In the past one or two years, the "inner coil" of power batteries in terms of continuous driving, safety, fast charging and other performance has been continuously intensified, and there are various technologies that can achieve better characteristics. Driven by the continuous improvement of the market size and penetration rate of new energy vehicles, the pace of technological innovation and research and development of power batteries is accelerating, bringing a new variable to the reshaping of the industrial pattern.
Silicon anode battery
It is understood that GAC Aion LXPLUS is equipped with a new type of nickel-cobalt-manganese ternary lithium battery, and the system energy density reaches 205Wh/kg. Unlike ordinary nickel-cobalt-manganese ternary lithium batteries, the negative electrode of the new battery is added with a silicon wafer as soft as a sponge. This design allows the expansion and contraction of silicon during charge and discharge to be limited and buffered without fragmentation, and also like a sponge absorbing water, allowing the silicon anode to exert the advantage of large capacity and store more energy, its core advantage is to greatly reduce the mass and volume of the battery.
According to the official information of GAC New Energy, through this self-developed "sponge silicon anode plate battery technology", under the same power situation, the power battery cell can reduce the volume by 20% and the weight by 14%. The current cell energy density of this new battery can reach 280Wh/kg, and this value is expected to increase to 315Wh/kg through future technology iterations.
At this stage, the anode material of continental power batteries is mainly artificial graphite, but its gram capacity is close to theoretical values, and it is difficult to further improve, so the development of new anode materials and technologies for lithium batteries has become the focus of research and development.
The anode of commercialized silicon materials is generally a silicon-carbon composite system, and its industrial application is gradually promoted as the relevant technologies gradually mature. Statistics from Xinzhu Information show that in 2020, the shipment of silicon carbon anode materials in the mainland will be 0.9 million tons, accounting for about 2%.
Tesla, which has always been known as the vane of the new energy automobile industry, turned its attention to silicon anode technology a few years ago. Since the Model S and Model X, Tesla has incorporated silicon material into the graphite anode of the power battery. Among the 21700 cells used on the Model3, the proportion of silicon has been increased again, and the energy density is about 20% higher than that of the previous generation of 18650 batteries. It is worth noting that Tesla also said that the latest 4680 battery will be introduced into the silicon anode to replace the original carbon-based material. It has also been learned that Tesla recently acquired the American battery startup SiILion, which has a patent for "large battery anode containing silicon particles", which has now been transferred to Tesla's name.
The new domestic car-making forces are not far behind in the application of new technologies for power batteries. In January this year, WEILAI Automobile said that it will deliver 150kWh battery packs in 2022, the positive electrode uses nano-coated ultra-high nickel materials, the negative electrode uses pre-lithiumized silicon carbon anode, and the semi-solid electrolyte is used, and the energy density of the monomer can reach 350Wh/kg. The Zhiji L7, which was listed in April this year, has a 118kWh high-end version of the power battery using the "silicon-doped lithium supplement" technology cooperated with CATL, and the official said that the maximum energy density of its battery cell can reach 300Wh/kg, with 200,000 kilometers of zero attenuation and "never spontaneous combustion" characteristics.
Internationally, Panasonic and Samsung SDI's cylindrical batteries have previously been introduced into the silicon-carbon anode. In addition, Toyota, Mitsubishi, Hitachi Chemical, etc. are also major silicon-based anode material technology patent applicants.
In China, mainstream power battery suppliers have long seen the development potential of silicon anode batteries, BYD, Ningde times, Guoxuan Hi-Tech, Beiterui, Shanshan shares, Lishen, BAK, Wanxiang and so on have launched related layouts. For example, at the beginning of this year, Guoxuan Hi-Tech first launched a new lithium iron phosphate battery with an energy density of 210Wh/kg. The company said that this performance improvement is inseparable from the key "high-gram capacity silicon anode materials and advanced pre-lithionization technology."
According to reports, silicon carbon anode materials can greatly improve the energy density of lithium batteries because of their large specific capacity, which is the development direction of a new generation of anode materials. The research report of Northeast Securities shows that the negative electrode of lithium batteries from graphite system to silicon-based anode will be the direction of future upgrading. With the improvement of the energy density requirements of power batteries, silicon carbon anode with high nickel ternary materials has become a development trend. In the next two years, with the gradual maturity of high-nickel ternary material technology, the industrialization of silicon carbon anode is coming.
