However, because of cobalt, the application of ternary lithium batteries in electric vehicles has encountered obstacles. For this lithium battery "hero", the battery industry is constantly trying to make it "go away, remain anonymous". There has finally been a breakthrough recently.
On September 28th, during the Beijing International Auto Show, Honeycomb Energy released a product planning meeting for cobalt-free batteries. The company announced that it will mass-produce cobalt-free batteries in June 20021year. This means that human beings have got rid of the limitation of cobalt in the technical route of high specific energy material batteries.
In this way, the high-specific energy power battery will have more room for cost reduction, and at the same time, it can continue to improve the energy density, thus promoting electric vehicles with longer battery life and more economy to enter the homes of ordinary people.
The appearance and departure of cobalt is a meaningful chapter in the history of human struggle to conquer lithium batteries.
Cobalt as a lithium battery?
Open the periodic table of elements, the top on the left is hydrogen, and then lithium.
This position of lithium in elements is related to its characteristics.
What is the atomic weight of lithium? 6.94 is the lightest of all metals. What is the standard electrode potential of lithium? -3.045v； The lowest of metals; In addition, the specific capacity of lithium is also the highest among metals, while the electrochemical equivalent of lithium is the smallest. The above four characteristics make lithium have the inherent advantage of becoming a high energy density energy storage element.
In the middle and late 20th century, lithium metal began to be used as the negative electrode of batteries. However, the attempt to directly use metallic lithium as a negative electrode in large-scale application is a fiasco due to problems such as lithium dendrites generated during charging.
Schematic diagram of dendrite penetrating diaphragm to produce short circuit and then striking fire.
The development of lithium batteries needs subversive solutions. Chemists have been trying to find a way to use a compound containing lithium ions as the positive electrode instead of lithium metal as the negative electrode, which can not only have enough electricity, but also maintain the stability of the material structure during charging and discharging.
What compound is it?
20 19 John, winner of the nobel prize in chemistry? B? Goodnow made a decisive discovery: Cobalt-containing materials are the best and the most stable.
This material is lithium cobalt oxide. It has maximum true density (5. 1g/cm3) and compaction density (about 4.3? G/cm3), which makes it unique in the field of batteries with strict requirements on battery size.
1980, he announced this brand-new high energy density anode (cathode) material-lithium cobaltate.
Oxford University erected a plaque outside Goodenough's laboratory to commemorate the discovery of lithium cobalt oxide as the positive electrode of rechargeable battery. Source: Wikipedia.
On the other side of the ocean, Japanese chemist akira Yoshino (two winners of the 20 19 Nobel Prize in Chemistry) completed the last puzzle of lithium cobaltate battery: a lithium-ion battery was constructed with polyacetylene (later converted into carbon) as anode (negative electrode). This design completely removes lithium metal and improves the safety of the battery. This technical paradigm establishes the basic concept of lithium-ion battery.
199 1 year, Sony commercialized it. Since then, lithium cobalt oxide batteries have been widely used.
Cobalt: unbearable weight
If lithium cobaltate batteries are only used in consumer electronic products, about cobalt can always exist in lithium-ion batteries. Because the consumption of consumer electronic batteries is relatively small, the sensitivity to cost is far less than that of automobiles.
However, after Tesla successfully applied lithium cobaltate batteries to pure electric vehicles, the problem of cobalt was magnified.
Resources are scarce and expensive, and its overcharge safety performance is poor.
The cobalt content in lithium cobaltate is about 60.2%.
That is to say, in 1 ton lithium cobaltate, the content of lithium is only 0.07 ton, but the content of cobalt should reach 0.6 1 ton, which is more than 8 times that of lithium. The content of cobalt in the earth's crust is only one sixth of that of lithium, and the cobalt ore mined every year is only half of that of lithium ore.
60% of the global cobalt production comes from the unstable Congo (Gold). In 20 16 and 20 17, the national production of cobalt was 66,000 tons and 64,000 tons respectively. China, which ranks second in output, only produces 7,700 tons in 20 16.
Cobalt ore
Low output means easy manipulation, and prices fluctuate greatly.
