Determination Of Metal Impurities In Electrolyte Of Lithium Ion Batteries By Inductively Coupled Plasma Emission Spectrometry

As a new energy source,lithium-ion batteries have attracted worldwide attention.At the same time,lithium-ion batteries are favored by more and more people.Lithium ion electrolyte is an indispensable part in lithium-ion batteries,which plays an important role in ion conduction between positive and negative electrodes.At the same time,it has a vital impact on the specific capacity,working temperature,cycle efficiency and safety performance of batteries.The content of metal impurities in lithium ion electrolyte has an important influence on the performance of lithium ion batteries.The content of metal impurities in lithium ion electrolyte was determined by ICP-AES.In this paper,wet digestion and dry digestion(ashing)are used in the pretreatment of lithium ion electrolyte and the two methods are compared.The ashing method can completely decompose the organic components in the sample and eliminate the interference caused by the organic components.At the same time,the method has the characteristics of simple operation,small amount of reagents and low blank.The use of self-made water encapsulation devices in the process of drying samples by low temperature heating makes it possible to form a local super-clean system,which can reduce the risk of external pollution and ensure that the measured samples can be more realistic and accurate.In this paper,the working conditions of the instrument were optimized in the experiment of measuring electrolyte of lithium ion batteries by ICP-AES.The plasma power was 1300W,the cooling gas flow rate was 15.0/(L/min),the auxiliary gas was argon(Ar),the flow rate of the atomizer was 0.2/(L/min),the flow rate of the atomizer was 0.8/(L/min),the pump speed of peristaltic pump was 1.5/(mL/min),and the equilibrium time was 15 sec.At the same time,standard addition method and matrix matching method were used to determine the content of metal impurities in lithium ion electrolyte.The detection limit of each element to be determined by standard addition method is between 0.0004 and 0.0035 g/mL,the quantitative limit is between 0.0014 and 0.0117 g/mL,the precision is between 0.18%and 1.39%,and the recovery is between 90.1%and 105.6%.This method can meet the needs of lithium ion electrolyte determination,but for enterprises,the operation is complex,and Gradient Calibration of each sample is needed.The detection limit of matrix blank plus matrix standard curve method is between 0.0004 and 0.0032 g/mL,the quantitative limit is between 0.0014 and 0.0107 g/mL,the precision is between 0.17%and 1.56%,and the recovery is between 94.9%and 103.1%.This method adds the lithium standard solution of the same amount to the blank and standard solution,which effectively eliminates the influence of the matrix lithium on the elements to be measured.At the same time,this method is simpler and more convenient for the production of enterprises.For the lithium ion electrolyte of the same type and different batches,only one set of standard solution needs to be prepared.Through the experimental analysis of other types of electrolyte in enterprises,this method is proved to be effective.lt is also suitable for the determination of metal impurities in other types of lithium ion electrolytes.The results of ICP-AES and AAS are compared.The conclusion is that the results of ICP-AES and AAS are basically the same.The results of ICP-AES can meet the production standards of electrolyte enterprises.The detection ability and stability of ICP-AES and AAS are compared.The results show that the detection limit of ICP-AES is lower and the precision of ICP-AES is higher than that of AAS.At the same time,ICP-AES has the advantages of fast analysis speed,high sensitivity,good reproducibility,and can simultaneously determine many elements.It is more suitable for the detection of metal impurities in lithium ion electrolyte.