Stabilized Octahedral Frameworks in Layered Double Hydroxides by Solid-Solution Mixing of Transition Metals

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Lee, Ji Hoon; Lee, Hyeon Jeong; Lim, Soo Yeon; Chae, Keun Hwa; Park, Sung Hyeon; Chung, Kyung Yoon; Deniz, Erhan; Choi, Jang Wook

Issue Date
John Wiley & Sons Ltd.
Advanced Functional Materials, Vol.27 No.7, p. 1605225
Pseudocapacitors have received considerable attention, as they possess advantages of both rechargeable batteries and electric double layer capacitors. Among various active materials for pseudocapacitors, alpha-layered double hydroxides (alpha-TM(OH)(2), TM = transition metal) are promising due to their high specific capacities. Yet, irreversible alpha-to-beta phase transitions of alpha-TM(OH)(2) hinder their long-term cyclability, particularly when the TM is nickel. Here, it is reported that binary TM ion mixing can overcome the limited cycle lives of alpha-TM(OH)(2) by stabilizing the octahedral frameworks of alpha-TM(OH)(2). In particular, an alpha-TM(OH)(2) with equal amounts of nickel and cobalt exhibits long-term capacity retention (89.0% after 2000 cycles) and specific capacity (206 mA h g(-1)), which are better than those of individual TM counterparts. A series of analyses reveals that the improved performances originate from the synergistic effects between the TM ions; the preferred trivalent state of cobalt ions stabilizes the octahedral framework by accommodating the detrimental Jahn-Teller distortion of Ni3+. The stabilized framework also widens the redox swing range of the nickel up to 4+, thus, increasing the specific capacity of the corresponding alpha-TM(OH)(2). This study indicates that proper mixing of TMs is a prolific approach in enhancing the vital properties of alpha-TM(OH)(2), a promising family of pseudocapacitor materials.
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College of Engineering/Engineering Practice School (공과대학/대학원)Dept. of Chemical and Biological Engineering (화학생물공학부)Journal Papers (저널논문_화학생물공학부)
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