Preparation And Properties Of Flexible Supercapacitor Based On Polymer Solid Electrolyte

With the popularity of power facilities,rechargeable mobile devices have been widely promoted and popularized.Traditional dry batteries,lead-acid batteries,calomel batteries and other energy storage devices are no longer in line with today's social development concepts due to low power density and serious environmental pollution.Therefore,supercapacitors with the advantages of high power density,fast charge and discharge rate,light weight,simple structure,etc.have attracted widespread attention.Supercapacitors are usually composed of electrodes and electrolyte.The electrolyte will affect its safety and maximum working voltage.Traditional electrolytes include liquid electrolytes and solid electrolytes.However,liquid electrolytes have several common drawbacks,such as leakage of electrolyte during assembly and inconvenience to carry.As a result,solid electrolytes have become the first choice of most scientific researchers.Compared with other solid electrolytes,polymer electrolytes have better flexibility and higher operating temperature,and can be used in more severe environments.At present,some polymer materials have been used in supercapacitor electrolytes,such as Polybenzimidazole,polyvinyl alcohol,chitosan,etc have received widespread attention due to their good film-forming properties,high proton conductivity and excellent mechanical strength.Prior to this,some workers have already applied it to the field of supercapacitors and achieved good results.In this paper,from the perspective of molecular design,a cage-like cross-linking structure(c PBIOH-X)was designed inside the polymer system,that is,the introduction of siloxane structure,one end of siloxane is connected with the polymer system,and the other end is hydrolyzed to form a Si-O-Si cross-linking network.The crosslinking network can not only improve the phosphoric acid absorption capacity,but also improve the phosphoric acid retention capacity and mechanical properties.The fracture strength of c PBIOH-30 can reach about 8 MPa in wet film,and the proton conductivity of c PBIOH-30 can reach 50m S cm^-1 at 170°C.After the capacitor is assembled,the capacitance value increases in a gradient with the temperature rising.At 150°C,the maximum capacitance value can reach62.3 F g^-1.After 5000 charge-discharge cycles,the capacitance retention rate can reach96.1%.Due to the poor compatibility between polybenzimidazole and electrode materials,we selected chitosan,which has good compatibility with activated carbon electrodes,as our next research.By quaternizing chitosan,mixing it with polyvinyl alcohol(PVA),adding ionic liquid to prepare a gel electrolyte,and adding carbon nanotubes to it to form ion transport channels inside the gel,and at the same time carbon The addition of the tube also improves the mechanical properties of the gel.In the end,the proton conductivity of the gel we prepared was 33 m S cm^-1 at room temperature.After being assembled into a supercapacitor device,the capacitance value of the device is 43.15 F g^-1,and the maximum energy density can reach 10.03 Wh kg^-1.And the gel shows excellent sensing ability,the sensing factor is 0.995,the response time is 180 ms,and the excellent performance can still be maintained after multiple cycles.