In 20 17, the price of cobalt on the London metal exchange rose to $75,000 per ton, with an annual increase of over 130%. On February 2, 20 18, the price of cobalt broke through the integer mark of $80,000, and reached a new high of $95,000 per ton on March 2 1 day.
In addition, cobalt mining also involves child labor and artisanal mining.
The breakthrough of lithium cobalt oxide cathode material has once again raised the industry's greater expectations for lithium-ion batteries, and scientists are still looking for better cathode materials to further improve the performance of the batteries. However, their attempts never got rid of cobalt.
1997 -2000, enterprises in Japan and the United States successively invented ternary materials of nickel, cobalt, aluminum or nickel, cobalt and manganese, which challenged lithium cobaltate as cathode material.
But the real commercialization of ternary materials is Jeff Dagen (? Jeff. Dahn, the one who cooperated with Tesla today). 200 1 Jeff Dagen, a professor of physics at Dalhousie University in Canada and the chief scientist of 3M Group Canada, invented a ternary composite cathode material of nickel, cobalt and manganese, which can be commercialized on a large scale, and broke through the last step to the market.
Although Goodenough's team and other chemists have also given the technical routes of materials such as lithium ferrous phosphate, lithium manganate and lithium titanate, among the technical routes of high specific energy batteries, ternary batteries containing cobalt are the absolute mainstream.
At present, ternary materials have become the main technical route in the field of electric vehicles, and the trend of high nickel and low cobalt has become very obvious. Under the four proportions of111/523/622/811,the cobalt content of Ni-Co-Mn ternary materials decreased to 2 1.3% and/kloc-0 respectively.
Can we go further and completely remove cobalt?
Break up with cobalt
Panasonic and Tesla took the lead in issuing the "cobalt-free" declaration.
In 20 18, Panasonic announced that it was developing cobalt-free batteries for electric vehicles.
Tesla, which has been using Panasonic batteries, its CEO Musk also said that in Tesla Model? 3. The cobalt content has dropped below 3%. They will continue to improve their technology and strive to completely give up cobalt in the next generation of batteries.
Contemporary Ampere Technology Co., Ltd. also said that it has reserved cobalt-free battery technology.
In order to realize cobalt-free, three problems must be solved, one is the mixed discharge of Li/Ni, the other is the poor cycle performance; Thirdly, the electrolyte is oxidized and decomposed under the high pressure platform. Enterprises that fail to commercialize cobalt-free batteries are basically subject to this.
However, these enterprises were robbed by a new battery force.
Honeycomb Energy, which was born out of Great Wall Motor, was the first to release cobalt-free batteries on 20 19. They made a nickel-manganese battery by adding manganese on the basis of lithium nickelate.
Source: Honeycomb Energy
Honeycomb mainly solves the above problems through three technologies, namely cation doping technology, single crystal technology and nano-network coating technology.
The so-called cation doping technology refers to doping cations with high chemical bond energy with oxygen in the crystal structure to increase the upper limit voltage of the material. Yang Hongxin, president of Honeycomb Energy Company, explained that they used two elements with stronger chemical bonds instead of cobalt and doped them into the material. Through intensive study, a stable oxygen octahedral structure can be constructed, the mixed discharge of Li/Ni can be reduced, and the stability of the material can be greatly improved. It can work stably at a voltage of 4.3-4.35 V, and the energy density is 40% higher than that of lithium iron phosphate.
The second key technology is single crystal technology. The battery needs to go through a key process-high-strength rolling in the process of pole piece production. This is to add more active substances in the limited space, so it is necessary to pursue higher compaction density.
At present, many battery enterprises use polycrystalline materials. The polycrystalline material particles are obviously broken during the rolling process, which will directly lead to the reaction between the positive electrode and the electrolyte to produce a large amount of gas, which will lead to the accelerated decay of the battery life and lead to safety problems. At the same time, the structure of the material will also collapse, and lithium ions cannot move, resulting in a rapid decline in life.
Single crystal material has stronger particle strength and more stable structure, and its compressive strength can be increased by 10 times compared with polycrystalline material, which can effectively improve the energy density of the battery. At the same time, the single crystal material is not easy to collapse, and the battery life is 70% higher than that of polycrystalline high nickel ternary battery.
