Hello everyone, last time, the video about understanding semiconductors was more popular than I expected. Many people complimented that it helped them understand semiconductor concepts that were difficult before. So, this time, I brought a video about secondary batteries. Before that, I hope you watch the semiconductor video as well. Following semiconductors, I prepared to explain secondary batteries in an easy way. Please hit the like button first, and in today's video, I will try to explain the key points as simply as possible. Now, if you take notes while listening, it would be great. So, please get your notebook and pen ready. Have you got them? Then, let's start right away. Secondary batteries were a hot topic in March, showing a sharp upward trend. As many investors are focusing on secondary battery-related stocks, numerous related articles and securities reports have been pouring out.

When you read articles about secondary batteries, various words like cathode material, anode material, separator, electrolyte, battery cell, and module come up, which can be difficult. I am also a liberal arts major, so naturally, I find these topics challenging, but we still need to study. If we avoid studying just because it's difficult, we won't be able to progress in the future. Understanding the industry that attracts attention in the market and the industry you invest in is essential. I believe it's necessary. I will explain it easily, so let's study together. So, what is a secondary battery? It might be easier to start by talking about primary batteries. Just like we distinguish between conductors and semiconductors when studying semiconductors, there are primary batteries and secondary batteries. Primary batteries cannot be recharged. When you use a primary battery, it only discharges. Disposable batteries can be considered primary batteries. On the other hand, secondary batteries can be recharged. Now, we need to use our smartphones, but the battery is...

Continuous reversal and no charging can be troublesome. In addition, disposable batteries are constantly being discarded, so environmental issues are serious. However, secondary batteries can be recharged, making them environmentally friendly and cost-effective. Therefore, secondary batteries are used in smartphones, electric vehicles, and more. Now, how is the inside of a secondary battery designed to allow for recharging? The image right now is a battery made by Samsung SDI. The exterior looks like a typical battery, but this time, let's take a look inside. Upon examining the interior, we can identify the four components that make up this battery: the positive electrode, negative electrode, separator, and electrolyte. So, in future articles related to secondary batteries, if you come across these four words: positive electrode, negative electrode, separator, and electrolyte, remember that these are the components that make up a secondary battery. Now, let's delve into these four components.

Before we look at each one individually, let's first go over the lithium, which plays a very important role in secondary batteries. There are various types of secondary batteries such as nickel-hydrogen batteries, lead-acid batteries, nickel-cadmium batteries, and many others. Currently, the most widely used type of battery is lithium-ion batteries. Simply put, lithium is inside the battery. Why is lithium the most widely used among many substances? Let me briefly explain the principle of how secondary batteries are charged and discharged. When lithium ions at the cathode move to the anode, it is charging. And when lithium ions at the anode move to the cathode, it is discharging. So, in the process of charging and discharging lithium, it needs to go back and forth. In order to do this back and forth well, what characteristics should it have? It should be light so that it can move easily. Lithium is light, like hydrogen and helium.

Next, the third lightest material is lithium. When compared to other materials, lithium has a large energy capacity and can last a long time. That's why lithium-ion batteries are the most widely used. Do you understand so far? Now, let's delve into the four elements that make up a secondary battery. The first is the cathode material. As I mentioned earlier, lithium is used in batteries, and the space where lithium is placed is the cathode. Among the four components of our battery, the cathode is the most important. That's why it's said that the cathode is the heart of the battery because it has the biggest impact on the battery's capacity and cost. Why is battery capacity important? If you have a choice between a smartphone that can be used for two days on one charge and one that can be used for only one day, of course, you would choose the one that lasts two days.

If it's an electric car, you would choose a car that is fully charged and has a long driving range. Therefore, the electrode plays an important role in determining the capacity and usage time of the battery. When we charge or use the battery, various reactions occur inside the battery. However, lithium alone is somewhat unstable in its reactions. Therefore, materials that can react with lithium are added to the electrode to enhance the battery's reaction. These materials include nickel, aluminum, manganese, cobalt, and iron phosphate. This part can be considered as the reason why it accounts for 40% of the battery's cost because various raw materials are involved, and if the supply of these raw materials becomes unstable, the price can only go up. Do you understand? However, depending on how these materials are composed and the ratio they are combined in, the properties change.

