| Excessive consumption of fossil fuels and the objectives for carbon dioxide peaking and carbon neutrality have drawn widespread concern about energy and environmental issues.At the same time,green and sustainable energy has always been a research hotspot and a prerequisite for the healthy development of society.A wide variety of electrochemical energy storage devices such as rechargeable batteries,fuel cells,and supercapacitors have been extensively studied.The advantages such as capacity and safety and environmental protection of aqueous electrolytes are particularly concerned.In particular,the layered double hydroxide（LDH）-based asymmetric supercapacitor（ASC）combines the large surface area and large number of electrochemically active sites of the LDH cathode material with the fast capacitive energy storage behavior of carbon-based anode material.They also incorporate environmental protection and safety advantages of aqueous electrolytes,making it a hot research topic today.However,the performance of LDH is affected by its morphology and structure,which limits the practical application of electrodes.As a result,designing a multi-dimensional nanoarray structure that enhances surface reaction and improves the utilization of active materials can help to improve the performance of supercapacitor electrodes.Based on this,we presented various synthesis methods to produce LDH and its composites with various morphologies,while choosing suitable anode materials to construct high-performance asymmetric supercapacitors.Details are as follow:（1）One-step solvothermal approach was used to generate flower-like Ni Mn-LDH on hr GO substrate.The hr GO supported Ni Mn-LDH development while also offering an extra electron transport channel.Ni Mn-LDH/hr GO electrodes were produced and their electrochemical characteristics assessed using graphite paper as the current collector.When compared to Ni Mn-LDH electrodes,Ni Mn-LDH/hr GO electrodes have a greater specific capacitance and rate performance.Bi（OH）3/hr GO was employed as the anode to compensate for the narrow potential window of the cathode,resulting in high-performance ASC devices.The gadget may function normally when the ASC is linked in series with the LED light group and the timer,indicating its versatility.（2）In the previous work,the cathode LDH material was found to be prone to oxygen evolution at high potential,which led to a limited potential window and limited cycling performance.Based on this,a simple co-precipitation method was used to construct a three-dimensional layered stable structure of Co Al-LDH.The potential window was increased to-0.1 V-0.5 V,and the cycle stability was outstanding,with just a 5.7 percent loss in specific capacitance after 4000 cycles.To improve the cycle stability of ASC,an anode is built using A4 paper-derived activated carbon material.After 3000 cycles,the built Co Al-LDH/AC ASC device had a capacitance retention rate of 95.6 percent.We have successfully linked two ASC devices in series to power fans and boat models,demonstrating that great performance of ASC is suited for a variety of practical applications.（3）The active material synthesized in the previous works require a binder during the electrode preparation process,which significantly limits their performance to some extent.The preparation of LDH electrodes by electrodeposition can solve this problem effectively.The spherical Ni Co-LDH electrode was prepared by in situ electrodeposition on graphite paper and its microstructure was observed by SEM and TEM.The electrochemical properties demonstrates that the specific capacitance is 735 F g-1at a current density of 1 A g-1.After 3000 charge-discharge cycles at a current density of 10 A g-1,the capacitance retention rate is 80.4%.Furthermore,Ni Co-LDH//AC asymmetric supercapacitors is constructed using A4 paper-derived activated carbon as anode material from previous research.It is applied to a power model vehicle,which further illustrates the potential application of Ni Co-LDH-based ASC in the power system. |
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