Preparation And Property Research Of The Composite Cathode Materials For Lithium-Sulfur/Selenium Battery

Lithium ion battery has been applied in many aspects of human life because of it's high power density, environment friendly. With the development of society and economy,however,Lithium ion battery can't meet the people's need for higher power density battery systems. As a result, this new battery systems become the research hotspot, such as lithium-sulfur battery, lithium-selenium battery, etc, which can provides the higher power. Sulfur and selenium are belong to the same group, have those advantages that higher theory volume capacity density, abundantly and environment friendly. However, their commercialization has been hided for the low electrical conductivity of active materials and the "shuttle effect" in proceed of electrochemistry,which can lead to the bad cycle stability. In this paper, we were synthesized the sulfur/selenium cathode composites that improve the material electrical conductivity,and the structure can encapsulate the intermediate in substrates to relieve the he "shuttle effect",as a result, the cathode materials realize the preferable battery performance.Lithium-sulfur ?Li-S? battery has been considered as one of the most promising candidates due to its high theoretical energy density of 2600 W h kg^-1, which is 5 times greater than commercial lithium ion battery that built with a LiCoO2 cathode and a graphite anode. However, it's commercialization has been hided for the low electrical conductivity of active materials and the "shuttle effect" in proceed of electrochemistry,in our work, we have loaded the sulfur in carbon substrates that Ketjen black were uniformly distributed in porous carbon to form S/ ?KB@HPC? composite, which exhibited excellent battery performance. At the rate of 0.5 C, the cathode provides the discharge capacity of 1783 mA h g^-1 at the initial cycle and the reversible capacity of 963 mA h g^-1 after 100 cycles, furthermore, it can provides the reversible capacity of 555 mA h g^-1 after 300 cycles at a high rate ?2 C?. For the KB@HPC carbon substrates,hierarchical pore structure can load more sulfur, and the Ketjen black can improve the Li+/e- conductivity and the kinetics of cathode reaction.The theoretical volume energy density of Lithium-selenium battery is fairly with the Lithium-Sulfur battery that is research hotspot. We loaded the selenium in coconut shell charcoal ?CSC? to synthesis Se/CSC composites for lithium-selenium that can provide outstanding battery performance. At 0.5 C, the cathode has provided the reversible capacity of 370 mAh g^-1 after 100 cycles and 280 mAh g^-1 after 200 cycle at 1 C. For the CSC substrate, its micropores structure can the encapsulated the polyselenide to relieve"shuttle effect" availably to exhibited preferable performance. The raw material comes from Hainan province and cheap for availability. The Se/CSC cathode provided more choice for high energy density battery system.