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Proton Ion Exchange Reaction in Li 3 IrO 4 : A Way to New H 3+ x IrO 4 Phases Electrochemically Active in Both Aqueous and Nonaqueous Electrolytes
Author(s) -
Perez Arnaud J.,
Beer Robin,
Lin Zifeng,
Salager Elodie,
Taberna PierreLouis,
Abakumov Artem M.,
Simon Patrice,
Tarascon JeanMarie
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.201702855
Subject(s) - electrolyte , redox , electrochemistry , protonation , sesquioxide , oxide , crystal structure , inorganic chemistry , dissolution , chemistry , ion , materials science , electrode , crystallography , organic chemistry
Progress over the past decade in Li‐insertion compounds has led to a new class of Li‐rich layered oxide electrodes cumulating both cationic and anionic redox processes. Pertaining to this new class of materials are the Li/Na iridate phases, which present a rich crystal chemistry. This work reports on a new protonic iridate phase H 3+ x IrO 4 having a layered structure obtained by room temperature acid‐leaching of Li 3 IrO 4 . This new phase shows reversible charge storage properties of 1.5 e − per Ir atom with high rate capabilities in both nonaqueous (vs Li + /Li) and aqueous (vs capacitive carbon) media. It is demonstrated that Li‐insertion in carbonate LiPF 6 ‐based electrolyte occurs through a classical reduction process (Ir 5+ ↔ Ir 3+ ), which is accompanied by a well‐defined structural transition. In concentrated H 2 SO 4 electrolyte, this work provides evidence that the overall capacity of 1.7 H + per Ir results from two additive redox processes with the low potential one showing ohmic limitations. Altogether, the room temperature protonation approach, which can be generalized to various Li‐rich phases containing either 3d, 4d or 5d metals, offers great opportunities for the judicious design of attractive electrode materials.