It may not replace lithium batteries, but it will crush fuel vehicles. Technical analysis of sodium battery

For ordinary consumers, we don't talk about Chun Xue. The reason why fuel vehicles can still stand in front of pure electric vehicles at this stage is because the price is too expensive. For pure electric vehicles, the power battery is the absolute cost center, and the once dazzling engine and gearbox cannot compete with it in cost ratio. Because the unit capacity cost of lithium battery is high, but under the influence of battery life anxiety, there is no battery capacity in the brain, forming a spiral state in which the cost rises from expensive unit price to large capacity. In this context, the former "spare tire" sodium battery began to heat up, and it is likely to usher in a formal "substitute debut" opportunity this year. From a technical point of view, can sodium batteries really reduce the price of pure electric vehicles? If the price problem is solved, can the last technology of the fuel car, the horse refusal pile, be removed?

How much cheaper can it be to replace sodium batteries?

From the technical basis of sodium battery and lithium battery, the advantage of sodium battery lies in its huge stock and the disadvantage lies in its low efficiency. Let's start with stocks. As far as mineral resources in the earth's crust are concerned, sodium is nearly 400 times that of lithium, and its distribution is more uniform. Specific to raw materials, the price of sodium carbonate is only a few thousand yuan per ton, while lithium carbonate once approached the exaggerated price of 600 thousand yuan per ton. Even if the raw material price of lithium carbonate falls back to 400,000 yuan/ton, the price of sodium carbonate with the same weight is far from the level of lithium carbonate 1% under quite conservative calculation.

However, this certainly does not mean that replacing the sodium battery can reduce the cost of the power battery by 99%. As for how much cost can be reduced, there is actually a background to be explained, that is, sodium batteries have not yet formed a stable technical route, so the calculation dimensions are different. But the core part can be applied to more familiar lithium batteries, because sodium batteries only use sodium instead of lithium in cathode materials and electrolyte. In particular, the cost of cathode materials is relatively high, accounting for about 40% of the cost in the technical path of lithium batteries, while sodium batteries can reduce the cost of cathode materials to about a quarter.

However, the different technical routes lead to the difference in the cost of cathode materials. We also introduced the familiar Contemporary Amp Technology Co., Ltd.. The route of Prussian blue compound cathode material sacrifices some characteristics of sodium battery except price to a certain extent, and then it is exchanged for high energy density with simple process and low cost. The anode routes of layered epoxy compounds and polyanionic compounds are also unique. In the automobile environment, the lower energy density and higher processing cost of the latter are more limited, but the advantages of high working voltage, high thermal stability and cycle life are more like those from ternary lithium batteries. As for the former, it is actually close to the performance of Prussian blue compound route, but the controllability in handling may be a potential watershed in the vehicle regulatory environment.

In a word, although sodium battery belongs to "alternative debut", many technical paths have not reached the height of ternary lithium battery. The production process of sodium battery and lithium battery is in the same state, and the technology has high repeatability and portability. This will not only affect the overall cost control, but also help sodium batteries to gain a firm foothold in automobile regulations as soon as possible from a technical point of view. According to the prediction of most institutions, according to the current price difference of raw materials, the cost of the officially launched sodium battery is expected to be reduced by about 30-40% on the basis of lithium iron phosphate battery. Similarly, taking the statement that the power battery accounts for about 40% of the vehicle cost as a reference, even taking the Hong Guang MINIEV, which started at more than 30,000 yuan, as an example, the price is expected to be reduced by about 5,000 yuan. If it is a medium-sized pure electric vehicle with a class of 200,000, the price may be reduced by more than 30,000 yuan at one time. Of course, again, this is only an extremely extensive inference reflecting the "lethality" of sodium batteries on the cost of electric vehicles.

How many advantages of sodium battery are covered by shortcomings?

