Improving Performance Of Sulfur Cathode By Using ?-polyglutamic Acid As A Binder

Lithium-sulfur(Li-S)battery which possess a high theoretical energy(Its volumetric energy density is as high as 2800Wh·L-1)densities attract most people's attention.Take advantage of Sulfur's environmental benign and low cost,Li-S batteries has been one of the most popular battery systems.However,Li-S batteries has many drawbacks such as the insulating nature of sulfur,the shuttle effect,and the large volume change of sulfur during cycling.Those problems result in the low content of sulfur and poor cycle performance,which have been the main barriers for its commercialization.There are plentiful electron-rich groups in the ?-PGA molecular chain which can curb loss of the soluble polysulfides into the electrolyte.Thus,we adopt y-PGA as the functional binder to improve the electrochemical performance of the lithium-sulfur batteries.The main research contents and results are as follows:At first,y-polyglutamic acid(y-PGA)was adopted as a functional binder in the Lithium-sulfur(Li-S)battery to improve the electrochemical performance of Lithium-sulfur battery.With the comparative analysis of three different kinds sulfur cathode prepareed by PVDF?LA 132?and ?-PGA binder,we found that PGA cathode exhibited better electrochemical performance.Then,the influence of the y-PGA content in the sulfur cathode was explored in this paper.The result showed that the sulfur cathode with 7 wt%?-PGA exhibited a highest initial discharge capacity.After 80 cycles,its capacity retention can be as high as 73.4%.At last,sulfur cathode with a high sulfur content of 77 wt%was prepared.With a sulfur content of 77 wt%,the sulfur cathode exhibited a good cycle performance.It delivered an initial discharge capacity of 915.6 mAh·g-1 and a a high reversible capacity of 600.4 mAh g-1 after 100 cycles.