Structure of the Secondary Battery

Principles of secondary battery and anode materials

The structure of a secondary battery is composed of an anode, cathode, separator, and electrolyte.

The battery cell is the basic unit of a secondary battery, which contains an anode, cathode, separator, and electrolyte.

The battery cell is sensitive to external impacts, so it is bundled with a certain number of battery cells to protect it from heat, vibration, etc. This is called a battery module.

Then, various control and protection systems, cooling systems, etc. are installed to be mounted on a vehicle. This is called a battery pack. Finally, the battery pack is mounted on the vehicle.

The following picture shows a battery pack that was mounted on the BMW i3. It consists of 8 modules and 96 battery cells.

Battery Cell

Battery Cell is the smallest unit of a secondary battery, which is composed of electrolyte, cathode material, and anode material. It is a single set of anodic and cathodic plates in a single case, immersed in electrolyte and separated from other cells. A single cell of a vehicle battery generates 2 volts.

The cell is responsible for allowing the vehicle to perform its maximum performance. To do this, it must have high capacity per unit volume and a long lifespan. It must also be able to withstand the impact delivered during driving, and have stability enough to withstand low and high temperatures. The basic cell of the battery is responsible for these parts.

Battery Module

Battery Module is a battery assembly that is bundled with a certain number of battery cells to protect them from external impacts, heat, and vibration. It is made up of multiple cells that are connected in series and/or parallel, and are embedded in a mechanical structure It is often referred to as a “battery” in general.

Battery Pack

Battery Pack is a combination of multiple battery cells into one. It serves to protect the battery from physical impacts from the external environment. It is the final form of the battery system that is installed in electric vehicles. It is completed by installing various control and protection systems such as BMS (Battery Management System) and cooling system on the battery module.

Roles of materials, parts and equipment in battery cells, battery modules, and battery packs

The main materials of a battery are the cathode material, anode material, separator, and electrolyte. The cathode material determines the capacity and voltage, while the anode material determines the charging speed and lifespan. The separator is a path for lithium ions to move within the battery, while the electrolyte is an environment (water) for the movement (swimming).

Companies such as EcoPro and L&F, which we are familiar with, are companies that manufacture these battery materials. The reason why these companies’ stocks have risen significantly is because the technology related to the cathode material greatly affects the performance of the battery.

We need a case to hold these materials? The parts companies are usually related to battery pack, cell container and related products. And there are some essential parts (slot die) used in some manufacturing processes. They are relatively unknown compared to the material and equipment companies. Companies such as SiinHeung SEC, Sangsin EDP, GI Technology, etc. are involved. The bag company is not making much money.

To explain the equipment, you need to know the stages of manufacturing the battery. The electrode process, where the materials are combined to make the anode and cathode, the assembly process where the anode/cathode plates are combined with the separator to form a cell, and the activation and post-processing process where the assembled battery is charged and discharged, automated, tested, etc.

The recent hot topic in Korea, P&T, is a company that supplies equipment for the ‘Coating’ process in the manufacturing process. Hana Technology is a company that supplies Assembly line equipment for assembly line.

Cathode

High-Nickel and Ultra-High-Nickel Cathode Materials: Definition and Outlook

Cathode materials are the energy source for lithium-ion batteries, playing a pivotal role in the performance, safety, and cost of batteries. Cathode materials account for approximately 40% of the production cost of electric vehicle batteries and are essential materials that determine key performance factors such as driving range, charging, and discharging.”

Anode

Anode materials are crucial components that determine the charging speed and lifespan of batteries. Currently, graphite is primarily used for this purpose. However, recently, silicon-based cathode materials have gained prominence as a significant material for battery differentiation. It is expected that the market size for silicon-based cathode materials will grow from 4,000 tons in 2021 to 200,000 tons by 2030.

Electrolyte

The battery electrolyte is a material that separates and conducts electricity between the cathode and anode inside the battery. In currently widely used lithium-ion batteries, liquid electrolytes are employed. However, in the future, solid-state batteries with solid electrolytes are also being developed.

