The Reasons of Thermal Runaway in Nickel-Cadmium Batteries

摘要

Background: A thermal runaway phenomenon occurs in batteries of all the electrochemical systems. In the case of the thermal runaway occurrence, a battery heats up sharply and afterwards a battery body inflammation is possible followed by an explosion. In this case inevitably, a system contained the battery goes unserviceable. Objective: The goal of this work is to review the most important results received on thermal runaway by the present moment. Results: It has been established experimentally that a probability of a thermal runaway in the nickel-cadmium accumulators KSX-25 grows with an increase of a constant-voltage charge as well as of an environmental temperature and an accumulator time in service. It was shown on the basis of charge current, terminal voltage, and change in battery temperature that during thermal runaway, the observed changes cannot be explained by the self-acceleration of known reactions (due to overheating), battery charging and electrolyte decomposition. The observed changes can only be explained if we assume, that the thermal runaway is associated with a powerful electrochemical reaction going within the battery with a terminal voltage approximately 0.55 V. It is shown that the recombination reaction of atomic hydrogen accumulated in the electrodes is exothermic thermal runaway reaction in alkaline batteries. Conclusion: New mechanism of thermal runaway in Ni-Cd batteries, which explains all the experimental data known currently is proposed. Based on the proposed mechanism received patents for a method of diagnosing a predisposition of batteries to thermal runaway.