Lithium-ion batteries are now considered a cornerstone for contemporary, portable electronic devices, electric vehicles, and renewable energy storage solutions. Everyone wants them because of their large energy density, long lifespan, low temperature affects lithium-ion battery, and less maintenance.
However, like any battery, they will self-discharge in any event, but much depends on temperature. How temperature affects lithium-ion batteries self-discharge, what mechanisms govern this process, and what practical implications this has for end-users and manufacturers are elaborated below.
Self-Discharge in Li-ion Batteries
Self-discharge indicates a loss in a battery if the latter is not connected to a load or, in other words, if the battery is not in use. Several parameters define the rate at which this occurs in lithium-ion batteries, including chemistry, age, state of charge, and environment.
Lithium-ion batteries’ self-discharge is quite low compared to other battery chemicals such as NiCd or NiMH. But this is especially important for long-term storage or standby power as an application.
Temperature is among the most influential in the self-discharge rate in lithium-ion batteries. Temperature does so by dependence on self-discharge in lithium-ion batteries. However, it is so complex that it could be linked to many chemical and physical processes in the battery. The following section discusses the various temperature affects lithium-ion battery self-discharge.
How Low Temperature Affects Lithium-Ion Battery
Lithium-ion batteries have minimal self-discharge rates at temperatures of less than 0°C. This property can explain the diminution in electrochemical reactions at low temperatures. While this presents an opportunity for reduced self-discharge, the low temperatures are a disadvantage, adversely affecting the cell’s overall performance and health.
Reduced Electrochemical Activity
Lithium ions move slowly at a lower temperature from anode to cathode, slowing self-discharge. The converse side of this is true; this will also reduce the battery’s capacity and power rating.
High Internal Resistance
Low temperatures increase the internal resistance of the battery. Therefore, apart from offering lower efficiency, it could even cause damage to the battery overall if it has been charged and discharged too many times under such conditions.
Freezing of Electrolytes
At extremely low temperatures, the electrolyte inside the battery is very dense or even frozen, making the movement of the ions even more difficult and significantly giving rise to the formation of dendrites, which results in an internal short circuit.
While this decreases the self-discharge, it also brings health and overall performance risks to the battery.
Moderate Temperatures
Lithium-ion works best in moderate temperatures- this is between 20°C and 25°C or 68°F and 77°F. In this optimal LFP battery temperature range specified in lithium-ion batteries, the self-discharge is at the minimum value, and the batteries would perform at their best.
Stable Electromechanical Reactions
Most of the electrochemical reactions in the battery are stable when in middle-range temperatures. The self-discharge is kept to the minimum with a high rate of performance and efficiency.
Internal Resistance
The battery’s internal resistance is extremely low and entirely stable during efficient charge-discharge cycles without energy loss or heat generation.
Longevity
Intermediary temperatures offer the best operating conditions regarding battery life as they incur less stress on the internal components; there is less thermal runaway risk or any other failure mechanisms.
It is at intermediate temperatures that lithium-ion batteries give the best conditions. These give the best trade-off between the self-discharge rates. Which are low, and performance and longevity, which are likely to be higher.
Is High Temperature Affects Lithium-Ion Battery
High temperatures, normally greater than 30 °C, increase the self-discharge rate for the lithium-ion batteries. High temperatures raise the rate at which all cell chemical reactions happen, thus raising the degradation and energy loss.
Increased Chemical Activity
Higher temperatures cause undesirable side reactions, then raise the self-discharge rate. Those reactions may degrade the electrolyte and electrode materials, thus reducing general battery capacity and life.
From warm through to hot temperatures, the battery is taken into thermal stress, eventually leading to swelling, leakage, or even thermal runaway in severe cases. This will increase self-discharge but, at the same time, promote potential safety concerns.
- When an electrolyte decomposes more, over high temperatures and during a long battery period, an increase in general self-discharge and internal short circuits or any other failures occur.
- One of the worst enemies to befall a lithium-ion battery, which has a rapid self-discharge caused by hot temperatures, is the increase in aging rates and compromised performance or safety of the battery.
Mechanisms of the Process
The in-depth explanation of the mechanisms of the process of temperature-dependent self-discharge in lithium-ion batteries considers the chemical and physical processes the battery is exposed to. There are various key mechanisms combined to cause this phenomenon.
Electrolyte Decomposition
Most electrolytes in a lithium-ion battery consist of a lithium salt in an organic solvent. At elevated temperatures, the electrolyte degrades to release gas and various other products. These catalyze more self-discharge through the consumption of active lithium ions, create insulating layers over the electrodes as well as hinder ion mobility.
SEI Layer Failure
During the first few charge cycles, the temperature affects lithium-ion battery processes, and a thin layer of solid electrolyte interphase forms on the anode, adding stability to the battery. The SEI layer decomposes at hot temperatures, and the self-discharge goes up.
Degradation now exposes even larger anode surface areas to further reactions with the electrolyte, consuming more lithium ions and increasing the self-discharge rate. It is the result of parasitic reactions.
Undesirable side reactions, such as parasitic reactions in the battery, consume the active material, releasing heat during the process. The heat liberation is temperature-dependent, whereby parasitic reactions, with an increase in temperature, increase in the number of amplitudes, creating an increased self-discharge rate.
Typical parasitic reactions are the reduction of electrolyte solvents and the formation of solid by-products.
Thermal Runaway
In the worst cases, high temperatures would escalate the risk of thermal runaway. In this perfect storm state, the battery’s internal temperature spirals out of control, leading to rapid self-discharge, gaseous winds, and fire or explosion.
Thermal runaway usually occurs due to short circuits, mechanical damages, and overcharging, but this is only aggravated by high temperatures.
Conclusion
Temperature affects lithium-ion battery sensitivity, one factor that dominantly influences the lithium-ion battery’s self-discharge rate. In a further implication, it influences performance, safety, and life issues. At the same moment, low temperatures are the leading factor promoting low self-discharge rates, but several risks are also presented to the keep battery’s health.
In comparison, moderate temperatures would be relevant to minimize self-discharge and offer the best performance from the self-discharge point of view. Hot temperatures would see big increases in self-discharge and would accelerate the battery’s degradation process.
