Systems and apparatus of cyclic coulometry

A system for testing an electrochemical cell, comprising:

• a current generator configured to electrically couple to the electrochemical cell, and to generate symmetric charge current and discharge current in a cycling period to respectively charge and discharge the electrochemical cell,
• a cyclic coulometer including:
• a controller circuit, coupled to the current generator, configured to:
• adjust at least one of a charge time or a discharge time for controlling a monitored cell voltage of the electrochemical cell toward a specific setpoint using a feedback controller;
• and
• control the current generator to electrically cycle the electrochemical cell using the charge current and the discharge current according to at least one of the adjusted charge time or the adjusted discharge time;
• and
• a measurement circuit configured to couple to the electrochemical cell to measure one or more electrical parameters of the electrochemical cell during the cycling period, and to generate, under each of a plurality of test conditions, a respective performance metric indicative of coulombs applied into or out of the electrochemical cell using the measured one or more electrical parameters;
• wherein the performance metric includes one or more of an amount of total charge applied per frame, a self-discharge rate, an equivalent series resistance (ESR), or an ESR change rate.