Lithium negative electrode preform, preparation method thereof, lithium negative electrode, and lithium secondary battery

Abstract

The invention relates to a lithium negative electrode preform, a preparation method thereof, a lithium negative electrode, and a lithium secondary battery. The lithium negative electrode preform is prepared by integrally laminating a plastic base layer, a solid electrolyte layer, and a lithium layer. The manufacturing is simple and easy to perform. The contact interface between the lithium negative electrode and solid electrolyte is effectively improved to prevent the formation of lithium dendritic crystals, and the performance of an all solid state battery is obviously enhanced.

Description

technical field [0001] The invention relates to the technical field of lithium metal batteries, in particular to a method for protecting a lithium metal negative electrode and a lithium metal secondary battery. Background technique [0002] With the increasing environmental pollution and the depletion of fossil fuels, the field of new energy has attracted more and more attention. At present, lithium-ion batteries, as the main energy storage devices, are not only widely used in portable electronic products but also in the automotive industry due to their high operating voltage, good cycle performance, high energy density and power density, and environmental friendliness. With the research and development of battery products and the increase of the cruising range of automobiles, the current lithium-ion battery anode material graphite used in batches has reached the theoretical limit (372mAh / g), and there is an urgent need to develop new materials, while metallic lithium has a ...

AI Technical Summary

Problems solved by technology

[0003] However, when metal lithium is used as a negative electrode, there are the following problems: (1) the solid electrolyte layer (SEI film) formed at the interface between metal lithium and electrolyte thickens with time, the interface impedance continues to increase, the Coulombic efficiency decreases, and the battery capacity decays rapidly; ( 2) The SEI film is unstable, and it breaks-falls-regenerates continuously during the lithium-deintercalation process, consuming metallic lithium and electrolyte; (3) The current density distribution during the lithium deposition-extraction process is uneven, forming lithium dendrites, causing safety Hidden dangers and "dead lithium" cause Coulombic efficiency to decrease

[0004] Aiming at these problems of metal lithium anodes, common methods include adding additives to the electrolyte to form a dense and stable SEI film, or using various inorganic, organic, and physical methods to modify the metal lithium anode to isolate the lithium anode from the electrolyte. For example, in CATL’s new energy application publication number CN107305950, a polymer protective film with ionic liquid is coated on the surface of lithium metal. Due to the fluidity of the liquid, it is easy to cause uneven coating. The lithium metal secondary battery using this as the negative electrode will lead to uneven current density during the cycle, and then generate lithium dendrites, resulting in deterioration of battery performance

[0005] It is a development trend that solid-state electrolytes replace the commonly used organic electrolytes. At present, the production process of all-solid-state batteries is generally that the positive and negative electrodes and all-solid-state electrolytes are combined under a certain pressure. Therefore, the interface contact with the positive and negative electrodes is not close, and after a long cycle, there is a situation of rapid attenuation, and the application is also subject to certain limitations.

Images