Preparation And Properties Of Carbon-based Anode Materials For Sodium Ion Hybrid Capacitors

In recent years,with the continuous development of human society and the rapid growth of population,the consumption of all kinds of fossil energy has accelerated day by day,resulting in serious energy crisis and environmental degradation.As the largest developing country in the world,China has a huge demand and consumption of energy and faces the most challenges.In this context,the importance of vigorously promoting the energy revolution and actively developing new green energy is self-evident.As energy storage and conversion equipment,energy storage devices are the key technical support of energy revolution.Electrochemical energy storage represented by lithium-ion battery has become the most widely used energy storage technology with its outstanding advantages.However,lithium resource reserves are limited and unevenly distributed,and its price is also rising with the large consumption of lithium,which is bound to restrict its further application.In contrast,sodium is abundant,widely distributed and cheap,and its physical and chemical properties are similar to lithium.Therefore,sodium is recognized as an available electrochemical energy storage raw material,and has become a research hotspot of a new generation of energy storage devices all over the world.Sodium-ion hybrid capacitor is a new type of electrochemical energy storage device,which has broad application prospects.However,the cathode and anode dynamics of sodium-ion hybrid capacitors do not match.The key lies in the development of excellent electrode materials,especially battery anode materials.Therefore,this paper focuse s on the application of biomass based carbon materials and Sb based composites in the field of sodium storage.The main contents are as follows:（1）Biomass derived porous carbon（BDPC）materials were designed and prepared by pre-carbonization and activation based on the inherent pore structure of Qamgur,a biomass from Xinjiang,China.The structure of the material was characterized by scanning electron microscopy,X-ray diffraction,Raman spectroscopy,X-ray photoelectron spectroscopy and nitrogen adsorption/desorption test.The electrochemical properties of the materials were characterized by cyclic voltammetry,constant current charge discharge,cyclic rate and electrochemical impedance analysis.The results show that BDPC-600 has good sodium storage performance because it contains nitrogen and oxygen heteroatoms（the contents are 3.36 at.%and 7.61 at.%,respectively）:at 0.1 A g^-1 current density,after 100 cycles of charge and discharge,the reversible capacity is 187.7 mAh g^-1 and the capacity retention rate is 88.7%.In addition,BDPC-900 has excellent magnification performance due to its large specific surface area(2396.60 m² g^-1)and pore volume(1.70 cm³ g^-1).（2）Biomass derived porous carbon composites loaded with metal Sb were prepared by a simple liquid-phase reduction method（Sb@BDPC）,it was confirmed that the metal Sb existed in the pores of porous carbon by various structural characterization methods,and the composite material was used as anode to assemble a half cell to test its sodium storage performance.Due to the synergistic effect of Sb nanoparticles and porous carbon,Sb@BDPC-900 shows excellent electrochemical performance:it maintains 302.7 mAh g^-1after 100 cycles with the capacity retention of 85.24%.Even when the current density is 1 A g^-1,a reversible capacities of 168.3mAh g^-1can still be maintained after 500 cycles with the capacity retention rates of 97.56%.In addition,a sodium-ion hybrid capacitor was assembled with BDPC-900 composites as anode and commercial activated carbon（AC）as cathode.Its energy density was 180.3 Wh kg^-1 and power density was 1342 W kg^-1.