Charge transport mechanisms in potassium superoxide
Zongxiang Hu1, Wenchang Tan, Shunning Li
1School of Advanced Materials, Peking University, Shenzhen Graduate School, Shenzhen 518055, People's Republic of China. tanwch@pku.edu.cn lisn@pku.edu.cn panfeng@pkusz.edu.cn.
Physical Chemistry Chemical Physics : PCCP
|October 22, 2020
Summary
Potassium superoxide (KO2) in K-O2 batteries exhibits superior charge transport compared to Li2O2. This study reveals hole polarons and potassium ion vacancies as key charge carriers, explaining the battery
Area of Science:
- Materials Science
- Electrochemistry
- Computational Chemistry
Background:
- Rechargeable metal-air batteries are attractive due to the O2/O2- redox process.
- Potassium-oxygen (K-O2) batteries show a reduced potential gap compared to lithium-oxygen (Li-O2) systems.
Purpose of the Study:
- To investigate the charge transport mechanisms in potassium superoxide (KO2), the discharge product of K-O2 batteries.
- To provide a theoretical understanding for the improved performance of K-O2 batteries.
Main Methods:
- First-principles calculations were employed to study KO2.
- Calculated intrinsic carrier concentration and mobility.
- Analyzed charge transport pathways and conductivity.
Main Results:
- Identified hole polarons and negatively charged potassium ion vacancies as primary charge carriers in KO2.
- Calculated electronic conductivity via polaron hopping (2 × 10^-12 S cm^-1), significantly higher than Li2O2.
- Determined ionic conductivity to be approximately 1 × 10^-13 S cm^-1.
Conclusions:
- The calculated charge transport properties rationalize experimental observations in K-O2 batteries.
- Findings offer a theoretical foundation for understanding superoxide discharge products in metal-air batteries.
- Highlights the potential of KO2 as a superior discharge product for advanced battery technologies.
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