PUBLISHER: SNE Research | PRODUCT CODE: 1565778
PUBLISHER: SNE Research | PRODUCT CODE: 1565778
Electric vehicles themselves do not emit greenhouse gases, but the manufacturing process of electric vehicles has been criticized for emitting carbon and destroying the environment. A representative example is the battery, which accounts for about 40% of the manufacturing cost of electric vehicles.
During the battery manufacturing process, a considerable amount of electric energy is consumed, especially in drying and recovering NMP, which is a cause of greenhouse gas emissions. According to one research result, 42 kg of CO2 is generated per kWh due to solvent drying in the wet manufacturing process, and volatile organic compounds (VOCs), which are environmental pollutants, are also emitted into the atmosphere. In contrast, dry electrodes do not have a solvent drying and recovery process, so they consume less electric energy and do not emit VOCs, making them an environmentally friendly process.
In order to increase energy density, a thick film electrode of >100 micrometer or more is required. In the current wet process, it is difficult to make a thick film electrode due to the layer separation phenomenon between the solvent and the material. Since the specific gravity of each material such as the active material, conductive material, and binder is different, if the coating is thick, the binder and conductive material float to the electrode surface. In the wet process, it is difficult to coat the electrode with a thickness of about 100 micrometer or more.
By using a dry process, the active material-conductive material-binder can be evenly distributed without this layer separation phenomenon, so a thick-film electrode can be created, which can increase the capacity and energy density of the battery.
In 2019, Tesla acquired Maxwell Technologies, a supercapacitor company with dry electrode technology, and announced at Battery Day in September 2020 that it would introduce dry electrodes. Tesla sold Maxwell to UCAP in 2021, two years later, but was able to secure dry electrode technology. According to experts who directly obtained and analyzed the Tesla 4680 battery, the battery applied a dry electrode only to the anode, and the existing wet electrode was adopted for the cathode.
It is not known why Tesla has not yet applied the dry electrode process to the cathode, but there is analysis that the yield of the dry electrode process is low and cannot be mass-produced. There are also foreign media reports that the low yield of the 4680 battery is affecting the production of the Cybertruck.
The principle of the dry coating process is simple, but there are considerable challenges at each stage in implementing it in practice. It is not easy to evenly mix the active material, conductive material, and binder without using a solvent. It is even more difficult to evenly apply the non-viscous powder to the current collector. If the yield is low, the production cost increases. Dry electrodes were introduced to reduce costs, but they can actually act as a cost increase factor.
In addition to Tesla, domestic and foreign companies are currently announcing that they are developing a P/P scale dry process, but it is expected that all 46-phi cylindrical batteries to be initially produced will be produced using a wet process. The 4680 battery that LGES will produce in the fourth quarter of 2024 on a P/P scale will apply a wet process to both cathode and anode, and this battery will be supplied to Tesla. Recently, LGES announced that it will complete the construction of a dry electrode process P/P line in the Ochang Energy Plant in the fourth quarter of 2024 and will apply it starting in 2028. Samsung SDI, SK On, Panasonic, CATL, and Kumyang, which recently announced that they are also developing dry electrode technology.
In addition, Volkswagen of Germany announced in June 2023 that it was developing a dry electrode process with Koenig & Bauer, a German printing equipment specialist. Volkswagen plans to start industrial production by 2027. It is not known exactly how Volkswagen and Koenig & Bauer are developing the dry electrode.
The dry process can reduce energy costs by 30% because the drying process is unnecessary, and the area required for drying can be reduced by 50%. The 4680 battery using the dry process can theoretically be cheaper than the LFP battery, but the technology development has not been successful yet.
The introduction of the dry process has great potential as a carbon-neutral process for manufacturing lithium secondary batteries, and the commercialization of dry electrode technology is expected to greatly contribute to reducing battery manufacturing costs while improving performance. Although no company has succeeded in mass production so far, it is very likely that the dry electrode process will become a trend in the near future as major companies are spurring technology development. In addition, the development of the dry electrode process can be applied to the manufacturing process of all-solid-state batteries, which are next-generation batteries. In fact, interest in all-solid-state batteries is increasing both domestically and internationally, and plans for mass production are being established.
This report provides technical information such as the necessity of developing a carbon-neutral process in the secondary battery industry, issues with the existing wet process, and issues with the current dry process, as well as information on recent development trends in dry electrode processes and all-solid-state battery development by many companies, with the aim of forecasting the current and near-future status of the dry process.
Advantages | Super caps | compact | ||
Challenges | Risk of segregation | Risk of segregation | Risk of segregation | mixing |
Key players | Tesla(Maxwell Technologies | Technical Univ. Dresden Fraunhofer IWS | Technical Univ. Dresden Fraunhofer ISIT | Technical Univ. Braunschweig Fraunhofer IPA |
TRL | 6 | 5 | 4->6 | 4->6 |
References | US Patent US2006/0133012A1 10/817 590. Apr. 1. 2008. | Germany Patent DE102017208220A1. Nov. 22. 2018. | Proc. Fraunhofer ISIT - Achievements Results Annu. Rep., 2017.pp.32-33 | Energy Technol., vol. 8, no. 2. 2020. Art. no. 1900309 |