Solve the problem of lithium supplement -Lithium - Ion Battery Equipment

How to correctly solve the lithium supplement problem? -Lithium - Ion Battery Equipment

The topic of lithium supplement has been a commonplace. We have simply summarized the current mainstream lithium supplement process. In general, the technology of using metal Li powder and Li foil to directly supplement lithium to the negative electrode is highly mature, which is also the main method used by power battery manufacturers at present. However, safety issues and high costs are unavoidable problems of metal Li lithium supplement. In contrast, the anode lithium supplement process has good safety and does not change the existing process, but the technology maturity is low, so relevant material manufacturers need to launch corresponding products.

In addition to adding a small amount of lithium oxide with high capacity to the positive electrode system, another method of lithium supplement for positive electrode is to add excessive Li element during the synthesis of positive electrode material, so as to store excessive Li in the positive electrode material. During the first charge, excessive Li can be released to supplement the Li element consumed by the negative electrode, so as to improve the first efficiency.

There are generally two ways to add excess lithium to the positive electrode material. The first is to embed Li+into the positive electrode material through electrochemical reaction. Generally, the positive electrode material and metal Li form a half battery to embed lithium into the positive electrode material, and then the positive electrode material and ordinary negative electrode form a full battery to achieve the purpose of lithium supplement. This method is relatively simple and can well control the amount of embedded Li. It is suitable for use in the laboratory, but its shortcomings are also obvious. The operation is relatively complex and has no practical value in actual production. The other method is to add excessive Li in the process of synthesis by chemical method. Although the technical difficulty is relatively high, it does not need to add additional processes in battery production, so it has more practical value.(Lithium - Ion Battery Equipment)

The concept of positive pole pre lithiation comes from GiulioGabrielli et al. of Germany. GiulioGabrielli first reported that Li1+XNi0.5Mn1.5O4 material was synthesized by chemical method in 2016, but at that time GiulioGabrielli hoped to improve the reversible capacity of LiNi0.5Mn1.5O4 material (147mAh/g) by synthesizing Li1+XNi0.5Mn1.5O4 material (200mAh/g), Until 2017, Giulio Gabrielli and other talents discovered the potential of Li1+XNi0.5Mn1.5O4 material in solving the problem of low efficiency of lithium ion batteries for the first time. After excessive Li was removed during the first charging process, Li1+XNi0.5Mn1.5O4 material was transformed into normal LiNi0.5Mn1.5O4 material. By controlling the mixing of Li1+XNi0.5Mn1.5O4 material with LiNi0.5Mn1.5O4 material in different proportions, the proportion of excess Li can be accurately controlled, Therefore, the irreversible capacity loss of the cathode during the first charging process can be completely compensated, which is also an innovation and breakthrough in the anode lithium supplement process.

GiulioGabrielli synthesized Li1+XNi0.5Mn1.5O4 material by chemical synthesis, which directly added excessive Li in the process of material synthesis, so it is more practical and effective to solve the problem of low efficiency of lithium ion battery containing SiOx for the first time. However, it is not easy to add excessive Li to the cathode material to form a stable structure and ensure that the cycling performance of the material will not be affected. The editor also reviewed all the articles published by Giulio Gabrielli. At present, there is no report that Giulio Gabrielli has applied this method to other materials (such as NCA and NCM materials), which also reflects that this method is not suitable for all cathode materials.

Recently, VanchiappanAravindan from India found that this method can also be applied to LiVPO4F material. VanchiappanAravindan adopted a relatively simple electrochemical embedding method, which is to first make a battery of LiVPO4F and metal Li, conduct discharge to embed Li+into LiVPO4F material to form Li1.26VPO4F, and then dissect the battery. Li1.26VPO4F and anode material (a-Fe2O3 used here) form a full battery, The irreversible capacity (about 503mAh/g) of a-Fe2O3 material in the first lithium insertion process is compensated by the excessive Li element in Li1.26VPO4F material, which greatly improves the energy density of the whole battery. However, this method needs to first form a half battery and embed Li+into the cathode material by electrochemical method, so it is of little significance in practical production. Therefore, it is necessary to continue to explore how to directly synthesize Li1.26VPO4F material with excessive lithium by chemical method to realize lithium supplement for the cathode.



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