LR41 battery

Development of LR41 battery technology at home and abroad

Since the industrialization of lithium-ion batteries in 1991, graphite has been the dominant negative electrode material for batteries. Lithium titanate, as a new type of negative electrode material for lithium-ion batteries, has been valued since the late 1990s due to its many excellent properties. For example, the crystal structure of lithium titanate materials can maintain a high degree of stability during the insertion and extraction of lithium ions, and the lattice constant changes very little (volume change <1%).

This "zero strain" electrode material greatly extends the cycle life of lithium titanate batteries. Lithium titanate has a three-dimensional lithium ion diffusion channel unique to the spinel structure, and has the advantages of excellent power characteristics and high and low temperature performance. Compared with carbon negative electrode materials, lithium titanate has a high potential (1.55V higher than that of metallic lithium), which results in the solid-liquid layer that usually grows on the electrolyte and the carbon negative electrode surface being basically not formed on the surface of lithium titanate.

More importantly, lithium dendrites are difficult to form on the surface of lithium titanate within the voltage range used by normal batteries. This largely eliminates the possibility of short circuits caused by lithium dendrites inside the battery. Therefore, the safety of lithium-ion batteries with lithium titanate as the negative electrode is the highest among all types of lithium-ion batteries that I have seen so far.

Most people in the industry have heard that the cycle life of lithium batteries with lithium titanate replacing graphite as the negative electrode material of lithium batteries can reach tens of thousands of times, which is much higher than the common traditional lithium-ion batteries, which die after only a few thousand cycles.

Since most professional lithium battery people have never really made LR41 battery products, or have only made them a few times and ended them hastily when they encountered difficulties. So they have not been able to calm down and think carefully about why most perfectly made traditional lithium-ion batteries can usually only complete 1000 to 2000 charge and discharge cycle lifespans?

Is the fundamental reason for the short cycle life of traditional lithium-ion batteries due to one of the basic components - the graphite negative electrode being unable to bear the heavy load? Once the graphite negative electrode is replaced with a spinel lithium titanate negative electrode, the basically same lithium-ion battery chemical system can be cycled to tens of thousands or even hundreds of thousands of times.

In addition, when many people talk about the low energy density of lithium titanate batteries, they ignore a simple and important fact: that is, lithium titanate batteries have an extremely long cycle life, extraordinary safety, excellent power characteristics and good economy. These characteristics will be an important cornerstone for the large-scale lithium battery energy storage industry that is currently emerging.

In the past 10 years, research on LR41 battery technology at home and abroad has been surging. Its industrial chain can be divided into lithium titanate material preparation, LR41 battery production and integration of LR41 battery systems and their application in electric vehicles and energy storage markets.

1. Lithium titanate materials

The leading companies in the international research and industrialization of lithium titanate materials include the American Aoti Nanotechnology Company, Japan Ishihara Industry Co., Ltd., and the British Johnson Matthey Company. Among them, the lithium titanate materials produced by the American Aoti have excellent performance in terms of rate, safety, long life and high and low temperature. However, due to the overly lengthy and delicate production method, the production cost is relatively high, making it difficult to promote commercialization.

Ishihara Industries is one of the largest titanium dioxide manufacturers in Asia, with production bases in Japan, Singapore and Taiwan. Ishihara Industries has made full use of its abundant raw material resources and successfully developed a number of low-cost, high-rate, and different particle size lithium titanate products using a wet process. Its products with similar performance have a greater price advantage over the lithium titanate materials of Aoti in the United States, but are slightly inferior to domestic products in China. Johnson Matthey took over the lithium iron phosphate and other materials owned by the former German Southern Chemical Company, but insufficient investment in the research and development and production of lithium titanate materials made it difficult to stabilize product quality.

There are already many companies in China that mass produce lithium titanate materials, such as Sichuan Xingneng New Materials Co., Ltd., Zhuhai Yinlong New Energy Co., Ltd., Huzhou Weihong Power Co., Ltd., Shenzhen Beite New Energy Materials Co., Ltd., Hunan Shanshan New Materials Co., Ltd., and several smaller lithium titanate manufacturers in Anhui and Shenzhen.

Sichuan Xingneng is a professional manufacturer of lithium titanate materials with an annual production capacity of 3,000 tons. The lithium titanate production process is customer-adaptable and stable. It can be flexibly adjusted without changing the existing production line and equipment to produce lithium titanate that meets the requirements of different customers and maintain the stability of product technical indicators. Xingneng relies on upstream lithium and titanium ore resources to achieve coordinated production from raw ore to final materials, thereby improving the performance of lithium titanate products and reducing costs, avoiding the impact of raw material market fluctuations.

