Co-N-C@RGO composite material, preparation method and application to modification of lithium-sulfur battery diaphragms

Abstract

The invention discloses a method for preparing porous carbon@graphene composite material by taking a bimetal organic framework material as a precursor and application to modification of lithium-sulfur battery diaphragms thereof. The preparation method comprises the following steps: taking zinc salt and cobalt salt in a certain ratio as the raw materials, synthesizing a zinc / cobalt-bimetal organic framework@graphene composite material through a room-temperature liquid phase method, taking the zinc / cobalt-bimetal organic framework@graphene composite material as the precursor, carrying out high-temperature reaction under inert atmosphere, pickling and drying to obtain a cobalt / nitrogen double-doped porous carbon@graphene (Co-N-C@RGO) composite material. Co-N-C@RGO has high conductivity; the specific surface area of Co-N-C@RGO reaches up to 750-1000m<2> / g; the content of Co is 2-4At%; the content of N is 10-20At%. When the material is applied to the modification of the lithium-sulfur battery diaphragms, the material has the function of obviously inhibiting polysulfide shuttle effect and is capable of greatly improving actual specific capacity and cyclic performance of the lithium-sulfur batteries; meanwhile, the raw materials needed for synthesizing the material are simple; the operation is convenient; the large-scale production can be achieved; the material has certain promoting effect on commercialization of lithium-sulfur battery systems.

Description

technical field [0001] The invention relates to the field of lithium-sulfur batteries, in particular to a method for preparing a cobalt / nitrogen double-doped porous carbon@graphene (Co-N-C@RGO) composite material and its application in the improvement of lithium-sulfur battery commercial separators. Background technique [0002] With the continuous development of new energy and green technology, people have higher and higher requirements for power batteries and mobile power equipment. In this context, it is of great significance to develop new lithium-ion secondary batteries with high specific energy, high stability and environmental friendliness. At present, traditional lithium-ion battery cathode materials such as LiMn 2 o 4 、LiCoO 2 , LiNiO 2 、LiFePO 4 Due to the limitation of its theoretical specific capacity, it is difficult to make a major breakthrough in a short period of time. The theoretical specific capacity of elemental sulfur is as high as 1675mAh / g, and th...

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Problems solved by technology

In this method, first of all, although the organometallic framework material has the performance of conducting lithium, the metal ion and the ligand are tightly combined, and the mutual influence between the functional groups cannot produce effective chemical adsorption on the polysulfide; secondly, , metal organic framework materials must be physically mixed with conductive agents to ensure sufficient conductivity, but the effect is not ideal; third, other heteroatoms (such as nitrogen) in addition to metal elements generally form a certain type of chemical bonding with carbon elements In order to play its original role in adsorbing polysulfides, the presence of non-metallic elements in the metal-organic framework such as oxygen and hydrogen cannot produce corresponding effects

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