Fully Conjugated Phthalocyanine Copper Metal-Organic Frameworks for Sodium-Iodine Batteries with Long-Time-Cycling Durability.
basic_science · Level V
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- Record sourced from PubMed, PMID 31815328.
- Also identified by DOI 10.1002/adma.201905361.
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Abstract
Rechargeable sodium-iodine (Na-I<sub>2</sub> ) batteries are attracting growing attention for grid-scale energy storage due to their abundant resources, low cost, environmental friendliness, high theoretical capacity (211 mAh g<sup>-1</sup> ), and excellent electrochemical reversibility. Nevertheless, the practical application of Na-I<sub>2</sub> batteries is severely hindered by their poor cycle stability owing to the serious dissolution of polyiodide in the electrolyte during charge/discharge processes. Herein, the atomic modulation of metal-bis(dihydroxy) species in a fully conjugated phthalocyanine copper metal-organic framework (MOF) for suppression of polyiodide dissolution toward long-time cycling Na-I<sub>2</sub> batteries is demonstrated. The Fe<sub>2</sub> [(2,3,9,10,16,17,23,24-octahydroxy phthalocyaninato)Cu] MOF composited with I<sub>2</sub> (Fe<sub>2</sub> -O<sub>8</sub> -PcCu/I<sub>2</sub> ) serves as a cathode for a Na-I<sub>2</sub> battery exhibiting a stable specific capacity of 150 mAh g<sup>-1</sup> after 3200 cycles and outperforming the state-of-the-art cathodes for Na-I<sub>2</sub> batteries. Operando spectroelectrochemical and electrochemical kinetics analyses together with density functional theory calculations reveal that the square planar iron-bis(dihydroxy) (Fe-O<sub>4</sub> ) species in Fe<sub>2</sub> -O<sub>8</sub> -PcCu are responsible for the binding of polyiodide to restrain its dissolution into electrolyte. Besides the monovalent Na-I<sub>2</sub> batteries in organic electrolytes, the Fe<sub>2</sub> -O<sub>8</sub> -PcCu/I<sub>2</sub> cathode also operates stably in other metal-I<sub>2</sub> batteries like aqueous multivalent Zn-I<sub>2</sub> batteries. Thus, this work offers a new strategy for designing stable cathode materials toward high-performance metal-iodine batteries.