Solid-state low-temperature lithium batteries exhibit low electrochemical performance at low temperatures. Lithium-ion battery charging at low temperature will generate heat in the chemical reaction of the positive and negative electrodes, resulting in electrode overheating. Due to the instability of the positive and negative electrodes at low temperatures, it is easy to cause the electrolyte reaction to generate air bubbles and lithium precipitation, thus destroying the electrochemical performance. Therefore, low temperature is an inevitable process in the aging process of battery.
Lithium-ion battery charging temperature is too low at low temperature, which will form harm to the positive and negative electrodes. When the battery charging temperature is lower than room temperature, the positive electrode of the battery reacts and thermally decomposes, and the gas and heat generated accumulates in the gas formed in the positive electrode, causing the cell to expand. If the temperature is too low during discharging, the poles will become unstable. In order to maintain the activity of the negative electrode and the positive electrode, the battery must be charged continuously, therefore, the positive electrode active material should be kept in a certain position as much as possible when charging.
The battery capacity decays faster during low temperature cycling and has a significant impact on battery life. Low-temperature charging leads to excessive volume changes in the positive and negative electrodes, which in turn leads to the formation of lithium dendrites and thus affects the battery performance. The loss of power and capacity degradation during the charge/discharge cycle is also a major factor affecting the battery life, and the decomposition of LiCoSiO 2 cathode and LiCoSiO 2 cathode at high temperatures generates gas and bubbles along with the solid electrolyte, which affects the battery life. The reaction of positive and negative electrodes with electrolyte at low temperature generates bubbles that destabilize the positive and negative electrodes during the battery cycle, thus causing the battery capacity to decay rapidly.
The cycle life extension depends on the discharged state of the battery and the lithium ion concentration during charging. High lithium ion concentration will inhibit the cycling performance of the battery, while low lithium concentration will inhibit the cycling performance of the battery. As charging at low temperature will cause the electrolyte to react violently, thus affecting the positive and negative electrode reaction, which will cause the interaction between the positive and negative electrode active substances thus causing the negative electrode to react and produce a large amount of gas and water, thus increasing the heat of the battery. When the lithium ion concentration is lower than 0.05%, the cycle life is only 2 times/day; when the charging current of the battery is higher than 0.2 A/C, the cycle system can maintain 8-10 times/day, while when the lithium dendrite concentration is lower than 0.05%, the cycle system can maintain 6-7 times/day.
At low temperature, water loss will occur in the negative electrode and diaphragm of Li-ion battery, which will lead to the decrease of cycle performance and charging capacity of the battery; the polarization of the positive electrode material will also cause brittle deformation of the negative electrode material, resulting in lattice instability and charge transfer phenomenon; the evaporation, volatilization, desorption, emulsification and precipitation of electrolyte will also lead to the decrease of cycle performance of the battery. In LFP batteries, the active material on the surface of the battery gradually decreases as the number of charge and discharge increases, and the reduction of active material will lead to a decrease in battery capacity; during the charge and discharge process, as the number of charge and discharge increases, the active material at the interface reassembles into a solid and reliable battery structure, which makes the battery more durable and safe.
Post time: Nov-15-2022