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KVP 2 O 7 as a Robust High‐Energy Cathode for Potassium‐Ion Batteries: Pinpointed by a Full Screening of the Inorganic Registry under Specific Search Conditions
Author(s) -
Park Woon Bae,
Han Su Cheol,
Park Chunguk,
Hong Sung Un,
Han Ugyu,
Singh Satendra Pal,
Jung Young Hwa,
Ahn Docheon,
Sohn KeeSun,
Pyo Myoungho
Publication year - 2018
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.201703099
Subject(s) - triclinic crystal system , monoclinic crystal system , materials science , electrochemistry , cathode , potassium , ion , phase (matter) , crystallography , analytical chemistry (journal) , crystal structure , chemistry , electrode , metallurgy , organic chemistry , chromatography
Candidates for high‐energy cathodes in potassium‐ion batteries (KIBs) are selected by fully screening the inorganic compound structure database. The compounds that satisfy the specific conditions for plausible KIB cathodes are further subjected to theoretical and electrochemical verification, and KVP 2 O 7 is finally pinpointed. KVP 2 O 7 can reversibly desert/insert ≈60% of K + (60 mA h g −1 ) during either chemical or electrochemical oxidation/reduction. KVP 2 O 7 shows an average discharge potential of ≈4.2 V versus K/K + , which corresponds to an energy density of 253 W h kg −1 at 0.25 C. This high energy density characteristic of KVP 2 O 7 is maintained both during fast charge/discharge (C/D) and prolonged redox cycles. The C/D of KVP 2 O 7 is also accompanied by a phase transition between a monoclinic KVP 2 O 7 ( P 2 1 / c ) and a triclinic K 1− x VP 2 O 7 ( P 1 ¯ ) . The structure interpretation of a new K 1− x VP 2 O 7 phase indicates that K + ‐extraction induces a conformational change of two tetrahedral PO 4 units in pyrophosphates. The P 1 ¯phase of K 1− x VP 2 O 7 ( x ≈0.6) remains stable during the C/D process, although it returns to the inborn P 2 1 / c phase after thermal treatment. It is believed that the data‐mining protocol designed for this study will provide a new strategy for materials discovery and that the pinpointed KVP 2 O 7 can be utilized as a reliable KIB cathode.