Jitendra Kumar Yadav

Developing high‐performance energy storage devices is essential to meet the rising energy demands. The present work demonstrates the improved electrochemical properties of rGO/ZFO by Mg, Mn codoping approach. The incorporation of rGO (reduced graphene oxide) with dual‐doped zinc ferrite significantly improves charge storage behavior, thereby enhancing the capacitance. The doping of Mg and Mn is ensured by X‐ray diffraction (XRD), while Brunauer–Emmett–Teller (BET) shows the enhanced surface area due to doping. Dielectric permittivity ( ε ) and tangent loss (tan δ ) were analyzed over different frequency ranges. Electrochemical performance was evaluated using both three‐electrode and symmetric coin‐cell (SCC) configurations. In the 3‐electrode system, the specific capacitance ( C _sp ) was found to be 157.39 and 376.68 F g ⁻¹ while corresponding SCC devices deliver 68.17 and 90.57 F g ⁻¹ at 1 mV s ⁻¹ . The energy density ( E _D ) and powder density ( P _D ) was 8.22 and 14.26 Wh kg ⁻¹ and 28.7 and 28.8 W kg ⁻¹ at 0.04 A g ⁻¹ for rGO/ZFO and Mg, Mn doped rGO/ZFO SCC, respectively. Moreover, the Mg, Mn doped rGO/ZFO SCC device shows an exceptional capacitance retention of 96% after 10 000 cycles at 0.4 A g ⁻¹ . These results highlight the effectiveness of dual doping and rGO incorporation in advancing zinc ferrite‐based supercapacitors (SCs).

The use of photo-assisted rechargeable batteries integrating solar harvesting and electrochemical storage represents a sustainable approach for next-generation energy devices.

Fe-ion batteries offer low cost, earth abundance, and eco-friendly operation. X-ray absorption spectroscopy reveals electrode structural changes, Fe redox behavior, and degradation pathways, enabling strategies for improved stability and performance.

Rechargeable Iron‐ion batteries (IIBs) are emerging as a sustainable alternative to conventional rechargeable batteries; however, their cathode development is hindered by sluggish Fe‐ion diffusion, limited conductivity, and interfacial instability. Addressing these challenges requires designing cathode materials with high conductivity, large surface area, and stable electrochemical interfaces. This work explores carbon aerogel (CA)‐based cathodes to overcome these limitations and enhance Fe‐ion storage performance. Highly porous CA, used as the cathode material, is synthesized using the sol–gel process and confirmed using transmission electron microscopy, field emission scanning electron microscopy, X‐ray diffraction, and Brunauer–Emmett‐Teller measurements. Detailed cyclic voltammetry is investigated at different scan rates to understand the characteristics of the Fe‐ion storage in CA hosts during cycling. The galvanostatic charging–discharging (GCD) is determined at various current densities, showing a high discharge capacity of ≈150 mAh g ⁻¹ and ≈45 mAh g ⁻¹ at 35 mA g ⁻¹ and 1000 mA g ⁻¹ discharge current densities, respectively. The capacity retention is more than ≈60%, with more than 85% Coulombic efficiency (CE) after 750 cycles at 1000 mA g ⁻¹ , and fast charge–discharge characteristics of ≈18C rate. The galvanostatic intermittent titration technique (GITT) measurements are also performed to check the diffusion characteristics of the Fe‐ion during charging and discharging. A digital clock and 5V light‐emitting diode are connected to CA‐based Fe‐ion coin cells to demonstrate the potential of IIBs. A detailed electrochemical impedance spectroscopy and postmortem measurements before and after the GCD cycling suggest a slight degradation of electrochemical performance, which is attributed to the oxidation of the anode during cycling.

Modification strategies for LiMn ₂ O ₄ -based cathode materials towards high operating voltages and power densities.

Photo-rechargeable supercapacitors (PRSCs), which simultaneously harvest and store solar energy, have received significant attention in the technological field for powering portable and autonomous devices. Unlike separate devices such as supercapacitors and solar cells, creating a single device that efficiently converts and stores solar energy presents a challenge for researchers. We fabricated a two-electrode configuration-based PRSC using bifunctional photoactive nanosized zinc oxide particles (NZPs) that simultaneously facilitate energy conversion and storage in the device. Multi-walled carbon nanotubes (MWCNTs) are used as a counter electrode with NZPs as a photoactive material, and their electrochemical characteristics are examined under dark and light conditions. The electrochemical energy storage capacity of the PRSC demonstrates ∼44% relative capacitance enhancement at a scan rate of 50 mV s⁻¹ under light illumination. This enhancement is attributed to the pseudocapacitive charge storage process, which is initiated in the presence of light, as observed from electrochemical measurements. The PRSC achieved a maximum voltage of 0.65–0.7 V under light illumination without the application of any external current. Additionally, the device demonstrated an excellent capacitance retention of 88% and stability over 1500 cycles at a current density of 20 mA g⁻¹ under light illumination. The overall efficiency of the PRSC is ∼0.47%, making it suitable for future practical application in smart, portable, and photo-sensitive devices owing to its unique simultaneous energy conversion and storage feature.

Owing to iron's natural abundance, low cost, and affordability, nonaqueous rechargeable iron‐ion (Fe‐ion) batteries have the potential for alternative rechargeable energy‐storage devices. However, developing cathodes with adequate superior Fe²⁺ storage during charge–discharge is a major challenge. Herein, V₂O₅ porous microspheres (V₂O₅–PMS) are synthesized as efficient cathodes due to their unique characteristics, including high surface area and large interlayer spacing, which provide high electrochemical performance and fast charge kinetics. The nonaqueous Fe‐ion battery is fabricated under ambient conditions using mild steel as an anode and a V₂O₅–PMS cathode. The cyclic voltammetry measurements suggests a high diffusion coefficient of Fe²⁺ ions in the redox process during charge–discharge. The V₂O₅–PMS‐based cathode shows ≈205 mAh g⁻¹ gravimetric capacity at 33 and ≈70 mAh g⁻¹ at 1 A g⁻¹ (≈15 C). It exhibits capacity retention of ≈70% in 600 cycles at a very high current rate of 3 A g⁻¹. The impedance spectroscopy measurements are carried out between the cell's cycling to understand the electrode–electrolyte interface resistance over cycling. The four CR‐2032 coin cells are assembled in series to glow a white and red light‐emitting diode to demonstrate its potential as an alternative energy‐storage system.