Written by / Tu Yanping
Editor/ Liu Baohua
Design / Leather
In 1799, the Italian physicist Volte immersed a zinc plate and a silver plate in brine, and found that there was a current in the wire connecting the two metals, so he put many zinc sheets and silver sheets on a cardboard soaked with brine, and used wires to connect the two ends. The world's first battery, the volt stack, was born.
More than two hundred years later, batteries have become inseparable from human daily life, and today's batteries are far from what they were.
Today's common lithium-ion batteries were born in the 1960s, commercialized by Sony Corporation of Japan in 1991, and then gradually applied to mobile phones, computers, and automobiles.
In the historical process of electric vehicles replacing fuel vehicles, lithium-ion batteries have played an important role. The explosive growth of China's new energy vehicle market in 2021 is inseparable from the continuous iteration of battery technology.
Increasing energy density while ensuring safety has always been at the heart of the development of power battery technology. Around this core, power battery developers have been conducting innovative research on electrochemical material systems.
Lithium-ion battery cells include positive and negative electrodes, electrolytes, separators, etc., from the cell level to improve the battery energy density, it is necessary to start from these components.
From NCM111 to NCM523, and then from NCM622 to NCM811, ternary cathode materials have been developing in the direction of high nickelization, and at the same time, low cobalt and even no cobalt have gradually become the mainstream.
In terms of anode materials, in addition to graphite, the research and development and application of silicon-based anode materials and lithium metal anode materials have also ushered in new breakthroughs.
In terms of electrolyte materials, its morphology is developing from electrolyte to gel electrolyte (semi-solid), quasi-solid electrolyte, and all-solid electrolyte.
Therefore, the path of increasing the energy density of lithium-ion batteries is very clear, that is, the cathode material + anode material + electrolyte are three-pronged.
The 150kWh battery pack released by Weilai in early 2021 fits this technology upgrade route. The battery pack has innovations in the positive electrode, negative electrode, electrolyte and other levels, respectively, the application of ultra-high nickel cathode materials, high-performance silicon carbon composite anode materials and solid-liquid electrolytes, greatly improving the mileage of the model. The NIO ET7 equipped with this battery pack will have a cruising range of more than 1,000km.
Lithium-ion batteries dominate the field of power batteries, but with the rapid growth of the scale of electric vehicles, limited lithium resources will sooner or later make the entire industry face a crisis. This makes the sodium-ion battery have an opportunity. With richer reserves and better low-temperature performance, sodium-ion batteries may not replace lithium-ion batteries, but it has already entered the stage of automobile electrification.
After sodium ions, there are more "× ion batteries" in the mood.
Looking globally, Indian battery research and development company Saturnose announced a surprising news in 2021 that its enhanced altered aluminum-ion battery plans to be commercialized in 2022 and to replace lithium-ion batteries. It is said that the energy density of this aluminum-ion battery is expected to exceed 600Wh/kg and is 50% cheaper than lithium-ion battery technology.
In August 2021, a research group of Dai Hongjie, a member of the Chinese American Academy of Sciences and a professor in the Department of Chemistry at Stanford University, published a research result in the journal Nature, rechargeable sodium/chlorine and lithium/chlorine batteries, which solved the problem that a class of batteries could not be recharged twice for half a century. This battery system uses a carbon material with a high microporous as the positive electrode, metal sodium or lithium as the negative electrode, chlorine as the oxidizer, and thionyl chloride as the electrolyte, and can store 6 times more power than a common rechargeable lithium-ion battery.
At the same time, the research and development data of new battery technologies such as lithium-ion battery niobium technology, magnesium battery, zinc battery, sodium-sulfur battery and solfore battery are also constantly refreshed in the laboratory.
Since the day the battery was invented, human beings have not stopped improving battery technology. When the battery meets the century-old great changes in the automobile industry, it has ushered in an unprecedented large market, and various power battery technologies have blossomed.
Looking back at 2021, the power battery field is very lively: sodium-ion batteries turned out to be born, cobalt-free batteries were mass-produced and loaded, silicon anode batteries were industrialized, metal lithium battery products were baked, and semi-solid-state batteries also began to test the waters of industrialization.
These five major battery technologies are all innovations at the material level. From the laboratory to the industrialization, they interpret the charm of electrochemistry, and before you see it, every battery technology has undergone a difficult tempering process. Who says battery technology is stagnant? Scientists don't say yes.
Sodium-ion batteries
In the 1970s, people began to develop sodium-ion batteries. At present, there are more than 20 enterprises around the world engaged in the development of sodium-ion battery industrialization.
Because of the entry of the Ningde era, sodium-ion batteries have become a hot spot in the battery industry in the past year and have entered the public vision.
On July 29, 2021, CATL released the sodium-ion battery, whose cathode material uses Prussian white material with a high gram capacity, and the negative electrode material uses a hard carbon material with a unique pore structure.
