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Electrochemical Exchange Reaction Mechanism and the Role of Additive Water to Stabilize the Structure of VOPO 4 ⋅2 H 2 O as a Cathode Material for Potassium-Ion Batteries

Title
Electrochemical Exchange Reaction Mechanism and the Role of Additive Water to Stabilize the Structure of VOPO 4 ⋅2 H 2 O as a Cathode Material for Potassium-Ion Batteries
Authors
Hyoung, JooeunHeo, Jongwook W.Chae, Munseok S.Hong, Seung-Tae
DGIST Authors
Hong, Seung-Tae
Issue Date
2019-03
Citation
ChemSusChem, 12(5), 1069-1075
Type
Article
Article Type
Article
Author Keywords
additive waterexchange reactionintercalation mechanismpotassium-ion batteryvanadyl phosphate dihydrate
Keywords
AdditivesCathodesCrystal structureEthyleneIon exchangeIonsMoleculesSecondary batteriesVanadium compoundsAnhydrous electrolytesCapacity retentionCath-ode materialsCrystal water moleculesDihydratesExchange reactionIntercalation mechanismsPotassium ionsElectrolytes
ISSN
1864-5631
Abstract
VOPO 4 ⋅2 H 2 O is demonstrated as a cathode material for potassium-ion batteries in 0.6 m KPF 6 in ethylene carbonate/diethyl carbonate, and its distinct exchange reaction mechanism between potassium and crystal water is reported. In an anhydrous electrolyte, the cathode shows an initial capacity of approximately 90 mAh g −1 , with poor capacity retention (32 % after 50 cycles). In contrast, the capacity retention dramatically improved (86 % after 100 cycles) in a wet electrolyte containing 0.1 m of additive water. VOPO 4 ⋅2 H 2 O contains two types of water (structural and crystal). Upon discharge, potassium ions are intercalated whereas the crystal water is simultaneously de-intercalated from the structure. Upon charging, a completely reverse reaction takes place in the wet electrolyte, resulting in high stability of the host structure and excellent cyclability. However, in the anhydrous electrolyte, some portion of the extracted crystal water molecules cannot be reinserted into the host structure because they are distributed over the anhydrous electrolyte. Keeping some concentration of water in the electrolyte turns out to be was the key to achieving such high reversibility. The potassium ions (90 %) and proton or hydronium ions (10 %) seem to be co-intercalated in the wet electrolyte. This work provides a general insight into the intercalation mechanism of crystal-water-containing host materials. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
URI
http://hdl.handle.net/20.500.11750/9678
DOI
10.1002/cssc.201802527
Publisher
Wiley-VCH Verlag
Related Researcher
  • Author Hong, Seung-Tae Discovery Lab(Batteries & Materials Discovery Laboratory)
  • Research Interests Magnesium, sodium and lithium ion rechargeable batteries; New inorganic materials discovery; Solid state chemistry; Crystallography; Mg, Na, Li 이온 이차전지; 신 무기재료 합성; 고체화학; 결정화학
Files:
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Collection:
Department of Energy Science and EngineeringDiscovery Lab(Batteries & Materials Discovery Laboratory)1. Journal Articles


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