Preparation And Performance Research Of Plant-Based Carbon Electrode Materials

The rapid growth of the global economy and the over-exploitation of fossil energy have irreversibly caused increasingly serious problems,such as energy depletion and environmental pollution.The development of green energy is an ideal alternative to traditional fossil energy sources,such as solar,hydro and wind energy.However,low-frequency,irregular and intermittent characteristics of such energy sources often severely restrict the efficiency in energy conversion and storage.The integrated self-powered energy storage system that consists of triboelectric nanogenerator（TENG）and supercapacitor（SC）has the characteristics of excellent adaptability,high cycle stability and fast charging/discharging rates,which provides a viable solution to the conversion and storage of green energy.As a crucial component of device,electrode with plant-based porous carbon is widely investigated by researchers for its high specific surface area,great stability and excellent electrical conductivity properties.In this paper,Pistia stratiotes and Salvinia adnata were selected to prepare plant-based porous carbon materials and applied as electrode materials in self-powered energy storage system,which can convert mechanical energy into electrical energy and eventually store it in device.The studies are as follows:（1）Pistia stratiotes was selected as biomass precursor for the preparation of porous carbon material by two-step carbonisation and activation method.Exploring the effect of activator ratio and activation temperature on the structure and performance of the product.As the electrode material for supercapacitors,PSC-1-800 achieves a specific capacitance of 301.8 F g^-1 at a current density of 0.5 A g^-1.Symmetrical supercapacitors（PSC-SCs）exhibit an energy density of 9.305 Wh kg^-1 at a power density of 498.4 W kg^-1,and PSC-SCs retain 96.9%of its initial performance after 5000 charge/discharge cycles.As triboelectric nanogenerator electrodes,PSC-TENG exhibits a short-circuit current（Isc）of 1.22 μA and open-circuit voltage（Voc）of 7.81 V at 1 Hz operating frequency of 1 Hz.The self-powered energy storage device PSC-TENG-SCs consists of PSC-SCs and PSC-TENG modules,which can store energy and light up the LED via 115.6 s charging time at an operating frequency of 1 Hz.The PSC-TENG-SCs integrated system shows high efficiency in energy conversion and storage,while it also possesses the eco-friendly,low-cost and easy processability properties of plant-based porous carbon materials.（2）The manganese oxide loaded Salvinia adnata carbon material（SAC-MnO）was prepared by hyperaccumulation cultivation and two-step carbonisation/activation process,the obtained SAC-MnO exhibits ultrahigh specific surface area of 2396 m² g^-1 and superior pore volume of 1.538 cm³ g^-1.Owing to the synergistic effect of EDLC and pseudocapacitance,SAC-MnO-0.020 achieves an excellent specific capacitance of 436.8 F g^-1 at a current density of 1 A g^-1.The symmetric supercapacitor（SCs）shows an energy density of 9.573 Wh kg^-1 at a power density of 694.4 W kg^-1,with outstanding cycle stability of 94.7%at 5 A g^-1 after cycling 1000 times.As electrode materials for triboelectric nanogenerator,SAC-MnO-0.020 based TENG achieves an open-circuit voltage and short-circuit current of 20.3 V and 3.68 μA,respectively.The device also exhibits a performance retention rate of 97.8%after 1000 cycles,at an operating frequency of 1 Hz.Furthermore,the self-powered energy storage system TENG-SCs is obtained by the integration of SCs and TENG modules,and the device can be charged to 2V after 137 s.Based on the synergistic effect of plant-based porous carbon and manganese oxide,TENG-SCs demonstrates excellent electrical output performance.Additionally,the integrated printing of carbon electrodes on packaging materials can be realized by screen printing technology,which shows promising applications in the field of Internet of Things and Smart Packaging.