Multilayer positive plate with lithium/sodium supplementing function, battery and preparation method

Abstract

The invention discloses a multilayer positive plate with a lithium / sodium supplementing function, a battery and a preparation method, and belongs to the field of energy storage devices. The multilayerpositive plate comprises a current collector, a positive electrode material layer and a lithium / sodium supplement material layer. A positive electrode material layer and a lithium / sodium supplementing material layer are symmetrically arranged on the two sides of the current collector. The positive electrode material layer and the lithium / sodium supplementing material layer are laminated. The lithium / sodium supplementing material layer contains a special lithium / sodium-containing functional material. When the positive electrode is charged for the first time, a decomposition reaction occurs, sothat lithium / sodium ions in molecules of the positive electrode are irreversibly released into the battery, and the released lithium / sodium ions are supplemented into the negative electrode of the battery through an electrolyte, so that the problem of poor performance of the whole battery caused by low initial charge-discharge coulombic efficiency of an existing high-capacity negative electrode material is solved. The composite positive plate can efficiently supplement lithium / sodium to the negative electrode in the lithium / sodium ion total battery, has no adverse effect on the positive electrode material and the total battery, and can improve the energy density and the utilization rate of the positive electrode material of the battery, so that the cost of the battery can be reduced.

Description

technical field [0001] The invention belongs to the field of lithium / sodium ion energy storage appliances, and more specifically relates to a multilayer positive electrode sheet with the function of replenishing lithium / sodium, a battery and a preparation method. Background technique [0002] In order to meet the large-scale energy storage requirements of applications such as electric vehicles, next-generation lithium-ion batteries require electrodes with higher specific capacities to further achieve high energy densities. However, most of the current high-capacity negative electrodes have a large amount of active lithium loss due to the SEI film and other side reactions during the first lithium intercalation process, which makes the initial Coulombic efficiency of the full battery low and further affects the cycle life of the battery, which severely limits high-capacity negative electrodes. wide application. Similarly, high-capacity anodes for Na-ion batteries also face th...

AI Technical Summary

Problems solved by technology

After the ternary pre-lithiation reagent removes lithium / sodium, useless metal oxides will be left, which will reduce the energy density of the battery, which runs counter to the pre-lithiation effect, and the possibility of large-scale application is low

[0007] However, the large-scale application of inorganic binary pre-lithium / sodium reagents and organic pre-lithium / sodium reagents still faces many problems.

The main problems include: (1) This type of reagent has poor conductivity and cannot match the excellent conductivity of the positive electrode material. When used directly in combination, the internal resistance of the positive electrode will increase, which will affect the performance of the positive electrode material of the battery.

In this way, more conductive agents need to be added to reduce the volume energy density of the positive electrode material; (2) although the lithium supplement / sodium supplement reagent contains more lithium / sodium ions in its molecule, its electrochemical reactivity is low, and it can be used in actual use. The number of lithium / sodium ions that can be extracted within the working voltage window of the positive electrode is far less than its theoretical value, that is, the actual amount of lithium / sodium supplementation is limited, which is significantly smaller than its theoretical value; More voids are left inside, which increases the porosity of the pole piece, which not only reduces the energy density of the battery, but also leads to the deactivation of some positive electrode materials, which affects the performance of the positive electrode material itself and the cycle stability of the full battery; (4) part Preconditioning / sodiumizing reagents have poor stability at room temperature and need to be operated in a dry environment, which increases production costs;

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