Electrochemical Characterization of Sodium‐Ion Energy Storage Devices Using a Low‐Cost Microcontroller‐Based Instrument

This study addresses the challenge of characterizing the chemistry and electrical performance of sodium‐ion supercapacitors (SCs) and batteries, driven by growing interest in alternatives to lithium‐ion technology. The primary objective is to design and implement a cost‐effective, microcontroller‐based instrument for accurate, real‐time voltage and current characterization of these devices. The developed system connects to a computer via a USB interface for data transmission, processing, and storage, enabling rapid electrochemical analysis through cyclic voltammetry. The design prioritizes affordability while achieving performance comparable to commercial instruments. The instrument automates the charging and discharging of electrochemical devices using switchable constant currents, controlled by an Arduino Uno microcontroller and electromechanical relays. Key parameters, including capacitance, equivalent series resistance (ESR), energy density, and power density, are evaluated. Circuit designs were developed and simulated in LTSpice before construction, with a commercial 20 F/2.5 V SC serving as a test standard. Measurements on the standard SC yielded capacitance values between 18 and 22 F, stored energy between 43.56 and 53.24 J, and an ESR of 5.59 , aligning well with commercial specifications. Oscillatory behavior observed during high‐current discharges highlighted SC degradation.