Text/Peach Lee
The development of the new energy field so far, the biggest progress is the continuous improvement of power, although there are many different development directions, various forms of energy have become the object of new energy research, but pure electric vehicles are still the main force of new energy, in the future for a long time, the research of power batteries will be a focus. So now that there are so many kinds of batteries, how to judge who is better? Don't worry, today we will bring you a few indicators to judge the quality of the battery.
1. Energy density:
The energy density of a battery refers to the energy contained in a unit weight or unit volume. The size of its value will directly affect the endurance of electric vehicles, and now the battery energy density per unit weight has become the most important indicator to measure the advanced nature of battery technology. In the limited space and total weight of the vehicle, the total mass and volume of the battery can not be too large, otherwise it will affect the riding space, but this will affect the endurance of the electric vehicle, so the battery with large energy density at this time will have more advantages.
Under the same mass or volume, the endurance performance of a car with a high energy density will be better. This is also why many car companies choose ternary lithium batteries as power batteries, ternary lithium-ion power batteries have now seen the "ceiling" of energy density, as the second largest market share of lithium iron phosphate batteries are much worse in comparison.
2. Battery life
Life, is one of the most critical indicators of power battery application in the car, which is mainly due to the owner of the vehicle for the use of life and mileage of the vehicle to make two considerations, according to this requirement the battery life can be divided into including cycle life and calendar life two measures.
Cycle life refers to the attenuation of the battery after a certain depth of charge and discharge cycles; calendar life refers to the decay of the battery itself over time, these two parameters are also the most important assessment basis in the power battery roadmap.
3. Operating temperature range:
Taking lithium-ion batteries as an example, the temperature drop will accelerate the attenuation of the remaining capacity of the lithium battery, and the lower the temperature, the faster the capacity decay. Therefore, in the northern region where the weather is relatively cold, electric vehicles will be subject to greater restrictions, and the performance of the battery needs to be considered when choosing, and the lithium ion and electrode material inside the battery should be selected as low as possible to maintain high activity, the remaining capacity is high, the discharge capacity is reduced, and the battery with a large charging rate is allowed.
At higher temperatures, the maximum operating temperature of general lithium batteries is about 50 ° C. The SEI film on the surface of the negative electrode can begin to dissolve at about 90 ° C, so that the battery cell enters the autothermal stage, the self-heat brings additional temperature rise, different batteries behave differently at high temperatures, and many cars will spontaneously combust because of the high temperature. Therefore, if it is in a hot environment, it is necessary to try to choose the positive and negative electrode materials of the battery, the diaphragm and electrolyte can still maintain good stability, can work normally at high temperatures, the life will not accelerate attenuation, and the high temperature is not easy to cause thermal runaway accidents in the battery.
security:
Whether the car can run and how far it can run is something we are all concerned about, but this must be under the premise of safety. Battery safety is affected by many aspects, such as the energy density of the battery and battery safety, there is a certain contradiction relationship, with the improvement of energy density, battery safety and safety redundancy boundaries are limited, especially in different temperatures when running, which for the vehicle, need to do more work.
summary:
The above is a few reference indicators that we often use when choosing a battery, of course, in addition to the above, there are also battery capacity, battery cost and other indicators, but these can be seen more from the data of the car brand, here is not much to say, we can choose from these aspects to consider comprehensively.