Cao Guangping, an independent researcher of new energy and intelligent networking, told the "China Automotive News" reporter that the current silicon anode or silicon carbon anode material with high silicon content has the advantage of having a large gram capacity, which is theoretically several times or more than 10 times that of the existing graphite anode, so the use of silicon as a negative electrode can improve the energy density of lithium-ion batteries. Silicon is a homogeneous element of carbon, and silicon or silicon carbon anode materials can electrochemically achieve lithium embedding and delithionization. "However, because silicon expands in the process of lithium embedding, it is easy to collapse after delibeing, so it is difficult to design in theory and has a poor service life." He said.
In this regard, some insiders pointed out that the silicon carbon negative electrode is suitable for the "partner" of the high nickel ternary cathode with a relatively short life, and the production cycle life meets the needs of conventional use and has a high energy density of the battery cell.
"Now, the cost of silicon carbon anode is slightly higher, and there are challenges such as volume expansion, low first efficiency and immature lithium supplementation technology, and it is expected that as these problems are solved, more models will be equipped with silicon carbon anode power batteries." The relevant person in charge of a new energy automobile company said.
"Before the industrialization of lithium anode or lithium hybrid anode, silicon carbon or silicon anode is likely to have a certain market window, the length of which depends on whether it can make up for its own shortcomings and when the problem of the next generation of lithium anode will be overcome." Cao Guangping thinks.
Sodium-ion batteries
This year, the Ningde era successfully brought "fire" sodium-ion batteries. At the new product online conference, CATL launched a sodium-ion battery with a cell energy density of up to 160Wh/kg, and plans to increase the energy density of the next generation of products to 200Wh/kg. In addition, the sodium-ion battery in the Ningde era has obvious advantages in fast charging performance, charging for 15 minutes at room temperature, the power can reach more than 80%; in the low temperature environment of minus 20 °C, it can also have more than 90% discharge retention rate, and the system integration efficiency can reach more than 80%.
At present, sodium-ion batteries are still in the early stage of industrialization, and power battery companies have laid out related technologies and production capacities. CATL said that it plans to basically form a sodium-ion battery industry chain in 2023. In addition, Zhongke Hai Sodium, Sodium Innovative Energy, And Starry Sky Sodium Electricity are also carrying out related layouts. Internationally, foreign companies such as British FARADION, Japan's Panasonic, and Toyota are also exploring the industrialization of sodium-ion batteries.
It is understood that the mainland's sodium reserves are abundant, widely distributed and low cost, which can be used to support the sustainable development of large-scale energy storage technology. Hu Yongsheng, chairman of Zhongke Haina, pointed out that the high-capacity, long-life, ultra-low-cost and environment-friendly new soft carbon anode material they developed - high-temperature cracking anthracite coal laid a key foundation for the practical application of anode materials for sodium-ion batteries, and the invention patents have been authorized in China, the United States and Japan.
According to the data, more than 80% of the mainland's lithium raw materials rely on imports, and its rising prices have also put the industry under obvious pressure. In contrast, sodium resources are large and simple to extract. According to the calculation of Zhongke Hai Sodium, benefiting from lower material costs, sodium-ion batteries usually cost 30% to 40% lower than lithium-ion batteries.
According to the research report of GF Securities, in 2025, the potential application scenario demand for domestic sodium-ion batteries will be 123GWh, measured at the price of lithium iron phosphate batteries, corresponding to a market space of about 53.7 billion yuan.
Earlier, the Ministry of Industry and Information Technology replied to the CPPCC proposal that the relevant departments will support sodium-ion batteries to accelerate the transformation of innovative achievements and support the capacity building of advanced product mass production.
"Sodium-ion batteries have been trial-produced in small batches, but large-scale application still needs to pass the process pass, quality pass, boarding pass, use pass, and further promotion is limited by the low energy density and other shortcomings." Cao Guangping introduced.
