Micro- and Nanocrystalline Inverse Spinel LiCoVO₄ for Intercalation Pseudocapacitive Li⁺ Storage with Ultrahigh Energy Density and Long-Term Cycling

Abstract

Intercalation pseudocapacitance has been recognized as a new type of charge storage mechanism in crystalline metal oxides, wherein Li + intercalation is not limited to surface structures, instead extended to the bulk crystalline framework of the material. This may possibly narrow the performance gap between pseudocapacitors and batteries. Hitherto, very few crystalline materials have been found to exhibit such an intrinsic capacitive property. Here, we report for the first time that the inverse spinel LiCoVO 4 exhibits intercalation pseudocapacitive Li + storage property in aqueous electrolyte. Micro-and nanocrystalline LiCoVO 4 were synthesized via conventional solid-state reaction and hydrothermal reaction followed by calcination, respectively. In particular, nanocrystalline LiCoVO 4 demonstrated better Li + intercalation benefited from its small crystallite size with highly exposed Li + selective crystallographic pathways toward electrolyte. The LiCoVO 4 nanocrystals demonstrated excellent capacitive performance, including high specific capacitance (929.58 F g −1 at 1 A g −1 ) and cycling stability. Moreover, asymmetric hybrid cells were assembled using nanocrystalline LiCoVO 4 and MWCNT as the positive and negative electrode, respectively. The hybrid cells exhibited an unprecedented energy density (148.75 Wh kg −1 at a power density of 264.6 W kg −1 ) and superior cycling stability (94% capacitance retention after 5000 cycles).

Antiferromagnetic Inverse Spinel Oxide LiCoVO4 with Spin‐Polarized Channels for Water Oxidation

“…Inverse spinel oxide LiCoVO 4 with Co 2+ Oh was synthesized using sol-gel methods. [11] The ZnCo 2 O 4 spinel oxide with Co 3+ Oh was synthesized according to the previous report. [12] The X-ray diffraction (XRD) patterns of LiCoVO 4 and ZnCo 2 O 4 are shown in Figure 1a.…”

“…Inverse spinel oxide LiCoVO 4 with Co 2+ Oh was synthesized using sol–gel methods . The ZnCo 2 O 4 spinel oxide with Co 3+ Oh was synthesized according to the previous report .…”

Solid-State Fabrication of Co3V2O8@C Anode Materials with Outstanding Rate Performance and Cycling Stability by Synergistic Effects of Pseudocapacity and Carbon Coating

“…In this equation, b is a constant that reflects the determined step during the electrochemical reaction. If the value of b is near 1.0, the electrochemical process is pseudocapacitive-controlled. − As shown in Figure b, the value of b can be determined from the slope of log­( i ) versus log­( v ) for different potentials of the redox peak. The values of b are determined to be 0.91, 1.00, 0.94, 0.92, and 0.94 for the five peaks I–V, which clearly indicate that the electrochemical process is surface-controlled.…”