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Rational construction of multidimensional composites with abundant heterointerfaces is still a persistent challenge, especially dual interface structure. Herein, a facile interface engineering strategy has been put forward to construct NiO/NiCo2O4/CoO heterostructures within graphene networks by controlling salt-templated solvothermal reactions and calcination treatments. The heterostructure produces dual interfaces of NiO/NiCo2O4 and CoO/NiCo2O4. The resultant composite combines the merits of the unique properties of each component and exerts their synergistic effects. The density function theory calculations reveal that the interface structures can endow the hybrid with higher states at Fermi level, fast electron transfer, and efficient Li+ adsorption ability. Furthermore, benefiting from the abundant active sites and porosity, this unique porous structure can accommodate the volume expansion and promote the diffusion of electrolyte ions, which greatly boosts the electrochemical performances of hybrids. Consequently, the NiO/NiCo2O4/CoO/Gra heterostructure electrodes achieve a remarkably reversible capacity of 1932.8 mAh g−1 at 0.1 A g−1, a superior rate capability (1210.5 mAh g−1 at 1 A g−1), and impressive cycling stability of 83.5% after 500 cycles at 0.5 A g−1. This work provides a new insight of developing multiple heterostructures anode materials for high-performance energy storage and conversion.

Till now, the counter electrode (CE) material for dye sensitized solar cells (DSSCs) has been developed by improving the conductivity and electrocatalytic activity of the material. This work proposes a new technique to further enhance the exploration of advanced CE materials. In the new technique the reflectivity of the CE material (MoS2 based) is increased by vertically inclining the MoS2 on the substrate (FTO). The MoS2 is synthesized through chemical vapor deposition (CVD), which eliminates the complicated CE fabrication process. As a result, the CE possesses high reflectivity which facilitates the absorbance of more photons, and also leads to create more active edge sites exposed to I−/I3− redox couple in the electrolyte. This technique yields an efficiency of approximately 7.5% which excels that of the Pt based (7.28%) electrodes.

A novel sandwiched gel polymer electrolyte (GPE) was prepared using a facile method as separator solely for rechargeable Lithium–Sulfur batteries. As a result of the strong physical shielding and chemical absorption of GPE, the separator can not only suppress shuttle effect in ether-based electrolyte, but also improve utilization of sulfur significantly resulting in a high capacity. The PVDF layers could absorb ether-based electrolyte largely and then enhance Li + transfer; the PMMA layer can be utilized to trap the dissolved polysulfides. Lithium–Sulfur batteries with the sandwiched GPE separator shows an encouraging electrochemical performance. A high initial discharge capacity of 1711.8 mAh g −1 is obtained, and the capacity retains at 1145.3 mAh g −1 after 50 cycles at 200 mA g −1 , which is higher than that of the cell with the commercial separator. These results indicate that the appropriate GPE separator is more suitable in Lithium−Sulfur batteries applications.

Carbon materials have unique stability and controllable structure for all-carbon lithium-ion capacitors (LICs) electrode materials. In this paper, we used chitosan as a carbon source and self-doped nitrogen source, zinc nitrate as a templating agent. Hierarchical porous carbon nanosheets (PCNS) materials with graphene-like structure and abundant nitrogen doping were prepared through a one-step carbonization process. The PCNS materials were used as both capacitor-type cathode and battery-type anode for LICs. Due to the multi-mesoporous and ultrathin nanosheets structure, a large specific surface area (1321.3 m2 g−1) was obtained of PCNS materials, which ensures a high specific discharge capacity of 65.8 mAh g−1 at 3 A g−1 for the capacitor-type cathode. The interconnected graphene-like structure not only provides a large adsorbable area but also reduces the diffusion distannce of ions between the surface of the electrode and electrolyte. When the PCNS materials used as an anode for LIC, it also appeared a high specific discharge capacity of 285.0 mAh g−1 at a big current density of 20 A g−1. Finally, all-carbon symmetric LIC with a broad voltage window of 0.01–4.5 V was constructed successfully. The symmetric LIC shows a high energy density of 146 Wh kg−1 (at a power density of 1125 W kg−1) and an excellent capacity retention rate of 84.5% (10,000 cycles at 5 A g−1).