Please listen to this part three times, which may be a bit difficult. When combined with nickel, cobalt, and aluminum, it's called an NCA battery. When combined with nickel, cobalt, and manganese, it's called an NCM battery. When combined with phosphorus and iron, it's called an LFP battery. NCA and NCM batteries are called ternary batteries because they use three substances. LFP is called a binary battery because it uses two substances, phosphorus and iron. The three major domestic battery companies usually use ternary batteries. LG Energy Solution and SK use NCM batteries with nickel, cobalt, and manganese, while Samsung SDI adopts the NCA battery method, using aluminum instead of manganese. Additionally, EcoproBM, which saw a significant increase this year, is the number one domestic producer of cathode materials. Among them, in the NCA battery sector, they hold the second-largest global market share. In contrast, China uses binary batteries.

The cylindrical battery has a slightly lower energy density than the 3D battery, so the driving range is short. However, the advantage is that it is inexpensive and has high stability against fires. Now, the table on the screen compares the LFP, which is a cylindrical battery, and the 3D battery. Please compare them in terms of materials, density, manufacturing cost, risk, and production country. Additionally, as I mentioned, South Korea is in competition with China in the battery industry. China uses cylindrical batteries, while South Korea uses 3D batteries. In 2021, when Tesla announced that they would use cylindrical batteries in Tesla electric vehicles, South Korean domestic companies emphasized the use of 3D batteries. At that time, the stock prices of battery companies dropped. Therefore, currently, domestic companies are responding to the inexpensive cylindrical batteries by focusing on nickel and cobalt, which are a bit expensive.

Lowering the proportion of cobalt and increasing the proportion of relatively inexpensive manganese, we are making efforts to develop lower-cost batteries to compete with lithium-ion batteries. Now that you have a basic understanding of the cathode material, let's move on to the anode material. I mentioned earlier that the space containing lithium is the cathode, but when we plug in the charger, the lithium ions on the cathode move to the anode. As the lithium ions gradually move, the charging process takes place. The anode is responsible for storing these lithium ions well and when we use smartphones or electric cars, it releases the lithium ions, allowing the flow of current. If the cathode material determines the battery capacity, the anode material plays a crucial role in the battery life, accounting for 15% of the battery cost. After 2 to 3 years from when we first purchased a smartphone, we need to recharge it.

Even if you charge it, the battery runs out quickly. What determines how long you can use the battery is the cathode material. Just like there were nickel, cobalt, manganese, etc., in the anode active material, there is also a cathode active material, which is graphite. This graphite plays a role in storing lithium ions. However, recently, silicon has been attracting attention as a next-generation material. Silicon can store about 10 times more lithium ions than graphite, so it is receiving attention as a next-generation material. While it has the advantage of being able to store so many lithium ions, silicon has the disadvantage of expanding. During the process of charging and discharging, silicon expands, which can destroy the internal structure. Therefore, further technological development is needed in this area. Do you understand up to this point? Thirdly, in the past...

It is the electrolyte. Earlier, I mentioned that in the charging and discharging process of lithium-ion, the anode and cathode move back and forth. The electrolyte is what serves as the means of transport for lithium ions. Simply put, it is the medium that helps lithium ions move back and forth between the anode and cathode. During the operation of the battery, this electrolyte must not cause any reactions that could degrade the battery performance. Therefore, it is crucial in determining the battery's performance characteristics and accounts for 10 to 15% of the battery cost. Now, the term electrolyte means that the medium transporting lithium ions is liquid. This electrolyte is sensitive to temperature changes, which can cause the battery to expand and even lead to leakage issues. That's why solid-state batteries have been gaining a lot of attention and rapid development in the battery industry recently. You may have heard of solid-state batteries.

Batteries are relatively safe because they use solid electrolytes instead of liquid electrolytes, so there is naturally no problem with leakage or the risk of heating. Furthermore, since this solid electrolyte also plays the role of a separator membrane, there is no need for a separate separator membrane. Therefore, there is an advantage in being able to increase the capacity by filling the vacant space in the absence of this separator membrane with battery components. That's why many people refer to solid-state batteries as the dream batteries in this way. As it is still in the research and development stage, it has not been commercialized yet. Most companies are expected to commercialize it around the end of 2020 or by 2030. Who will be the first to dominate this solid-state battery technology is expected to be a crucial issue. Lastly, the main component of a battery is the separator membrane, which separates the positive and negative electrodes. When these positive and negative electrodes meet, it can lead to fire or combustion.

