Biomass thermochemical processes result in a common byproduct char. The char is also called biochar particularly when it is used as a soil amendment for soil health improvement. Effective utilization of biochar is critical for improving economic viability and environmental sustainability of biomass thermochemical technologies. Application of biochar for both agricultural and environmental benefits has been studied and reviewed extensively. However, there are limited reviews on other biochar applications, such as for catalysis and adsorption. This paper provides an overview of recent advances in several biochar utilizations including its use as catalyst, soil amendment, fuel cell, contaminant adsorbent, gas storage and activated carbon. Discussions on biochar production methods, properties and advanced characterization techniques are also provided. Biochar is a valuable resource, however, its effective utilization require further investigation of its structure and properties, and methods to modify those.

Recent advances in utilization of biochar

An overview of the recent development in the production of activated carbon electrodes from agricultural waste biomass for application in supercapacitors is presented. The use of agricultural waste biomass as precursor for the production of activated carbons has been on the increase lately because it is cheap, readily available and also viewed as a veritable way of combating waste disposal problem in the agricultural industries. The effects of activating methods (physical, chemical and microwave-induced) and conditions on the properties of activated carbons are reviewed. The survey of articles published in the last decade indicates the viability of biomass active carbons being used as electrodes in supercapacitors. Under optimum process conditions, active carbons with specific capacitance as high as 374 F g−1 and high-rate long-cycle stability at 4 A g−1 have been produced. In this review, the influence of surface modification on activated carbon properties is also discussed. From the survey literature, it can be seen that the changes in surface chemistry and the introduction of specific surface functionalities on the surface of activated carbons impacted more on the electrochemical properties than the physiochemical properties of the activated carbons.

Recent development in the production of activated carbon electrodes from agricultural waste biomass for supercapacitors: A review

Graphene is an atomically thin, two-dimensional (2D) carbon material that offers a unique combination of low density, exceptional mechanical properties, thermal stability, large surface area, and excellent electrical conductivity. Recent progress has resulted in macro-assemblies of graphene, such as bulk graphene aerogels for a variety of applications. However, these three-dimensional (3D) graphenes exhibit physicochemical property attenuation compared to their 2D building blocks because of one-fold composition and tortuous, stochastic porous networks. These limitations can be offset by developing a graphene composite material with an engineered porous architecture. Here, we report the fabrication of 3D periodic graphene composite aerogel microlattices for supercapacitor applications, via a 3D printing technique known as direct-ink writing. The key factor in developing these novel aerogels is creating an extrudable graphene oxide-based composite ink and modifying the 3D printing method to accommodate aero...

Supercapacitors Based on Three-Dimensional Hierarchical Graphene Aerogels with Periodic Macropores.

The ever increasing penetration of renewable energy systems (RESs) in today deregulated intelligent power grids, necessitates the use of electrical storage systems. Energy storage systems (ESSs) are helpful to make balance between generation and demand improving the performance of whole power grid. In collaboration with RESs, energy storage devices can be integrated into the power networks to bring ancillary service for the power system and hence enable an increased penetration of distributed generation (DG) units. This paper presents different applications of electrical energy storage technologies in power systems emphasizing on the collaboration of such entities with RESs. The role of ESSs in intelligent micropower grids is also discussed where the stochastic nature of renewable energy sources may affect the power quality. Particular attention is paid to flywheel storage, electrochemical storage, pumped hydroelectric storage, and compressed air storage and their operating principle are discussed as well. The application of each type in the area of power system is investigated and compared to others.

Emergence of energy storage technologies as the solution for reliable operation of smart power systems: A review

Preparation of highly porous binderless activated carbon electrodes from fibres of oil palm empty fruit bunches for application in supercapacitors.

Porous wood carbon monolith for high-performance supercapacitors

Fabrication of promising LiFePO4/C composite with a core–shell structure by a moderate in situ carbothermal reduction method

Template-free synthesis of porous–LiFePO4/C nanocomposite for high power lithium-ion batteries

Mesoporous cobalt oxide has been successfully synthesized by a facile chemical precipitation method assisted by cetyltrimethylammonium bromide (CTAB) micelles. Electrochemical characterization is performed using cyclic voltammetry, chronopotentiometry and impedance spectroscopy, respectively. The results indicate that the prepared cobalt oxide has excellent electrochemical properties. A maximum specific capacitance of 250 F g−1 could be achieved in 2 M aqueous KOH with the potential range from −0.1 to 0.4 V (vs. SCE) at a current density of 5 mA cm-2 in a half-cell setup configuration. Furthermore, the effect of CTAB mass on electrochemical capacitance characteristics has also been systematically explored.

Peng Zhang

Papers

Porous wood carbon monolith for high-performance supercapacitors

Fabrication of promising LiFePO4/C composite with a core–shell structure by a moderate in situ carbothermal reduction method

Template-free synthesis of porous–LiFePO4/C nanocomposite for high power lithium-ion batteries

Low temperature formation of mesoporous Co 3 O 4 and their supercapacitive properties