Supercapacitors Performance Evaluation AbstractThe performance of a supercapacitor can be characterized by a series of key parameters, including for instance the cell capacitance, operating voltage, equivalent series resistance, power density, energy density, and time constant. To accurately measure these parameters, a variety of methods have been proposed and used among academia and industry. As a result, some confusion has been caused due to the inconsistencies between different evaluation methods and practices. Such confusion hinders effective communication of new research findings, and creates a hurdle in transferring novel supercapacitor technologies from research lab to commercial applications.Based on public sources, this review article is an attempt to inventory, critique and hopefully streamline the commonly used instruments, key performance metrics, calculation methods, and major affecting factors for supercapacitor performance evaluation. Thereafter the primary sources of inconsistencies are identified and the possible solutions are suggested correspondingly, with emphasis on device performance vs. material property and the rate dependency of supercapacitors. We hope, by using reliable, intrinsic and comparable 11 parameters produced, the existing inconsistencies and confusion can be largely eliminated so as to facilitate further progress in the field.

h i g h l i g h t s g r a p h i c a l a b s t r a c tcapacitance retention rates were achieved after 5000 charge/discharge cycles. Such excellent performance demonstrated great potential of lignin derived carbons for electrical energy storage.

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The conversion of crumpled graphene materials to planar graphene sheets was performed through hydrogen gas treatment of graphene oxide at various temperatures. The resulting graphene materials were incorporated into supercapacitors and systematically examined. Up to 500 C, a monotonically increasing relationship between the specific capacitance and treatment temperature was identified.