There is intense interest in graphene in fields such as physics, chemistry, and materials science, among others. Interest in graphene's exceptional physical properties, chemical tunability, and potential for applications has generated thousands of publications and an accelerating pace of research, making review of such research timely. Here is an overview of the synthesis, properties, and applications of graphene and related materials (primarily, graphite oxide and its colloidal suspensions and materials made from them), from a materials science perspective.

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Graphene and Graphene Oxide: Synthesis, Properties, and Applications

Supercapacitors, also called ultracapacitors or electrochemical capacitors, store electrical charge on high-surface-area conducting materials. Their widespread use is limited by their low energy storage density and relatively high effective series resistance. Using chemical activation of exfoliated graphite oxide, we synthesized a porous carbon with a Brunauer-Emmett-Teller surface area of up to 3100 square meters per gram, a high electrical conductivity, and a low oxygen and hydrogen content. This sp 2 -bonded carbon has a continuous three-dimensional network of highly curved, atom-thick walls that form primarily 0.6- to 5-nanometer-width pores. Two-electrode supercapacitor cells constructed with this carbon yielded high values of gravimetric capacitance and energy density with organic and ionic liquid electrolytes. The processes used to make this carbon are readily scalable to industrial levels.

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Carbon-based Supercapacitors Produced by Activation of Graphene

Although electrochemical capacitors (ECs), also known as supercapacitors or ultracapacitors, charge and discharge faster than batteries, they are still limited by low energy densities and slow rate capabilities. We used a standard LightScribe DVD optical drive to do the direct laser reduction of graphite oxide films to graphene. The produced films are mechanically robust, show high electrical conductivity (1738 siemens per meter) and specific surface area (1520 square meters per gram), and can thus be used directly as EC electrodes without the need for binders or current collectors, as is the case for conventional ECs. Devices made with these electrodes exhibit ultrahigh energy density values in different electrolytes while maintaining the high power density and excellent cycle stability of ECs. Moreover, these ECs maintain excellent electrochemical attributes under high mechanical stress and thus hold promise for high-power, flexible electronics.

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Laser Scribing of High-Performance and Flexible Graphene-Based Electrochemical Capacitors

Graphene has attracted tremendous research interest in recent years, owing to its exceptional properties. The scaled-up and reliable production of graphene derivatives, such as graphene oxide (GO) and reduced graphene oxide (rGO), offers a wide range of possibilities to synthesize graphene-based functional materials for various applications. This critical review presents and discusses the current development of graphene-based composites. After introduction of the synthesis methods for graphene and its derivatives as well as their properties, we focus on the description of various methods to synthesize graphene-based composites, especially those with functional polymers and inorganic nanostructures. Particular emphasis is placed on strategies for the optimization of composite properties. Lastly, the advantages of graphene-based composites in applications such as the Li-ion batteries, supercapacitors, fuel cells, photovoltaic devices, photocatalysis, as well as Raman enhancement are described (279 references).

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Graphene-based composites

Graphene based materials: Past, present and future

Potassium manganese hexacyanoferrate (MnHCF) is a promising cathode material in aqueous zinc-ion batteries (ZIBs) due to its high capacity and operating potential. This study improves its electrochemical performance by using ethanol (EA) as the electrolyte solvent, which can effectively inhibit the dissolution of Mn ions and crystalline phase transformation of MnHCF. This study is of great significance for improving the cycling stability of ZIBs. This study prepared MnHCF nanocubes by citric acid-assisted method and aplplied them in zinc ion batteries. In addition, we found that using ethanol as the electrolyte solvent can avoid the dissolution and phase change of MnHCF during the electrochemical reactions thus improving the cycling stability of the Zn/MnHCF battery. 

High-Cycling Stability of Zn/MnHCF Batteries Boosted by Non-Aqueous Ethanol Electrolyte

The inherent "solid-liquid-solid" multi-step reactions in lithium-sulfur battery (LSB) are accompanied by sluggish kinetics. In particular, those redox reactions concerning short-chain lithium polysulfide (LiPS), Li2Sx (x ≤ 4) ↔ lithium...

Manganese-nickel bimetallic oxide electrocatalyzing redox reactions of lithium polysulfide in lithium-sulfur batteries

Solid-state lithium-sulfur battery (SSLSB) faces the difficulty of slow S8 (solid) ↔ Li2S (solid) conversion kinetics. Such solid reactions are highly ion-transmission demanding and only take place at/near the electrode/electrolyte...

Chengyang Wang

Papers

High-Cycling Stability of Zn/MnHCF Batteries Boosted by Non-Aqueous Ethanol Electrolyte

Manganese-nickel bimetallic oxide electrocatalyzing redox reactions of lithium polysulfide in lithium-sulfur batteries

Gradient distribution of functional components in PAN-based electrolyte endowing solid-state lithium sulfur battery with long cycle life

Anti-Corrosion Properties of Array-Structured Superhydrophobic Surfaces

“Anode-free” Zn/LiFePO4 aqueous batteries boosted by hybrid electrolyte