In addition, Tesla also has new trends. Reuters reports that Tesla is currently working with Canadian mining company Giga Metals (Giga? Metals) discusses how to develop a large mine and wants to buy a lot of low-carbon nickel metal. According to the data, the mine has measured and shown that the nickel reserves are 2.36 million tons and the cobalt reserves are 65,438+04.10,000 tons. Giga plans to produce 40,000 tons of nickel and 2,000 tons of cobalt every year for 20 years.
So, does Tesla want to spread the eggs in different baskets? Batteries with high endurance and high cost should also be grasped, as should cobalt-free batteries. Although there is still some time before Battery Day, we can also get a glimpse of the contents of this conference according to the relevant news exposed by the media before.
Dry electrode technology+pre-lithiation of negative electrode
In 20 19, Tesla successively acquired Maxwell and Hybal. Maxwell's main business areas involve supercapacitors and dry electrode technology, and Hybal is an expert in battery manufacturing.
Maxwell Company claims that dry electrode technology is expected to increase the energy density of the battery to 500Wh/kg in the future. What is this concept? At present, Tesla models? The energy density of NCA8 1 1 ternary lithium battery on the 3rd battery is 340Wh/kg, which is twice as high as that of lithium iron phosphate battery (only from the point of view of single battery, the whole battery package after using CTP module is not considered). From a technical point of view, there is a high possibility that the energy density will be improved by pre-lithiation of the negative electrode.
What is dry electrode technology?
In the traditional manufacturing of lithium ion anode and cathode, a binder solvent (such as 60% PTFE or NMP solvent) and a conductive agent are mixed into slurry, and then the slurry is coated on copper foil or aluminum foil, and the solvent is evaporated by drying, while the dry electrode directly mixes the powder and presses it on the current collector.
What is pre-petrochemical?
Simply put, it is to prepare some lithium for the battery in advance to supplement some unnecessary lithium lost during the battery reaction.
When the battery is charged and discharged for the first time, the organic electrolyte will undergo redox reaction at the negative electrode of the battery, forming an SEI film. The consumption of lithium ion is irreversible, and the lithium ion that has formed SEI film can only exist in the battery in the form of SEI film, and cannot be converted into lithium ion to contribute to the battery capacity. Pre-lithiation can effectively improve the battery capacity and cycle life.
But can pre-lithiation of all batteries effectively improve the energy density of batteries? Not exactly.
Pre-lithiation can obviously improve the battery with silicon or silicon-based materials as the negative electrode. At present, the irreversible lithium loss of graphite anode widely used is only 5% ~ 10%, which is still in a relatively acceptable range. However, if the anode material with higher capacity is used, the proportion of lithium loss will increase significantly, and the first cycle efficiency of pure silicon anode is only 50%. Combined with the silicon nanowire technology previously released by Tesla, pre-lithium is imperative.
Maxwell's pre-lithiation technology is to mix lithium metal powder with positive and negative active materials and press them into electrodes. Using adhesive and conductive agent instead of solvent, the negative electrode material was mixed with lithium powder and directly combined with the current collector. Combined with Maxwell's dry electrode technology, it is simply the best partner.
Some people may ask, isn't Tesla doped with 10% silicon in the anode material now, and does Tesla currently adopt pre-lithiation technology?
Not yet.
One is because Tesla's current shallow charge and shallow discharge strategy has little effect on the battery, and Model? 3. It also improves the cruising range of the vehicle by increasing the battery capacity; Moreover, due to the complicated operation and high environmental requirements of the current negative electrode lithium supplement technology, it is also intuitively reflected in the high cost, which leads to the industrialization of pre-lithium technology.
It is easy to mention that Maxwell is developing a super capacitor, which can recover the kinetic energy of pure trams. Supercapacitors can be regarded as an emergency storage device, which consumes less energy than recycling power into batteries. In the process of rapid acceleration, the supercapacitor can realize high-power discharge, avoid lithium dendrites generated by direct high-power discharge of the power battery, and prevent irreversible damage to the battery structure.
Silicon nanowires?
