[battery complete conquest](30) Will LG Energy Solution Release Dry Electrode Technology Before Tesla?

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At the beginning of this month, there was a notable conference at 'Inter Battery 2024' held at COEX in Gangnam, Seoul. It was a presentation on dry electrode technology by the Fraunhofer Institute for Material and Beam Technology (IWS) in Germany. Despite little promotion, the lecture hall was packed to the point where seats were insufficient.

This has been a consistent trend in recent presentations and lectures on dry electrode technology. Dry electrodes have become a popular topic as a key trend in next-generation batteries.

Interest in dry electrodes increased after Tesla announced at Battery Day in September 2020 that it would introduce this technology in its 4680 cylindrical batteries. Four years have passed since then, but Tesla has yet to complete the dry electrode technology. This indicates how challenging the technology is.

LG Energy Solution, which announced mass production of cylindrical 4680 batteries starting August this year, will also initially produce them using the conventional wet electrode process rather than dry. Other companies producing 46mm diameter cylindrical batteries have also not yet developed dry electrodes at a commercial level.

Dry electrodes are evaluated as an environmentally friendly technology that can increase battery productivity and expand energy capacity. They are expected to be applicable to thick electrodes and solid-state batteries, making them a versatile solution.

In the battery materials sector, the technological capabilities among leading companies are becoming more leveled. Chinese CATL is rapidly catching up with Korean battery companies in ternary battery technologies such as NCM (Nickel, Cobalt, Manganese), which were once considered Korean strengths.

Experts suggest that Korean companies need to make another leap forward through process innovations like dry electrodes. If Korean companies complete dry electrode technology before Tesla, they could outpace competitors and firmly establish leadership in the global battery market.

Why Are Dry Electrodes Considered Versatile?

Until now, battery cathodes and anodes have been manufactured using wet processes. Active materials for cathodes or anodes are mixed with conductive agents and binders along with solvents in a mixer to create a viscous slurry. This is called the mixing process.

Then, the slurry is thinly coated onto the current collector (aluminum for cathodes, copper for anodes). The coated electrodes pass through a drying oven with a hot air blower, where the solvent evaporates and the coating hardens. This is called the drying process. The dried electrodes are then pressed together using a press machine.

While all processes are important, the drying process consumes the most cost and space. Typically, coating and drying equipment are connected, with lengths ranging from tens to 100 meters.

Moreover, in the wet process, the solvent NMP (N-Methyl-2-Pyrrolidone) is used for cathodes. NMP is expensive and toxic, so battery cell manufacturers operate NMP recovery systems. The height of NMP recovery facilities can reach 20 to 30 meters, comparable to high-rise apartments.

Dry electrode technology eliminates this drying process by directly coating a powder mixture of active material, conductive agent, and binder onto the current collector. Since the drying step is omitted, the manufacturing process is simplified, and equipment investment costs are significantly reduced. Without bulky drying equipment, more batteries can be produced in the same space.

Battery manufacturing processes often become a recurring topic whenever the environmental friendliness of electric vehicles is debated. While electric vehicles themselves emit no greenhouse gases, they have been criticized for carbon emissions and environmental damage during manufacturing. Batteries, which account for about 40% of the manufacturing cost of electric vehicles, are a prime example.

In particular, drying and recovering NMP during battery manufacturing consumes significant electrical energy, contributing to greenhouse gas emissions. Research shows that solvent drying in wet manufacturing produces 42 kg of CO2 per 1 kWh. It also emits volatile organic compounds (VOC), which are environmental pollutants.

In contrast, dry electrodes do not require solvent drying and recovery, resulting in lower electricity consumption and no VOC emissions, making the process environmentally friendly.

The wet process also limits battery performance improvements. To increase energy density, thicker electrodes are preferable, known as thick electrodes.

In the wet process, it is difficult to produce thick electrodes due to layer separation between the solvent and materials. Since the densities of active materials, conductive agents, and binders differ, coating thick layers causes binders and conductive agents to float to the electrode surface. Typically, coating electrodes thicker than about 100 micrometers (μm) is challenging in wet processes.

Using dry processes, uniform dispersion of active materials, conductive agents, and binders is possible without layer separation, enabling thick electrodes and thus increasing battery capacity and energy density.

Tesla Also Incomplete, "Dry Electrode Applied Only to Anode in 4680"

Tesla acquired Maxwell Technologies, a supercapacitor company with dry electrode technology, in 2019. The following year, at Battery Day in September 2020, Tesla announced plans to introduce dry electrodes. Although Tesla sold Maxwell to UCAP in 2021, it secured the dry electrode technology.

Tesla planned to apply dry electrodes to its 4680 cylindrical batteries but seems to have encountered setbacks. Tesla produces 4680 batteries at its Gigafactory in Austin, Texas, which are installed in the Cybertruck. Experts who obtained and analyzed Tesla's 4680 batteries found that dry electrodes were applied only to the anode, while the cathode used conventional wet electrodes.

It is unknown why Tesla has not yet applied dry electrode processes to the cathode. However, it is speculated that the yield (good product rate) of the dry electrode process is low and not yet suitable for mass production. Foreign media have reported that the low yield of 4680 batteries is affecting Cybertruck production.

Although the principle of dry coating is simple, there are significant challenges at each step. Uniformly mixing active materials, conductive agents, and binders without solvents is difficult. Even more challenging is evenly applying non-viscous powder onto the current collector.

