Study On The Super Capacitive Properties Of Transition Metal Sulfide/Graphene Flexible Electrodes Constructed By Inkjet Printing

Supercapacitor（SCs）is a potential electrochemical energy storage device with high power density,long cycle life and environmental protection.However,its practical application is seriously restricted due to the low energy density.It is an effective way to improve the overall performance of SCs to develop high-performance and low-cost electrode materials or construct new structured electrode.Ink-jet printing technology has the advantages of low cost,high precision,no contact and no substrate selectivity,etc,and which has been used in the fabrication of solar cells,sensors and other devices.In this paper,the transition metal sulfides and graphene were selected as electrode active materials.And the electrodes with superior structure were constructed by inkjet printing technology.The electrochemical performance of the electrode was investigated and its practical application ability was evaluated.The specific studies of this paper are as follows:The Mo S₂/N-r GO/Ag@P electrode was constructed by deposition Mo S₂/N-r GO composite materials prepared by hydrothermal method and siliver nanowires onto A4 paper by inkjet printing.The results of relevant electrochemical characterization show that the electrical conductivity of the electrode is enhanced due to the added of Ag NWs,and the electrochemical performace is further enhanced.And the areal specific capacitance of Mo S₂/N-r GO/Ag@P electrode is 101 m F·cm^-2 at the current density of 0.1 m A·cm^-2.A symmetrical supercapacitor was assembled,which could achieve the specific capacitance of3.9 m F·cm^-2 at the current density of 0.1 m A·cm^-2.The capacitance of the device remains77.2%of its original value after 1000 charge and discharge cycles at the current density of 0.3m A·cm^-2.The Ni₃S₄/NiS/r GO@CC electrode with coating structure was prepared by deposition of Ni₃S₄/NiS/r GO and r GO on carbon cloth substrate by inkjet printing technology.And the electrochemical performance of Ni₃S₄/NiS/r GO@CC electrode was investigated in 3 M KOH.The results show that the Ni₃S₄/NiS/r GO@CC electrode exhibits a high specific capacitance of 942.8 F·g^-1 at 1 A·g^-1 and excellent capacity retention about 78.2%after 2000 charge and discharge cycles at 5 A·g^-1.The Ni₃S₄/NiS/r GO@CC//AC asymmetric supercapacitor was assembled with activated carbon negative electrode.Which achieves a high stable voltage of1.6 V.The device delivers a maximum specific capacitance of 205 F·g^-1 and the energy density of 73.2 Wh·kg^-1.The capacitance retention rate of the device is 76.7%after 2000charge and discharge cycles at high current density.The Ni₃S₄/Co S/r GO@CC electrode with core-shell structure was prepared by inkjet printing r GO on Ni₃S₄/Co S nanosheets that synthesized by hydrothermal and electrochemical deposition.The Ni₃S₄/Co S/r GO@CC electrode exhibits a high specific capacitance and excellent cycle life due to the interaction of the internal 3D network structure of the electrode and the surface r GO.The specific capacitance of Ni₃S₄/Co S/r GO@CC is as high as 1092.8F·g^-1 at 1 A·g^-1,and the capacitance retention rate is 83.29%after 2000 charge and discharge cycles at 10 A·g^-1.The practical application capacity of the Ni₃S₄/Co S/r GO electrode active materials was investigated by assembled asymmetric supercapacitor with active carbon negative electrode.The Ni₃S₄/Co S/r GO@CC//AC asymmetric supercapacitor achieves a high specific capacitance of 275 F·g^-1 and a high energy density of 97.69 Wh·kg^-1.Furthermore,the device also has excellent cyclic stability,with only 12.13%capacitance attenuation after2000 cycles at current density of 15 A·g^-1.