Zhuhai Yinlong completed the acquisition of 53.6% of the shares of the American Aoti Nanotechnology Company in 2011, thus becoming one of the few domestic companies that simultaneously owns multiple core technologies and more than 30 patents for the preparation of lithium titanate materials, battery production, lithium titanate electric vehicles, energy storage systems, frequency modulation and peak regulation, etc.

At present, the annual production capacity of lithium titanate materials of Northern Aoti Nanotechnology Co., Ltd. (referred to as "Northern Aoti") is 100 tons, and it provides high-quality nano-grade lithium titanate for Northern Aoti and Zhuhai Yinlong. Zhuhai Yinlong New Energy has also carried out strategic cooperation with Ishihara Industry on the research and development of new lithium titanate materials. The cost of the materials will decrease as its output increases, and it is expected to be close to the current cost price of graphite negative electrode materials in the next few years.

Huzhou Weihong is currently one of the most successful companies in promoting LR41 battery technology and other fast-charging batteries in the domestic industry.

The lithium titanate materials produced by Huzhou Weihong are mainly used for its own LR41 battery products. The continuous expansion of Huzhou Weihong's LR41 battery products in the domestic and foreign markets has also played a good demonstration role in the application of lithium titanate technology in the electric vehicle and energy storage markets.

Shenzhen BTR is currently the world's largest supplier of lithium battery carbon negative electrodes. The company has a strong R&D team and is also one of the drafters of the lithium titanate industry standard. Shenzhen BTR's strong sales network will also take the lead in the sales of lithium titanate in the market. It has launched two products: carbon-coated lithium titanate and carbon-free lithium titanate. However, lithium titanate materials are not BTR's main products at present. As the LR41 battery market has not yet been fully developed, the company has not yet made a long-term plan for the production of lithium titanate materials.

2. Lithium titanate batteries and their applications in electric vehicles and energy storage

There are not many manufacturers in the world that can mass-produce lithium titanate batteries, mainly represented by the American Aoti and the Japanese Toshiba Group. The application markets of lithium titanate batteries mainly include electric vehicles, energy storage markets and industrial applications.

American Aoti has its own unique core technology in the manufacture of lithium titanate batteries. It is still in a leading position in the international manufacture of large-scale lithium titanate batteries and has solved the so-called "flatulence" problem. At present, its fourth-generation 65Ah single LR41 battery has been used in energy storage systems, and there is still no obvious capacity decay after tens of thousands of cycles at 65°C.

In terms of the application of LR41 battery systems, the hybrid electric buses provided by Aoti for California, USA, have been put into operation since 2008. Its fuel economy index is 106.4kg/L, which is much higher than the 23.8kg/L of ordinary diesel generators. The company provided a 1MW storage system for the 10.5MW wind farm of the Hawaii Natural Energy Institute and connected it to the local power grid, while providing a three-year technical support service. This LR41 battery energy storage system is mainly used to regulate the voltage fluctuations of renewable energy and control the load change rate of the unit within 1MW/min.

Aoti's 1MW large-capacity and high-power energy storage unit is currently the only large-capacity LR41 battery product in the US power grid that has been in field commercial operation and performance quality inspection for more than two years. The energy storage system has more than 500,000 cycles, the total charge and discharge power exceeds 3,300MWh, the system capacity loss is less than 2%, and the power has no obvious attenuation.

Toshiba of Japan mass-produces lithium titanate batteries under the brand "SCiB". Among them, 3.2Ah, 10Ah and 20Ah aluminum shell square batteries are mainly used for electric motorcycles, electric vehicles and car start-stop batteries. SCiB batteries have the advantages of fast charging and long life. They can be charged to more than 90% in 10 minutes, and the capacity decay is less than 10% after repeated charge and discharge for 3,000 times. They have been applied in batches to "EV-neo" electric motorcycles.

In terms of energy storage, Toshiba is applying lithium titanate batteries to large-scale energy storage power stations and home energy storage systems with the help of Japan's New Sunshine Project. Another Japanese company, Murata, has developed a new type of LR41 battery using 5V nickel manganese oxide as the positive electrode. Its voltage difference is 3.2V, and the energy density can reach 130Wh/K song, which exceeds the current level of lithium iron phosphate batteries.

There are many domestic LR41 battery manufacturers, such as Huzhou Weihong, Zhuhai Yinlong, Shenzhen Bolei Da, Tianjin Jiewei Power Industry Co., Ltd., Sichuan Xingneng, CITIC Guoan Mengguli Power Technology Co., Ltd., Hunan Shanshan, and several smaller LR41 battery manufacturers in Anhui and Shenzhen.

Huzhou Weihong has been committed to the development of lithium titanate technology since its establishment in 2006. The company has vertically integrated the lithium titanate materials, diaphragms, electrolytes and cathode materials required for its LR41 battery production. In recent years, in order to meet market demand, Huzhou Weihong has a daily production capacity of 80,000 10Ah LR41 battery products and a production capacity of multi-electrode lithium battery products that is twice that of lithium titanate batteries.

