The Study On Performance Of Li-S Battery With Carbon Paper As Functional Interlayer

With the increasing demand of the world energy consumption, more and more environmental materials are used in primary electrical energy storage devices and power equipment. Li-ion batteries have been widely used for its advantages, such as lightweight, high energy density, environment-friendly and recycle. Lithium sulfur battery(Li-S) is regarded as one of the most promising systems for next generation batteries due to a high theoretical capacity of 1675 mAh g-1 and a higher specific energy of 2600 Wh kg-1. But its development in practical use is hindered by many shortages, such as the low conductivity of the intermediates during discharge progress and the “shuttle effect”, which lead to the low utilization of cathode materials. In this article, we analyze the papers of study on cathode, anode and electrolyte in Li-S batteries. In our experiment, we solve the problem of low conductivity and the “shuttle effect” through the addition of interlayer. Our work includes the following two aspects: on one hand, three different thickness of carbon paper(100 μm, 200 μm and 300 μm) were cut into the same size as the separator. Then we analyze the cathode materials and the different morphologies of the carbon paper and the electrochemical properties of the three different cells. We found that 300μm was the best choice among the three kinds of thickness. The CP-300 delivered a reversible capacity 490 mAh g-1 after 200 cycles with a 0.5 C rate and it had the best rate performance. On the other hand, a novel interlayer was made using polypyrrole(PPy) adhered to carbon paper of the three kinds of thickness. Due to the porous structure and conductivity of the as-prepared interlayer, the battery exhibited excellent cycle performance and rate performance than the CP batteries. Surprisingly, the PPy coated CP-200 displays a reversible capacity 555 mAh g-1 after 200 cycles with a capacity retention of 65%, higher than the CP-300 of 57%. The PPy-200 exhibits 310 mAh g-1 at 5 C, which shows an excellent rate performance. This novel way to treat carbon paper may have a promising prospect in the battery field.