As early as a few days ago, when Tesla released the poster of Battery Day, some people saw hidden silicon nanowires in the background of the poster. The theoretical specific capacity of silicon anode material reaches 4200mAh/g, but there is a fatal disadvantage in practical application-serious volume change of silicon will occur during ion deintercalation, which will lead to the destruction of anode structure and the deterioration of battery cycle capacity. However, the charging and discharging process of lithium-ion batteries requires the deintercalation of lithium ions.
Silicon nanowire refers to a silicon material with a width of about 10 nanometer and unlimited longitudinal length. The linear material with this structure can release the pressure caused by volume strain through lateral expansion, and the gaps between silicon nanowires can accommodate volume expansion, preventing the materials from squeezing and breaking each other and affecting the normal work of the battery.
Tesla and Amprius cooperated to develop a new manufacturing process of silicon nanowires: using a template coated with silicon nano-coating, silicon nanowires were directly grown on the base material by cvd process. This method is also suitable for compounding or doping other materials on silicon nanowires to improve their conductivity and strength.
Tesla put silicon nanowires directly on the poster, which shows that silicon nanowires must be of great significance at this battery day conference. Tesla's previously predicted million-mile battery is likely to apply this technology, or this technology will be related to the future development of Tesla batteries.
Cobalt-free/high nickel battery?
The news that Tesla cooperated with Contemporary Amperex Technology Co., Limited is widely known, which further confirms that the achievements of Contemporary Amperex Technology Co., Ltd. in lithium iron phosphate batteries may be used by Tesla. Isn't lithium iron phosphate battery another way of saying cobalt-free battery? But we can't press the table here. After all, Tesla officials also said that cobalt-free is not necessarily lithium ferrous phosphate.
Musk has always been a staunch supporter of cobalt-free batteries. 20 18 he said that in the future, the cobalt content of Tesla's power battery will drop to zero, realizing a truly cobalt-free state. As a scarce metal, cobalt has a small output and uneven distribution, which will increase the cost of batteries. The appearance of cobalt-free batteries is bound to bring earth-shaking changes to today's battery system and new energy industry.
How difficult is it to remove cobalt?
Take NCM battery, which is widely used now, as an example, lithium ion is easy to affect the stability of cathode structure during the deintercalation of cathode materials, and the addition of cobalt can stabilize the layered structure of cathode materials and improve the cycle and rate performance of materials, which is also one of the difficulties in cobalt removal.
Tesla's partner Jeff Dagen's team mainly achieved cobalt reduction through single crystal materials, electrolyte additives and breakthroughs in increasing nickel content, which coincides with Tesla's plan to develop mines mentioned above. The results show that in NCA battery system with high nickel content (Tesla model? (3) The type of battery used, the role of cobalt is not irreplaceable. Adding metals such as aluminum, manganese and magnesium can also play this role to some extent. Therefore, Tesla has a high probability of adopting a new type of high nickel cathode material to realize Musk's cobalt-free dream.
Millions of miles of electricity?
The technical terms of pre-lithiation, dry electrode and nanowire are too far away from us, and the release of million-mile batteries is the highlight.
Since Tesla announced the news of the million-mile battery, it has received widespread attention. Major media have turned out all the patents of Tesla and its partners in recent years, and the above technologies have gradually entered the public eye. In addition to the "single crystal nickel-cobalt-aluminum battery technology", some data show that it is very likely to be installed on new batteries, and whether other technologies are really installed will not be known until the battery day.
But for consumers, all technologies that are not installed are gimmicks. If the million-mile battery can really achieve the previously predicted performance, the total cruising range is expected to exceed 6,543.8+0,000 miles, or about 6,543.8+0.6 million kilometers. After 4000 charge and discharge cycles, the capacity of the new battery is still 90%, and the number of charge and discharge cycles can be increased to more than 6000 in a wide temperature range. Many consumers are expected to do so.
These technologies mentioned above will significantly improve the performance of Tesla batteries, so which technology will Tesla adopt? September 22nd, let's wait and see!
This article comes from car home, the author of the car manufacturer, and does not represent car home's position.