A nickel coordination polymer derived from 1,2,4,5-tetraaminobenzene for fast and stable potassium battery anodes

We report the application of a Ni-based coordination polymer derived from 1,2,4,5-tetraaminobenzene (P1) as a fast and stable potassium battery anode. In a voltage range of 0.5-2.0 V vs. K+/K, a reversible capacity of 220 mA h g-1 was obtained at 0.1 A g-1. Even with a relatively high electrode loading of 5.0 mg cm-2 and only 10 wt% carbon additive, 118 mA h g-1 was still retained at 1 A g-1. For thinner electrodes with 30 wt% carbon, a capacity of up to 104 mA h g-1 was observed at 10 A g-1 (charging in ∼40 seconds). An areal capacity of up to 2.73 mA h cm-2 was demonstrated. The capacity fade at 1 A g-1 was only 4.4% after 200 cycles. Structure transformations of P1 during charge/discharge were studied using X-ray photoelectron spectroscopy and in situ X-ray diffraction.