Can The Energy Density Of A Power Battery Really Determine The Quality Of An Electric Car?

Can The Energy Density Of A Power Battery Really Determine The Quality Of An Electric Car?

Date:Mar 14, 2019

A friend considers buying an electric car (no way, persuaded not to listen), in the process of accompanying him to watch the car, the author found that the salesperson began to use the energy density of the battery as a target. The words "The energy density of this car is up to XXX" and "The battery brand is XXX" are usually stated in the sales consultants who sell electric vehicles. When asked about the energy density, the sales consultant paused for a few seconds and said: "In short, the higher the energy density, the better the car, the more subsidies the country must have!" Obviously, energy This is the density of things, not even some car sales consultants are too clear.

In fact, the expansion of some new products and new technologies has existed in almost all industries. But what exactly are these new gadgets used for? How much value is there? After the consumers were surrounded by the fog, they didn't seem to care much about these problems. They only thought that this thing was really bullish. Today we talk about the energy density of the battery, how much it affects the quality of pure electric vehicles.

What is the energy density?

First of all, we simply understand what the energy density of the battery is. There are two kinds of energy density, weight energy density and volume energy density. The weight reference energy density is the most commonly used. The formula is: weight energy density=battery capacity×discharge platform/weight, the unit is Wh/kg (Wh/kg/ (kg); and the volumetric energy density calculation method only needs to change the "weight" of the above formula to "volume" in units of Wh/L (Wh/L).

Simply put, energy density is an evaluation of the battery's ability to store electricity. Such evaluations were not originally used to determine the quality of electric vehicles, but rather the policy requirements for the power storage capacity of enterprises. According to the requirements, the company's power battery specific energy needs to exceed 300 watt-hours/kg in 2020, and the system's specific energy strives to reach 260 watt-hours/kg. From the marketing point of view, since this is the standard of policy making, it must be attractive to consumers, so it has become a gimmick in the sales process of some pure electric vehicles.

The evaluation of energy density is not fully mature

For now, the assessment of energy density is not absolutely fair, because it is directly linked to the interests of car companies. As we said before, the policy will require energy density, and in terms of new energy support, energy is also one of the reference standards. The higher the energy density, the more new energy subsidies are obtained. This has led to some "arms races" in the power battery of some car companies, and there are still many tricks.

To know how car companies can increase energy density, they have to start with the formula just now: weight energy density = battery capacity × discharge platform / weight. To increase the final value of this formula, there are two most direct methods, one is to increase the battery capacity, and the other is to reduce the weight of the battery.

The method of increasing the battery capacity is a conscience. There are many ways to increase the capacity, and the most is to start with the material of the battery. At present, the ternary lithium battery is the most dominant type of power battery in the country, while the proportion of lithium iron phosphate battery is falling very fast. However, the practice of conscience can not be done in the hands of those who are not well-intentioned. In order to increase the battery capacity, some manufacturers have lowered the requirements for battery stability, and the safety risks have increased. Therefore, some insiders worry that the quick success in battery capacity will affect the safety of electric vehicles.

Another way is to reduce the overall weight of the entire power battery, which is actually a temporary solution. Some high-quality power batteries each have a separate cell so that the entire battery pack does not affect the failure. To reduce the weight of the power battery, these cells are the first to bear the brunt. Either develop new materials to reduce weight without affecting the protection of the battery, or simply cut materials or change materials that are lighter but less powerful.

Therefore, there are many ways to increase the energy density. For car companies, reducing materials is a “win-win” approach, and the safety issue is of course 60 cents. In the absence of uniform requirements on the structure and materials of the battery, the safety and quality of the high-energy-density power battery are in a good, good or excellent level, and consumers have no way to measure it.

In fact, in terms of measuring the cruising range of electric vehicles, the simplest and most rude method is to directly look at the total capacity of the battery. If you want to consider the factors of battery safety and vehicle quality, the current environment is not a big technology open, the manufacturing cost is high, the electric car is still a penny. To put it bluntly, under normal circumstances, the price of the car is still good or bad. If the relevant part can improve the fairness of various evaluation standards of electric vehicles, it has a very positive effect on the improvement of stimulation technology and the protection of consumer rights.

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