Stable High‐Capacity Organic Aluminum–Porphyrin Batteries

• Published in: Advanced energy materials Vol. 11; no. 32
• Main Authors: Han, Xue, Li, Shijie, Song, Wei‐Li, Chen, Nuo, Chen, Haosen, Huang, Shanyan, Jiao, Shuqiang
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01.08.2021
• Subjects: Aluminum; aluminum–porphyrin batteries; Basicity; Coordination compounds; Electrode materials; Energy storage; fast kinetics; Flux density; Functional groups; Ion diffusion; ion‐coordination mechanism; large π‐conjugated; Organic materials; Porphyrins; Stability; Storage batteries; superior cycle stability
• ISSN: 1614-6832; 1614-6840
• DOI: 10.1002/aenm.202101446

Aluminum‐ion batteries (AIBs) attract interest for their promising features of superior safety and long‐life energy storage. Organic materials with engineered active groups are considered promising for promoting energy storage capabilities. However, the corresponding energy density (both voltage plateau and sufficient active sites required) and stability are still unexpectedly poor. To address these challenges, here π‐conjugated organic porphyrin molecules, that is, 5,10,15,20‐tetraphenylporphyrin (H2TPP) and 5,10,15,20‐tetrakis(4‐carboxyphenyl) porphyrin (H2TCPP), are selected as the positive electrode materials for AIBs. Owing to the highly reversible coordination/dissociation with aluminum complex cations, H2TPP presents long‐term cycling stability beyond 5000 cycles at 200 mA g−1. Compared with the specific capacity of H2TCPP (≈24 mA h g−1 at 100 mA g−1), the enhanced capabilities in H2TPP (reversible specific capacity of ≈101 mA h g−1 at 100 mA g−1) are attributed to removal of the carboxyl functional groups, which plays a role in reducing the basicity of porphyrin induced via electron withdrawing effects. Additionally, the mechanism of electrochemical reaction between AlCl2+ and porphyrin as well as ionic diffusion behaviors on the surface of the electrode are investigated. The results establish a platform to develop long‐term organic aluminum batteries for safe and stable energy storage. Stable high‐capacity organic aluminum–porphyrin batteries are assembled and the large delocalized π bond in porphyrins can effectively promote the active sites and improve stability of the molecular structures. These features allow the aluminum–porphyrin batteries to deliver long‐term stability and high rate capabilities, which enable the fabrication of a high‐capacity organic Aluminum‐ion batteries.