Now the first consideration that affects whether users buy an electric car is battery life, and the time to replenish energy is also an important part of the battery life experience. Because of the shortened battery life in winter and the difficulty of charging in holiday traffic jams, many new energy vehicle owners are complaining about the problem of "electric fathers".
Electric vehicles are mainly composed of batteries, motors, and electronic controls. At present, batteries occupy the most important position. The cost of batteries accounts for nearly 40% of a vehicle, just like the "heart" of electric vehicles. The importance of the battery is self-evident, it determines the power performance, battery life, and safety (whether it will spontaneously ignite) of an electric vehicle.
The goal of pure electric vehicles is to adapt to urban commuting to inter-city commuting. In 2022, a batch of products with a theoretical mileage of 1,000 kilometers have been launched, and the key to alleviating the "range anxiety" is the improvement of battery performance. To make the battery lighter, cheaper, shorter charging time, higher safety, better cold and heat resistance, the key to choosing a pure electric vehicle is to choose a battery.
The new car industry has launched a battery war in the past ten years. Because of different technical routes, players are automatically divided into two camps: lithium iron phosphate and ternary lithium. Under the combined effect of the three factors of performance, safety and cost, the market share of lithium iron phosphate and ternary batteries has increased. Whether it is production, sales or vehicle loading, ternary batteries have had the upper hand in the past few years, but by 2020, the output of lithium iron phosphate batteries will exceed that of ternary batteries for the first time.
However, whether it is a ternary battery or a lithium iron phosphate battery, there are still weaknesses, and they are not necessarily the ultimate battery solution. More technical solutions are under simultaneous research and development, such as more advanced technologies represented by solid-state batteries.
4680 is not a real breakthrough?
Tesla's long-established 4680 battery is finally about to be mass-produced and delivered. According to Tesla's official news, the California pilot plant produced 1 million 4680 batteries in January, which marked the start of mass production of 4680 batteries. The storage capacity of the 4680 battery will be 5 times that of the 2170 battery, and the power will be as high as 6 times. It is expected to increase the driving range of the vehicle by 16% and reduce the cost by 14%.
Yield has always been one of the biggest problems that plagued the mass production of 4680 batteries. In July last year, Musk also admitted that the 4680 battery encountered a bottleneck in mass production, that is, there was a problem in the positive electrode rolling process. At the end of 2021, Panasonic and Sony announced that the yield rate of 4680 batteries has increased from 20% to 80%. This may also be the basis for Panasonic's announcement that it will achieve trial production this year.
In September 2020, Tesla released the 4680 battery on Battery Day, a ternary lithium battery. The full name of the 4680 battery is the 4680 specification electrodeless cylindrical battery, the diameter of the 46-point cylindrical battery is 46mm, and the height of the 80-point battery is 80mm. The advantage of the 4680 battery is that compared with the previous 2170, 18650 and other cells, the volume has been greatly increased, and more energy can be stored in the single capacity, which is the same as simply increasing the number of batteries in the battery pack. same.
The 4680 battery has a single cell capacity of 9000mAh, and the previous 2170 only has a 5000mAh energy increase, which is naturally more obvious. Taking Tesla’s best-selling Model 3 as an example, the current M3 P uses 2170 cells, and it takes 4416 cells to fill the entire battery pack, and the battery capacity is about 78.3kWh. These more than 4,000 cells are densely packed into the battery pack. The small size of the cells leads to smaller gaps, and the assembly of each cell requires more time and materials.
In contrast, a battery pack filled with M3 P only needs 960 4680 cells, and the total capacity can reach 130kWh, an increase of 75%. In addition, due to the larger volume of the 4680 single cell, the number of packaging materials is reduced, the cost of packaging the cell shell is reduced, and the weight will also be reduced. At the same time, another advantage brought by the large size of the cells is that the gap between the cells becomes larger, making it easier to arrange the heat sink.
