No abstract

The development of coordination polymers with π‐d conjugation (CCPs) provides ide prospects for exploring the next generation of environmental‐friendliness energy storage systems. Herein, the synthesis, experimental characterizations, and Na‐ion storage mechanism of π‐d CCPs with multiple‐active sites are reported, which use quinone‐fused aza‐phenazine (AP) and aza‐phenazin (AP) as the organic ligands coordinated with the metal center (Ni2+). Among them, NiQAP as the cathode material exhibits impressive electrochemical properties applied in sodium‐ion batteries (SIBs), including the high initial/stable discharge specific capacities (180.0/225.6 mAh g−1) at 0.05 A g−1, a long‐term cycle stability up to 10,000 cycles at 1.0 A g−1 with a high reversible capacity of 100.1 mAh g−1, and good rate capability of 99.6 mAh g−1 even at 5.0 A g−1. Moreover, the Na‐ion storage mechanism of NiQAP is also performed by the density functional theory (DFT) calculation, showing multiple‐active sites of C≐O and C≐N (in the quinone and phenazine structure) and NiO4 (in the coordination unit) for Na‐ion storage. These results highlight the importance of organic electrode material with the coordination units and provide a foundation for further studying the CCPs with multiple active sites for energy storage systems.

Quasi‐solid‐state lithium‐organic batteries have attracted widespread attention in view of their high safety, good mechanical strength, compromise ionic conductivity, and environmental friendliness. However, most organic electrode materials suffer from the undesirable interfacial compatibility, thus causing poor cycling stability. Herein, a quinone‐fused aza‐phenazine (THQAP) is reported with multi‐active site and compatible groups as the cathode material for constructing poly(vinylidene fluoride hexafluoro propylene) (PVDF‐HFP)‐based quasi‐solid‐state lithium‐organic batteries. Benefitting from the high compatibility between cathode material (THQAP) and gel polymer electrolytes (PVDF‐HFP), the dissolution and shuttle reaction of THQAP with hydroxyl groups are suppressed compared with its counterparts (QAP) without hydroxyl groups. As a result, THQAP in quasi‐solid‐state lithium‐organic batteries not only delivers excellent reversible capacity of 240 mAh g−1 at 50 mA g−1, but also exhibits stable cyclability with capacity retention of 78% (160 mAh g−1) after 200 cycles at 200 mA g−1. This study offers a promising strategy to develop quasi‐solid‐state lithium‐organic batteries with higher capacity and cycling stability.

No abstract

No abstract