Rational designing of a facile synthetic protocol for synchronously generating NiCo2O4 and conductive carbon is a great challenging for high-performance supercapacitors. Herein, a one-pot and scalable approach has been developed to in-situ construct oxygen-vacancy-rich NiCo2O4/nitrogen-deficient graphitic carbon nitride (Ov-NiCo2O4/ND-g-C3N4) hybrids. The in-depth investigations reveal that there is an intriguing interaction between NiCo2O4 and g-C3N4, which unexpectedly enables the generating of Ov-NiCo2O4 and transforming of g-C3N4 into ND-g-C3N4 structures. Moreover, the g-C3N4 plays the skeleton and template role to form the foam-like structure. Benefiting from abundant active species and improved electrical conductivity, the resultant Ov-NiCo2O4/ND-g-C3N4 exhibits an unrivalled specific capacitance of 1998 F g−1 (equalling 277.5 mAh g−1) at a current density of 2 A g−1 and excellent rate capability (78.66% capacity retention at 20 A g−1). Besides, the assembled Ov-NiCo2O4/ND-g-C3N4//activated carbon asymmetric supercapacitors deliver a maximum energy density of 70.22 Wh kg−1 at a power density of 800 W kg−1, and a remarkable cycling stability with 95.22% retention even after 5000 cycles, outstripping most of reported NiCo2O4-based supercapacitors. Thus, this work sheds light on the developing of advanced pseudocapacitive materials for electrochemical energy storage.

Graphene-based conductive organic composites are a class of electrode materials with great potential for next-generation energy storage devices due to their good flexibility, high conductivity and abundant redox sites. Herein, a series of novel 7-aminoindole/rGO composites are successfully synthesized by a universal solvothermal method. With rGO as supporting framework, the morphology, structure and conductivity of the composites are optimized by the synergistic effect of 7-aminoindole and rGO to comprehensively enhance the electrochemical performance of the electrode. The obtained optimal electrode delivers a high specific capacitance of 391.88 F g−1 at 0.5 A g−1. Simultaneously, the assembled symmetric device also exhibits an energy density of 11.97 Wh kg−1 at a power density of 325 W kg−1 and a super-long cycling stability (97.62%) after 25,000 cycles at a current density of 5 A g−1. Such measurement results strongly demonstrate that the synthesized novel composite electrodes have a great potential for application in new energy storage devices such as flexible electronics and wearable devices.

In this study, we report modification of few-layer graphene grown by chemical vapour deposition via nitrogen plasma ion irradiation and its application as counter electrodes in bifacial dye-sensitized solar cells (DSSCs). The incorporation of nitrogen (N) atoms and defects are confirmed by X-ray photoelectron spectroscopy and Raman spectroscopy. Electrochemical impedance spectroscopy measurement reveals that the charge transfer resistance of graphene for triiodide reduction shows a decrease with increasing plasma treatment time, which is attributed to the increase of catalytic sites. The energy conversion efficiency of 3.12% is obtained when using the N-doped graphene films as counter electrodes, which is nearly 3 times higher than that of the pristine graphene films in DSSCs. More importantly, the DSSCs based on N-doped graphene CEs show much higher η rear /η front ratio and better long-term stability than that based on Pt CEs. These results reveal the promising potential of this transparent N-doped graphene CEs in low cost and effective bifacial DSSCs.

A novel and simple in-situ solid-state reaction route is developed to synthesize a three-dimensional (3D) porous carbon fiber film-supported Li 3 V 2 (PO 4 ) 3 membrane electrode. The carbon film is obtained via the carbonization of a bioproduct rice paper (RP). The carbon film can function as both a current collector and a 3D electronic conduction network for the loaded Li 3 V 2 (PO 4 ) 3 particles. The structure and electrochemical properties of the Li 3 V 2 (PO 4 ) 3 membrane electrode are characterized. As a free-standing membrane electrode, it exhibits good rate performance at room temperature with a specific capacity of 108 and 142 mAh g −1 at 10 C rate in the voltage range of 3.0–4.3 V and 3.0–4.8 V, respectively. It also shows good cycling performance with a specific capacity of 123 mAh g −1 after 500 cycles at 1 C rate in the voltage range of 3.0–4.8 V.