Improved method for manufacturing lithium ion battery electrode

Abstract

The invention discloses an improved method for manufacturing a lithium ion battery electrode; the method comprises the steps of preparation of an electrode active compound, current collector pretreatment, electrode active compound pretreatment, variable area densification treatment and batch electrode manufacture. On the basis of an existing electrode manufacturing process suitable for an aqueoussolution, a physical pressing step does not need to be avoided, the improved electrode is efficiently adapted to the cyclic voltammetry characteristic representation of a lithium intercalation material, the obtained cyclic voltammetry curve has a narrow and sharp outlet peak, no distortion, and low background region current, and the current noise caused by the fact that the electrode polarizationoccurs, the unit area active material content is not low and the active layer compaction uniformity is not high enough can be overcome.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to a method for manufacturing an electrode of an aqueous lithium ion battery with high stability. Background technique [0002] Lithium-ion batteries have energy density and power density that are difficult to achieve for most rechargeable battery systems of the same kind in the past, and can achieve the purpose of short-term rapid charge and discharge while improving the battery life of the system. At present, lithium-ion batteries are widely used in modern digital products represented by mobile phones and notebook computers. For the lithium ion energy storage system, each charge and discharge means that an equal amount of lithium ion charge is transferred and stored between the positive and negative electrodes through the electrolyte. The difference in the lithium storage mechanism of the electrode active material determines the difference in the energy storage capac...

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Problems solved by technology

Generally speaking, when the current passes through the path from the current collector to the lithium intercalation material, it must cross several physical contact points, so the finally obtained electrochemical behavior information of the lithium intercalation material must also include noise components such as electrode polarization. Affect the follow-up judgment of the researcher

On the other hand, it must also be pointed out that the general method of making an electrode suitable for aqueous solution is to directly physically press the once-shaped electrode active compound with the cleaned stainless steel mesh, and the electrode prepared in this way can only meet the requirements for the performance of lithium intercalation materials. The test (cycle and rate) is not suitable for electrochemical behavior characterization (cyclic voltammetry test). The performance test uses a constant current as an excitation, and the potential of the lithium intercalation material is used as a feedback. There is no time limit, so that there is enough Time describes the whole picture of the potential change. As long as the differential capacitance curve of the constant current charge and discharge curve is made accordingly, the relationship between the material phase change and the potential trend can be indirectly described. However, this indirect relationship is derived based on the constant current, which is different from the cyclic volt The results of the safety test are different, because the feedback current changes when the linear scanning potential is used as the excitation, including the interaction information between the electrode and the electrolyte; not only that, but the existence of the scanning speed also limits the test time, which means that you want to To obtain an effective cyclic voltammetry curve, it is necessary to control the content of the active material per unit area of ​​the electrode so that it is low enough to ensure that the corresponding redox reaction is completely carried out when the potential sweeps the region near the phase transition potential; the reaction kinetics of various lithium intercalation materials The difference in chemistry determines the speed of the reaction, in other words, the difference in the speed of deintercalation of lithium. For lithium intercalation materials with relatively slow reaction kinetics, a better electrode manufacturing process is bound to be required, and it is difficult to reduce the general electrode method suitable for aqueous solution. The content of active material per unit area of ​​the electrode and the densification uniformity of the active layer are not high enough, so that the electrode is only barely suitable for the electrochemical behavior characterization of lithium intercalation materials with faster reaction kinetics

And Y.G.Wang (Y.G.Wang, J.Y.Luo, C.X.Wang, Y.Y.Xia, Hybrid Aqueous Energy Storage Cells Using Activated Carbon and Lithium-Ion IntercalatedCompounds, Journal of The Electrochemical Society, 153(2006) A1425-A1431) talked about the use of micropowder electrodes (Micropowder Electrode) avoids the instability caused by the physical pressing method to meet the needs of the cyclic voltammetry test environment, but the production of a complete electrode requires the use of glass tubes, platinum wires, gas torches, sandpaper and aqua regia. It is cumbersome and consumes too much material while bearing certain risks

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