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A Layered Inorganic–Organic Open Framework Material as a 4 V Positive Electrode with High‐Rate Performance for K‐Ion Batteries
Author(s) -
Hameed Abdulrahman Shahul,
Katogi Akihiro,
Kubota Kei,
Komaba Shinichi
Publication year - 2019
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201902528
Subject(s) - materials science , faraday efficiency , electrolyte , chemical engineering , electrode , battery (electricity) , ion , oxide , power (physics) , metallurgy , organic chemistry , thermodynamics , chemistry , physics , engineering
K‐ion batteries (KIBs) are promising for large‐scale energy storage owing to various advantages like the high abundance of potassium resources in the Earth's crust, high operational potentials, and high power due to fast diffusion of K + ions. However, to realize the practical application of KIBs, electrode materials are needed with high operational voltage, good capacity, long cycle life, and low‐cost. This work reports a layered open framework material, K 2 [(VOHPO 4 ) 2 (C 2 O 4 )], composited with reduced graphene oxide (rGO) as a 4 V positive electrode material for KIBs. The material is prepared by a simple precipitation reaction at room temperature. The material demonstrates reversible K‐extraction/insertion with conventional carbonate ester KPF 6 solutions; however, with low specific capacity and low Coulombic efficiency. A high discharge capacity of >100 mAh g −1 with good cycling stability and higher Coulombic efficiency is achieved in a highly concentrated electrolyte, 7 mol kg −1 of potassium bis(fluorosulfonyl)amide (KFSA) in dimethoxyethane (DME) at 0.1 C rate. Due to the facile migration of K + ions in the framework, the material exhibits excellent rate capability with a discharge capacity of 80 mAh g −1 at 10 C rate, and a good capacity retention of 67% after 500 cycles at 2 C rate.