Study On 3D Porous Carbon Nanotube Interlayer High Performance Of Lithium-Sulfur Battery

With the rapid development of electric vehicles and electronic mobile devices,the electronic market has put forward higher requirements for the performance of chemical power sources in energy storage systems,especially next-generation batteries with higher capacity and energy density.Lithium-sulfur batteries are a new type of energy storage system that uses elemental sulfur as the positive electrode and metal lithium as the negative electrode.Elemental sulfur cathode materials have the advantages of rich sources,cheap prices,environmental friendliness,and good battery safety.Therefore,lithium sulfur batteries are considered to be the next generation of the most promising battery systems that can provide high specific energy.However,a series of problems such as low conductivity of the active material,volume expansion,strong shuttle effect,and growth of the lithium dendrite of the negative electrode have seriously affected the charge and discharge efficiency of the battery,making the actual energy density much lower than the theoretical energy density.The service life is reduced,which further prevents the commercial production of lithium-sulfur batteries.The three-dimensional porous carbon nano tube sandwich uses its 3D porous structure.A large specific surface area can significantly enhance the physical adsorption of polysulfides,and the failed sulfur ions after being adsorbed can be reused,which improves the utilization rate of active materials.Moreover,the three-dimensional porous carbon nanotube sandwich as a secondary current collector makes full use of the active material,and the synergistic effect can effectively suppress the shuttle effect.The three-dimensional porous carbon nanotube sandwich high-performance lithium-sulfur battery has a specific discharge capacity of 1367 mAh/g for the first time at a rate of 0.05 C and an active material utilization rate of 81.6%;after 300 cycles at a rate of 1 C,the discharge specific capacity still reaches 694.5 mAh/g,which is 84%of the first specific capacity,and the Coulomb efficiency is still maintained at 97.4%,showing good rate and cycle performance.The tris(2-carboxyethyl)phosphine carbon nanotube sandwich structure can adsorb high-order polysulfides,and then use its phophophilic ester to shear and reduce disulfide bonds,inhibit the formation of high-order polysulfides,and reduce the loss of active materials.Activity,thereby improving the coulomb efficiency of lithium-sulfur batteries.At 0.1 C,the initial discharge capacity of the S-TCEP-AP lithium-sulfur battery reached 1544 mAh/g.After 400 cycles at 1 C,the specific discharge capacity is still maintained at 609 mAh/g,and the attenuation rate is extremely low at 0.029%.This structure shows good rate and cycle performance.The hydroxylated carbon nanotube cellulose interlayer can use the hydrophilic hydroxyl functional groups produced by the hydroxylated carbon nanotubes(MWCNTs-OH)to adsorb polysulfides,prevent the diffusion of polysulfides,increase the utilization of effective substances and suppress the occurrence of the shuttle effect,thereby improving the capacity and cycling performance of lithium-sulfur batteries.At a rate of 1/10 C,the first discharge specific capacity of the MWCNTs-OH sandwich structure lithium-sulfur battery is 1532 mAh/g,and the utilization rate of the active material reaches 91.5%.Stable cycling 500 times at 1 C rate,the discharge specific volume still maintains 516 mAh/g,and the weekly cycle decay rate is 0.028%,showing excellent magnification.