Machining And Energy Storage Of Multifunctional Threedimensional Electrodes For Flexible Wearable Devices

Intelligent wearable electronic devices（IWEDs）have been widely used in daily life,and IWEDs are developing towards lightweight and flexibility.Traditional micro energy devices（MEDs）integrated with current collectors are too rigid and bulky,which are obviously not suitable for portable device.In addition,MEDs have been transformed into integrated multifunctional integrated systems,which are based on the original functions（energy supply and wearable）,additional functions such as electrochromic,transparency and self-healing,making MEDs more suitable for smart wearable electronic devices.As the core component of the battery/capacitor,the current collector is mainly used to carry active materials and collect and transfer electrons.Commercial flat aluminum foil and copper foil current collectors only can carry limited active materials,which results in low energy density and high mass of the entire device.Therefore,the development of high-load,lightweight and flexible three-dimensional current collectors and integration into multifunctional MEDs has been particularly critical.Previous work focused on reducing the thickness of the current collector,but the limited load is always difficult to achieve good energy supply and function,so it is difficult to apply to the market.Therefore,a three-dimensional lightweight and thin flexible metal micromesh current collector is prepared by combining photolithography with electrochemical deposition technology,and the integrated smart energy supply device has a high specific capacity.The main research is as follows:（1）The flexible ultra-thin three-dimensional ordered interconnected conductive micro-mesh（3D NM）is constructed through ultraviolet lithography and electrodeposition technology.The 3D NM is characterized by tensile and bending tests and shows that constant resistance after multiple bending,excellent mechanical flexibility,and much better area density than the flexible 3D collectors currently available in the market.The 3D NM and highly capacity nickel-cobalt bimetal hydroxide（NiCoBH）are integrated into a flexible smart supercapacitor.The electrochemical test shows that the 3D NM@NiCoBH electrode has higher specific capacitance and excellent rate performance compared to the planar 3D NM@NiCoBH electrode.Moreover,the 3D NM@NiCoBH and 3D NM/NPC integrated a flexible smart hybrid supercapacitor exhibits high specific capacity and excellent stability,which shows the power change of the device to users through color changes（1.5 V:dark green,0 V:brown）.（2）By designing and adjusting the duty ratio and pattern shape of the metal grid pattern,ultra-light and flexible transparent 3D NM is obtained via combining photolithography and electrodeposition techniques,and the composite 3D NM@Cu（OH）₂@NiCoBH transparent electrode is further obtained via electroplating Cu and etching.The 3D hierarchical structure can enlarge the interface with the electrolyte,while the self-supporting electrode can realize rapid electron transfer,which is beneficial to improve the specific capacity and rate performance.Optical and electrochemical test results show that the specific capacitance of 3D NM@Cu（OH）₂@NiCoBH electrode is as high as 66.03μAh cm^-2,63%@550nm（transmittance）;the integrated a flexible solid-state transparent alkaline zinc battery has high specific capacity(44.86μAh cm^-2)and high light transmittance（36%@550nm）.