Rechargeable aqueous zinc-based batteries are very attractive alternative devices for current energy storage by virtue of their low cost and high security. However, the performance of vanadium oxide cathode strongly relies on the distance of interlayer spacing. Here, we employ layered PEDOT-NH 4 V 3 O 8 (PEDOT-NVO) as a cathode material, which produces an enlarged interlayer spacing of 10.8 Å (against 7.8 Å for the single NVO) by effectively conducting polymer intercalation. This cathode material exhibits an improved capacity of 356.8 mAh g À1 at 0.05 A g À1 and 163.6 mAh g À1 , even at the highest current density of 10 A g À1 (with a high retention from 0.05 to 10 A g À1 ), and features an ultra-long lifetime of over 5,000 charge-discharge cycles with a capacity retention of 94.1%. A combination of mechanism analyses and theoretical calculations suggest that the oxygen vacancies and larger interlayer spacing through polymer assistance account for the improved electrochemical performance.

Prussian blue analogues (PBAs) have been widely investigated as cathode materials in aqueous Na-ion batteries (ASIBs) due to their special openframework structure. Herein, nanoscale nickel hexacyanoferrate with carbon nanotubes (NiHCF@CNTs, NC for short) has been fabricated via a facile route. According to transmission electron microscopy (TEM) images, NiHCF is a randomly aggregated particle and CNTs are universally tangled with NiHCF. In ASIBs, NC delivers a discharge capacity of 54.1 mAh g −1 at 0.1 A g −1 . An astonishingly long life with a capacity retention of 80% over 10 000 cycles at 10 A g −1 is also achieved. Significantly, this material exhibits excellent rate capability with a capacity of 47.9 mAh g −1 even at an ultrahigh current density of 10 A g −1 . Such superior rate performance is owing to the extrinsic intercalation pseudocapacitive response. This surface-controlled mechanism suggests that developing pseudocapacitive materials is a feasible pathway to promote the rate performance of PBAs as cathodes for ASIBs.

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