Nickel hexacyanoferrate/carbon composite as a high-rate and long-life cathode material for aqueous hybrid energy storage.

A nickel hexacyanoferrate (NiHCF)/carbon composite is prepared to realize reduced structure vacancies and enhanced conductivity simultaneously. The resultant composite as a cathode material exhibits good capacity retentions both for rate capability (93% of that at 0.1 A g for 2 A g) and cycle stability (94% after 900 cycles at 0.5 A g). This feature is also kept in an aqueous hybrid energy storage device, after coupling with rGO as the anode. After 5000 cycles at 2 A g, 94% of the initial capacity is preserved, exhibiting extraordinary stability at high rates.