14 research groups participated in the analysis study out of a total of 38 groups who were invited. Web of Science was used to find appropriate research groups to invite. Groups were selected to be invited if they had published research containing the keyword "supercapacitors" within the past 3 years. No judgement was made on the quality of a group's publications when inviting them to the study. Groups from a range of different countries were invited to attempt to ensure the diversity of the study. The role of the participating groups was to analyse the electrochemistry data provided by the coordinating group independently. Experimental work was carried out for the sole purpose of obtaining standardised datasets for the participating groups to analyse. The coordinating group (Y.C., J.W.G., D.L., and A.C.F. at the University of Cambridge) did not provide analysis of the electrochemistry data for this study. Each participating group was provided with identical data and instructions, specifically, the five datasets (File 1 -5) as .txt files, and an instruction sheet detailing the required analysis. A copy of the data files and the instruction sheet is provided as Supplementary Information. Researchers can check if they are performing the analysis of supercapacitor data correctly by analysing the data files provided and comparing their results to those given for each data file in the Results and Discussion section below, and in SI Section 4.