As of the end of 2014, Huzhou Weihong's 10-minute fast charging battery system has equipped more than 3,000 hybrid electric buses, mainly sold to the United Kingdom, the Netherlands and Chongqing, China. In the energy storage market, Huzhou Weihong has installed LR41 battery energy storage systems for grid frequency regulation and grid demand management in Vermont, the United States and Chongqing, China.

Zhuhai Yinlong's current mass-produced LR41 battery products include 20Ah and 65Ah soft-pack batteries and 25Ah, 30Ah and 55Ah cylindrical batteries, and their performance indicators have reached the lithium titanate batteries produced by Aotai in the United States. The battery has a cycle number of more than 16,000 times at 10% DOD, and 1.6 million times at 10% DOD. These batteries have all passed the third-party test of the Northern Automobile Quality Supervision, Inspection and Identification Test Institute (Institute 201).

In terms of application, Yinlong's new pure electric bus uses cylindrical, long-life, fast-charging and fast-discharging lithium titanate batteries, with a range of 30 to 80 km. It only takes 6 to 10 minutes to quickly charge, and can also be fully charged in 30 to 60 minutes at night. This series of models has been successfully put into use in the bus systems of Zhanjiang, Guangdong, Handan, Hebei, Shijiazhuang and other places.

The antique-style tram designed and developed by Yinlong for Beijing public transportation was put into commercial operation in September 2014. The car was also designated as the official designated car for the Beijing APEC meeting. In the energy storage market, Yinlong has cooperated with the State Grid and China Southern Power Grid to undertake the 863 national projects in energy storage, and provided partial modules, battery box design and system solutions for two 2MWh and one 600kWh lithium titanate systems for the Zhangbei wind and solar storage demonstration station and the Shenzhen Baoqing battery energy storage station, respectively.

Shenzhen Bolei Da can prepare Li4Ti5O12 materials with good performance through unique material processing methods, and through technical research projects, starting from the improvement of the production process of lithium titanate batteries, the design and preparation of high-performance Li4Ti5O12 has made significant progress. The current mass-produced products include 17Ah, 20Ah and 25Ah cylindrical batteries, which solve the problem of easy flatulence of lithium titanate batteries, obtain high-performance LR41 battery products, and obtain authoritative third-party test reports.

Starting from the design of high-power Li4Ti5O12 electrode materials, BoLeida studied the interface side reactions of Li4Ti5O12 materials to reveal the gas production mechanism and solution mechanism for the large-scale application of Li4Ti5O12 electrode materials in power batteries and made a major breakthrough.

Tianjin Jiewei obtained the transfer of LR41 battery production technology from Aotai of the United States, and combined with its own technical accumulation in the production of polymer soft-pack power batteries for many years, it has its own unique characteristics. The company has successfully overcome the problem of flatulence and has the technology and ability to mass-produce large-scale monomer lithium titanate batteries. The battery capacity reaches 60Ah and the cumulative shipment volume is 20 million Ah.

The battery can withstand continuous charging and discharging of more than 10C, with a life of more than 20,000 times and a temperature range of -40 to 60℃. It is mainly used in fast-charging buses and frequency-modulated energy storage power stations.

Difficulties in the development of LR41 battery technology and its development direction

1. Reasons for developing LR41 battery technology in China

LR41 battery technology should have the advantages of time, place and people in the competition among various energy storage batteries in my country. In terms of service life alone, the ultra-long cycle life of lithium titanate batteries is far superior to that of various lead-acid batteries; its efficiency, cost and electrochemical performance are even better than those of sodium sulfur and liquid vanadium battery systems.

Over the years, the main market for lithium battery products has been portable appliances such as mobile phones and laptops. Although China has a large consumption of mobile phones and laptops, most of them are not domestic brands. Therefore, domestic lithium battery manufacturers are inferior to Japanese and Korean products in lithium battery sales capabilities for portable appliances.

However, the applicable market for lithium titanate technology is hybrid electric vehicles, special industrial applications and energy storage applications such as frequency modulation and grid voltage support. These markets are still in their infancy around the world, and it is still unknown who will take the lead. Lithium titanate technology is expected to become a leader in these markets.

China's population base accounts for about 1/5 of the world's population. Due to its large population, China's electric vehicle, energy storage and industrial application market is a huge market coveted by multinational companies in many countries. In recent years, the Chinese government has attached great importance to the development of the electric vehicle and energy storage industries, and various national incentive policies have been introduced. The LR41 battery system produced in China has accumulated commercial application data for several years in hybrid electric buses in Chongqing and Europe, wind and solar storage demonstration stations in Zhangbei, and energy storage power stations in Baoqing, Shenzhen.

