Bipolar battery, lithium-sulfur battery, lithium metal battery, PPT battery, which one is better?

The first cobalt-free battery has rolled off the production line, and the sodium-ion battery and 4860 battery are already on the verge of being launched. In addition to these, what other technological breakthroughs will there be in the field of power batteries in 2021 ?

As we all know, any technological breakthrough in power batteries, which are known as the "heart" of new energy vehicles , will have an impact on the performance of electric vehicles . I believe that every automotive industry practitioner and consumer knows this. However, with the rapid development of the global new energy vehicle market, the evolution and update speed of battery technology seem to be unable to keep up with the pace of the market. As a result, major automobile manufacturers, battery companies, and even scientific research teams around the world are seeking breakthroughs and even changes in power battery technology in their own way. So what breakthroughs have been made in power battery technology in the past 2021?

The first cobalt-free battery rolls off the production line. Will the fear of a cold winter for electric vehicles become a thing of the past?

In the field of electric vehicles, the biggest challenge facing power batteries is the endurance problem. This situation is more obvious in the extreme cold weather in the north, where the battery activity is reduced and the endurance is greatly reduced. Therefore, almost all car companies hope to seek breakthroughs in the endurance mileage .

After five years of technical research, GAC Aion took the lead in developing sponge silicon negative electrode battery technology, which can reduce the volume of lithium-ion battery cells by 20% and the weight by 14%. While increasing the energy density of the battery, it can also reduce the weight of the battery. More importantly, the power battery equipped with sponge silicon negative electrode battery technology has been installed on GAC Aion's newly launched AION LX Plus model, and the CLTC operating range has reached 1,008 kilometers. This achievement also makes it the first pure electric vehicle with a range of over 1,000 km to be "certified" by the Ministry of Industry and Information Technology.

Another company that has also completed the implementation of new technologies is Honeycomb Energy, a subsidiary of Great Wall Motors. On July 16, 2021, it announced that the world's first cobalt-free battery was officially mass-produced and applied to the Cherry Cat model of Great Wall Euler. It is believed that it will gradually be installed on more new energy models under Great Wall in the future. According to Honeycomb Energy, the energy density of the mass-produced cobalt-free batteries reaches 240Wh/kg, and the capacity is 115Ah-MEB. The energy density is very high. It should be noted that the energy density of the current ternary lithium battery pack in the industry is at the level of 160-190Wh/kg. Such a high-density power battery also means that pure electric vehicles will have a longer range, and even if there is a range reduction in the cold winter, it will not have much impact.

Of course, whether battery technology is advanced depends not only on energy density, but also on its cost and safety. In this regard, the life of this cobalt-free battery cell is longer than that of the same-level high-nickel ternary battery. The cell cycle life exceeds 3,000 times, and it can easily pass the 150°C hot box test and the 140% SOC overcharge test, and has passed multiple standard certifications such as GB/IEC62660/UL2580.

Sodium-ion batteries are on the way, are cheaper electric cars coming?

In 2021, the development of power batteries is still rapid. There are new technology batteries that have been put into use , and there are also new power batteries that are about to roll off the production line. Among them, the new product released by Musk, the 4680 battery, has also made new progress. In previous reports, Tesla released a video of the new 4680 battery and its production line on social media, saying that this production line will be used in the super factories in Texas and Berlin, USA, which further proves that the 4680 battery is about to roll off the production line.

Compared with the currently used 21700 batteries, Tesla's 4680 batteries are made using laser engraving non-polar ear technology, which increases the energy by 5 times and the power capacity by 6 times. When applied to Tesla cars, the cruising range can be increased by 16% and the cost per kilowatt-hour can be reduced by 14%. In addition, the 4680 battery also has the advantage of higher energy density. Since the 4680 cylindrical battery has a high matching performance with the silicon-based negative electrode, the specific capacity of the silicon-based negative electrode is higher than that of the graphite negative electrode, so it is easier to make the battery carry more power per unit volume, thereby increasing the vehicle's cruising range. However, due to the high production cost, the 4680 battery may only be one of the mainstream batteries for luxury electric vehicles in the future .

