Study On The Process Of Synthetising Lithium Nitrate By Electrodialysis-metathesis

Lithium nitrate is an important lithium salt.It's widely used as a raw material for the synthesis of ternary battery cathode materials.However,there are some limitations in the existing synthesis process of Lithium nitrate,such as tedious operations,high costs,and terrible environment pollution,which need to be solved urgently.The paper first proposed a synthetic route for lithium nitrate by electrodialysis-metathesis.The core component of the experiment is a four-compartment electrodialysis membrane stack,which was independently designed and built.The route of synthetizing lithium nitrate was studied first in the batch mode and then the continuous mode.In this paper,the synthesis of lithium nitrate by electrodialysis-metathesis was discussed deeply and a new and efficient way has been developed.First of all,The batch electrodialysis-metathesis method which synthetizing different concentrations of lithium nitrate was mainly carried out in the following aspects:the online data of the membrane stack were studied,which consisted of voltage?current?resistance and other parameters.The offline data of the membrane stack were also analyzed,which consisted of the variation of volume and ion concentration in chamber,current efficiency and other parameters.It found that the main ion concentration of the product chamber rose constantly when the main ion concentration of feed chamber continued to increase.However,the purity of product kept falling.The relevant parameters were compared,which demonstrated that the route of synthetizing lithium nitrate is feasible and the feed solution of 1M was regarded as optimal concentration.The current efficiency was 78%and the purity of product was97%.Based on the results of batch electrodialysis-metathesis experiment,the paper carried out a follow-up experiment of synthetising lithium nitrate by continuous electrodialysis-metathesis method,which would have stronger effect on the continuous production that operated in the large-scale industry.The 1M was chosen for the best value of feed solution.Lithium nitrate with different concentrations was synthetised by adjusting the value of supply liquid.The relevant parameters were studied,including online and offline data of the membrane stack.The experiment found that both concentration of the feed chamber and the product chamber could be stable in a certain range,which would be considered to reach equilibrium.It also found the content of Na⁺impurities had a negative effect on the quality of product.It was the 1.50M which was chosen for the most suitable concentration that was used for the synthesis of Li NO₃ by continuous electrodialysis-metathesis method.The current efficiency was 75%.However,the purity of product was only 92%.In summary,this paper shows that the electrodialysis-metathesis method of synthetising lithium nitrate is feasible at the first time.Besides,it is also a green and efficient process,which will have great potential to be used in practical industrial production.