Abstract: In order to study the thermal runaway gas production behavior of lithium iron phosphate batteries, this paper selects 105 Ah lithium iron phosphate batteries, and analyses the thermal runaway process and gas production characteristics of the batteries under overheating and overcharging conditions. It has been found that overcharging can directly cause electrochemical reactions between battery electrodes and electrolyte. Therefore, compared with the thermal runaway of the battery caused by overheating, the proportion of H2 generated by thermal runaway of the battery caused by overcharging decreases and the proportion of CO increases. When the overcharge rate increases, the total amount of CO and H2 produced by the thermal runaway of the battery becomes larger, the maximum gas production rate also becomes larger, and the maximum gas production rate of the battery at the overcharge rate of 1.0C and 1.5C is 0.845 g/s and 1.411 g/s separately. Compared with the overheating condition, the overcharging produces more gas mixture. The research results can provide support for the safety designs of energy storage systems.

Key words: overheating, overcharging, lithium iron phosphate battery, thermal runaway