• Energy Research

Currently, a major constraint in employing supercapacitors as a solitary energy storage device in applications like electric vehicles is their low energy density. In aqueous asymmetric supercapacitors, the energy density is limited by the voltage window, which is governed by the electrode’s work functions. Here, the preinsertion of different metal cations such as Li + , Na + , and K + ions into manganese dioxide (MnO 2 ) to tune the electrode’s work function is demonstrated. Sodium-doped MnO 2 (NaMnO 2 ) exhibited a lower work function than Li + and K + preinserted electrodes. This lowering of the work function leads to a higher voltage window. The work function tuned NaMnO 2 is coupled with a high-work-function negative electrode material, molybdenum oxide (MoO 2 ), to fabricate a 2.5 V aqueous asymmetric supercapacitor. The supercapacitor delivered a maximum energy density of 78 Wh kg –1 , a power density of 4.6 kW kg –1 , and capacitance retention of 98.6% after 5000 cycles. This work brings new insights into the engineering of electrode’s work function for developing high-voltage and high-energy supercapacitors.

Supercapacitors are fast-charging energy storage devices of great importance for developing robust and climate-friendly energy infrastructures for the future. Research in this field has seen rapid growth in recent years. Therefore, consistent reporting practices must be implemented to enable reliable comparison of device performance. Although several studies have highlighted the best practices for analysing and reporting data from such energy storage devices, there is yet to be an empirical study investigating whether researchers in the field are correctly implementing these recommendations, and which assesses the variation in reporting between different laboratories. Here, we address this deficit by carrying out the first interlaboratory study of the analysis of supercapacitor electrochemistry data. We find that the use of incorrect formulae and researchers having different interpretations of key terminologies are the primary causes of variability in data reporting. Furthermore, we highlight the more significant variation in reported results for electrochemical profiles showing non-ideal capacitive behaviour. From the insights gained through this study, we make additional recommendations to the community to help ensure consistent reporting of performance metrics moving forward.

As electric vehicles (EVs) are evolving, innovative technologies like “energized composite” that can store energy in the car's body helps extend its range per charge. The composite's unique ability to function as both structural body panel and charge storage medium stems from its unique pattern design between “electrochemical areas (EcA)” and “epoxy area (EpA)”. Herein, a design optimization study is presented to obtain a balanced ratio between EcA versus EpA to maximize the charge storage ability of the composite while maintaining a decent tensile and bending strength. Simulations using ANSYS software and experimental confirmation using universal testing machines and electrochemical analyzers are used to derive optimum ratios between EcA and EpA. Uniaxial tension test and 3‐point bend test have been performed to optimize the tensile and bend strengths, whereas cyclic voltammetry, galvanic charge–discharge, and electrochemical impedance spectroscopy are used to determine the electrochemical performance of various design configurations by modulating the ratios of EcA versus EpA. Overall, the highest achieved energy storage per lamina is 2531 mWh m−2 for a maximum of 81.6% EcA with a tensile strength of 417.73 MPa and bending strength of 263.13 MPa. This study is highly beneficial for EVs and aerospace applications.