Cobalt(II) dicarboxylate-based metal-organic framework for long-cycling and high-rate potassium-ion battery anode

- A layered MOF was applied as anode for potassium-ion battery for the first time.
- A reversible capacity of 188 mAh g−1 is maintained at 1 A g−1 after 600 cycles.
- Both Co centers and organic ligands participate in the K-ion storage.

Metal-organic frameworks (MOFs) are promising electrical storage materials due to their abundant electroactive components and large ion diffusion tunnels, however, there is no report on the employment of MOFs as electrodes for potassium-ion batteries (PIBs) hitherto. Here in this work, we firstly develop a cobalt(II) terephthalate-based layered MOF (referred as 'L-Co2(OH)2BDC', BDC = 1,4-benzenedicarboxylate) as an anode material for PIBs. The exceptional potassium storage performance of L-Co2(OH)2BDC is demonstrated with a high reversible capacity of 188 mAh g−1 after 600 prolonged cycles at 1 A g−1, revealing the considerable foreground of MOFs as superior potassium storage anodes. Moreover, the redox chemistry investigation of L-Co2(OH)2BDC based on X-ray absorption near edge structure (XANES) and soft X-ray spectroscopy (sXAS) techniques substantiate that both Co centers and organic ligands participate in the potassium storage, and the coordination between oxygen ions and cobalt significantly ensures the reversibility of potassiation and depotassiation processes. This work represents a significant step forward for the intensive application of MOFs in rechargeable metal batteries.

Cobalt(II) terephthalate-based layered MOF anode material for potassium-ion battery with superior long-term cyclic performance is reported for the first time.180