Preparation And Performance Of Bacterial Cellulose-based Lithium-ion Battery Separator

Bacterial cellulose?BC?,as a natural nano-fiber material with abundant availability and environmental friendliness,has attracted the attention of scholars in various fields.BC is a series of bands with a continuous width of 50-80nm and a thickness of 3-8nm composed of a three-dimensional porous micro-network structure,which is produced by the decomposition of d-glucose by bacteria.BC demonstrates high purity and crystallinity,excellent liquid absorption and mechanical stability,as well as excellent biological affinity.Its high aspect ratio and rich hydroxyl can be easily attached with different nanostructured materials?such as inorganic and conductive polymer nanoparticles or nanofibers?through strong interactions.In this paper,taking BC membrane as the substrate,the composite separator was prepared by attaching BC membrane with HNTs or ANFs,or by TEMPO oxidation.The main research contents and achievements are as follows:?1?The BC membrane was utilized as the substrate,and mixed uniformly with the inorganic filler HNTs.Then the BC/HNTs composite separator was prepared by vacuum filtration.The experimental test results showed that when the mass ratio of HNTs to BC is 1:150,the ionic conductivity of the prepared BC/HNTs-150 composite separator could reach5.13 m S?cm^-1,the porosity could reach 83.0%,and the liquid absorption rate could reach369%.The tensile strength was 84.4MPa,which is much higher than that of pure BC film.While charging and discharging at a rate of 0.2C,the lithium ion battery equipped with BC/HNTs-150 composite separator demonstrated a discharge capacity of 162m Ah?g^-1.After 100cycles Capacity reservation accounted for 95%.?2?By adding the nanofiber ANFs to the substrate BC membrane,the ANFs/BC composite separator was prepared by vacuum filtration after uniform mixing.When the proportion of ANFs accounting for 2%,the ANFs/BC membrane realized higher mechanical properties than the pure BC membrane,the ion conductivity could reach 12.54m S?cm^-1,the porosity was 83.9%,and the liquid absorption rate showed 303%,The lithium ion battery equipped with 2%ANFs/BC composite separator demonstrated a discharge capacity of 157m Ah?g^-1,and the capacity reservation after100 cycles accounted for 93%.?3?Taking BC membrane as the substrate,TOBC separator was prepared by oxidizing BC fiber by TEMPO-Na Br-Na Cl O system.The prepared TOBC1.0 film showed excellent properties in terms of liquid absorption,porosity,wettability,thermal stability,mechanical properties and ionic conductivity.Among them,the tensile strength reached 97 MPa,the porosity reached 91.1%,and the liquid absorption reached 339%.At the same time,the discharge capacity of the lithium-ion battery with TOBC1.0 separator realized 166m Ah?g^-1.After 100 cycles,the capacity reservation is 94%,which showed rate performance and cycle stability.