高比表面积炭材料中间层构筑高性能锂硫电池

A carbon interlayer with high specific surface area for high-performance lithium-sulfur batteries

电动汽车的发展和应用对电化学储能领域的能量密度提出了更高的要求。锂硫电池的理论能量密度为2600 Wh·kg^(-1),是非常有前景的电化学储能体系,其面临的主要障碍包括:单质硫低的导电率影响其放电比容量;充放电中间产物的穿梭效应降低了电池的循环稳定性。针对这些问题,本实验选用具有高比表面积的多孔炭材料PC修饰聚丙烯隔膜作为中间层。PC优异的导电性可以促进活性物质的利用。通过中间层的物理阻挡和PC对多硫化物的吸附作用抑制锂硫电池的穿梭效应。添加PC中间层的锂硫电池在0.1 C的放电比容量为1150.2 mAh·g^(-1),循环100次容量保持在806.6 mAh·g^(-1),在2 C下的比容量为444.7 mAh·g^(-1)。PC中间层显著提升了锂硫电池的循环稳定性和倍率性能。

The electrochemical energy storage with more higher energy density is required due to the development and application of electric vehicles.Lithium-sulfur(Li-S)batteries,with a theoretical energy density of 2600 Wh·kg^(-1),is a promising candidate.The main obstacles of Li-S batteries include:the low conductivity of sulfur decreases the capacity;the shuttle effect during cycling reduces the cycle stability of batteries.So,in this paper,the porous carbon(PC)with high specific surface area was coated on polypropylene separator and acted as an interlayer between cathode and separator to enhance the electrochemical performance of Li-S batteries.The excellent conductivity of PC can promote the utilization of active substances.And the PC with abundant porous structure can adsorb the polysulfides.Moreover,the PC interlayer acts as a physical barrier to inhibit the shuttle effect of Li-S batteries.As a result,The Li-S batteries with PC interlayer exhibit a high capacity of 1150.2 mAh·g^(-1) and retains 806.6 mAh·g^(-1) after 100 cycles at 0.1 C,and a high capacity of 444.7 mAh·g^(-1) at 2 C.