In addition, the upstream and downstream of my country's lithium battery industry chain have long been established. In addition to the complete battery material supply and equipment manufacturing capabilities, the production capacity of lithium battery products is also divided into three parts with Japan and South Korea. This makes my country's lithium battery manufacturers have the innate conditions to transform from traditional lithium battery production to LR41 battery product production.

my country has long had companies such as Sichuan Xingneng, Zhuhai Yinlong, and Huzhou Weihong that are both powerful and experienced in the production of lithium titanate materials. Representative companies that have stood out in the production of lithium titanate batteries include Huzhou Weihong, Zhuhai Yinlong, Shenzhen Bolei Da, Tianjin Jiewei, etc.

These companies have initially established their own sales channels in the domestic and foreign electric vehicle and energy storage markets. It is particularly worth noting that Shenzhen Bolei Da has a series of proprietary technologies and intellectual property rights from material production to battery manufacturing and system integration. At present, it is still a rare manufacturer with independent intellectual property rights in the Chinese lithium battery industry.

2. Bottlenecks in the production of lithium titanate materials, batteries and battery packs

Since LR41 battery technology has many advantages that other lithium batteries cannot match, why has it been rarely used in the Chinese energy industry and even in the world's energy field so far? There are three reasons:

① Production of lithium titanate materials The production of lithium titanate materials is not complicated in principle. However, to be used as the negative electrode material of lithium-ion batteries, it is necessary not only to pay attention to the material having a suitable specific surface area, particle size, density and electrochemical properties, but also to be able to adapt to large Large-scale lithium battery production process. One of the reasons why lithium titanate materials cannot be produced normally on many traditional lithium battery production lines is that the pH of the material is 11 or 12, and it is extremely hygroscopic.

② LR41 battery production In fact, it is not as simple as just replacing graphite with lithium titanate materials to directly use conventional lithium-ion battery production lines to produce LR41 battery products. Because the humidity requirements of lithium titanate materials are much higher than those of conventional lithium-ion battery production. In order to control humidity, some preparation processes need to be adjusted accordingly to adapt to the special requirements of LR41 battery product production. In addition, some production equipment also needs to be improved accordingly. If conditions permit, it is best to redesign a compact, small, and fully enclosed automated production line specifically for LR41 battery products.

③ LR41 battery packs are different from conventional lithium-ion batteries. At present, lithium titanate batteries produced at home and abroad often have trace amounts of gas generated in the single cells of the soft pack after being put into use for a period of time. These gases are different from the gases generated when fresh batteries are formed. The former can be removed through the battery production process. But the latter is generated during the use of the battery, or it is difficult to avoid under the current process conditions.

The author believes that studying the chemical reaction mechanism of gas generation during circulation should be a good scientific research topic. In addition, one of the advantages of LR41 battery technology is its high power performance. Although the battery itself can withstand high current charging and discharging, thick single cells are still not suitable for high-power applications because the battery is too thick, which will cause the heat generated by the high current to be difficult to dissipate. Therefore, for high-power lithium titanate batteries, a large and thin soft-pack battery structure is still a reasonable choice.

3. Future development direction of lithium titanate technology

Finally, it is necessary to summarize the advantages and disadvantages of lithium titanate materials as lithium battery negative electrodes. Advantages: ultra-high safety, ultra-long life, wide high and low temperature working range, high power, low cost and green environmental protection. Disadvantages: lithium titanate materials have low energy density and strong water absorption. The environment requirements for battery production are high, the production process needs to be updated accordingly, the new process requires investment in necessary equipment and higher requirements for humidity control, and the application market of lithium titanate batteries has not yet been fully opened.

Conclusion

Under the current environment where the Chinese government vigorously advocates the development of new energy and related industries, how to promote LR41 battery technology and its application in the electric vehicle and energy storage markets is a once-in-a-lifetime opportunity for China's LR41 battery industry. For domestic companies such as Zhuhai Yinlong, Huzhou Weihong, Shenzhen Bolei Da, Sichuan Xingneng, Shenzhen Beite Rui, etc., which have some advantages of independent intellectual property rights and sales channels, it should be a unique opportunity. Many people do not realize that China's intellectual property advantages in lithium titanate technology are not possessed by the so-called "mainstream chemistry" currently dominated by lithium iron phosphate batteries.

Developing high-capacity and high-potential positive electrode materials to improve the energy density of lithium titanate batteries is a great move to catch up with Japan and South Korea. Of course, the entire lithium-ion battery chemical system must also be studied, such as high-potential electrolytes and antioxidant diaphragms. The efforts of China's lithium battery industry to develop LR41 battery technology will be rewarded by the emerging electric vehicle, energy storage and industrial application markets.

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