Computer Control of Electrochemical Experiments with Application to Zinc/Nickel Oxide Cells

摘要

A computer-controlled test system has been designed and constructed to allow the simultaneous and continuous cycling of 16 or more electro-chemical cells. The system offers resolution and stability within 0.025% of full-scale, and response times are typically 1 ms. A wide variety of charge and discharge regimes, including pulsed charge and power discharge profiles, are implemented through various computer algorithms. The software configuration allows two programs to execute concurrently in the computer memory and to communicate with each other through a set of codified messages. This arrangement permits flexible interaction with all experiments and provides on-line data reduction and display. The test system has been employed to investigate the effects of constant-current and various pulsed-current charging modes on the cycle life and capacity retention of Zn/NiOOH cells cycled at 100% depth-of-discharge. Test results included cell voltages, potentials of the NiOOH and Zn electrodes versus Hg/HgO reference electrodes, coulombs, watt-hours average voltages, and associated efficiencies. Post-mortem tests included Zn electrode x-ray studies. A 30ms-ON/90ms-OFF pulse profile, with a 15mA/cm exp 2 peak current density, improved the operating conditions of the cells by minimizing the overpotentials on the Zn and NiOOH electrodes. In contrast to all other charge profiles tested, it eliminated cell shorting (for at least 100 cycles) and slowed the loss of ZnO reserve, thereby preventing rapid cell capacity decline. (ERA citation 08:023679)