Pain point: Temperature is one of the biggest direct factors in the performance of lithium batteries, and extreme high and low temperatures can have an irreversible negative impact on the overall reliability, life and other performance of the battery. Therefore, in some special scenarios, Li-ion batteries need to be equipped with powerful and efficient temperature management functions. As a professional lithium battery manufacturer, LYBATT has very professional experience and strength in high and low temperature solutions, which I will introduce to you below.
1. Develop and use electric cells that can operate normally at extreme temperatures and increase the range threshold of high and low temperatures of lithium batteries themselves to meet the needs of extreme ambient temperature operation;
2. By integrating a heating or cooling system into the lithium battery system, the lithium battery is always kept at the optimum operating temperature range.
1. Use of wide temperature batteries:
LYBATT and CBAK and other leading battery cell companies have jointly developed a variety of industry-leading battery cells that can meet extreme high and low temperature environments. Compared to conventional battery cell temperature thresholds, LYBATT uses wide temperature battery cells that can operate continuously in environments ranging from -40°C to 85°C. Ternary lithium (18650), lithium iron phosphate (26700) are available. In addition to its strong temperature adaptability, it also has a discharge multiplier of up to 5C.
Advantages: High and low temperature environments can be used, reducing the hardware configuration of other temperature management systems, saving and reducing the internal space and overall volume of the battery; increasing the overall energy density; temperature has a small impact on the life of the lithium battery, and other performance.
Disadvantages: The unit cost is much higher than that of conventional lithium batteries, and if the temperature range of the cells is exceeded, any other temperature management system will need to be involved.
2. Air-cooled system solutions
The air-cooling system is designed to enhance the contact area between the air and the surface of the battery by optimising the structure of the internal space to carry away the heat from the battery. It also assists the fan to accelerate the air circulation and improve the efficiency of heat dissipation.
Advantages: simple construction, relatively low system mass, no possibility of liquid leakage; can be adapted to most application scenarios.
Disadvantages: single function, only the function of heat dissipation and cooling; low heat exchange coefficient between air and battery surface, minimum heat dissipation efficiency, additional holes are required in the battery casing for ventilation, making it impossible to be waterproof and increasing the difficulty of dustproofing.
3. Liquid cooling systems
Liquid cooling systems make use of the high heat exchange coefficient of liquids in relation to air, which can quickly carry heat away to achieve cooling purposes. It is also possible to integrate a heating module into the liquid cooling system, which can heat the liquid in the pipe when the battery pack needs to be heated, thus realising the heating function inside the battery. The current LYBATT liquid cooling system uses a non-direct contact method, with the liquid flowing in a closed pipe. This effectively avoids condensation, and the risk of liquid leakage.
Pros: Fully functional, heats and dissipates heat from the battery. Maximum heat exchange efficiency.
Disadvantages: technically difficult, complex internal structure, large size, requires external heat pump equipment, highest cost, requires battery power and affects overall range.
4. Phase change material (PCM) cooling systems
The PCM cooling system is a passive cooling system that adds phase change energy storage material between the cells and uses its phase material heat absorption properties to achieve thermal management of the battery.
Advantages: simple construction, ability to reduce the size of the battery system, no additional consumption of battery energy, better cooling efficiency than air cooling.
Disadvantages: single function, can only provide cooling function; relatively high cost of phase change material, unable to control temperature precisely, limited heat absorption.
5. Heat pipe cooling systems
The heat pipe principle of heat dissipation is to store the heat from the evaporation side (heat generation side) in the form of phase change heat in the phase change material and to transfer the heat to the condensation side (heat dissipation section, usually the battery casing) with the help of the transport capacity of the mass to achieve a large heat flow with a small temperature difference and a rapid reduction of the battery temperature.
Advantages: high heat exchange efficiency, significantly better cooling effect than single phase change material cooling system; long life, no additional battery power consumption
Disadvantages: single function, only cooling function; and high technical requirements for the overall structural design, relatively complex system process and manufacturing process, high system cost, not easy to carry out later system maintenance.
6. Resistance heating systems
The resistance heating system is used to heat the battery by means of a resistance wire built into the silicone heating film. It is currently one of the mainstream heating systems.
Advantages: simple structure, relatively simple design and manufacturing process, relatively low cost.
Disadvantages: single function, can only provide heating function; the electric cell is easily heated unevenly, heating efficiency is low and requires extra energy consumption of the battery, which affects the range performance.
In conclusion: the temperature management of lithium batteries is a relatively complex and systematic function. Through the analysis and research of various conventional thermal management systems, when a single thermal management system cannot meet the needs of the battery working scenario, it is necessary to combine the advantages of various other solutions, try to avoid and overcome their shortcomings, and design a composite thermal management system that brings together a variety of systems to achieve the best effect of controlling the battery temperature.
