The applicability of recently discovered materials with extremely high (“colossal”) dielectric constants, required for future electronics, suffers from the fact that their dielectric constant ${\epsilon }^{\prime }$ only is huge in a limited frequency range below about 1 MHz. In the present report, we show that the dielectric properties of a charge-ordered nickelate, ${\text{La}}_{15/8}{\text{Sr}}_{1/8}{\text{NiO}}_4$ , surpass those of other materials. Especially, ${\epsilon }^{\prime }$ retains its colossal magnitude of $>10000$ well into the gigahertz range.

Some of the technical problems that appear are obtaining solar cell parameters from I-V curve measurement data. One simple method is using linear graphical fit at zero current or voltage conditions. Although the accuracy of the obtained values is acceptable, other problems may arise regarding the number of parameters which could be obtained. We report a comparison between manual or graphical fit and fit using Shockley’s equation. The single I-V curve under the lighting was inferred to obtain the intrinsic parameters of the solar cells’ performance. The fittings were performed using the nonlinear equation of Shockley by determining some initial values of fittings such as R_s, R_sh, n, I₀, I_ph, and T. In the case of the Shockley equation fit, the iteration was performed several times to obtain the least possible inferred parameters. We have successfully obtained a better result of nonlinear Shockley fitting compared to the manual linear fit.

The consumption of electrical energy grows alongside the development of global industry. Generating energy storage has become the primary focus of current research, examining supercapacitors with high power density. The primary raw material used in supercapacitor electrodes is activated carbon (AC). To improve the performance of activated carbon, we used manganese dioxide (MnO₂), which has a theoretical capacitance of up to 1370 Fg⁻¹. The composite-based activated carbon with a different mass of 0–20% MnO₂ was successfully introduced as the positive electrode. The asymmetric cell supercapacitors based on activated carbon as the anode delivered an excellent gravimetric capacitance, energy density, and power density of 84.28 Fg⁻¹, 14.88 Wh.kg⁻¹, and 96.68 W.kg⁻¹, respectively, at 1 M Et₄NBF₄, maintaining 88.88% after 1000 test cycles.

The development of materials and electrochemical energy storage (EES) technologies are currently taking the lead and showing excellent performance in the global effort to tackle the issues of sustainable energy supply. Supercapacitors have been widely studied among the EES technologies as they exhibit quick charging rates under high‐power conditions. Manganese dioxide (MnO ₂ ) has attracted renewed interest as a promising material due to its high theoretical capacitance and high energy density. However, the widespread application is immediately impacted by low conductivity. Hence, combining nanomaterials and various morphologies of MnO ₂ can improve the electrochemical performance of supercapacitors. This paper presents a review based on the composites of nanomaterials/MnO ₂ with various morphologies. Their mechanism and practical applications in supercapacitors are introduced in detail. Finally, the challenges and next steps in developing MnO ₂ electrode materials are proposed.