Electrochemically Induced Crystallite Alignment of Lithium Manganese Oxide to Improve Lithium Insertion Kinetics for Dye-Sensitized Photorechargeable Batteries

• Published in: ACS energy letters 2021-04, Vol.6 (4), p.1198-1204
• Main Authors: Lee, Myeong-Hee, Kim, Byung-Man, Lee, Yeongdae, Han, Hyun-Gyu, Cho, Minjae, Kwon, Tae-Hyuk, Song, Hyun-Kon
• Format: Article
• Language: English
• ISSN: 2380-8195; 2380-8195
• DOI: 10.1021/acsenergylett.0c02473

The insertion of lithium into lithium manganese oxide spinel (LiMn2O4 (LMO) to Li2Mn2O4 (L2MO)) was used to store light energy as a form of chemical energy in a dye-sensitized photorechargeable battery (DSPB). Herein, we investigate the effect of crystallite size of LMO on DSPB performance. The crystallite size of graphene-wrapped submicrometer-sized LMO (LMO@Gn) was tuned electrochemically from 26 to 34 nm via repeated LMO-to-L2MO transitions. The different crystallite orientations in LMO@Gn particles were ordered in an identical direction by an electric stimulus. The LMO@Gn having a 34 nm crystallite size ( L 34 and L 34* ) improved DSPB performances in dim light, compared with the smaller-crystallite LMO@Gn ( L 26 ). The overall energy efficiency (η overall) of 13.2%, higher than ever reported, was achieved by adopting the fully crystallized and structure-stabilized LMO@Gn ( L 34* ) for DSPB. The phase transition between the cubic and tetragonal forms during the LMO-to-L2MO reaction was suspected to be responsible for the structural ordering.