Blockbuster!Lithium cobalt oxide battery, this time really go up!
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2020/12/19 17:11:48
Power supply is an important support for the continuous operation of spacecraft in the vast space.During the Chang 'e-5 mission, Institute 811 of the 8th Institute of China Aerospace Science and Technology Corporation undertook the research and development of the power products of the orbiter, lander and lifter on four platforms: lander, lifter, orbiter and returner.Power system by the power source controller, lithium ion battery and solar cell array, in order to ensure the best performance guarantee of the mission, China aerospace science and technology corporation, which is eight yuan 811 developed by researchers gather enough horsepower, "power controller than the highest power of domestic and international leading, lithium ion battery application space than the highest energy, the solar cell array area than the highest power of domestic", are they to hand over a satisfactory answer.
In lunar missions, the probes require much more energy than traditional satellites.Chang 'e-5 is designed to be a four-vessel mission, and it needs to accomplish three goals of "orbiting, landing and returning" at one time. It requires more energy than any other lunar or deep-space exploration mission in China.Therefore, it is an important problem for researchers to improve the energy supply capacity of solar arrays and lithium ion batteries.
"In order to improve the solar array's power generation, we have set ourselves a goal to maximize the patch area on the front of the solar array," said Chen Cheng, chang 'e-5 solar cell circuit technology chief.
However, during the lunar exploration mission, the solar cell panel area is severely limited. At the same time, different from ordinary satellites, the configuration of the probe itself determines the irregular shape of the panel. The Chang 'e-5 solar cell panel has various shapes such as triangles and polygons.Baseplate area is small, and strange shape, how to do?
"For normal satellite models, we only design solar cell circuits with a single size solar cell.For Chang 'e-5, we broke the conventional thinking and used batteries of various sizes to mix cloth pieces, so that the efficiency of cloth pieces reached more than 91%, which was 5%-10% higher than conventional products.At the same time, the solar cell with the highest efficiency should be selected. The photoelectric conversion efficiency of the Chang 'e-3 and Chang 'e-4 solar cells is 28.6 percent and 30.84 percent respectively, and the Chang 'e-5 solar cell is more than 31 percent.After unremitting efforts, chang 'e-5 solar panel output power per unit area not only in the product development, even now, are the highest level in China.
Specific energy is a major performance index of lithium-ion batteries. The higher the value, the more energy can be stored per unit volume or weight.At the beginning of the research, the highest specific energy of domestic lithium-ion battery cell is 155Wh/kg, and the highest energy is 165Wh/kg in the world.Aiming at the characteristics of Chang 'e-5 lithium ion battery products, such as short service life and high discharge depth, the researchers made a solution after carefully analyzing the feasibility of the technical indicators, referring to a large number of literatures and investigating the technical data of lithium battery enterprises."We chose lithium cobalt oxide positive and graphite negative materials with higher energy than others, selected high molecular weight binder materials to reduce the amount of binder, and optimized the electrode formula to increase the content of active substances," said Wang Xiaorui, chief designer of Chang 'e-5 lithium-ion battery.Behind the light introduction are a large number of process tests, new electrode materials, new material ratio, and completely different physical and chemical parameters in the past, leading to great changes in the process of powder mixing and pulping, etc., but the researchers have verified each process step by step.After 8 months of effort, they increased the weight to energy ratio of the battery to 195Wh/kg.This value, for the current space lithium ion battery specific energy maximum value.
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