摘要
锂离子电池具有工作电压高、循环寿命长及能量密度大等突出优点广泛应用众多领域,其中负极材料直接决定电池性能。为提高锂离子电池负极材料性能,利用微弧氧化技术在钽片表面制备出一种以Ta_(2)O_(5)为主晶相的多孔膜层,将该膜层作为锂离子电池负极,锂片为对电极并组装电池。利用X射线衍射(XRD)及扫描电镜(SEM)对材料进行表征,使用电池测试系统测量电池容量及循环稳定性,通过电化学工作站获得循环伏安曲线与电化学阻抗谱特性。结果表明:多孔膜主要成分Ta_(2)O_(5)均匀分布在钽片表面,其组装的电池在100μA·cm~(-2)的电流密度下,首圈放电比容量为3043.5 m Ah·cm^(-3),达到Ta_(2)O_(5)理论放电比容量的77.0%,稳定后其库伦效率保持在100%左右,表现出较高的比容量。在1和2 m V·s^(-1)扫描速度下,电极循环伏安(CV)测试形状几乎保持不变,具有良好的动力学可逆性。在阻抗测试中该负极材料的电荷转移电阻为215Ω,锂离子扩散速度快,有利于电子长程传导,从而降低欧姆极化。在钽金属表面制备了一种合成方便、效率高且性能优越的锂离子电池负极。微弧氧化技术可高效地制备多孔状及无粘结剂的Ta_(2)O_(5)负极材料,其高容量的电化学性能具有良好的发展前景。
Lithium-ion batteries are involved in almost every field,especially mobile consumer electronics,because of their outstanding advantages such as high operating voltage,long cycle life and high energy density.As an important part of lithium-ion batteries,anode directly determines the performance of lithium-ion batteries.Traditional anode preparation process for lithium-ion batteries is complex and time-consuming,and the binder hinders lithium ion diffusion channel and affects the electrochemical performance.In the acidic electrolyte,the tantalum surface undergoes reaction to form a stable anodic oxide coating.The oxide tantalum pentoxide(Ta_(2)O_(5))has a theoretical specific capacity of up to 482 mAh·g-1.Micro-arc oxidation is a technology that uses plasma discharge in the electrolyte to form a ceramic coating layer in situ on the surface of valve metals such as aluminium,magnesium,titanium,and others.Microarc oxidation technology offers several advantages,including simple operation,high efficiency,short processing time,low cost,low requirements for the experimental environment,etc.It can be completed at room temperature and normal pressure without the need for post-treatment.Currently,micro-arc oxidation technology has been widely used to improve the wear resistance,biocompatibility,and resistance to high-temperature oxidation of materials.However,its application in the field of energy batteries is still relatively limited.Therefore,the aim of this paper was to grow a porous coating layer with Ta_(2)O_(5) as the primary crystalline phase on the surface of tantalum sheet in-situ through the micro-arc oxidation process.This coating could be directly used as the anode of lithium-ion batteries due to its high-capacity electrochemical performance,and it held promising potential for further development.Through the micro-arc oxidation reaction,the porous Ta_(2)O_(5) coating layer was grown in-situ on the tantalum sheet.The abundant pore structure facilitated the diffusion of the electrolyte and accelerated the movement of lithium ions to the electrode surface.The experimental operations were as follows:Ta sheet was pre-treated before the experiment,and the metal surface was mechanically polished using SiC sandpaper to remove the oxide layer until the surface was smooth and flat.Subsequently,the surface was washed and air-dried in anhydrous ethanol.In the silicate electrolyte system,the polished and cleaned tantalum sheet was immersed as the anode,while a stainless steel tank served as the cathode.The experimental parameters were configured to carry out the micro-arc oxidation reaction.Taking the tantalum sheet that had reacted,cleaning the residual electrolyte on the surface and drying it to obtain Ta_(2)O_(5) coating layer.The coating layer was used as the anode of the lithium-ion battery,and the lithium sheet functioned as the counter electrode to assemble the battery.The cell assembly of cut specimens was conducted in a glove box(H2O<0.1×10-6,O2<0.1×10-6)in an argon atmosphere,following the order as:positive shell,negative material,electrolyte,diaphragm,electrolyte,lithium sheet,gaskets,shrapnel,and negative cover.X-ray diffractometer(XRD)and scanning electron microscope(SEM)were used to characterize the phase composition of the coating layer and the surface phase appearance.In the study of electrochemical performance,the constant current charge/discharge performance of lithium-ion battery was tested within the voltage range of 0.01~3 V.Cyclic voltammetry(CV)was carried out in the same voltage range but with different scan rates.Electrochemical impedance spectroscopy(EIS)of the battery was investigated using an electrochemical workstation with a frequency of 100 kHz to 0.01 Hz.XRD results showed that the micro-arc oxidation technique could be used to grow in-situ on the tantalum surface with Ta_(2)O_(5) as the main crystalline phase.This coating layer could provide a theoretical capacity of up to 482 mAh·g^(-1),surpassing that of graphite anode and some conventional oxides.Thus,it had potential applications in electrochemical energy storage.According to SEM images,it could be seen that the substance was uniformly distributed on the surface of the tantalum sheet.The pore distribution was uniform,the binding was good,and a large number of micropores provided high activity for the specimen.Charge-discharge cycles were performed on the assembled battery at a current density of 100μA·cm^(-2).The first-turn discharge specific capacity was 3877.0 mAh·cm-3,reaching 98.1%of the theoretical discharge specific capacity of Ta_(2)O_(5),which demonstrated a high specific capacity and suggests potential applications in electrochemical energy storage.In EIS test,Ta_(2)O_(5) anode material had the advantages of lower charge transfer resistance and faster lithium ion diffusion,which was beneficial for long-range electron conduction,ultimately reducing ohmic polarization.In the present study,lithium-ion battery anode was prepared on the surface of tantalum metal using a simple synthesis method,achieving high efficiency and excellent performance.The micro-arc oxidation technique could efficiently prepare porous,binder-free Ta_(2)O_(5) anode materials,and its high-capacity electrochemical performance had promising application prospects.
作者
郝国栋
田雪
Hao Guodong;Tian Xue(College of Chemistry and Chemical Engineering,Mudanjiang Normal University,Mudanjiang 157011,China;College of Materials and Engineering,Jiamusi University,Jiamusi 154007,China;Provincial Key Laboratory of Optoelectronic Functional Materials of Heilongjiang Province,Mudanjiang Normal University,Mudanjiang 157011,China)
出处
《稀有金属》
EI
CAS
CSCD
北大核心
2024年第7期1050-1055,共6页
Chinese Journal of Rare Metals
基金
国家自然科学基金项目(51672120)
黑龙江省自然科学基金项目(LH2023E101)
牡丹江师范学院教学改革项目(SJGY20210900)资助。
关键词
钽
微弧氧化
锂离子电池
负极材料
tantalum
micro-arc oxidation
lithium-ion batteries
negative electrode material
