In this review, the efforts done by different research groups to enhance the performance of the electric double-layer capacitors (EDLCs), regarding the effect of the modification of activated carbon structures on the electrochemical properties, are summarized. Activated carbon materials with various porous textures, surface chemistry, and microstructure have been synthesized using several different techniques by different researchers. Micro-, meso-, and macroporous textures can be obtained through the activation/carbonization process using various activating agents. The surface chemistry of activated carbon materials can be modified via: (i) the carbonization of heteroatom-enriched compounds, (ii) post-treatment of carbon materials with reactive heteroatom sources, and (iii) activated carbon combined both with metal oxide materials dan conducting polymers to obtain composites. Intending to improve the EDLCs performance, the introduction of heteroatoms into an activated carbon matrix and composited activated carbon with either metal oxide materials or conducting polymers introduced a pseudo-capacitance effect, which is an additional contribution to the dominant double-layer capacitance. Such tricks offer high capacitance due to the presence of both electrical double layer charge storage mechanism and faradic charge transfer. The surface modification by attaching suitable heteroatoms such as phosphorus species increases the cell operating voltage, thereby improving the cell performance. To establish a detailed understanding of how one can modify the activated carbon structure regarding its porous textures, the surface chemistry, the wettability, and microstructure enable to enhance the performance of the EDLCs is discussed here in detail. This review discusses the basic key parameters which are considered to evaluate the performance of EDLCs such as cell capacitance, operating voltage, equivalent series resistance, power density, and energy density, and how these are affected by the modification of the activated carbon framework.

Friction surfacing is a solid-state coating process that uses plastic deformation to improve the efficiency of the core metallic pattern, resulting in fine-grained coatings with superior wear and corrosion properties. This article focuses on the development of inherently homogeneous, non-diluted coating of AISI316Ti stainless steel above EN8 and also encloses the empirical relationship for the prediction of bond strength (B_s), coating thickness (C_t), and coating width (C_w). The key individualities for bonding geometry were believed to be the process parameters such as rotational speed (rpm), traverse speed (mm/s), and axial load (kN). The effect of input parameters on the bond’s external dimensions and strength was investigated using a multi-objective optimization approach through experimentation. The bond’s strength improved as the coating thickness was reduced and the coating width was increased. The grain-refined coatings superimposing martensitic microstructure with no deposition of carbide particles added value to the metallurgical study using the scanning electron microscope.

In this research, the first work was carried out to manufacture MgO-based metal matrix composite containing 3 wt%. Sintering parameters, such as temperature, pressure, and time were subjected to Taguchi analysis to identify the most significant effect on magnesium oxide physical and mechanical characteristics. The impact of each sintering parameter explores using the analysis of variance-structure and microstructure analysis using XRD and EDS-equipped FE-SEM. The mechanical properties of the composite are evaluated by testing its Rockwell hardness (HR) and Vickers hardness (HV). The results showed that sintering temperature was the most influential of the sintering factors on microhardness. Densification at its peak was 100%, while it peaked at 62.19 Rockwell hardness and 58.7 Vickers hardness.

Poly(3-methylthiophene) electrode based redox supercapacitors are presented using phosphoric acid, ammonium, and lithium salt electrolytes. The study of the redox supercapacitor cells prepared by two different techniques: 1) constant current and 2) constant voltage, electrodeposition of electrode materials has been presented. Their performance studies are carried out using cyclic voltammetry measurements. The ionic species and the acidic environment play a vital role in the improvement of supercapacitor cell’s performance. The specific capacitance of ~36 F/g has been achieved for the propylene carbonate (PC) LiClO₄ electrolyte based cells.