Preparation Of Rice Husk-derived Novel Carbonaceous And ZnO Composites Anode Materials And Their Electrochemical Performance

With the extensive application of electric vehicles and the rapid development of high-tech,the traditional energy storage devices have been unable to meet the requirements of the market.Lithium-ion battery?LIB?gradually replaced the traditional battery because of its unique advantages such as high energy density,high operating voltage and stable cycling performance.In order to develop new high-performance LIB anode,transition metal oxides?TMOs?materials basing on alloying reaction have been studied extensively in the past few years.Among the TMOs anodes,ZnO has received much attention as it possesses theoretical capacity as high as 978 mAh g^-1.However,because of its high working potential,the structure of ZnO is easy to be broken down when the large volume change happened in the Li⁺insertion/extraction process.The destruction of the electrode structure makes the capacity attenuation become relatively fast.To overcome this problem,a well-accepted method is to fine assembly of ZnO and carbon as LIB anodes,which obtained synergistic effects by combining the excellent conductive of carbon and the high theoretical capacity of ZnO.In this way,electrode materials with stable cycle performance can be prepared.In recent years,graphite,as a traditional LIB anode material,has been limited in practical application due to its small interlayer spacing and low theoretical capacity.Some carbon materials with good lithium storage properties have been studied extensively.However,the production cost of these carbon materials is high;the production process is complex and even has potential safety hazards.It makes researchers pay more attention to biomass carbon materials.In this paper,rice husk in agricultural waste was selected as raw material,and cellulose and lignin in rice husk were used as carbon sources to prepare rice husk-based carbon and zinc oxide composites with different morphologies.In order to explore the properties of the materials,the micro-Characterization and electrochemical performance tests were carried out.The main content of this article is as follows.?1?Taking cellulose in rice husk as carbon source,impurities such as silicon dioxide and lignin in rice husk were removed by alkali boiling and acid pickling.Cellulose was carbonized into amorphous carbon materials connected by a large number of hollow spheres under hydrothermal conditions,and then compounded with ZnO nanorods by electrostatic interaction to form a stable three-dimensional composite structure.The influence of different parameters in the hydrothermal carbonization process and the material comparison between the two materials on the electrochemical properties of the material was investigated.The synthesis mechanism of composites and the relationship between structure and properties were analyzed.Finally,the composite was compared with the pure phase.The materials exhibited promising Li storage properties and high specific charge capacities of 920 mAh g^-11 at 0.2 C after 100 cycles.?2?The lignin in the waste liquor of cellulose extraction was used as carbon source.The lignin was filtered out by acid analysis,activated by zinc chloride,and compounded with ZnO nanoparticles by two different methods under solvothermal conditions.The ZnO was loaded on the surface of rough and porous amorphous carbon.First,the two methods were compared by electrochemical performance test,and the synthesis mechanism and structural advantages were analyzed.Next the composite was compared with the pure phase to determine the effect provided by the different components.Under the electrochemical test,the material exhibited good cyclic stability and rate performance,and the capacity was 898.1 mAh g^-1 after 110 cycles at 0.2 C.