This novel carbon–carbon composite electrode has superlative electrochemical properties with flexibility, mechanical robustness, and weldability.

An electrode composed of defective NiO nanostructures supported on carbon nanofibers and immersed in an Li⁺-based aqueous electrolyte is studied using Raman spectroscopy under dynamic polarization conditions to address the charge-storage phenomenon.

The increasing demand for smart portable electronics and electric vehicles is driving advancements in high-energy-density lithium-ion batteries (LIBs). Among various cathode materials, lithium manganese iron phosphate (LiMn_yFe_1−yPO₄ – LMFP) stands out due to its cost-effectiveness, excellent safety profile, long cycle life, high operating voltage, robust thermal stability, and competitive energy density. However, despite notable progress, LMFP still encounters key challenges such as limited electronic conductivity, sluggish Li-ion diffusion, manganese dissolution affecting cycling stability, and low tap density. To address these issues, significant efforts have been devoted to developing multimetal LMFP and other multimetal olivine-based cathodes with enhanced electrochemical properties. Nevertheless, a comprehensive review of these recent advancements remains lacking. This article aims to bridge this gap by examining emerging strategies and recent developments in multimetal LMFP cathodes for LIBs. It systematically compares various optimization approaches, including (i) doping with single or multiple elements at Li-, M-, or Li & M-sites, (ii) integrating additional primary constituents or structural components, and (iii) increasing the configurational entropy of electrode materials. The advantages and limitations of these strategies are critically assessed. Furthermore, key synthesis methodologies and processing techniques used to enhance LMFP cathode performance are discussed. Finally, the review provides insights into the benefits and challenges associated with these materials, highlighting future perspectives and potential research directions.

A double-channel transmission line impedance model was applied to the study of supercapacitors to investigate the charge transport characteristics in the ionic and electronic conductors forming the electrode/solution interface. The macro homogeneous description of two closely mixed phases (Paasch–Micka–Gersdorf model) was applied to study the influence of disordered materials on the charge transport anomalies during the interfacial charge–discharge process. Different ex situ techniques were used to characterize the electrode materials used in electrical double-layer (EDLC) and pseudocapacitor (PC) devices. Two time constants in the impedance model were adequate to represent the charge transport in the different phases. The interfacial impedance considering frequency dispersion and blocked charge transfer conditions adequately described the charge storage at the interface. Deviations from the normal (Fickian) transport involving the ionic and electronic charge carriers were identified by the dispersive parameters (e.g., n and s exponents) used in the impedance model. The ionic and electronic transports were affected when the carbon-based electrical double-layer capacitor was converted into a composite with strong pseudocapacitive characteristics after the decoration process using NiO. The overall capacitance increased from 2.62 F g⁻¹ to 536 F g⁻¹ after the decoration. For the first time, the charge transport anomalies were unequivocally identified in porous materials used in supercapacitors with the impedance technique.

This study combines operando XRD & Raman spectroscopy and DFT simulation to reveal how Li₂CO₃ formation and reversibility may contribute to energy storage in supercapacitors.