Low yield increases production costs. Introducing dry electrodes to reduce costs could ironically become a factor that raises costs.

Tesla's 4680 battery performance is also reportedly below expectations. German automotive consulting firm P3 Group compared Tesla's 4680 battery with dry anode electrodes to China's Gotion High-Tech 4695 battery with wet electrodes. Tesla's product showed lower energy density.

The Chinese 4695 battery's gravimetric energy density was 281 Wh/kg, while Tesla's 4680 was 227 Wh/kg. This contradicts the conventional idea that dry electrodes increase capacity and energy density.

According to P3 Group's analysis, Tesla's 4680 battery anode thickness was 1.5 times thicker than the Chinese product. However, Tesla used pure graphite without silicon in the anode, resulting in lower energy capacity.

Additionally, a large amount of fluorine was detected in the anode, presumed to be due to the use of PTFE (Polytetrafluoroethylene) binder. Increasing PTFE binder content for the dry process reduces the proportion of active materials, lowering capacity. (Refer to Complete Battery Mastery Episode 29 for PTFE binder details.)

Except for Tesla, all currently announced 46mm cylindrical batteries domestically and internationally are produced using wet processes. LG Energy Solution's 4680 batteries, scheduled for mass production in August, apply wet processes to both cathode and anode. These batteries are reportedly supplied to Tesla. Samsung SDI and Kumyang's 46mm batteries are also made using wet electrode processes.

Which Company Leads in Dry Electrode Technology?

Since dry electrode technology is not yet mature, there is no standardized process. The well-known dry electrode manufacturing technologies include the Maxwell method, Fraunhofer IWS method (direct calendering), and electrostatic spray method, classified by coating technique.

The Maxwell method is the most well-known and technologically mature. First, active materials, conductive agents, and PTFE binder are mixed. This powder is fed into roll-to-roll equipment, where PTFE fibers form a thin film. This film is then roll-coated onto the current collector.

The Maxwell method is also called the free-standing method because the active material film is separately produced. This method requires high expertise as the film can easily tear or stretch. Maxwell and Tesla reportedly hold extensive patents on this technology.

Fraunhofer IWS uses a direct calendering method. The dry electrode is produced in a calender and immediately coated onto the current collector via roll-to-roll equipment. Fraunhofer IWS claims that using their equipment can reduce the length of coating and drying equipment from 100 meters to under 10 meters.

The Fraunhofer IWS method allows fast production by coating electrodes immediately after production but, like the Maxwell method, has the drawback of low mechanical strength. Fraunhofer IWS developed the direct calendering technology with Saueressig, a German equipment company that also supplies battery cell equipment to Tesla, suggesting Tesla might adopt the direct calendering method for dry electrodes.

Dry electrode technology of Fraunhofer IWS. Image source=Fraunhofer IWS

A recently notable technology is the electrostatic spray method. This uses electrostatic principles to spray electrode powder onto the current collector, followed by pressing.

American venture company AM Battery is adopting the electrostatic spray method. In December last year, the company raised $30 million in Series B funding from Toyota Ventures, Porsche Ventures, Asahi Kasei, and others. The total accumulated investment has reached $60 million.

The electrostatic spray method has the advantage of uniformly coating large-area current collectors but suffers from slow production speed. To spray, binder content must be increased, which reduces active material content, lowering capacity and energy density?issues that need resolution.

Schematic diagram of the dry process of AM battery. Image source=AM battery

Additionally, in June 2023, Germany's Volkswagen announced it would develop dry electrode processes with German printing equipment specialist Koenig & Bauer. Volkswagen plans to start industrial production by 2027. Details of their dry electrode development remain undisclosed.

Domestically, LG Energy Solution is considered the most advanced company in dry electrode technology. Before Tesla acquired Maxwell Technologies, LG Energy Solution was already jointly researching dry electrodes with Maxwell.

LG Energy Solution is researching dry electrode processes at its technology research institute in Daejeon. It is also reportedly planning to establish a pilot line for dry electrode production in the new OC10 building at the Energy Plant 2 in Ochang, Chungbuk.

LG Energy Solution's Chief Technology Officer (CTO) Kim Jeyoung is explaining dry electrodes during the keynote speech at InterBattery 2024. Photo by Kang Heejong

LG Energy Solution is understood to be close to mass-producing dry electrodes. Industry insiders predict LG Energy Solution may mass-produce cathode electrodes before Tesla. CTO Kim Jae-young stated at Inter Battery 2024 that "pilot development for various cathode materials is nearly complete and at a quasi-mass production level."

The Korea Institute of Energy Research is developing dry electrodes through the National Science and Technology Research Council's (NST) project titled 'Development of Material/Process Innovation Convergence Solutions for Carbon-Neutral High-Energy Density Batteries.' The project aims to develop CNT dry conductive agents, solvent-free dispersible binders, and new high-capacity silicon-based composite active materials optimized for dry processes.

Public institutions such as the Korea Electrotechnology Research Institute, Korea Institute of Materials Science, and Korea Institute of Science and Technology, along with private companies including Samsung SDI, Hanwha Momentum, and Chunbo, are participating in this project. The Korea Institute of Energy Research appears to have made significant progress. Dr. Kim Jin-soo, who oversees the research, said, "We plan to complete the project by August 2026 and have filed various patents based on the research results."

Korea Institute of Energy Research, Dry Electrode Technologies for Carbon-Neutralized High-Energy Density Batteries, 2023.3.7