Therefore, the separator plays a role in blocking the meeting of the cathode and anode, ensuring the safety of the battery. This separator accounts for 15% of the battery's cost. Some may wonder how lithium ions can move back and forth with a separator present. Well, the separator has very fine holes that only lithium ions can pass through, ensuring safety. A thinner and stronger separator is better as it can hold more material. So, summarizing the four components of a battery very briefly, the cathode determines the battery's capacity, the anode determines the battery's lifespan, the electrolyte determines the battery's performance.

The separator can be said to determine the safety of the battery. I tried to explain it as simply as possible. How do you like it? But this is not the end here. There is a little more to study. Secondary batteries are divided into cylindrical, prismatic, and pouch types according to their shapes. Each shape has its own characteristics. Can you see the picture now? Cylindrical batteries are round-shaped batteries. They are the oldest type of batteries, so the technology has already been verified. They are inexpensive, easy to mass-produce. However, due to the fixed specifications, it is difficult to make them larger or smaller. Therefore, it is a bit challenging to use other products besides standardized products. In other words, the range of usability is limited. Also, since it is cylindrical, it is not very space-efficient, and it has a short lifespan. Panasonic mainly produces cylindrical batteries.

Tesla electric cars use cylindrical batteries. Secondly, they use pouch-type batteries. These batteries are packaged in thin and soft film, which is why they are called pouch-type. By stacking and packaging the battery materials in this way, the energy density is very high. Another advantage is that depending on how the packaging is done, various shapes demanded by electric car companies can be produced. However, there are disadvantages such as complex manufacturing processes, increased costs for custom production, and difficulties in heat management. Pouch-type batteries are manufactured by companies like LG Chem, SK Innovation, and are being installed in electric cars from Hyundai, Kia, GM, Ford, Renault, Volvo, Nissan, and others. Lastly, there are prismatic batteries. These batteries are packaged in aluminum can cases in a rectangular shape. Since they are square, they are more efficient than cylindrical batteries.

The space utilization is high, and because it is an aluminum case, it has good durability, so it can withstand car accidents well. Mass production is also possible. However, it is a bit heavy, difficult to scale up, and does not dissipate heat well. It is produced by Samsung SDI, CATL, BYD, and is installed in electric cars such as BMW, Audi, Volkswagen, Porsche. Now, what do you think, everyone? Earlier, we learned about the four battery components, and then we learned about the different shapes of batteries - cylindrical, pouch, and prismatic - and their characteristics. However, one more thing remains, which is about battery cells, battery modules, and packs. These are common terms when reading articles about secondary batteries. What is a battery cell, and what is a battery module? There is no need to think too hard. Just consider them as units of the battery. Battery cells are grouped together to form a module.

You can think of making this module and bundling several of them into a pack, and in the end, in the case of electric cars, the battery ultimately goes in the form of one pack. Let me call this a pencil for you. Let's say we call one pencil a shaft, and a bundle of 12 pencils a dozen, and put them in a box and deliver them to Daiso in multiple quantities. If you think the same way, in the BMW i3, a total of 96 battery cells are installed. By bundling 12 cells into one module and bundling 8 modules into one pack, they eventually go into the BMW i3 in the form of a pack. Looking at the picture will help you understand better. Battery cells can be seen as the basics of batteries that we just learned, and battery modules are used to protect the battery cells from external shocks, heat, and vibrations. Battery packs contain cooling systems and various protective structures inside.

By installing the system, it will be completed. In the past, battery companies focused on developing batteries themselves, but now there is a certain direction for developing battery cells. So, recently, there is a growing interest in module and pack technologies. Ultimately, in electric cars, the form that is finally installed is in pack form. Therefore, depending on how slim the pack is and how well it protects the battery stably, it can affect the overall design and specifications of electric cars. Yes, we have learned some basic information about secondary batteries. Today's content is quite extensive, but these are essential basics that you must know, so please take notes. It would be much better if you listen to it again for the second time. In the future, through today's video, you will have an amazing experience of reading articles related to secondary batteries smoothly.

I'm scared. Well then, if today's video was helpful, please press the subscribe and like buttons. Then, I will conclude today's video here. Goodbye.

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