Solid-state batteries involve the technology of making the electrolyte a solid material. Currently, this technology is reducing the risk of explosions in lithium-ion batteries and making them smaller in size. Therefore, it is expected to be even more beneficial when applied to electric vehicles.

Separator

The separator is a crucial material related to the safety of batteries. It serves the purpose of preventing the cathode and anode from coming into contact with each other.

Parts of Battery

The battery pack case is a protective casing for the battery pack, serving to shield the battery from external impacts and contamination.

This case does not directly affect the performance or lifespan of the battery but plays a crucial role in ensuring battery safety. Therefore, it is advisable to choose a product with high durability and waterproof features when selecting a battery pack case.

The battery cell case is a casing designed to protect individual battery cells, safeguarding them from external impacts and contamination. The battery cell case also does not directly impact the battery’s performance or lifespan but is vital for ensuring safety.

Typically, battery cells store electricity generated by generators or supplied from external power sources and provide this electricity to other electrical systems. They are housed in cases made of materials such as aluminum. For instance, the case provides an internal space where the battery cells can be accommodated, with the front and rear ends of the case ensuring that the battery cells do not come into contact with each other.

Battery Production Process

Electrode Process

The electrode manufacturing process is a manufacturing process for creating the anode and cathode of a battery. It consists of the following steps:

1. Mixing Process: This process involves mixing the materials that make up the anode and cathode. High-speed mixers are used to blend the materials.
2. Coating Process: The intermediate materials produced in the mixing process, known as anode and cathode slurries, are thinly coated onto aluminum foil and copper foil, respectively, using a coating machine.
3. Roll Pressing Process: Once the coating and drying are completed, the electrodes are passed through a roll pressing process between two large rollers. Flattening the electrodes increases energy density.
4. Slitting and Notching Process: The flattened electrodes, produced through the roll pressing process, are cut vertically into various sizes in the slitting process. Subsequently, the notching process horizontally trims the electrodes, creating V-shaped grooves and tabs for the anode (+) and cathode (-). With this, all the steps in the electrode manufacturing process are completed.

Assembly Process

The assembly process is the manufacturing step in which materials such as the anode, cathode, separator, and electrolyte are brought together to form the battery’s physical structure. The sequence of the assembly process is as follows:

1. Once all electrode processes are completed and any residual moisture on the anode and cathode is removed, the assembly process begins.
2. Along with the battery materials composed of the anode, cathode, separator, and electrolyte, a pouch case or cylindrical case is required depending on the battery’s form.
3. The manufacturing sequence and techniques vary based on the battery’s form.
4. In the assembly process, equipment such as ‘notching equipment’ is used to cut the electrode material (sheets) into specific sizes. Additionally, equipment like ‘stacking equipment’ is used to stack the cut electrodes on top of each other.

Activation Process

Activation and Post-Processing are the final steps in battery manufacturing. These steps are crucial for making the battery capable of performing its role in charge and discharge. During this process, a small amount of electricity is supplied to enable the materials that make up the anode and cathode to begin generating electrical activity. Subsequently, after undergoing performance and lifespan tests using inspection equipment, the batteries are shipped. In the case of large-scale batteries used in electric vehicles, they undergo comprehensive testing before supplying them to manufacturers either at the cell level or as modules or packs. Additionally, some companies may choose to outsource production through OEM companies rather than manufacturing directly.

Vision of Battery equipments stock

The electric vehicle market is still in its early stages. Just by looking at the vehicles on the road, it’s clear that internal combustion engines are still more prevalent. However, if construction machinery (such as dump trucks and cranes) and various equipment also transition to electric power, the demand will increase even more. To manufacture these secondary batteries, factories are needed. To build these factories, the performance of equipment-related companies can only improve.

Furthermore, South Korean companies are expanding their business beyond the domestic market to the United States and Europe. They are constructing factories, and this expansion requires equipment. Therefore, the outlook for equipment companies in the next 2 to 3 years looks promising.