Lignin nitrogen-rich carbon/zinc oxide nanocomposite as well as preparation method and application thereof

Abstract

The invention discloses a lignin nitrogen-rich carbon / zinc oxide nanocomposite as well as a preparation method and application thereof. The method comprises the following steps: (1) dissolving ligninin an alkaline solution, carrying out hydrothermal pretreatment, conducting cooling, and adjusting a pH value to 3-5 to obtain an acid-soluble lignin solution; (2) adding a mixed solution of soluble zinc salt and soluble carbonate into the acid-soluble lignin solution, conducting a hydrothermal reaction, then adding hydroxymethylated melamine, and continuing the hydrothermal reaction to obtain a nitrogen-doped lignin / zinc oxide compound; and (3) carbonizing the nitrogen-doped lignin / zinc oxide compound to obtain the lignin nitrogen-rich carbon / zinc oxide nanocomposite. In the obtained composite material, lignin carbon is uniformly doped with the nitrogen element, and the lignin nitrogen-rich carbon uniformly coats the surfaces of zinc oxide particles to form a uniform carbon layer with a continuous structure, so the problems of serious volume expansion and poor conductivity of zinc oxide serving as a lithium ion negative electrode material are solved, and the specific capacity, the initial coulombic efficiency and the rate capability of a lithium ion battery are improved.

Description

technical field [0001] The invention belongs to the technical field of negative electrode materials for lithium ion batteries, and in particular relates to a lignin nitrogen-rich carbon / zinc oxide nanocomposite material and its preparation method and application. Background technique [0002] Graphite, as a traditional lithium-ion battery (LIB) anode material, has a low theoretical specific capacity (372mAh g -1 ), the low ion diffusion coefficient caused by too narrow layer spacing, and the easy formation of lithium dendrites during high-rate charge and discharge, causing safety hazards and other issues. This forces us to develop a new lithium battery anode material with high energy density, high rate performance and high safety. [0003] In recent years, transition metal oxides have been extensively studied as anode materials for lithium batteries. Zinc oxide (ZnO) has a high theoretical lithium storage capacity (978mAh g -1 ), moderate working potential (lithium interc...

AI Technical Summary

Problems solved by technology

However, there are two key problems that limit the application of ZnO in lithium battery negative electrodes: (1) During the charge and discharge process, the large volume change (about 228%) leads to easy agglomeration, pulverization and rapid capacity decay of the material; (2) The electronic conductivity of ZnO itself Low, poor rate performance

However, these composite materials have a micron-scale agglomerated block structure, and the ion transport resistance is too large, resulting in high irreversible capacity, low first-time Coulombic efficiency and specific capacity.

This is mainly due to the lack of proper pretreatment of industrial lignin in these materials, resulting in high aggregation of industrial lignin in aqueous solution and low reactivity, and lignin cannot be evenly loaded on the surface of zinc oxide during carbonization.

[0011] In summary, the nitrogen-doped lignin carbon and lignin carbon / zinc oxide composite materials prepared by the existing technology or process still have low lithium storage capacity, high irreversible capacity and the first Coulomb low efficiency

And because most of these materials have a micron-scale block structure, it is impossible to obtain a nitrogen-doped lignin carbon / zinc oxide composite material with good lithium storage performance through the direct compounding of the two materials or the superposition of the two preparation processes.

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