Preparation And Properties Of Composite Electrodes Based On Cellulose For Flexible Aqueous Zinc-ion Battery

In recent years,electronic products have gradually integrated into people’s daily lives.Among the devices currently used,batteries are the most common energy storage devices,and the lithium-ion batteries are very mature between them.However,they still have many shortcomings that cannot be ignored,such as the harsh production environment,expensive production costs,and organic electrolytes.At this time,the aqueous zinc ion battery has attracted the eyes of researchers at home and abroad due to its low cost,high safety,long cycle life and good energy density.Its electrochemical performance is highly correlated with electrode materials.While cellulose is widely used in nature,low recycling costs also provide great temptation and possibility as a substrate material.Therefore,this thesis takes the aqueous zinc ion battery as the research object,and studies the electrochemical performance of the composite electrode material made of cellulose and other active material.The specific research content of this paper mainly includes the following three parts:1)Solid-state flexible aqueous Zn-ion battery was fabricated by polyaniline-cellulose papers as the cathode and Zn-coated graphite papers as the anode.The separator was a flexible gel electrolyte with high ionic conductivity based on cellulose nanofibers.The Zn-ion battery exhibited an energy density of 117.5 and67.8 Wh/kg at a power density of 0.16 and 3.34 kW/kg,respectively(estimated from total active mass of both cathode and anode).The energy density of the Zn-ion battery was much higher than that of asymmetric supercapacitors with liquid electrolytes,while maintaining a comparable power density.Meanwhile,good cyclic stability was achieved with high capacity retention of 84.7%after 1000 charge/discharge cycles.More importantly,specific capacity changed little under mechanical bending,and there was only 9%loss after 1000 bending cycles.The solid-state flexible Zn-ion battery has great potentials as energy storage devices for flexible displays and wearable electronics.2)Wood pulp cellulose was used as the base material of the positive electrode,and the wood pulp cellulose can control electrochemical properties of the positive electrode by influence the polyaniline’s morphology.It can be clearly found that the polymerized polyaniline exhibits a coral and needle structure,which is smaller in size and larger in specific surface area.In this experiment,wood pulp cellulose was used as the reaction site.Interestly,the polyaniline in the case of its regulation,achieved superior morphology and capacity than those direct chemical growth.At a current density of 1 A/g,it has a capacity of 226.4 mAh/g.And with excellent rate performance,it meets the demand for"fast charge".What’s more,it was found that the electrochemical performance was almost unchanged under different angles of bending and under bending conditions.The 1000 charge-discharge test was conducted at a current density of 5 A/g,and the capacity was retained 72.6%compared to the initial,while the Coulomb efficiency was also maintained at 100%.The high-magnification flexible zinc-ion battery meets the demand for“fast charge”and has bright prospects in the future.3)Cotton cellulose treated with ionic liquid([BMIm]Cl)was used as the base material of the positive electrode,Which provides a mechanical skeleton for the composite cathode material and imparts flexibility.PANI exhibits nanospheres and needle microscopic morphology after polymerization on the surface,and the positive electrode loading can reach 2.5 mg/cm~2 after calculation.The prepared aqueous zinc ion battery has good bending performance and cycle life.At a current density of 1 A/g,it has a capacity of 150.3 mA·h/g.After 1000 cycles of charge and discharge cycles,these is also a high capacity retention rate of 84.7%.The zinc ion battery prepared in this experiment has high load,high capacity,and excellent bending properties.High-load batteries are the areas where researchers need to explore deeper of energy storage to help reduce the weight and miniaturization of electronic devices in daily lives.