In the context to develop ultra-efficient electrode materials with good physicoelectrochemical and electrostructural properties, for their application in high-performance supercapatteries, herein, a facile tartrate-mediated inhibited crystal growth method is reported to engineer thoroughly uniform ribbonlike nickel cobaltite (NiCo 2 O 4 ) microstructure with unique layerby-layer-assembled nanocrystallites. This material demonstrates significant kinetic reversibility, good rate efficiency and bulk diffusibility of the electroactive ions, and a predominant semiinfinite diffusion mechanism during the redox-based charge storage process. This material also shows bias-potential-independent equivalent series resistance, very low charge-transfer resistance, and diagonal Warburg profile, corresponding to the ion diffusion occurring during the electrochemical processes in supercapacitors and batteries. Further, the fabricated NiCo 2 O 4 -based all-solid-state supercapattery (NiCo 2 O 4 ||N-rGO) delivers excellent rate-specific capacity, very low internal resistance, good electrochemical and electrostructural stability (∼94% capacity retention after 10,000 charge−discharge cycles), energy density (31 W h kg −1 ) of a typical rechargeable battery, and power density (13,003 W kg −1 ) of an ultra-supercapacitor. The ultimate performance of the supercapattery is ascribed to low-dimensional crystallites, ordered inter-crystallite and channel-type bulk and boundary porosity, multiple reactive equivalents, enhanced electronic conductivity, and "ion buffering pool" like behavior of ribbon-like NiCo 2 O 4 , supplemented with enhanced electronic and ionic conductivities of N-doped rGO (negative electrode) and PVA/KOH gel (electrolyte separator), respectively.

In order to improve the electro-microstructural physiognomics of electrode materials for applications in better efficiency supercapacitors, herein graphitic carbon nitride (GCN)heterostructurized CoS−NiCo 2 S 4 is designed using a controlled material growth synthesis procedure. The developed CoS− NiCo 2 S 4 /GCN possesses ample hydrophilicity, possible charge transfer between GCN and CoS−NiCo 2 S 4 , uniform phase distribution, and distinctive microstructural characteristics. The preliminary electrochemical studies in the three-electrode setup show GCN-induced lower charge transfer resistance and very unique Warburg profile corresponding to extremely low diffusion resistance in CoS−NiCo 2 S 4 /GCN as compared to pristine CoS− NiCo 2 S 4 . Furthermore, GCN is found to significantly induce surface-controlled (capacitive-type) charge storage and frequency-independent specific capacitance up to 10 Hz in CoS−NiCo 2 S 4 . Furthermore, the CoS−NiCo 2 S 4 ||N-rGO and CoS−NiCo 2 S 4 /GCN||N-rGO all-solid-state hybrid supercapacitor (ASSHSC) devices were fabricated using N-rGO as the negative electrode material, and the inducing effect of GCN on the supercapacitive charge storage performance of the devices is thoroughly studied. Results demonstrate that the mass specific capacitance and areal capacitance of CoS−NiCo 2 S 4 /GCN||N-rGO are ∼2 and ∼4 times more than those of the CoS−NiCo 2 S 4 ||N-rGO ASSHSC device, respectively. Furthermore, the CoS−NiCo 2 S 4 /GCN||N-rGO offers more energy density, rate energy density, and additional charge− discharge durability (over ∼10,000 cycles) than the CoS−NiCo 2 S 4 ||N-rGO ASSHSC device. The multifold performance improvement of CoS−NiCo 2 S 4 with GCN heterostructurization is ascribed to GCN-induced supplemented porosity and pore widening, ionic nonstoichiometry (Ni 2±δ , Co 2±δ , and Co 3±δ ), wettability, integrated enhancement in the conductivity, and electroactive-ion accessibility in the CoS−NiCo 2 S 4 /GCN heterocomposite. The present study offers vital physicoelectrochemical insights toward the future development of low cost and high-performance electrode materials, and their implementation in high-rate and operationally stable all-solid-state hybrid supercapacitor devices, for application in the next-generation front-line technologies.

In order to develop ultra-efficient electrocatalysts for application in oxygen electrochemistry based energy conversion and storage devices, herein, an extremely facile synthesis procedure has been innovated to synthesize hierarchical CoMoS4...

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