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Status and Development of Power Lithium-Ion Battery and Its Key Materials

1.1 Market Status of Power Lithium-Ion Battery

Lithium-ion batteries (LIBs) were invented by Sony in 1990 and brought to the market for commercialization in 1991, which kicked off the rapid development of LIBs. Initially (before 2000), most of the world's lithium batteries were produced in Japan [1-3]. However, by the year of 1997, South Korea's lithium secondary battery market began to rise, and it once surpassed Japan in the field of portable mobile electronics. In 1996, China Electronics Technology Group successfully developed 18650 batteries that can be mass-produced, marking the start of China's lithium batteries industry. At present, as an advanced energy storage technology, power LIBs have been widely used in new energy electric vehicles, providing critical support for the current greenhouse gas emission reduction.

According to the International Energy Agency (IEA), there was 16.5?million electric vehicles in the world by the end of 2021. The electric car registrations and sales share in major countries and regions in the world from 2016 to 2021 were shown in Figure 1.1. It is estimated that the total number of electric vehicles in the world will reach about 200?million by 2030, accounting for 20% of the total number of vehicles worldwide. The booming development of electric vehicles will lead to an exponential increase in the demand for power LIBs.

According to SNE Research data, the global installed capacity of power LIBs will be approximately 296.8?GWh in 2021 with a yearly increase of 115%. In view of the huge market prospects of the lithium-ion power battery industry [4], the relevant companies from different countries have deployed the power battery industry development plans. Among the world's top 10 battery companies (Figure 1.2), five of them are from China, namely Contemporary Amperex Technology Co., Ltd. (CATL), Build Your Dreams (BYD), China Aviation Lithium Battery (CALB), Guoxuan High-tech (GOTION), and Envision AESC with a total market share of 47.6%; LG Chem (LGC), Samsung SDI, and SKI, located in Korea, have a total market share of 30.4%; and Panasonic's (Japan) global market share is 12.2%.

Based on the ground of national level, the current lithium-ion power battery industry has basically developed into "three-legged (China, Japan, and South Korea) stand-up" pattern, and each of them has a leading enterprise in the industry. The Chinese company CATL has become not only the leader of China's lithium battery industry but also the world's largest supplier of power LIBs since 2017 [5] and was the first company to realize the mass production of NCM811 square batteries, which were successfully selected by GAC and BMW. From the technical route point of view, CATL also successfully realized the transition from NCM523 to NCM811. For South Korea's companies, LGC began to study lithium batteries in 1996 [6], and in 2020, it became the sole supplier of GM Chevrolet Volt electric vehicles. LGC's advantage is its advanced theoretical technology on soft pack batteries. It is also the first company in the world to be proficient in laminated-stacked soft packs. However, in the application of NCM811, it is behind the CATL. The Japanese company Panasonic began to develop the lithium batteries as early as 1994 and was supported by the Sumitomo Consortium. In 2008, it began to cooperate with Tesla, the world's largest electric vehicle company and built a super battery factory in 2014. Panasonic is the first company worldwide to realize the mass production of NCA18650?+?silicon carbon anode cylindrical batteries, and it is also in a leading position in terms of the electrochemical system, production yield, and consistency.

Figure 1.1 Registration volume and market share of electric cars in major countries and regions in the world, 2016-2021.

Source: IEA.

Figure 1.2 Top 10 global lithium-ion power battery companies and their installed capacity.

Table 1.1 The main material production capacity of the world's major producers of lithium batteries.

Source: Data from Eddy et al. [7].

In addition, China has already set up a strong leading position in the manufacturing of key materials for power LIBs (Table 1.1). According to the report "The metal mining constraints on the electric mobility horizon," China's production capacity in cathode materials, anode materials, electrolytes, and separators is 42%, 65%, 65%, and 43% of the world's total production capacity, respectively, far ahead of other countries and regions. Japan, by contrast, has a minor advantage in manufacturing cathode materials, whereas South Korea has an advantage in manufacturing diaphragms. In addition, other countries and regions such as the United States and the European Union have a relatively small market share in the production and manufacturing of materials for powered lithium batteries. The report shows that the market space for battery production and manufacturing in Western countries still has the great potential.

1.2 Key Materials and Development of Power Battery

Power LIBs are mainly composed of cathode materials, anode materials, separators, electrolyte binders, and current collectors. The cathode materials account for more than 40% of the total cost of lithium batteries, whose properties directly affect a variety of performance indicators of lithium batteries. Therefore, the cathode materials take a core position in lithium batteries industry [7, 8]. Currently, commercialized cathode materials for lithium batteries include lithium cobalt oxide (LCO), lithium manganese oxide (LMO), lithium iron phosphate (LFP), and ternary materials. The proportion of LFP and ternary materials is as high as 90% in all the cathode materials.

1.2.1 Dominant Cathode Materials

1.2.1.1 Lithium Nickel Cobalt Manganese Oxide

The molecular formula of the lithium nickel cobalt manganese oxide (NCM) oxide ternary cathode material is LiNiaCobMncO2, where a?+?b?+?c = 1. The naming rule of specific materials is usually based on the relative content of the three elements, for example, LiNi0.8Co0.1Mn0.1O2 is referred to as NCM811 for short. The different proportions of the three elements endow the NCM cathode material with different properties, which can meet the needs of diversified applications. NCM material combines the advantages of three types of materials as follows: LCO, lithium nickel oxide (LNO), and LMO. By adjusting the ratio of transition metal elements, the performance of the cathode material can be effectively regulated, and the cost of the cathode material can be reduced. Among them, the Ni element is beneficial to the increase of the specific capacity of the cathode material, which, however, is harmful to its thermal stability [9]; the Co element is beneficial to improve the electrical conductivity and rate performance of the material, but it is expensive; the presence of Mn plays a role in stabilizing the crystal structure of the polycrystalline, but it will also reduce the specific capacity of the cathode material when an excessive content was used.

The main preparation methods of NCM cathode materials include high-temperature solid-phase, sol-gel, co-precipitation, hydrothermal synthesis, and other methods. At present, commercial NCM materials were generally prepared with NCM hydroxide by precipitation method. The NCM precursor is mixed with a lithium source and calcined to prepare a finished NCM cathode material. The production of NCM precursor generally adopts the hydroxide co-precipitation method, that is, the mixed salt solution of nickel, cobalt, and manganese, precipitating agent, complexing agent, etc., are added to the reactor at the same time, and the NCM precursor is synthesized under specific conditions. The internal structure of the reactor...