In 2021, another big news about power batteries is that the battery industry "giant" - CATL officially released its first generation of sodium-ion battery products. According to our previous understanding, the energy density of the sodium-ion battery cell displayed this time reached 160Wh/kg; the power can reach 80% after charging for 15 minutes at room temperature; in a low temperature environment of -20°C, it can maintain more than 90% of the battery efficiency. More importantly, the production cost of sodium-ion batteries is relatively low, and sodium is easier to obtain than lithium, so it has positive significance both in terms of expanding production capacity and reducing vehicle costs.

Of course, the disadvantages of sodium-ion batteries are also very obvious. Compared with lithium-ion batteries , sodium-ion energy density is relatively lower. The current energy density of sodium-ion battery cells is generally 120Wh/kg, which is much lower than the 240Wh/kg of ternary lithium batteries and 180Wh/kg of lithium iron phosphate batteries . At the same time, sodium-ion batteries are rarely charged and discharged, and the maximum number of cycles is generally only 1,500 times, which is almost not in the same order of magnitude compared with the 6,000 times of lithium iron phosphate batteries and the 3,000 times of ternary lithium batteries .

In response to these disadvantages, CATL launched the "AB battery solution", which is to integrate sodium-ion batteries and lithium-ion batteries into the same battery system, and then rearrange them to form a mix, series, parallel, and integrated system. The BMS is then used to balance the different batteries, which seems a bit complicated. However, after a series of research and development, CATL has made a breakthrough, claiming that the energy density of the next generation of sodium-ion batteries will exceed 200Wh/kg. As for when it will be launched and when the first car model can be equipped with sodium-ion batteries, it may take some time.

Bipolar battery /lithium-sulfur battery/lithium metal battery, which one is better, PPT battery?

In the new track of power batteries , major companies around the world are investing a lot of manpower and financial resources in its research, and there have been significant breakthroughs in power batteries in overseas markets, but unlike us, some of these technological breakthroughs are still in the early stages of the laboratory. For example, in 2021, Germany's ThyssenKrupp and Daimler are developing bipolar batteries for electric vehicles based on lithium-ion technology . The battery project is called EMBATT-goes-FAB. It is said that the optimized battery can enable electric vehicles to achieve a maximum range of 1,000 kilometers , which can effectively solve the current range anxiety problem and the problem of insufficient battery life.

Mercedes, as we all know, is also experimenting with power batteries, but its research and development method is different. In the concept car Mercedes EQXX, it simply redesigned the battery pack to have more than twice the power of mass-produced cars in a smaller space, which is a bit like the combination of Lego blocks. The advantage is that when a single battery cell fails, just pull out one of the modules and it can be easily replaced.

In a laboratory at the University of Michigan, researchers claim to have updated a related technology, the lithium-sulfur battery. The main reason is that lithium-sulfur batteries can store more energy, but because of their limited number of charge and discharge cycles, they cannot work better. The solution the researchers came up with is to use aramid nanofibers recycled from Kevlar ( the material used to make bulletproof vests), which can not only increase the number of charge and discharge cycles, but also increase the battery life of lithium-sulfur batteries by five times, and also have the ability to be used normally in extreme environments. However, after leaving the laboratory, the cycle life of this battery in the actual environment may be shortened due to fast charging , with a lifespan of only about ten years.

It is worth mentioning that among the "Top Ten Global Breakthrough Technologies" released by MIT Technology Review 2021, Silicon Valley startup QuantumScape developed a new lithium metal battery that was successfully shortlisted and won the award, sparking heated discussions in the industry. The main reason is that the solid electrolyte (ceramic) used in lithium metal batteries overcomes these defects of traditional lithium-ion batteries and can easily break through the energy density limit of traditional lithium-ion batteries. It can exceed 400 Wh/kg, which is more than 30% higher than the current lithium-ion batteries. There is no doubt that if this technology can eventually be applied to the automotive field, electric vehicles will have a longer range. However, many people still have concerns about lithium metal batteries, because in organic electrolytes, the uneven lithium deposition of lithium metal anodes causes safety hazards, so metal lithium batteries have never been used. As for whether this breakthrough will be commercialized, there is still a long way to go.