Research On The Preparation And Performance Of Flexible Memristors And Supercapacitors For Plant Wearable Devices

The flexible electronic devices have inspired emerging fields such as plant wearable devices because of their excellent biocompatibility and ductility.Their application in agricultural production is promising.Due to the influence of functional materials,most of the current research on plant wearable devices suitable for agriculture focuses on sensors,lacking good information preprocessing and energy supply devices.Two-dimensional(2D)materials are layered materials that can be reduced to single atom thickness,and exhibit terrific mechanical strength and flexibility.Memristor is a new type of information processing device with high speed and low energy consumption.Supercapacitor is an energy storage/supply device with high energy density.At these levels,research on flexible memristors and supercapacitors based on 2D materials has far-reaching significance for expanding the application of plant wearable devices in agriculture.However,there are still challenges to prepare high-performance flexible memristors and supercapacitors due to some limitations.Most previous studies of 2D material-based memristors have used sputtering or depositing metal electrodes directly on the material,which not only makes it difficult to obtain atomically flat electrode/switching layer contact interfaces,but also introduces additional defects,leading to unreliable switching behavior and high contact resistance.To solve the problem,a continuous 2D materials transfer method is designed in this experiment to fabricate novel Graphite/h-BN/Graphite van der Waals(vd W)heterostructur memristor.The single-crystalline h-BN layer is sandwiched between two thin graphite electrodes,avoiding the use of metal electrodes and the residue of transfer polymers,and obtaining atomically sharp contact interfaces.In such a device,a stable bipolar resistive switching(RS)behavior has been observed for the first time,and achieve an on/off ratio of >103 and a resistance retention time of >5 ×104 s.The variation coefficients of SET and RESET voltages are as low as 6.21% and 3.81%,respectively.In addition,after 800 bending cycles on a PI substrate,the electrical properties of the memristive device show no degradation.This part of the work proposes a new type of single-crystalline vd W heterostructure for future highperformance flexible memristor applications,and the Graphite/h-BN/Graphite memristor is expected to serve as an information preprocessing device for plant wearable devices.Supercapacitor based on 2D materials have been widely studied.However,there are usually some problems,such as complex preparation process,low controllability,need to use adhesive and so on,which affect the electrochemical performance of the device.In order to solve these problems,we fabricated a unique heterostructure(SCu Se@Ni Se)consisting of the Cu Se@Ni Se loaded on Cu foam through a simple onestep in-situ hydrothermal method,which is convenient to operate,reliable in controllability,and low in cost.Furthermore,it avoids the use of carbon black and adhesive in the electrode,resulting in an improvement of the electrode conductivity.This heterostructure is beneficial for electron transport and can adapt to the volume change of electrode materials during the charge and discharge process,causing an excellent electrochemical performance.The specific capacitance of the S-Cu Se@Ni Se is 1478 F/g at a current density of 1 A/g and stabilizes at 990 F/g at 8 A/g.The specific capacitance retention of S-Cu Se@Ni Se is 81.7% after 10000 cycles.Moreover,the allsolid-state flexible supercapacitors prepared with S-Cu Se@Ni Se as electrode(SCu Se@Ni Se-SFCs)also exhibit excellent flexibility and electrochemical performance.Its capacitance reaches 333 F/g at a current density of 1 A/g.Capacitance retention of79.3% has been obtained after 10000 charge-discharge cycles at 2 A/g.To further demonstrate its practicality,two S-Cu Se@Ni Se-SFCs are connected in series and the red LED is illuminated for a long time after a short charging period.Compared with other supercapacitors,S-Cu Se@Ni Se-SFCs can work for a longer time under a shorter charging time.This part of the work demonstrate that the 2D Cu Se@Ni Se heterostructure is a promising candidate material for use in high performance,flexible,all-solid-state supercapacitors,and S-Cu Se@Ni Se-SFCs is expected to be a highdensity energy storage/supply device for plant wearable devices.