Method for producing hard carbon lithium metal composite negative pole material for lithium ion battery

A lithium-ion battery and negative electrode material technology, applied in the direction of mixing methods, electrode manufacturing, battery electrodes, etc., can solve the problems of high sensitivity of electrolyte, low charge and discharge efficiency, limited stability, etc., and achieve convenient electrode production and low material cost , the effect of good application value

Inactive Publication Date: 2007-01-03
TSINGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The main problems of graphite negative electrode materials are: (1) Artificial graphite needs to be prepared by high-temperature graphitization at 1900°C to 2800°C, and the temperature is too high; (2) The theoretical specific capacity is 372mAh / g, which is relatively low; (3) Fragile structure leads to very limited stability and is also highly sensitive to electrolyte
However, in actual use, during the charging and discharging process of lithium metal in liquid electrolyte, dendritic dendrites will be generated on the surface of lithium metal, which will reduce the charging and discharging efficiency, and even break through the diaphragm, causing serious problems of battery short circuit and burning.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] Embodiment one: measure a kind of hard carbon sample at current density be 0.2mA / cm 2 The charge specific capacity of the first cycle is 500mAh / g, the discharge specific capacity is 300mAh / g, and the theoretical specific capacity of lithium is 3860mAh / g. According to the principle of compensating the first irreversible capacity of hard carbon with lithium, weigh 5 mg of lithium powder sample and 95 mg of hard carbon sample and mix them fully under argon atmosphere, which can fully compensate the first irreversible capacity of hard carbon and obtain hard carbon-lithium metal composite Material.

[0024] The composite material powder, acetylene black and PTFE are mixed in a ratio of 80:15:5, coated on the nickel foam substrate, pressed into an electrode sheet, and used as an electrode after vacuum drying, using a pure metal lithium sheet as a counter electrode, and selgard2400 as a diaphragm , EC+DEC(1:1)+1MLiPF 6 As the electrolyte, make a button-type simulated battery...

Embodiment 2

[0025] Embodiment two: measure a kind of hard carbon sample at current density be 0.2mA / cm 2 The charge specific capacity of the 1st cycle is 900mAh / g, and the discharge specific capacity is 500mAh / g. According to the principle of lithium compensation for the first irreversible capacity of hard carbon, weigh 10mg of lithium powder sample and 90mg of hard carbon sample and place them in a 100ml stainless steel container of a ball mill. , the ball milling time was 20 hours, and the hard carbon-lithium metal composite material was obtained.

[0026] The same test method as in Example 1 measured that the charge specific capacity of the button-type simulated battery in the first cycle of the sample was 500mAh / g, the discharge specific capacity was 500mAh / g, and the first-time efficiency was 100%. The discharge specific capacity at the 20th cycle was 480mAh / g.

Embodiment 3

[0027] Embodiment three: measure a kind of hard carbon sample at current density and be 0.2mA / cm 2The charge specific capacity of the 1st cycle is 800mAh / g, and the discharge specific capacity is 400mAh / g. Weigh 90 mg of hard carbon material, mix hard carbon material powder, carbon black and PVDF in a ratio of 90:10:10, apply it on the foamed nickel substrate, press it into an electrode sheet, and use it as an electrode after vacuum drying. Based on the principle of the first irreversible capacity of hard carbon, weigh 10 mg of lithium foil, place the lithium foil on the surface of the hard carbon material under a nitrogen or argon atmosphere, and then roll it firmly with a rolling machine. Finally, a hard carbon-lithium metal composite negative electrode material can be obtained.

[0028] Use pure metal lithium sheet as the counter electrode, selgard2400 as the diaphragm, EC+DEC (1:1)+1MLiPF 6 As the electrolyte, a button-type simulated battery is made, and the sample is me...

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Abstract

The present invention relates to lithium ionization cell used hard carbon - lithium metal compounding cathode material preparation method, belonging to chemical engineering and new material technology field, in particular relating to lithium secondary cell cathode material preparative technique field. One method is to make hard carbon material with lithium powder mixing upon inert gas atmosphere, to obtain hard carbon - lithium metal compounding cathode material. Another method is to prepare hard carbon material powder into electrode piece, then under inert gas atmosphere pressing lithium foil on hard carbon electrode piece surface to obtain hard carbon - lithium metal compounding cathode material. The mass ratio relation of lithium with hard carbon material in above-mentioned two methods satisfies that the lithic first excess loading capacity can compensate hard carbon first non-reversible capacity. Said invention provided method can prepare cathode material with more than first Coulomb 100 per cent, high electrochemical activity, large reversible capacity, fine cycle performance, low material cost, and simple technological process etc advantages.

Description

technical field [0001] The preparation method of a hard carbon-lithium metal composite negative electrode material for lithium ion batteries belongs to the technical field of chemical engineering and new materials, and particularly relates to the technical field of preparation of lithium secondary battery negative electrode materials. Background technique [0002] Lithium-ion battery is a new type of high-energy secondary battery that began to be put into practical use in the 1990s. It has outstanding advantages such as high voltage, high energy density, good cycle performance, small self-discharge, and no memory effect. It has been widely used in mobile phones and notebooks. Computers, digital products, electric tools and other portable equipment fields. As the power source of electric vehicles and hybrid vehicles, lithium-ion batteries have shown good application prospects and great application potential in many fields such as military equipment and aerospace. [0003] Si...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/04H01M4/58C01D15/00B01F3/18H01M4/38
CPCY02E60/10
Inventor 孙颢何向明任建国李建军王莉姜长印万春荣
Owner TSINGHUA UNIV
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