Preparation Of Carboxymethyl Cellulose/Polyacrylic Acid Conductive Hydrogel And Its Application In Sensors And Supercapacitors

Conductive hydrogel has become an ideal material for preparing flexible strain sensors and supercapacitors due to its unique conductivity and flexibility.However,in practical applications,it faces many difficulties such as poor biocompatibility,time-consuming and energy-consuming preparation process,short service life,low conductivity,insufficient sensitivity,and so on.In this work,conductive hydrogels with excellent self-healing and mechanical properties were rapidly prepared at room temperature with carboxymethyl cellulose（CMC）and acrylic acid（AA）as the main materials;After successful application in flexible sensors,highly conductive hydrogel electrolytes with excellent mechanical properties,self-healing properties,frost resistance and,moisture retention properties were prepared by introducing Li Cl,and their applications as flexible sensors were studied;The supercapacitor with excellent performance was assembled from the hydrogel electrolyte and activated carbon electrode.The specific research contents and results are divided into the following three parts:（1）Preparation of self-healing conductive hydrogel and its application in wearable sensors.CMC/PAA/Fe³⁺interpenetrating network hydrogels were rapidly prepared by utilizing a polyphenol-metal ions self catalytic system[sodium lignosulfonate（SLS）-Fe],using CMC and AA as the main raw materials.Among them,SLS-Fe self catalytic system is the key factor for rapid preparation of hydrogels at room temperature.The SLS content ectively increased the gel rate of the hydrogel.The effects of the contents of CMC,AA,and Fe³⁺on the mechanical properties of hydrogels were systematically analyzed.The results show that the addition of CMC increased the tensile strength of the hydrogel;With the increase of Fe³⁺content and AA content,the tensile strength（up to 434 k Pa）and toughness（up to 3.045 MJ/m³）of the hydrogel showed a trend of increasing first and then decreasing;The hydrogel has good self-healing property;When Fe³⁺content is 3%,the maximum conductivity is 2.23 S/m.The strain sensors assembled by CMC/PAA/Fe³⁺conductive hydrogel could detect large movements（fingers,elbow joints,wrist,and knee,bending）and small movements（swallowing）of the human body.（2）Preparation and performance analysis of self-healing antifreezing high conductive hydrogel and its application in wearable sensors.Li Cl was introduced into CMC/PAA/Fe³⁺conductive hydrogel to prepare CMC/PAA/Fe³⁺/Li Cl antifreezing conductive hydrogel.The effects of different Li Cl content on antifreezing performance,conductivity,and mechanical properties of hydrogels were systematically analyzed.The results show that at room temperature,when Li Cl content is 6%,the hydrogel has the maximum tensile strength and toughness,and has good self-healing performance and moisturizing properties.With the increase of Li Cl content,the conductivity first increases and then decreases,with a maximum of 5.89 S/m;At low temperature,the hydrogel still has corresponding mechanical and electrical properties.The conductive hydrogel was made into a multi-functional wearable sensor to test its sensing performance.The results show that the addition of Li Cl improved the sensitivity of the hydrogel sensor（GF=6.19）.When detecting various human activities,the output signal of CMC/PAA/Fe³⁺/Li Cl conductive hydrogel is superior to that of the CMC/PAA/Fe³⁺conductive hydrogel.（3）Preparation and performance analysis of self-healing and antifreezing flexible supercapacitors.A flexible all-solid-state supercapacitor was assembled with CMC/PAA/Fe³⁺/Li Cl antifreezing conductive hydrogel electrolyte and activated carbon electrode.The CMC/PAA/Fe³⁺/Li Cl_-6%hydrogel-based supercapacitor displayed better electrochemical capacitance,exhibiting a single-electrode specific capacitance of 122.36 F/g;After 3000 charge-discharge cycles,the capacitance retention rate can reach 81%;The supercapacitor still showed a single-electrode specific capacitance of 83.16 F/g at-23℃（68%of the one exhibited at 25℃）,indicating good electrochemical performance at low temperature.In addition,the supercapacitor also showed a good ability of flexible,self-healing,and practical application.