Interface protection structure, preparation method and battery comprising structure

Abstract

The invention provides an interface protection structure and a preparation method thereof and a battery comprising the interface protection structure. The interface protection structure comprises a metal fluoride and a binder. The metal fluoride is one or more of nickel fluoride, manganese fluoride, iron fluoride, titanium fluoride, copper fluoride, tin fluoride, and the like. The structure can form a protective layer containing lithium fluoride during the cycle process of lithium metal batteries to protect lithium metal electrodes. The interface protection structure is prepared by the following method: (1) providing a mixed slurry comprising a metal fluoride, a binder, a solvent and / or a carbon material; (2) coating one side of a diaphragm with the mixed slurry to obtain a diaphragm containing a first coating; and (3) baking the diaphragm containing the first coating to obtain the interface protection structure.

Description

【Technical field】 [0001] The invention relates to the field of electrochemistry, in particular to an interface protection structure of a lithium metal battery, a diaphragm structure with the coating, and its preparation and application. 【Background technique】 [0002] Thanks to the small volume change of ~10% of the graphite negative electrode during the cycle, the lithium-ion battery using it as the negative electrode material can obtain stable cycle performance and long service life. However, the lithium storage capacity of graphite anode materials is relatively low (339mAh / g in the case of lithium intercalation, and 372mAh / g in the case of lithium extraction), which has been unable to meet the needs of the industry in the process of continuously seeking higher energy density systems in the lithium battery market . [0003] If all potential technologies that may increase energy density are taken into consideration, the upper limit of energy density that lithium-ion batter...

AI Technical Summary

Problems solved by technology

[0006] However, the low cycle efficiency and poor safety of lithium metal in liquid batteries have been hindering its further promotion and application in the battery industry.

Volume expansion and dendrite problems can lead to increased electrode interfacial impedance and loss of battery capacity

Continuous dendrite growth can pierce the electrolyte diaphragm and cause a short circuit in the battery, making the lithium metal negative electrode always accompanied by a huge safety hazard during use, which also makes it difficult to be applied to such as electric vehicles, portable electronic devices, etc. In a demanding working environment

In recent years, through various solutions proposed by the industry, the service life and efficiency of lithium metal anodes have been significantly improved, but the degree of improvement is still difficult to meet the needs of large-scale commercialization

[0007] At present, the protection methods for lithium dendrites are as follows: First, the use of solid electrolytes can inhibit the growth of dendrites to a certain extent, but the low ionic conductivity and poor electrode / electrolyte interface will lead to a substantial increase in the internal resistance of the battery ; Second, adding film-forming additives to the electrolyte can accelerate the formation of a protective passivation layer on the electrode surface. However, the passivation layer itself does not have the mechanical properties to inhibit dendrite growth, and eventually the electrode surface will still occur. Inhomogeneous dendrite growth, and the excessive growth of dendrites can pierce the passivation layer, so that the part of the lithium metal that is not covered by the passivation layer directly contacts the electrolyte and regenerates a new passivation layer, so that passivation occurs repeatedly Layer rupture and regeneration will continuously consume lithium and electrolyte in the system

[0008] In summary, although there are alternative lithium metal protection methods in this field, the structural stability and cycle effect of lithium metal negative electrodes are still unsatisfactory.

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