The third black technology-nano-networked coating technology. In the process of synthesizing cobalt-free materials, the honeycomb energy adopts nano-network coating technology, and a layer of nano-oxide is coated on the surface of single crystal, which can reduce the side reaction between cathode materials and electrolyte, and this technology effectively improves the cycling performance of materials at high voltage.
Honeycomb 2 has no cobalt electricity?
According to the plan of Honeycomb, its first cobalt-free product is based on 590 modules, with a capacity of 1 15Ah and an energy density of 245wh/kg. It can be carried on most new pure-level platforms and will be launched in June next year. L6 thin plate has a long battery cell without cobalt, with a capacity of 226Ah. matrix pack can achieve a driving range of 880 km, and mass production will be realized in the second half of 202/kloc-0.
During the Beijing Auto Show, Honeycomb Energy further elaborated the planning of its cobalt-free products.
According to Yang Hongxin, the cobalt-free batteries in the honeycomb are divided into E platform and H platform. At present, * * * plans to launch four products, namely VDA with a capacity of 90Ah? 1.5x (size is 39x 148x 102.5mm) cobalt-free battery with capacity of 1 15Ah? VDA？ 2x (size 52x148x112mm) MEB with cobalt-free battery, capacity 1 15Ah? 1.5x (size: 33.4x220x 102.5mm) cobalt-free battery and L6 (size: 21.5x574x18mm) cobalt-free battery with a capacity of 226Ah.
Source: Honeycomb Energy
The cobalt-free batteries produced by platform E and platform H have different materials and processes. Among them, the battery materials of E platform mainly adopt high concentration cation doping, nano-network coating, micron particle size control and lithium intercalation path optimization. The annual production capacity of 202 1 will reach 160mAh/g, and will increase to 170 mAh/g in 2023. The battery materials of H platform mainly adopt nano-network coating technology, single crystal technology and cation-doped oxygen octahedron structure. In 2020, the capacity will reach 1.80 mAh/g, and in 2022, it will increase to1.85 mah/g.
Cobalt-free batteries produced by Honeycomb Energy H platform and E platform correspond to different vehicle positioning markets, covering all vehicles from 300 to 800 kilometers, which can realize the full scene application of A00-D vehicles and support the lifetime warranty of all categories.
At present, the cobalt-free battery of Honeycomb Energy has been loaded and tested. Soon, cobalt-free batteries will be put into mass-produced electric vehicles. The high specific energy power battery finally realized cobalt-free.
Significance of cobalt-free
The Goodenough team has introduced cobalt into lithium batteries for 40 years.
Today, 40 years later, the wave of popularization of electric vehicles led by China has spread to Europe, and there is a trend of further spread to the whole world.
However, there are at least two obstacles to overcome in the popularization of electric vehicles and traditional fuel vehicles. One is the real endurance, that is, considering the endurance of scenes such as winter, hot air conditioning and high speed, it needs to continue to improve, and the other is that the cost needs to continue to decline.
The former, under the background that the electric drive efficiency cannot be greatly improved in a short time, needs to be realized by loading more batteries, but it cannot increase the self-weight of too many batteries, that is to say, the power battery needs to continue to increase the energy density, so that the existing models can be loaded with more batteries to obtain longer battery life. The direction of high specific energy explored by ternary batteries must be adhered to.
The latter, in the context of mass production, the cost of power batteries is infinitely close to the material cost. Only by removing cobalt, the most expensive material, can the cost of power battery be reduced sufficiently.
The solution of cobalt-free battery has found an excellent balance between the performance of lithium-ion battery and cost reduction, which has removed a stumbling block for the development of electric vehicles.
China originally played a leading role in the popularization of electric vehicles. The earliest commercialization of cobalt-free batteries also helps China to maintain the leading edge of electric vehicles.
Looking ahead, the history of cobalt-free batteries may be more exciting than its predecessors-lithium cobaltate and nickel-cobalt-manganese batteries.
This article comes from car home, the author of the car manufacturer, and does not represent car home's position.