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A kind of li applied to the negative electrode of lithium ion battery 21 the si 5 Preparation of composite materials with graphene

A lithium-ion battery and composite material technology, applied in the field of preparing Li21Si5 and graphene composite electrode materials, can solve the problems of low delithiation capacity, loss of electrochemical activity, capacity fading, etc., and achieve high electrochemical activity and excellent electrochemical performance Effect

Active Publication Date: 2020-04-03
BEIJING UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The problem that lithium-silicon alloys face in the application process is that during the cycle, lithium-silicon alloys will continue to experience volume shrinkage and recovery, and gradually lose electrical contact with the surrounding electrodes and lose electrochemical activity. The increase of the capacity shows a rapid decay of the
[0004] However, lithium-silicon alloys have high chemical activity and are easy to react with water and most solvents, resulting in the irreversible loss of lithium in them, showing low initial delithiation capacity, so the preparation of lithium-silicon alloys with uniform composition and dense two-phase combination and graphene composite electrode material is one of the technical difficulties and major challenges in the field of lithium-containing alloy anode materials

Method used

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  • A kind of li applied to the negative electrode of lithium ion battery <sub>21</sub> the si <sub>5</sub> Preparation of composite materials with graphene
  • A kind of li applied to the negative electrode of lithium ion battery <sub>21</sub> the si <sub>5</sub> Preparation of composite materials with graphene
  • A kind of li applied to the negative electrode of lithium ion battery <sub>21</sub> the si <sub>5</sub> Preparation of composite materials with graphene

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Effect test

Embodiment 1

[0025] Weigh the same mass of graphene and silicon powder with a particle size of 50nm, and then pour them into ethanol to form 3g L -1 mixed solution. The mixed solution was ultrasonicated for 3 hours to fully mix the nano silicon powder and graphene. Afterwards, the mixed powder of nano silicon powder and graphene is obtained through suction filtration and drying, and its microscopic appearance is as follows: figure 1 shown. Weigh metal lithium sheets according to the mass ratio of lithium to silicon of 1.4:1, then alternately stack the above-mentioned mixed powder and metal lithium in a cemented carbide mold, and then prepare Li by spark plasma sintering technology. 21 Si 5 and graphene bulk composites. The sintering process parameters are: pressure 15MPa, temperature 300°C, heat preservation 30min. Finally, the sintered bulk material was ground to obtain Li 21 Si 5 @Graphene. Its microscopic appearance is as figure 2 As shown in , it can be seen that there is a s...

Embodiment 2

[0027] Weigh the same mass of graphene and silicon powder with a particle size of 50nm, and then pour them into ethanol to form 3g L -1 mixed solution. The mixed solution was ultrasonicated for 4 hours, so that the nano-silica powder and graphene were fully mixed and uniform. Then, the mixed powder of nano-silicon powder and graphene is obtained through suction filtration and drying. Weigh metal lithium sheets according to the mass ratio of lithium to silicon of 1.4:1, then alternately stack the above mixed powder and metal lithium in a cemented carbide mold, and then prepare Li by spark plasma sintering technology. 21 Si 5and graphene bulk composites. The sintering process parameters were adjusted as follows: pressure 15MPa, temperature 260°C, heat preservation 60min. Finally, the sintered bulk material was ground to obtain Li 21 Si 5 @Graphene, its phase is like Figure 6 shown.

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Abstract

The invention relates to preparation of a Li21Si5 and graphene composite material applied to a lithium ion battery negative electrode, and belongs to the field of a lithium-rich negative electrode material of a lithium ion battery. The preparation comprises the steps of pouring graphene and nanometer silicon powder into ethyl alcohol to form a mixed solution, performing ultrasonic dispersion and full and uniform mixing; performing filtering, and drying mixed powder; and weighing a metal lithium sheet, laminating the mixed powder and a metal lithium alternative layer in a die, and simultaneously achieving lithiation and structural densification of silicon by a discharging plasma sintering technology. By the method, graphene has favorable dispersion performance in Li21Si5, a large amount offavorably-bonded two-phase interfaces are ensured, and the promotion effect of the graphene on electrochemical performance of the Li21Si5 is more remarkable.

Description

technical field [0001] The invention belongs to the field of lithium-rich negative electrode materials for lithium ion batteries, in particular to a method for preparing Li 21 Si 5 and graphene composite electrode materials. Background technique [0002] In recent years, the rapid development of new energy vehicles has put forward higher requirements on the energy density of energy storage devices. Lithium-sulfur and lithium-oxygen batteries have become a research hotspot in the field of energy storage in recent years due to the advantages of high energy density and low cost. Among them, metal lithium as the negative electrode will form dendrites during the cycle, which poses a safety hazard, which seriously restricts the large-scale commercial application of these battery systems with higher energy density. [0003] Lithium-silicon alloy has become the most potential alternative material for lithium metal due to its high theoretical specific capacity and the advantages o...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/36H01M4/38H01M4/62H01M10/0525
CPCH01M4/362H01M4/386H01M4/62H01M4/625H01M10/0525Y02E60/10
Inventor 侯超宋晓艳杨科
Owner BEIJING UNIV OF TECH