Kim, Hee Jae Jo, Jae Hyeon Kim, Ji Young Jeong, Ji won Jae-Ho Park Jung, Hun Gi Chung, Kyung Yoon Kim, Min Gyu Lee, Naesung Sohn, Kee-Sun Aniskevich, Yauhen Streltsov, Eugene Myung, Seung-Taek 2024-01-12T02:33:44Z 2024-01-12T02:33:44Z 2022-11-24 2023-01 2405-8297 https://pubs.kist.re.kr/handle/201004/75866 We introduce an unexpected finding of the de/protonation associated conversion reaction occurred in K2V3O8 as a promising cathode material for zinc-ion batteries. The structure undergoes a conversion reaction between amorphous V5+ 2 O5 and V3+OOH upon cycling when a cut-off voltage up to 1.9 V is applied. A combination of operando X-ray diffraction, in situ Raman spectroscopy, X-ray photoelectron spectroscopy, time-of-flight sec-ondary-ion mass spectroscopy, and operando pH measurement analyses reveal that the reaction of the proton (H+) is indispensable for progression of the conversion reaction. The conversion reaction results in a large reversible capacity of 362 mAh g- 1 (-97 % of theoretical capacity) at 0.1 C (37 mA g- 1) on discharge and an activity even at a rate of 7 C (187 mAh g- 1), with the two-electron reaction by the V5+/3+ redox pair evidenced by operando X-ray absorption spectroscopy analysis. These findings underscore the importance of conversion reversibility associated with the proton reaction for a high cut-off voltage, contributing additional capacity to reach the theoretical capacity for cathode materials of zinc-ion batteries in mildly acidic aqueous systems. English Elsevier BV De/protonation associated sustainable conversion reaction applicable to high-capacity zinc storage in mildly acidic aqueous system Article 10.1016/j.ensm.2022.11.028 1 Energy Storage Materials, v.55, pp.105 - 116 Energy Storage Materials 55 105 116 N scie scopus 000918638800002 Chemistry, Physical Nanoscience & Nanotechnology Materials Science, Multidisciplinary Chemistry Science & Technology - Other Topics Materials Science Article NANOROD CATHODE ION CHEMISTRY H+ Conversion Proton Cathode Zinc Battery