Based on the breakthrough of the material system, the energy density of the first generation of sodium-ion battery cells in the Ningde era reached 160Wh/kg, which was slightly lower than that of lithium iron phosphate batteries, but it had obvious advantages in low temperature and fast charging, and there was still more than 90% discharge retention rate in the low temperature environment of minus 20 °C. In the future, the energy density of the second-generation sodium-ion battery in the Ningde era will be increased to 200Wh/kg.
In terms of manufacturing process, sodium-ion batteries can achieve perfect compatibility with lithium-ion battery production equipment and processes, and the production line can be quickly switched to complete the rapid layout of production capacity. At present, the Ningde era has started the industrialization layout of sodium-ion batteries, and will form a basic industrial chain by 2023.
In addition to the Ningde era, Relying on the sodium-ion battery technology of the Institute of Physics of the Chinese Academy of Sciences, Zhongke Hai Sodium is also promoting the industrialization of sodium-ion batteries.
On December 18, 2021, Zhongke Haina reached a cooperation with China Three Gorges Energy, China Three Gorges Capital and the People's Government of Fuyang City, Anhui Province, to jointly build the world's first large-scale mass production line of sodium-ion batteries. The production line is planned to have a production capacity of 5GWh, which will be built in two phases, and the first phase of 1GWh will be officially put into operation in 2022.
In general, sodium-ion batteries are still in the early stages of industrialization. In the long run, it will become a useful supplement to lithium-ion batteries.
Cobalt-free batteries
The global proven reserves of cobalt are only about 7.1 million tons, and some institutions predict that cobalt resources will be in short supply after 2026. In order to reduce the dependence on cobalt metal, less cobalt or even no cobalt has been a research and development direction that many battery companies are carrying out.
On August 29, 2021, Hive Energy announced that its cobalt-free battery pack system will be officially equipped with the Cherry Cat of the Great Wall Euler pure electric SUV model, and will achieve mass production and loading.
Starting from the most basic material link, Hive Energy significantly improves the nickel-lithium-ion mixed discharge problem and cycle life of cobalt-free layered materials through cation doping technology, single crystal technology and nano-network coating, so that cobalt-free materials can cross key obstacles and move towards the stage of large-scale application.
The cobalt-free battery pack system equipped with Cherry Cat has a total power of 82.5 kWh, a system energy density of 170Wh/kg, and a cruising range of more than 600 km at room temperature.
At present, Hive Energy cobalt-free batteries have planned a total of four mass production products, namely cobalt-free H series 115Ah batteries, 155Ah batteries, H Plus series 157Ah batteries and cobalt-free E series 115Ah batteries. Among them, the energy density of cobalt-free H series batteries is 240Wh/kg.
On December 16, 2021, Hive Energy's cobalt-free battery mass production line was put into operation at the Ma'anshan production base. After five years of deep ploughing of cobalt-free batteries, Hive Energy has become the world's first battery company to truly realize the industrialization of cobalt-free batteries.
In addition to Hive Energy, power battery companies such as Panasonic, LG, and CATL are also working to reduce the use of cobalt. According to the battery technology route planning of the Ningde era, it is expected that cobalt-free batteries will be launched around 2024.
Silicon anode battery
Since the 1990s, the research and development of silicon materials applied to the anode of lithium batteries has emerged. It was not until around 2014 that the industrialization of silicon carbon anode and silicon oxygen anode was realized.
Why use silicon as anode material? This is because the theoretical gram capacity of silicon materials is as high as 4200mAh/g, which is much higher than the 372mAh/g of graphite materials. However, the disadvantages of silicon anode materials are also obvious, that is, its volume expansion rate is 320%, which is much higher than the expansion rate of about 10% of existing graphite materials, which means that its service life is low.
Therefore, in practical applications, silicon anode materials are generally a mixture of graphite and silicon. For example, in 2017, Panasonic applied the silicon-based anode to the tesla Model 3 battery, that is, by adding 5%-10% silicon to the traditional graphite anode material, the battery capacity increased to more than 550mAh/g, and the monomer energy density reached 300Wh/kg.
Ningde Era, Lishen Battery, Guoxuan Hi-Tech, BYD, BAK Power, Micro-Macro Power, etc. are all accelerating the research and development and production of silicon carbon anode system.
On January 8, 2021, Guoxuan Hi-Tech released a soft-packed lithium iron phosphate battery with an energy density of 210Wh/kg, which successfully applied silicon anode material for the first time in the lithium iron phosphate chemical system.
On January 9, 2021, NIO announced at NIO Day that it will deliver a 150kWh battery pack with a single energy density of up to 350Wh/kg in 2022, and also uses a pre-lithium silicon carbon anode.
On January 5, 2022, GAC Aion LX Plus was launched, and its 1000-mile version has a range of 1008km, a battery pack capacity of 144.4kWh, and an energy density of 205Wh/kg. The battery pack applies GAC Group's self-developed sponge silicon anode plate battery technology.
