 mAh g-1 at -40°C and 152 mAh g-1 at -60°C.
Conclusions:
- The novel 2.4m-DEF electrolyte effectively enhances interfacial stability and Li+ transport in LMBs.
- This electrolyte enables excellent electrochemical performance, including high rate capability and stable cycling at room temperature.
- The formulation demonstrates significant potential for ultra-low-temperature operation of high-energy-density lithium metal batteries.
