NiCo2Al-LDH@P-Ni(OH)2 cathode material with high power density and super long life for aqueous Ni-Zn battery

Owing to its economic cost, abundant raw materials and intrinsic safety, zinc-based aqueous batteries are coming to be the research hotspot of worldwide. A high-performance cathode material is one of the key factors for Znbased aqueous batteries. Herein, we report a new cathode material, denoted as NiCo2Al-LDH@P-Ni(OH)2, that the phosphorus-doped Ni(OH)2 (P-Ni(OH)2) microrods are grown on nickel foam (NF) and the NiCo2Al-layered double-hydroxide (NiCo2Al-LDH) nanoflakes are grown on the P-Ni(OH)2 microrods. The NiCo2Al-LDH@P-Ni (OH)2 cathode material demonstrated excellent electrochemical properties with a high specific capacity of 2.95 mAh cm-2 at 4 mA cm-2 (surprisingly 368.7 mAh g-1), a sturdy rate ability of 64.78 % at about 67.8 C, (200 mA cm-2) as well as without any significant capacity degeneration after 10,000 cycles. The NiCo2AlLDH@P-Ni(OH)2//Zn battery achieves an impressive peak energy density of 5.02 mWh cm-2, a maximum power density of 306.6 mW cm-2 together with a long lifespan of 97.1 % capacity retention after 10,000 cycles, exceeding majority of the aqueous batteries and supercapacitors reported recently. A homemade NiCo2AlLDH@P-Ni(OH)2//Zn soft-package battery with a voltage of 3 V,which is formed by connecting two Ni-Zn batteries in series, can work even under puncturing, indicating that NiCo2Al-LDH@P-Ni(OH)2 hybrid cathodes have great potential for practical applications in high-performance Ni-Zn batteries.