Preparation And Properties Of Cellulose-based Lithium Battery Separator

As one of the key components in lithium-ion battery, the separator plays an important role in insulating the cathode and anode to avoid short circuits and also providing micropore structure for rapid transport of the ion carriers. What’s more, the excellent safety performance and low-cost of lithium-ion battery separator is one of the main goals in the future research. In this dissertation, we devote to exploring the application of biomass cellulose in lithium-ion battery separator. The main content is depicted as follows:(1) Hemp pulp, cotton pulp and wood pulp were ground by PFI pulping machine and ultrafine grinding machine, respectively. Then, the optimal pulp and beating technology were determined by investigating the separation and defiber of different cellulose pulp. As a result, hemp pulp was the best material to fabricate cellulose based composite separator by papermaking process in large scale.(2) Cellulose pulp and polysulfonamide pulp with different mass ratio were explored to fabricated composite separator by papermaking process. The performance of composite separator was investigated by wettability. heat tolerance, mechanical strength and electrochemical properties. It was demonstrated that cellulose pulp and polysulfonamide pulp with the mass ratio of3/1(w/w) obsessed the best comprehensive performance. What’s more, the lithium iron phosphate/lithium half cell using cellulose/polysulfonamide separator still exhibited stable charge-discharge capability even at℃120(3) Cellulose separator still has some disadvantages to be solved, such as large-sized pores and low mechanical strength. In order to tackle these problems, biomass dopamine was motivated to bind the surface of cellulose. Dopamine could self-polymerized to polydopamine at pH8.5, furthermore, the polydopamine coating layer endowed cellulose with the ability of adhesion which was beneficial to enhance the mechanical strength and safety performance. Meanwhile, the superior interfacial compatibility among electrode, electrolyte and separator was beneficial to improve electrochemical properties of batteries.