Of course, "a penny for a penny" is also our life experience. As for the sodium battery, as mentioned earlier, its efficiency is relatively short, which can be found from the periodic table of elements. Only the top activists can have higher efficiency between the positive and negative electrodes of the battery, so as to obtain stronger "cargo carrying" ability. On this basis, the adaptable metal elements are lithium, beryllium, sodium, magnesium, aluminum and so on. Beryllium is extremely rare, and there is no doubt that lithium batteries will win in the first stage. As for sodium, magnesium and aluminum, which are not as efficient as lithium, under the influence of cost factors, sodium batteries finally stand out and will stand out soon. Even if its energy density is far less than that of ternary lithium battery, it can only touch the threshold of lithium ferrous phosphate. This will certainly affect the cruising range performance of sodium battery after loading, but under the relatively low efficiency performance, is sodium battery really just a useless choice except cheap?

Broadly speaking, pure electric vehicles with sodium batteries may be closer to the feeling of fuel vehicles. The first is the safety of sodium batteries. Because of the stability of sodium and aluminum and the higher stability of sodium salt electrolyte, the thermal protection effect of sodium battery is better than that of lithium battery in theory. For example, sodium battery electric vehicles can be transported "empty electricity" in theory, which can ensure transportation safety without affecting future performance.

In addition, sodium batteries have excellent stability not only at high temperature, but also at low temperature. Although ternary lithium battery is superior to lithium iron phosphate battery in low temperature attenuation. However, at the low temperature of -20℃, the general charge-discharge retention rate of ternary lithium batteries can only be maintained at about 70%, while that of sodium batteries can reach 90%, which can almost ignore the influence of low temperature. In addition, low-temperature charging of lithium batteries can easily lead to lithium precipitation, while sodium batteries are fearless. In short, compared with lithium batteries that are afraid of heat and cold, sodium batteries can basically work normally in the temperature range of -40℃ to 80℃. Theoretically, the fuel truck can go wherever it can.

Even the inevitable problems of low capacity and less charge and discharge times of sodium batteries are not irreversible. For the capacity problem, the potential of sodium battery in fast charging may be the best way to make up for it. Due to the imbalance of lithium ions between the anode and cathode of lithium-ion batteries in the state of fast charging, especially in the case of overcharge, dendrites will be generated at the cathode in extreme cases, which is a potential threat that metal crystals will pass through the separator and lead to short circuit at the cathode. Therefore, lithium batteries tend to charge quickly, and the speed will be greatly reduced after 80%. And in order to cause permanent loss of battery capacity, it is generally not recommended to rely entirely on fast charging and recharging, let alone long-term high-voltage overcharging. In the case of sodium battery, the transmission speed of sodium ion in the positive and negative electrodes is faster than that of lithium ion, so the balance between the positive and negative electrodes can be achieved under the condition of high voltage and fast charging. In this way, the sodium battery not only has higher fast charging efficiency, but also is not afraid of overcharging. At the same time, its battery specific capacity is excellent. Simply put, the charged power is "real", and the difficulty of endurance calibration is greatly reduced. In this way, even if the cycle life is obviously weaker than that of lithium iron phosphate battery, even after 1000 charge and discharge cycles, the specific capacity retention rate of sodium battery can still be close to 95%, while that of lithium battery is basically about 80%. To sum up, sodium batteries have low capacity and short cycle life. But the limited capacity is solid, durable and safe, and the limited statement is more "substantial".

Write it at the end

With the price roller coaster in the bulk supply chain last year, the rise of raw materials made consumers realize that electric vehicle batteries are expensive. The unit price is expensive, and the capacity is also rolled up, so the overall car price is developing in a more expensive direction. This logic closed loop may not be ushered in until the sodium battery is officially listed. It is not that sodium battery is the ultimate choice to unify the rivers and lakes, but it provides a new idea for the development of pure electric vehicles when the capacity problem cannot be solved by nature. An idea that can completely incite ordinary consumers to rely on fuel vehicle routes in terms of safety, usage scenarios and price advantages.

This article comes from Luca Auto, the author of Easy Car, and the copyright belongs to the author. Please contact the author if reproduced in any form. The content only represents the author's point of view and has nothing to do with the car reform.