Industry experts pointed out that sodium-ion batteries can be used as a supplement to the current power battery technology route, but there are still many challenges to be faced for large-scale commercialization. For example, sodium-ion batteries have a heavier weight, and as a power battery, they must achieve a breakthrough in energy density. In addition, the supply of materials such as the positive and negative electrodes and electrolytes of sodium-ion batteries has not yet formed a scale. The future application scenarios of sodium-ion batteries may mainly focus on energy storage, low-speed electric vehicles and other fields.
CITIC Securities research report shows that in the era of energy change, sodium-ion batteries in terms of resource richness, cost advantages are obvious, in the next few years with the increase of industrial investment, technology to maturity, the industrial chain gradually improved, is expected to achieve commercial applications in the field of energy storage and other fields, to a certain extent, the formation of lithium-ion batteries, lead-acid batteries and other mature energy storage technology supplement.
Lithium metal batteries
From the perspective of the development of silicon anode technology, the focus of improving the energy density of power batteries has been expanded from the positive electrode to the negative electrode and other components. In this industry background, lithium metal secondary batteries using lithium metal as anode material have also received more attention.
Compared with lithium-ion batteries, the cathode material of hybrid lithium metal batteries is almost exactly the same as that of lithium-ion batteries. As an anode material, the theoretical capacity of lithium metal is 3860mAh/g, which is about 10 times that of graphite, which can be combined with existing high-capacity cathode systems. Lithium metal batteries with high energy density, with the advantages of the material itself, can achieve more than 40% energy density beyond conventional lithium batteries, reaching more than 400Wh/kg.
Recently, hybrid lithium metal battery supplier SES released Apollo lithium metal battery, with a capacity of up to 107Ah, which is said to be the world's largest lithium metal battery with a single capacity, and it is also the world's first public display of more than 100Ah monomer lithium metal battery.
According to reports, SES is building a Super Factory in Shanghai, which is scheduled to be completed in 2023 with a total area of 30,000 square meters. The gigafactory is located in Jiading International Automobile City, and the production capacity will reach 1GWh after completion, which will become the world's largest lithium metal battery factory with production capacity. SES founder Hu Qichao said that the possible time point of industrialization of hybrid lithium metal batteries is expected in 2025.
According to reports, compared with lithium-ion batteries, the technical route of hybrid lithium metal batteries can not only improve energy density, but also improve safety. Cao Guangping told reporters that compared with traditional lithium-ion batteries, hybrid lithium metal batteries use a large gram of lithium metal anode and a thinner solid electrolyte layer, which can greatly improve energy density.
Domestic mainstream battery companies also see the future development space of hybrid lithium metal batteries. CATL said on november 4 on the investor interactive platform that the company has been closely following the international frontier research, set up a 21C laboratory to carry out forward-looking technical research, and is currently promoting a new technology layout including metal lithium batteries, all-solid-state batteries, etc.
Peng Yanqiu of the Advanced Battery Research Institute of Ewell Lithium Energy Research Institute said that in recent years, Ewell Lithium Energy has focused on the research of metal lithium batteries, through the systematic analysis of the principles of key processes and related equipment, and adopted strategies such as new metal lithium incoming methods, new equipment development, parameter optimization, etc., to achieve automatic die cutting and semi-automatic lamination. Lithium metal secondary battery lamination time is only 1.7 minutes, and in the development of lithium-sulfur battery has been verified, followed by the development of die-cutting - lamination integrated equipment, to achieve a fully automatic lamination process, for high specific energy metal lithium secondary battery to provide reliable technical support.
Some insiders pointed out that although the storage capacity of lithium metal batteries is equivalent to 10 times that of lithium-ion batteries, it faces the problem of "stuck neck" in commercialization, that is, when lithium metal batteries are charged and discharged, lithium will be unevenly gathered on the electrodes. This accumulation greatly shortens the life of the power battery, and it may cause a short circuit or even a fire.
"The development of lithium metal battery technology mainly has three problems, one is that it is easy to grow lithium dendrites, which puncture the diaphragm but it is a big problem that affects safety; the second is that the lithium negative pole is easy to produce a violent expansion of the volume, which seriously affects the battery life; the third is that the chemical properties of lithium are lively, and it can react in humid air and other environments, so production needs to be carried out under special conditions, and there are many process problems to be improved." Cao Guangping told reporters. Peng Yanqiu also said that lithium metal secondary batteries are still a long way from achieving commercial applications.