The principle of sponge silicon anode plate battery technology is: let the silicon anode sheet inside the cell become as soft and elastic as a sponge, so that the expansion and contraction of silicon in the process of charging and discharging is limited and buffered, and will not break; let the silicon anode exert the advantage of large capacity, like a sponge to absorb water to store more energy.
Sponge silicon anode chip battery technology is involved in positive and negative electrode materials, binders, cell design, process manufacturing and a series of technology groups, through these technologies, the power battery cell in the case of the same amount of power, the volume can be reduced by 20%, the weight can be reduced by 14%, the battery cell energy density can reach 280Wh / kg.
GAC Aean is planning to invest 336 million yuan to build a self-developed battery cell trial production line, and sponge silicon anode chip battery technology is expected to move towards large-scale mass production.
In addition, the power battery equipped with Zhiji Automobile's first pure electric intelligent car Zhiji L7 is developed by Zhiji Automobile and Ningde Era using "silicon-doped lithium supplementation" technology, and its maximum energy density of the battery cell can reach 300Wh/kg, which can increase the vehicle NEDC endurance to 1000km.
Hybrid lithium metal battery
Innovative in anode materials are also hybrid lithium metal batteries.
On November 4, 2021, lithium metal battery manufacturer SES SolidEnergy Systems announced that it has developed a 107Ah hybrid lithium metal battery with a weight of 0.982 kg and an energy density of 417Wh/kg and 935Wh/L.
SES mixed lithium metal batteries follow the cathode material of lithium-ion batteries, but the negative electrode material is lithium metal, and the electrolyte is a high-concentration lithium salt electrolyte. Hu Qichao, founder and CEO of SES, said that such material improvement can solve the problem of lithium dendrites, "Each charge dendrite is still formed, but before it was a very sharp shape, easy to penetrate the diaphragm leading to a short circuit, now it is a very flat and very dense shape, will not puncture the diaphragm." ”
From the perspective of manufacturing process, about 60% of the manufacturing links of mixed lithium metal batteries produced by SES are exactly the same as those of traditional liquid lithium batteries, and the difference is mainly in the negative electrode and electrolyte part.
Founded in 2012, SES had developed all-solid-state lithium batteries in its early stages, but the progress was not smooth, and then decided to switch the technical route to hybrid lithium metal batteries.
SES has partnered with General Motors and Hyundai Motor to launch automotive-grade lithium metal battery A samples in 2022 and officially start commercial mass production of lithium metal batteries in 2025.
At present, SES is building a power battery super factory in Shanghai Jiading International Automobile City, with a total area of 30,000 square meters, which is scheduled to be completed in 2023, and the production capacity after completion will reach 1GWh.
Semi-solid-state batteries
Compared with liquid lithium-ion batteries, solid-state batteries use solid electrolytes instead of liquid electrolytes and separators, which improve energy density and safety.
However, the technical route of solid-state lithium batteries is not in one step, but from semi-solid to quasi-solid to all-solid, the three stages of liquid electrolyte mass percentage are respective
On December 10, 2021, the first batch of Dongfeng E70 electric vehicles equipped with Ganfeng lithium battery hybrid solid-liquid lithium-ion batteries were successfully commissioned in Xinyu, Jiangxi. This is the first time that a semi-solid-state battery has been installed in a pure electric vehicle in China.
Dongfeng E70 is equipped with the first generation of Ganfeng lithium battery solid-state battery, the hybrid solid-liquid lithium-ion battery adopts oxide electrolyte and flexible solid-state separator, the module adopts aluminum alloy frame + upper and lower high-precision seam laser welding technology, the overall composition rate is more than 86%, and the energy density is about 260Wh/kg.
Guoxuan Hi-Tech has achieved a cruising range of more than 1000km for the semi-solid-state battery of high-end pure electric vehicles in China. At present, its semi-solid-state battery can achieve 610Wh/L, 300Wh/kg and 1000 cycles in terms of performance.
Hive Energy has also made a breakthrough in the research and development of semi-solid-state battery technology, and has developed jelly batteries based on gel electrolyte. It has the characteristics of high electrical conductivity, self-healing, flame retardancy, etc., which can prevent heat diffusion while hardly reducing electrical properties, and increase the heat resistance temperature to 150 °C.
Fu Neng Technology's semi-solid-state batteries have entered the mass production stage in 2021, and it is expected to introduce the second generation in 2023-2025 and the third generation around 2027.
The solid-liquid hybrid battery launched by Weilan New Energy for the automotive field has an energy density of 270Wh/kg, and it is expected that in the second half of 2022, it can provide customers with batch verification.
At present, the general consensus in the industry is that the application of solid-state batteries in electric vehicles will be after 2030, and before that, semi-solid-state batteries will develop rapidly and become mainstream.