期刊
ENERGY STORAGE MATERIALS
卷 49, 期 -, 页码 291-298出版社
ELSEVIER
DOI: 10.1016/j.ensm.2022.04.025
关键词
NASICON; Multielectron reaction; Cathode; Low temperature
资金
- National Natural Science Foundation of China [52072033]
- State Key Laboratory of New Ceramics and Fine Processing of Tsinghua University [KF201816]
This study found that the reversible redox reaction of Na3V2(PO4)3 cathode can be activated by replacing a part of V3+ with Al3+, resulting in Na3V1.5Al0.5(PO4)3 cathode. The cathode exhibits favorable performance at both room temperature and low temperature, along with stable phase structure and high capacity retention. The Na+ storage mechanism of the cathode was elucidated through ex-situ XRD structural analysis.
The NASICON-type Na3V2(PO4)3 cathode based on vanadium multiple redox is particularly attractive for largescale sodium-ion battery application. In this work, it was found that the reversible redox of V4+/V5+ can be activated by replacing a part of V3+ with Al3+, obtaining Na3V1.5Al0.5(PO4)3 with typical NASICON phase structure and offering a reversible specific capacity of 163 mAh g-1 through a three-electron redox reaction with a small volume change (2.62%). The most surprising thing is that in addition to favorable room temperature electrochemical performance, Na3V1.5Al0.5(PO4)3 also exhibits a superior low temperature (-20 degrees C) cycling stability with a capacity retention of 98.9% after 1000 cycles at 5 C. Thin and conformal CEI film as well as stable phase structure across a broad temperature range are responsible for this superior electrochemical property. A Na+ storage mechanism consisting of two-phase and solid-solution electrochemical reactions for Na3V1.5Al0.5(PO4)3 cathode is elucidated via ex-situ XRD structural analysis. DFT calculations indicate that Al3+ substitution could manipulate the localized electronic state and strengthen the oxygen ligand skeleton in the NASICON matrix. Hence, the Na3V1.5Al0.5(PO4)3 cathode renders a slight lattice variation upon the repeated desodiation and sodiation and enhanced Na+ diffusion rate along with low charge transfer resistance.
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