The core of new energy vehicles: application of lithium iron phosphate power batteries

1 Battery technology determines the fate of energy vehicles

Regardless of whether new energy vehicles are hybrid or pure electric vehicles, they cannot do without the core technology of batteries. Currently, the battery technology with the greatest hope of industrialization is lithium iron phosphate battery (LiFePO4). Lithium resources are limited. According to estimates by the United States Geological Survey (USGA), the total global reserves of lithium metal are 1,340 tons. Lithium resources are extremely biased towards South America. China has 1.1 million tons of reserves, which cannot be used as a substitute like oil. This year, the domestic lithium price has skyrocketed, from 30 yuan per kilogram at the beginning of the year to nearly 60 yuan per kilogram, almost doubling in just a few months. Therefore, how to effectively utilize lithium resources has become the key to the research and development of new energy vehicle technology.

Lithium cobalt oxide (LiCoO2) batteries for mobile phones and notebooks are the most widely used, but they are unlikely to be used as power batteries because they are expensive and have poor safety and thermal stability. The power battery technology that has begun to be industrialized is a battery that uses carbon for the negative electrode and lithium iron phosphate or its composite material for the positive electrode. This technology was invented by Goodenough of Texas State University in the United States at the end of the last century, and there have been many patent lawsuits in the United States surrounding this patent. The best result achieved by Goodenough's laboratory was to synthesize lithium iron phosphate materials using a high-temperature solid-phase method, with a discharge capacity of 110 mAh/g at room temperature, while the theoretical maximum discharge capacity of lithium iron phosphate is 170 mAh/g.

After years of scientific research efforts by various countries, the latest laboratory technology has reached 150-160 mAh/g, and the factory industrialization has reached 130-140 mAh/g. The battery cycle life is more than 500 times, and the loss rate is generally less than 5%. BYD's iron-lithium battery is said to be rechargeable 2,000 times, which should be enough to meet the number of charging requirements based on the ten-year service life of the car. Lithium iron phosphate battery technology is relatively mature, and many companies have used their products in power tools, segways, and pure electric vehicles.

2 Comparison of LiFePO4 Power Battery Performance with Other Battery Performance

China's lithium iron phosphate battery technology is not backward in the world, especially in industrial production and manufacturing. There are two major lithium iron phosphate battery manufacturers in the United States, A123 and Valence Technology, whose lithium iron phosphate raw material production and battery manufacturing bases are in China, A123 in Changzhou and Valence in Suzhou. A123's products are widely used in Black & Decker's DeWalt hand tool product series, and it has begun to provide batteries for General Motors' electric vehicles.

The main manufacturers of lithium iron phosphate batteries in China are BYD and Wanxiang Group. BYD accounts for 30% of the world's lithium cobalt oxide battery market. Judging from the data of its lithium iron phosphate batteries, all indicators are not behind A123 and Valence Technology. Wanxiang Group's sales of automotive lithium batteries reached 11.5 million yuan in 2007 and are expected to reach 25 million yuan this year. In addition, Japan's Sanyo and Toyota are developing such batteries. There are also reports that South Korea's LG is also developing such batteries.