Determination of specific surface area by lithium iron phosphate BET

Lithium iron phosphate

Functional use

Lithium iron phosphate electrode materials are mainly used in various lithium ion batteries.

Lithium iron phosphate performance

1. High energy density, the theoretical specific capacity is 170mAh / g, the actual specific capacity of the product can exceed 140 mAh / g (0.2C, 25 ° C);

2. Safety is currently the safest cathode material for lithium ion batteries; it does not contain any heavy metal elements that are harmful to humans;

3. Long life. Under 100% DOD conditions, it can be charged and discharged more than 2000 times; (Reason: Lithium iron phosphate has good lattice stability, and the insertion and extraction of lithium ions have little effect on the lattice, so it has good reversibility. Existing deficiencies It is due to the poor transfer rate of electron ions, which is not suitable for charging and discharging of large currents, and it is blocked in application. Solution: coat the surface of the electrode with conductive material and dope to modify the electrode.

4. Memory effect;

5. Charging performance, lithium batteries with lithium iron phosphate cathode material can be charged at a large rate, and the battery can be fully charged within 1 hour at the fastest.

Domestic and international lithium iron phosphate material manufacturers:

Domestic: Tianjin Strand Peking University, Hunan Ruixiang, Suzhou Hengzheng, among which Tianjin Strand now has stable material batch production, and Peking University pioneers small batch production. International: Canada Phostech, American Valence, American A123, Japanese sony. Among them, A123 is the largest and has obtained Great funding from the US government.

Novelty and characteristics

Lithium iron phosphate is a new type of electrode material for lithium ion batteries. At present, many manufacturers around the world have started industrial production. The foreign companies Valence (America) and A123 (Gaobo), Tianjin Strand, Peking University, etc. It is characterized by large discharge capacity, low price, no toxicity, and no environmental pollution. Countries around the world are racing to achieve industrial production.

But its tap density is low, which affects the capacitance.

At present, the main production method is live method, and the product index is unstable. The specific surface area of ​​lithium iron phosphate is very important. The detection data of the specific surface area of ​​lithium iron phosphate is only reliable when the result is detected by the BET method. There are many instruments in China that can only be tested by the direct comparison method. eliminated. At present, the multi-point BET method is used uniformly for the specific surface area testing at home and abroad. The specific surface area measurement standards developed at home and abroad are based on the BET test method. Please refer to China's national standard (GB / T 19587-2004)-Gas adsorption BET principle Method for determining the specific surface area of ​​solid materials. The measurement of specific surface area is actually a time-consuming task. Due to the different adsorption capacity of the sample, the test of some samples may take a whole day. If the test process is not fully automated, then the tester ca n’t leave at all times. A high degree of concentration, observing the instrument panel, manipulating the knob, and a little inattention will lead to the failure of the test process, which will waste a lot of precious time of the tester. Among several domestic manufacturers of specific surface area analyzers, only the F-Sorb 2400 specific surface area analyzer of Beijing Jinyi Spectrum Technology Co., Ltd. is an instrument that can truly realize the detection function of the BET method (both with direct comparison method), and the more important Beijing Gold F-Sorb 2400 specific surface area analyzer is the only fully automated and intelligent specific surface area detection equipment in China. Its test results are highly consistent with international standards, and its stability is also very good. At the same time, it reduces human errors. Improve the accuracy of test results.

The performance of lithium-ion power batteries mainly depends on the positive and negative electrode materials. Lithium iron phosphate as a lithium-ion battery material has only appeared in recent years. The domestic development of large-capacity lithium iron phosphate batteries was in July 2005. Its safety performance and cycle life are unmatched by other materials, which are the most important technical indicators of power batteries. 1C charge and discharge cycle life reaches 2000 times. The single battery overcharge voltage 30V does not burn, puncture does not explode. The lithium iron phosphate cathode material makes a large-capacity lithium-ion battery easier to use in series. To meet the needs of frequent charging and discharging of electric vehicles. It has the advantages of non-toxic, non-polluting, good safety performance, wide source of raw materials, cheap price and long life. It is an ideal cathode material for a new generation of lithium ion batteries.

This project belongs to the development of functional energy materials in high-tech projects, and is a key support area for the national "863" plan, "973" plan, and "Eleventh Five-Year" high-tech industry development plan.

The largest domestic Tianjin Strand situation

He has been engaged in the research and development of lithium iron phosphate in 2002, the pilot test in 2004, and the mass industrial production in 2005. The current monthly production capacity is 60 tons. The monthly sales volume is around 50 tons, accounting for 60% of the current market in mainland China. The company recently invested another 40 million to expand production. It is planned to reach 140 tons in February next year, with an annual output of 2,000 tons.

At present, the main customers are: dozens of companies such as BYD Corporation are using them in batches.