Liquid cooling technology is gradually replacing traditional air cooling and becoming the mainstream choice for electric vehicle matching by major car companies.

　　Recently, JAC New Energy's iEV6E sports version was officially launched, and its self-developed liquid-cooled battery management and control technology was also used in micro electric vehicles for the first time.

　　According to reports, the liquid cooling technology equipped with this model can stably control the battery temperature within a suitable range of 15-35°C, and the vehicle can be used normally at ambient temperatures of -30°C to 55°C. At the same time, this technology also ensures that battery single failure will not cause fire or explosion in the battery pack, ensuring battery life, fast charging performance, low temperature performance and safety performance.

　　Coincidentally, Buick's VELITE6 PHEV, which will be launched within the year, also uses a cell-level independent liquid cooling system. It is understood that each single cell in the VELITE6 battery pack can pass through the cooling fin for heat dissipation circulation, ensuring that the temperature difference of each cell is within 2 degrees Celsius.

　　What is liquid cooling technology? It uses the coolant's large heat capacity and its ability to take away excess heat from the battery system through circulation to achieve the optimal operating temperature conditions of the battery pack.

　　Gaogong Lithium Battery learned that in addition to the above two car companies, domestic and foreign car companies currently include BMW, Tesla, General Motors, Chevrolet, Geely, BMW Brilliance, BAIC, GAC, Yundu, Xpeng Motors, Singularity Motors, etc. Liquid cooling technology is being introduced in battery thermal management systems.

　　A senior executive of a large pack company said: “There were relatively few people using liquid cooling technology in the early days, mainly because the market was dominated by A00-class models, which did not have high performance requirements. At the same time, liquid cooling technology was not used due to cost issues; and this year’s subsidies Policies focus on batteries with long cruising range and high energy density. Battery heating is becoming more and more serious. While ensuring the performance of the vehicle, it is also necessary to ensure a certain acceleration performance, so liquid cooling technology has become a mainstream choice."

　　Data shows that active liquid cooling technology is expected to account for 55% of the power battery cooling system assembly in 2022; by model, liquid cooling technology will account for 85% of the power battery cooling system of plug-in hybrid models, and that of pure electric vehicles Liquid cooling technology for the model’s power battery cooling system will account for 44%.

　　▌The inevitable choice for high-energy, high-rate batteries

　　According to the medium of heat transfer, battery cooling systems can be divided into: air cooling, direct cooling and liquid cooling.

　　Air cooling is mainly divided into natural cooling and forced cooling (using fans, etc.), using low-temperature air as the medium. This technology was widely used in early electric passenger cars, such as Nissan Leaf, Kia SoulEV, etc. Its obvious problems are slow cooling speed, low efficiency and poor internal temperature uniformity.

　　Direct cooling uses refrigerant direct cooling, using the principle of latent heat of evaporation of refrigerants (R134a, etc.) to establish an air conditioning system in the vehicle or battery system. The evaporator of the air conditioning system is installed in the battery system, and the refrigerant evaporates. evaporates in the device and quickly and efficiently removes the heat from the battery system. At present, the cooling method through direct cooling is basically used in electric passenger cars, the most typical one is the BMW i3 (i3 has two cooling solutions: liquid cooling and direct cooling). Although its cooling speed is fast, its temperature uniformity is poor.

　　Liquid cooling uses liquid convection heat transfer to take away the heat generated by the battery and reduce the battery temperature. The medium is mainly conductive liquids such as water. Liquid cooling is currently the preferred solution for many electric passenger cars. Typical products at home and abroad include BMW i3, Tesla, GM Volt, BMW Brilliance Zino, and Geely Emgrand EV. However, it should be noted that liquid cooling technology has high requirements for sealing, requires closed liquid pipelines, and has a complex structure.

　　Compared with other cooling technologies, liquid cooling technology has a high heat transfer coefficient and fast cooling speed, which has a significant effect on reducing the maximum temperature and improving the consistency of the temperature field of the battery pack. At the same time, the size of the thermal management system is also relatively small.

　　Industry analysts believe that the current cooling method for electric vehicle power batteries is still air cooling, but as the electric vehicle market puts forward higher demands for performance such as cruising range, energy density, battery capacity, and charging rate, liquid cooling technology It will gradually become a priority solution for major car companies.

　　Market data also directly confirms this judgment.

　　The main reason for this situation is that the current new energy market is dominated by A00 and A0-level models. Models at this level are generally pure electric vehicles. Since they are mainly used for transportation, their speed is not high, and their demand for fast charging is also limited. , so the demand for liquid cooling systems is limited and it is difficult to become the target market for liquid cooling technology.

　　This year, the market structure of new energy passenger vehicles is changing.

　　According to manufacturer data from the Passenger Car Association, wholesale sales of pure electric passenger vehicles from January to July 2018 were 304,800 units, a year-on-year increase of 90%. Among them, A00-class cars sold 173,700 units, a year-on-year increase of 63%; A0-class cars sold 42,600 units, a year-on-year increase of 295%; A-class cars sold 86,300 units, a year-on-year increase of 106%. The structure of pure electric models is accelerating upgrading.

　　At the same time, as subsidy thresholds increase and end users’ demands for long cruising range become stronger and stronger, car companies have begun to regard high-energy power batteries with fast charging functions as their first choice. In order to meet the needs of car companies, battery companies will choose ternary lithium batteries with higher energy density. In order to control the temperature of the power battery and control the temperature difference within a more stable range under high-rate discharge conditions, liquid cooling technology is gradually gaining favor. .

　　Dr. She Peiliang, chief engineer of Shuangdeng Fulante, said: "The ternary material is prone to oxygen evolution when overcharged, and is prone to autocatalytic reactions when thermally out of control. The speed is too fast to avoid risks such as explosion and fire. Therefore, it must be controlled well. Its operating temperature range".

　　"Battery companies, pack companies and car companies that make ternary material battery systems for passenger cars (there are also individual lithium iron phosphate batteries) will definitely use liquid cooling systems; some logistics vehicles use cylindrical ternary material battery systems, and they will also Using liquid cooling technology.” he added.

　　Ma Junfeng, senior R&D director of Huating Power, said: "Under the influence of subsidy policies, energy density is getting higher and cruising range is increasing, and liquid cooling will be the standard configuration. At present, the company uses liquid-cooled battery packs, with sales of 500 million last year. This year it is expected to be 1.5-2 billion, and sales of 700 million have been achieved so far.”

　　A senior executive of a large pack company said: “As battery performance gradually improves, liquid cooling will become an inevitable choice for new energy passenger car companies. This year, the market share of liquid cooling technology for battery cooling systems in pure electric passenger cars is expected to reach 60%. "

Read recommendations:

R6P

Correct maintenance methods for lead-acid batteries.18650 battery 3.7v 2000mah

3.2v 25ah lifepo4 battery cell.About 18650 cylindrical lithium battery

3.7V 18650 lifepo4 battery

602535 polymer battery