Home Technology Researchers Report Loss of Thermal Management Ability in Li-Ion Power Battery
Researchers Report Loss of Thermal Management Ability in Li-Ion Power Battery

Researchers Report Loss of Thermal Management Ability in Li-Ion Power Battery

Researchers from Xi’an University of Science and Technology conducted charging and discharging experiments on TAFEL-LAE895 type 100Ah ternary lithium ion power battery at different rates to study the rise of temperature and the uniformity of the battery

Lithium is the lightest of all metals. Rechargeable batteries with lithium metal on the anode can offer high energy densities. The lithium-ion (Li-ion) battery is widely used in electric vehicles (EVs) owing to its long lifespan, no memory effect, low self-discharge rate, and high energy density abilities. However, these features are temperature sensitive and the ideal range for operation of these batteries is 20 °C to 45 °C. Complex electrochemical reactions in the lithium battery can lead to generation of heat, which increases the battery temperature. Failure to release the generated heat in time may lead to continuous rise in battery temperature.

Battery thermal management system (BTMS) in EVs helps to prevent the power battery from overheating or undercooling to ensure the best performance of the EVs. Increase in rates of charging cycle leads to an increase in the surface temperature of the Li-ion battery, which decreases the temperature uniformity between the battery packs and the individual cells. The team found that the maximum temperature and the highest temperature difference of the surface of the battery are achieved when the phase change material with different graphite content is used for cooling the battery under different discharge rates.

The team also found that the thermoelectric sheet can be activated in the high-power discharge process for secondary cooling of the power battery. The combination of semiconductor refrigeration technology and composite phase change material can control the maximum temperature of the battery surface within 45 °C, and the temperature difference is controlled within 4 °C. The thermal conductivity of paraffin wax is low and its fluidity is strong after melting. This in turn causes loss of thermal management ability under the large-rate discharge condition. Although the expanded graphite and paraffin wax can effectively enhance the battery thermal management properties when mixed in a certain ratio, it also reduces the heat storage capacity of the composite phase change material under the same volume. The research was published in the journal MDPI Energies on May 20, 2019.