Recently, a new study released by Harvard University in the United States has combined the two directions of lithium metal and solid electrolyte, and has made a new breakthrough. Its lithium metal solid-state battery shows a very stable state, under the high energy density setting, it can still achieve more than 10,000 charge and discharge cycles, and the life expectancy of electric vehicles can reach 10 to 15 years, and the fast charging mode can be "full of blood" in 10 to 20 minutes.
4680 large cylindrical battery
Recently, Yiwei Lithium Energy issued an announcement that its subsidiary Yiwei Power intends to sign a contract with the management committee of Jingmen High-tech Zone to invest in the construction of 20GWh passenger car large cylindrical battery production line and auxiliary facilities project, 16GWh square lithium iron phosphate battery production line and auxiliary facilities project in Jingmen High-tech Zone, with a total fixed asset investment of about 6.2 billion yuan.
Liu Jincheng, chairman of Ewell Lithium Energy, said that the large cylindrical battery project to be built in Jingmen may be the first mass-produced 4680 and 4695 battery production bases in the world.
In fact, Panasonic, Tesla, BAK, Hive Energy and other companies are also laying out 4680 large cylindrical batteries, and some companies' products are about to usher in mass production.
Not long ago, Panasonic released a new 4680 battery for the first time, with a storage capacity of five times that of existing batteries, and plans to start trial production in Japan in March 2022. Panasonic said that the 4680 large cylindrical battery is manufactured to meet the requirements of Tesla's electric vehicles, and the production cost is halved. This year, Panasonic has established a 4680 battery test line in Japan. Panasonic also said that if the battery can be produced with higher efficiency than its peers, it will consider making large-scale investments and supplying it to car companies other than Tesla. In addition, Samsung SDI and LG Energy have also completed sample development for the more powerful 4680 battery, which is currently being tested to verify its structural integrity.
The cylindrical battery winding process is mature and the cost is low, but the heat in the core is not easy to dissipate, the effect of thermal management is slightly worse, and the volume energy density after the group is slightly lower. In this regard, enterprises through different innovative means to improve their existing problems. Lin Jian, chief scientist of BAK battery, said that through the optimization of positive and negative electrode materials and structural design, the development progress of BAK full-pole ear large cylindrical products meets expectations, and the fast charging performance is increased by 3 times on the basis of taking into account energy density, and the current products have been sampled for some customers, on the basis of meeting market demand, the test results are partially better than expected.
Yang Hongxin, chairman and CEO of Hive Energy, believes that the market prospect of large cylindrical batteries is broad, and it has application advantages in high-performance sports cars, SUVs and other fields, taking this as a breakthrough, cylindrical batteries can compete with square and soft pack batteries. This year, Hive Energy will also cut into the field of large cylindrical batteries.
Compared with the traditional cylindrical battery, the performance of the 4680 battery is significantly improved: first, the space utilization rate is improved, and the increase in the volume of the cylindrical volume can reduce the number of battery cells; second, the production cost is reduced, and the energy density of the single body is increased, which means that the number of cells is reduced; the third is the fast charging performance is improved, which can be charged to 80% of the power within 15 minutes, and the peak power density can reach more than 1000W/kg.
Due to historical reasons, the proportion of square power batteries in the mainland is large, and the application of cylindrical batteries is declining. Now, many vehicle companies and suppliers have refocused their attention on the upgraded large cylindrical battery. Driven by Tesla's localization, the loading volume of domestic cylindrical batteries has gradually returned to positive growth, reaching 8.35GWh in 2020, accounting for 13% of the domestic new energy vehicle battery loading.
Lin Jian said that the application potential of large cylindrical batteries is great, especially in the high-end passenger car and commercial vehicle markets. In addition, it can not only be equipped with the whole vehicle, but also some short-distance travel tools and terminal equipment with high driving requirements. The application value of cylindrical batteries in the field of new energy vehicles still exists, and its high consistency and low cost advantages can still find a suitable living space in some segments. With the mass production and listing, large cylindrical batteries may be favored by more car companies.
Source: New Energy Vehicle News EV