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Characterization of Electrode Materials for Lithium Ion and Sodium Ion Batteries Using Synchrotron Radiation Techniques
Published on: November 11, 2013
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"Mn-locking" effect by anionic coordination manipulation stabilizing Mn-rich phosphate cathodes
Wei Zhang1,2,3, Yulun Wu1, Yuhang Dai3
1School of Metallurgy and Environment, Engineering Research Center of the Ministry of Education for Advanced Battery Materials, Hunan Provincial Key Laboratory of Nonferrous Value-Added Metallurgy, Central South University Changsha 410083 P. R. China zhangzhian@csu.edu.cn laiyanqing@csu.edu.cn.
Chemical Science
|August 18, 2023
Summary
Fluorine doping enhances manganese-rich phosphate cathodes for sodium-ion batteries by improving stability and kinetics. This strategy boosts battery performance, enabling high power and stable cycling for advanced energy storage.
Area of Science:
- Materials Science
- Electrochemistry
- Energy Storage
Background:
- High-voltage cathodes are crucial for high-performance sodium-ion batteries (SIBs).
- Mn-rich phosphate cathodes face challenges due to low kinetics and structural instability, limiting capacity retention.
- Developing stable and efficient cathodes is essential for advancing SIB technology.
Purpose of the Study:
- To investigate the effect of light-weight fluorine (F) doping on Mn-rich phosphate cathodes for SIBs.
- To enhance the electrochemical performance, specifically power and cyclability, of these cathodes.
- To understand the mechanism behind F doping's impact on cathode stability and kinetics.
Main Methods:
- Density Functional Theory (DFT) calculations to analyze electronic structure and bonding.
- Fluorine (F) doping of Mn-rich phosphate materials.
- In situ and ex situ characterization techniques to study structural and chemical changes.
- Electrochemical testing to evaluate rate performance and cycling stability.
Main Results:
- Fluorine doping significantly reduced the energy gap from 1.52 eV to 0.22 eV.
- A
- Mn-locking
- effect was observed, strengthening Mn-ligand bonding and suppressing Mn dissolution.
- Improved structural stability and enhanced electronic conductivity were achieved.
- Electrochemical tests demonstrated outstanding rate performance up to 40C and stable cycling over 1000 cycles at 20C.
- F doping did not alter the fundamental Na+ storage mechanisms.
Conclusions:
- Light-weight fluorine doping is an effective strategy to improve the performance of Mn-rich phosphate cathodes.
- The
- Mn-locking
- effect induced by F doping enhances structural integrity and electrochemical kinetics.
- This anion doping approach offers a viable pathway for developing high-performance polyanionic cathodes for sodium-ion batteries.
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