In the management of the battery control system, the cost will also be reduced. Continuing to take M3 P as an example, more than 4,000 2170 cells need to be packaged into "Bank" and "brick", multiple cells will be packaged into one "brick", and multiple "bricks" are controlled by one "Bank", each Each "Bank" needs to be loaded into its own control module, and these tiny calculators are all cost. If 4680 cells are used, it is simpler. Due to the large size and capacity of the cells, the number of cells is reduced. Only one control module is needed for unified management, and the control is simpler and more efficient.
It is also worth noting that the 4680 battery adopts the electrodeless ear design, which cancels the traditional electrode structure and extends the copper foil as the current collector as the electrode. This is why the 4680's electrodeless design can also be called full The cause of the polar ear.
The benefits of electrodeless lugs are also obvious, previously it was necessary to solder the lugs separately for the electrical energy to flow through. Nowadays, the tab design is canceled, and the entire side of the cell is used as the tab. The power transmission is smoother, the transmission path is shortened, the internal resistance is reduced, the current density and heat generation at the tab are reduced, and the (full tab) can withstand more. the current. It is precisely because of the larger size of the tabs that the heat dissipation is more uniform, which indirectly improves the charging and discharging performance of the 4680 battery.
SNEResearch data shows that the global installed capacity of power batteries in 2021 will be 296.8GWh, an increase of 102.18% over the previous year. It is predicted that with the growth of Tesla's global sales and the increase in the penetration rate of 4680 batteries in ternary battery models, the sales of Tesla's models equipped with 4680 batteries will exceed 1.6 million in 2025, and the penetration rate in Tesla's total sales will be nearly 50%. %, the installed capacity is expected to reach 123GWh, the global installed capacity will reach 264GWh, and the penetration rate in power batteries is 22%.
In addition to Panasonic, South Korea's LG Energy, Samsung SDI, domestic BAK Battery, Yiwei Lithium Energy, Honeycomb Energy, etc. have also followed up the research and development of 4680 batteries. When "Ning Wang" is the dominant player in the power battery field, players who cannot shake its status have focused their attention on the inconclusive 4680 cylindrical battery.
4680 cells can be regarded as a breeze when the current battery technology encounters a bottleneck, providing new ideas for anxious major car manufacturers, and once again improving the overall performance of pure electric vehicles. In general, the 4680 battery is a good package. It is not a chemical breakthrough, and it cannot be regarded as a qualitative change, but it has improved its competitiveness in the industry, and it has also made the new energy vehicle battlefield, which is gradually returning to calm, tense again. up. At the same time, as the core component of pure electric vehicles, car companies will have more intense R&D competition in the battery field.
What is a solid state battery?
For EVs to sell at the same price as gasoline-powered cars, the cost of producing batteries per kilowatt-hour would have to drop to $100 per kilowatt-hour. What determines the speed at which electric vehicles can erode the fuel vehicle market is whether battery technology can achieve real change.
Most of the batteries used in electric vehicles today are ternary lithium batteries or lithium iron phosphate batteries, among which ternary lithium batteries have relatively high energy density and better performance. However, ternary lithium batteries have also encountered performance bottlenecks. Even for leading electric car companies like Tesla, the ternary lithium batteries on their cars only have an energy density of 260Wh/kg. Even if the energy density in the industry can exceed 300Wh/kg, this is already close to the ceiling. It is very difficult for ternary lithium batteries to greatly increase the energy density.
Seeing that the ternary lithium battery is not good enough, battery R&D personnel and major companies have also begun to look elsewhere. As a result, solid-state batteries have become the hottest topic in the industry.
In solid-state ionics, a solid-state battery is a battery that uses a solid electrode and a solid electrolyte to replace the electrolyte and separator of traditional lithium-ion batteries. Solid-state batteries generally have lower power density and higher energy density. Due to the relatively high power and weight of solid-state batteries, the energy density of future solid-state batteries will be about 30%-50% higher than that of current ternary lithium batteries.
Solid-state batteries have the inevitability of development. The solid-state battery uses a non-flammable solid electrolyte to replace the flammable organic liquid electrolyte, which greatly improves the safety of the battery system, and can better adapt to high-energy positive and negative electrodes, reduce the weight of the system, and achieve a simultaneous increase in energy density. Among various new battery systems, solid-state batteries are the next-generation technology closest to industrialization, which has become the consensus of the industry and the scientific community.
