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"Mn-locking" effect by anionic coordination manipulation stabilizing Mn-rich phosphate cathodes.

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Peer-reviewed

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Abstract

High-voltage cathodes with high power and stable cyclability are needed for high-performance sodium-ion batteries. However, the low kinetics and inferior capacity retention from structural instability impede the development of Mn-rich phosphate cathodes. Here, we propose light-weight fluorine (F) doping strategy to decrease the energy gap to 0.22 eV from 1.52 eV and trigger a "Mn-locking" effect-to strengthen the adjacent chemical bonding around Mn as confirmed by density functional theory calculations, which ensure the optimized Mn ligand framework, suppressed Mn dissolution, improved structural stability and enhanced electronic conductivity. The combination of in situ and ex situ techniques determine that the F dopant has no influence on the Na+ storage mechanisms. As a result, an outstanding rate performance up to 40C and an improved cycling stability (1000 cycles at 20C) are achieved. This work presents an effective and widely available light-weight anion doping strategy for high-performance polyanionic cathodes.

Description

Acknowledgements: W. Z. thanked the funding support from China Scholarship Council/University College London for the joint PhD scholarship. This work was supported by the financial support of the Engineering and Physical Sciences Research Council (EP/V027433/3), UK Research and Innovation (UKRI) under the UK government's Horizon Europe funding guarantee (101077226; EP/Y008707/1), STFC Batteries Network (ST/R006873/1), National Natural Science Foundation of China (52274309) and the Natural Science Foundation of Hunan Province, China (2020JJ1007).

Keywords

34 Chemical Sciences, 3406 Physical Chemistry, 7 Affordable and Clean Energy

Journal Title

Chem Sci

Conference Name

Journal ISSN

2041-6520
2041-6539

Volume Title

Publisher

Royal Society of Chemistry (RSC)
Sponsorship
STFC Batteries Network (ST/R006873/1)
National Natural Science Foundation of China (52274309)
Natural Science Foundation of Hunan Province (2020JJ1007)
Engineering and Physical Sciences Research Council (EP/V027433/3)
UK Research and Innovation (101077226)