Method for preparing conductive fiber paper with lithium-philic and lithium-phobic gradient structure and conductive fiber paper

Abstract

The invention provides a method for preparing conductive fiber paper with a lithium-philic and lithium-phobic gradient structure and the conductive fiber paper. The preparation method of the conductive fiber paper comprises the following steps: forming a lithium-philic coating layer on the surface of a carbon nanotube by adopting an atomic layer deposition method, and then carrying out gradient papermaking to form a film according to different proportions of lithium-philic / lithium-phobic materials by adopting a wet papermaking process. The invention further provides a preparation method of the composite metal lithium negative electrode, wherein solid lithium is heated to a molten state, and then the lithium in the high-temperature molten state is injected into a lithium-philic layer. The invention also provides a LiF protective layer formed on the surface of a composite metal lithium negative electrode through atomic layer deposition treatment or HF fluorination treatment. According to the invention, the lithium affinity of the formed conductive fiber paper is gradually weakened from the bottom layer to the top layer, and the top layer is completely lithium-phobic, so that the metal lithium can be uniformly deposited from the bottom layer to the top layer, the problem of deposition of the metal lithium on the top layer is solved, and the cycle stability and the cycle life of a lithium metal negative electrode are remarkably improved.

Description

technical field [0001] The invention belongs to the technical field of secondary batteries, and in particular relates to a method for preparing conductive fiber paper with a lithium-affinity-phobic gradient structure and the conductive fiber paper. Background technique [0002] Since the 21st century, mobile electronic information products have developed rapidly, and the capacity requirements for energy storage batteries have become increasingly stringent. The energy density of traditional lithium-ion batteries is close to the upper limit, making it difficult to meet the needs of 3C products. Li metal anode has attracted extensive attention due to its ultra-high specific capacity of 3860mAh / g and the lowest reduction potential of -3.04V. However, metal lithium anodes have been difficult to be applied in practice so far, mainly because of the problems of dendrite growth and low Coulombic efficiency during the battery cycle: on the one hand, lithium ion deposition is greatly a...

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Problems solved by technology

However, metal lithium anodes have been difficult to be applied in practice so far, mainly because of the problems of dendrite growth and low Coulombic efficiency during the battery cycle: on the one hand, lithium ion deposition is greatly affected by the current density, the larger the current, the more lithium ion deposition Faster, the more conducive to the growth of dendrites, until it pierces the separator to cause an internal short circuit in the battery, there is a danger of battery combustion explosion; on the other hand, lithium metal has strong chemical activity, and will continue to have side reactions with the electrolyte, resulting in low Coulombic efficiency

In addition, metal foam or carbon fiber is relatively hard, which is easy to pierce the separator and cause a short circuit of the battery, which poses a potential safety risk

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