Alternate Storage of Opposite Charges in Multisites for High‐Energy‐Density Al–MOF Batteries. Issue 13 (18th February 2022)

• Record Type: Journal Article
• Authors: Guo, Yuxi; Wang, Wei; Lei, Haiping; Wang, Mingyong; Jiao, Shuqiang
• Is Part Of: Advanced materials. Volume 34:Issue 13(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-02-18
• Subjects: Al–MOF batteries -- alternate storage -- high energy density -- multisites -- opposite charges; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adma.202110109
• Languages: English
• ISSNs: 0935-9648

Abstract

Abstract: The limited active sites of cathode materials in aluminum‐ion batteries restrict the storage of more large‐sized Al‐complex ions, leading to a low celling of theoretical capacity. To make the utmost of active sites, an alternate storage mechanism of opposite charges (AlCl4 − anions and AlCl2 + cations) in multisites is proposed herein to achieve an ultrahigh capacity in Al–metal–organic framework (MOF) battery. The bipolar ligands (oxidized from 18π to 16π electrons and reduced from 18π to 20π electrons in a planar cyclic conjugated system) can alternately uptake and release AlCl4 − anions and AlCl2 + cations in charge/discharge processes, which can double the capacity of unipolar ligands. Moreover, the high‐density active Cu sites (Cu nodes) in the 2D Cu‐based MOF can also store AlCl2 + cations for a higher capacity. The rigid and extended MOF structure can address the problems of high solubility and poor stability of small organic molecules. As a result, three‐step redox reactions with two‐electron transfer in each step are demonstrated in charge/discharge processes, achieving high reversible capacity (184 mAh g −1 ) and energy density (177 Wh kg −1 ) of the optimized cathode in an Al–MOF battery. The findings provide a new insight for the rational design of stable high‐energy Al–MOF batteries. Abstract : An alternate storage mechanism of opposite charges in multisite is demonstrated in a 2D Cu‐based metal‐organic framework (MOF) cathode to achieve a high energy density for Al–MOF batteries. The MOF can alternately uptake and release AlCl4 − anions and AlCl2 + cations in charge/discharge processes, which doubles the capacity compared with the storage of the same charge in one active site.