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Iron phthalocyanine (FePc) with an ideal N-coordinated environment has been regarded as a promising catalyst for the oxygen reduction reaction (ORR). However, its self-aggregation and inferior stability remain to be solved for further application. Herein, poly-FePc-based hyper-crosslinked polymers with tetrathiafulvalene (TTF) modification (named pFePc-TTF) are innovatively constructed and applied as an efficient ORR catalyst for aluminum–air batteries (AABs). Thanks to the donor (TTF)–acceptor (FePc) effect, the resultant pFePc-TTF catalyst exhibits satisfactory ORR activity with a half-wave potential of 0.90 V, a four-electron transfer process, methanol tolerance, and excellent stability in alkaline electrolytes. The improved electrocatalytic performance might be ascribed to the introduction of TTF as an electron donor, which effectively modulates the electron distribution of the Fe atom and optimizes the absorption energy of intermediate species. As expected, both liquid AABs and all-solid-state flexible AABs equipped with pFePc-TTF display outstanding battery performance in comparison to those equipped with commercial Pt/C. This novel metal macrocycle-based compound provides an effective strategy for the design of efficient and durable ORR catalysts for energy-related applications. [ABSTRACT FROM AUTHOR]

The development of stable electrolytes for high-voltage lithium metal batteries (LMBs) is crucial for advancing battery technology. Diluted high-concentration electrolytes (DHCEs) have shown promise in enhancing interfacial stability, yet challenges persist due to the thermodynamic instability associated with conventional hydrofluoroether diluents and the interphase issues of monofluoroaromatic hydrocarbon diluents under high voltage conditions. In this study, we propose the incorporation of methyl 1,1,2,2,3,3,4,4,4-nonafluorobutyl ether (CNFE) as an additive to fluorobenzene (FB)-based DHCEs for high-voltage LMBs. CNFE with a molecular structure devoid of β-hydrogen guarantees the thermodynamic stability of FB-based DHCEs compared to conventional hydrofluoroether-based DHCEs. Moreover, CNFE promotes the formation of a LiF-rich and stable solid electrolyte interphase (SEI) and cathode electrolyte interphase (CEI). Consequently, a Li‖LiNi0.8Co0.1Mn0.1O2 (NCM811) cell demonstrates a remarkable capacity retention of 84.8% in the 700th cycle at a high cutoff voltage of 4.4 V. [ABSTRACT FROM AUTHOR]