The industrialization stage of solid-state batteries is still in the early stage, but it is expected to develop rapidly in the future. At present, a small number of commercial solid-state battery products have not yet formed a sufficient competitive advantage over traditional lithium batteries. In the future, solid-state batteries will follow a phased development route, gradually transitioning from special fields to power batteries, and with the accelerated layout of international giants , solid-state batteries will enter a fast track of development.
The solid-state battery system revolution is smaller. Lithium-sulfur batteries, lithium-air and other systems need to replace the entire battery structural framework, and the problems are more and more serious. The solid-state battery mainly lies in the innovation of the electrolyte. The positive and negative electrodes can continue to use the current system, and the difficulty of implementation is relatively small.
Ganfeng Lithium's solid-state battery uses a solid-state flexible separator and a semi-solid electrolyte. It is also clearer here. Compared with the solid-liquid mixed electrolyte batteries released by Weilai before, they are not strictly solid-state batteries. However, the commercialization of solid-state batteries still takes time, and the semi-solid solution is not only technically feasible, but also has connectivity and can be produced using existing equipment. Compared with solid-state batteries, semi-solid-state batteries are not transitional products, but more mature iterative products for the current ternary lithium batteries.
Looking forward to the future development trend, the technology is advancing step by step, the application is infiltrating step by step, and the development path of solid-state batteries has been clear. Structurally, the current battery system contains part of the liquid electrolyte to learn from each other's strengths. In the process of technological development, the use of liquids will be gradually reduced, from semi-solid-state batteries to quasi-solid-state batteries, and finally to liquid-free all-solid-state batteries.
What problems do solid-state batteries need to solve?
The mass production time of solid-state batteries generally recognized in the industry is around 2025, and some practical problems still need to be solved. Before the commercialization of solid-state batteries, the cumulative sales of new energy vehicles will reach more than 60 million units, and the penetration rate will increase to 21.2%. This huge market has an urgent need for technological upgrading.
The electrolytes of solid-state batteries are divided into polymers, oxides, and sulfides, which have different performances. Among them, polymer electrolytes are usually used in consumer products, and most of the solid-state batteries to be carried in electric vehicles should be sulfide electrolytes. Companies such as CATL, Panasonic, and Samsung all plan to produce sulfide solid-state batteries for use as power batteries for electric vehicles.
Mass production of solid-state batteries with sulfide electrolytes is still some time away. At least until now, major companies including Qingtao, BYD, CATL, or some battery companies in Europe and the United States have not clearly stated that they can commercialize solid-state batteries used in electric vehicles.
Although solid-state batteries have high energy density and are safer, after switching to solid-state electrolytes, the ionic activity inside the battery will deteriorate, that is, the electrical conductivity will deteriorate. The diffusion rate of solid-state ions is only one-tenth of that of liquid state, and the energy density of current solid-state batteries is about 40% lower than that of liquid state, and the cost is higher. Secondly, the solid interface contact resistance of solid-state batteries is large, and the heat generation will also increase, which requires reasonable control.
In addition, solid-state batteries currently have the problem of poor cycling. To ensure frequent charging and discharging usage scenarios for car owners, it is necessary to ensure sufficient charging and discharging times. Finally, the production and manufacturing costs of solid-state batteries for electric vehicles must be reduced to a suitable range. Otherwise, it is completely meaningless to make solid-state batteries for dozens of vehicles.
Of course, if these problems are solved, the mass-produced automotive-grade solid-state batteries will shine. The outbreak of new energy electric vehicles can be described as a cross-epoch, and the replacement of ternary lithium batteries by solid-state batteries will also be revolutionary. From the perspective of the development stage of solid-state batteries, researchers are still gradually improving some of the defects of solid-state batteries, and are also waiting for the opportunity for their commercial mass production.
The lithium battery industry chain is an industry with good prospects for at least 10 years, and the development and rise of new technologies will continue to strengthen the industry's valuation and prospects. Under the industry's optimism and multi-party layout, the solid-state battery industry is expected to achieve rapid development, and it is expected to become a new explosion point and key technical guarantee for the industry in the future.
