Mesoporous nanohybrids of 2–D Cobalt–Chromium layered double hydroxide and polyoxovanadate anions for high performance hybrid asymmetric supercapacitors

An exfoliation-reassembling process is utilized to develop mesoporous intercalative nanohybrids of cationic 2-D cobalt-chromium-layered double hydroxide (Co–Cr-LDH) nanosheets and polyoxovanadate (POV) anions (Co–Cr-LDH-POV nanohybrids). The Co–Cr-LDH-POV nanohybrid displays a maximum specific capacity (SC) of 732 C g−1 at 1 A g−1, attributed to the layer-by-layer porous structures with expanded gallery height. An aqueous and solid-state hybrid asymmetric supercapacitor devices are fabricated by Co–Cr-LDH-POV nanohybrid as cathode and rGO nanosheets as an anode. An aqueous hybrid asymmetric supercapacitor (AHAS) device delivers an SC of 238.72 C g−1 at 0.8 A g−1 with a specific energy (SE) of 53.04 Wh kg−1 at 512 W kg−1 specific power (SP) and capacity retention of 85% over 10,000 cycles. Moreover, a solid-state hybrid asymmetric supercapacitor (SHAS) device displays a high SC of 148 C g−1 at 2.4 A g−1 with a SE of 27.59 Wh kg−1 at 2560 W kg−1 SP and capacity retention of 90.23% over 5000 cycles. Nevertheless, the obtained results suggest that such a new type of porous LDH-polyoxometalate (LDH-POM) based nanohybrids are useful as cathode for next-generation energy storage applications.