Researchers find new methods for improving energy density of EV lithium ion batteries

　　Author ：Iflowpower – Portable Power Station Supplier

South Korean researchers have recently found that the performance of lithium air batteries has a large correction with the content of carbon dioxide. The researchers believe that Li2CO3 in the battery can selectively act as the final product of the discharge reaction according to the dielectric properties of the electrolyte in the lithium air battery. In addition, they also verify that the Li2CO3 can be reversible in the lithium-oxygen / carbon dioxide battery cycle.

Related papers have been published in "American Chemistry Society". Researchers believe that understanding the chemical properties of CO2 in lithium air batteries and the use of carbon dioxide in electrolyte solutions to the development of lithium air batteries. In addition, there is a maximum advantage to minimize adverse reactions based on Li2CO3 to explore the charging lithium-oxygen / carbon dioxide battery.

The highest theoretical energy density of the lithium air battery is approximately 3,500 watt / kg, which is a good power source for the next generation of electric vehicle energy storage system, which can make electric vehicles to achieve longer form mileage. The structure of the lithium air battery is based on a pair of intercalation electrodes. When charging, the lithium ion moves from the cathode to the electrolyte and then anode; when discharging, the process reverses.

Lithium air batteries should be facing many technologies and engineering problems, including the low degree of understanding of battery response mechanisms, unstable electrolyte chemical performance, short cycle life, low ion transmission rate, etc. Large extent, the battery is too high load phenomenon. The researchers pointed out: I don't know what happens when the lithium air battery is tested in an oxygen-free environment, because most of the previous research is tested in aerobic environment and other components in the air The impact is ignored.

Therefore, it is proved that the effects of carbon dioxide related lithium air batteries must create a greenhouse environment, and the effects of other ingredients (nitrogen, argon, water, carbon dioxide) are studied one by one. It is assumed that the waterproof film can be removed (resulting in an important substance of electrolyte and anode deterioration), the chemical characteristics of the carbon dioxide should have the most significant effect, exceeding the influence of other ingredients in the air. The cathode voltage of the conventional lithium air battery is 3 volts, and when argon and nitrogen are contained in the surrounding environment, the electric chemical reaction cannot be activated, and the carbon dioxide can withstand the electrochemical reaction of the response due to its inert.

The difference in chemical stability means that the final product Li2O2 will always be converted to Li2CO3 by carbon dioxide, and the irreversible reaction limits the cycle performance of lithium air cells. Further, although the proportion of carbon dioxide is not high in the air, since carbon dioxide has high solubility (50 times higher than oxygen), it is applied to the battery reaction. In order to further develop lithium air battery technology, it is necessary to consider the effects of carbon dioxide and Li2CO3 related to lithium air battery performance.

Korean Senior Science and Technology Research Institute (SeoulnationalUniversity) research team studied various electrolyte conditions, using quantum mechanics simulation and test verification, studying the reaction mechanism of lithium oxygen / carbon dioxide battery. They found that a low dielectric electrolyte forms Li2O2, while high dielectric can activate carbon dioxide, LI2CO3. However, unexpected harvest is that they find high-electrical media such as dimethylphin (DMSO) to make Li2CO3 reversible reactions.

The researchers said that this discovery is very important because in an environment containing carbon dioxide, the formation of Li2CO3 in the lithium air battery is inexpensively, but it is currently found that the substance that can cause reversible reactions can cause the battery's cycle performance. Stablize. .