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Lithium negative pole, preparation method thereof and battery comprising lithium negative pole

A lithium negative electrode and battery technology, which is applied in the field of electrochemical batteries, can solve the problems of cycle performance degradation and large changes in the surface morphology of lithium powder electrodes, improve safety performance and cycle performance, reduce the probability of dendrite formation, and The effect of a large adjustment range

Inactive Publication Date: 2012-02-15
SHANGHAI INST OF SPACE POWER SOURCES
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, when the discharge capacity is large, the surface morphology of the lithium powder electrode changes greatly, that is, the cycle performance will decrease.

Method used

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  • Lithium negative pole, preparation method thereof and battery comprising lithium negative pole
  • Lithium negative pole, preparation method thereof and battery comprising lithium negative pole
  • Lithium negative pole, preparation method thereof and battery comprising lithium negative pole

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] Mesocarbon microspheres (MCMB) are used as lithium carriers, mixed with conductive agent carbon black (SP) and binder polyvinylidene fluoride (PVDF) at a mass ratio of 91:3:6, and N-methyl-2- Pyrrolidone (NMP) was used as a solvent, mixed with a high-speed emulsifier to form a slurry, and evenly coated on the Cu foil of the current collector, and then dried in a vacuum oven at 60 °C for 24 h, and set aside. With metal lithium sheet as the negative electrode, mesocarbon microspheres as the counter electrode, Celgrad 2325 as the diaphragm, 1.2 mol / L lithium hexafluorophosphate (LiPF 6 ) / ethylene carbonate (EC) + methyl ethyl carbonate (EMC) (volume ratio 3:7) as the electrolyte to assemble the battery.

[0028] The battery was first charged and discharged at a current density of 40 mA / g, and the voltage range was 0-3 V. After 10 cycles, it was discharged to 0 V, and then discharged at a constant current density of 40 mA / g for 9 h to electrochemically deposit a lithium me...

Embodiment 2

[0030] Graphite (MCP-1) is used as the lithium carrier, mixed with conductive agent carbon black (SP) and binder polyvinylidene fluoride (PVDF) at a mass ratio of 91:3:6, and N-methyl-2-pyrrolidone ( NMP) was used as a solvent, mixed with a high-speed emulsifier to form a slurry, and evenly coated on the Cu foil of the current collector, and then dried in a vacuum oven at 60 °C for 24 h, and set aside. With lithium metal sheet as negative electrode, graphite as counter electrode, Celgrad 2325 as diaphragm, 1.2 mol / L lithium hexafluorophosphate (LiPF 6 ) / ethylene carbonate (EC) + methyl ethyl carbonate (EMC) (volume ratio 3:7) + fluoroethylene carbonate (FEC, 5wt%) as the electrolyte to assemble the battery.

[0031] The battery was first charged and discharged at a current density of 31 mA / g, and the voltage range was 0-2 V. After 10 cycles, discharge to 0V, and then discharge at a constant current density of 31 mA / g for 5 h, and electrochemically deposit a lithium metal laye...

Embodiment 3

[0033] Using hard carbon (HC) as the lithium carrier, mixed with conductive agent carbon black (SP), conductive agent vapor phase grown carbon fiber (VGCF), and binder polyvinylidene fluoride (PVDF) at a mass ratio of 92:2:1:5, Using N-methyl-2-pyrrolidone (NMP) as a solvent, the slurry was mixed with a high-speed emulsifier and evenly coated on the Cu foil of the current collector, and then dried in a vacuum oven at 60 °C for 24 h, ready for use. With metal lithium sheet as the negative electrode, hard carbon as the counter electrode, Celgrad 2325 as the diaphragm, 1.2 mol / L lithium hexafluorophosphate (LiPF 6 ) / ethylene carbonate (EC) + methyl ethyl carbonate (EMC) (volume ratio 3:7) as the electrolyte to assemble the battery.

[0034] The battery was first charged and discharged at a current density of 40 mA / g, and the voltage range was 0-3 V. After 10 cycles, discharge to 0 V, and then discharge at a constant current density of 40 mA / g for 4 h, and electrochemically depos...

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Abstract

The invention discloses a lithium negative pole, a preparation method thereof and a battery comprising the lithium negative pole. The preparation method of the lithium negative pole comprises the following specific steps: step 1, lithium embedding: coating a carbon material on an affluxion body Cu foil and drying, thereby obtaining a carbon material pole piece; packing a battery by taking a lithium metal piece as a negative pole and the carbon material pole piece as a counter electrode, carrying out charge-discharge circulation so as to finish the step of lithium embedding; and step2,deposition of a metal lithium layer through overdischarge: carrying out overdischarge on the finished embedding lithium step battery at current density of 10-100 m A / g through constant current discharging for 2-20 hours, thus the lithium negative pole is obtained on a carbon material pole piece surface electrochemical deposition lithium metal layer. The lithium negative pole provided by the invention has the advantages of taking a carbon electrode as a carrier; compared with a general lithium metal negative pole, the safety feature and the cycle performance are effectively improved, the negative pole capacity can be designed by self according to the requirements of the positive pole capacity, therefore the adjustable range is large.

Description

technical field [0001] The invention belongs to the field of electrochemical batteries, and relates to a lithium secondary battery, in particular to a lithium negative electrode, a preparation method thereof and a battery containing the lithium negative electrode. Background technique [0002] Metal lithium has a potential of -3.045 V relative to the standard hydrogen electrode, and a specific capacity of 3861 mAh / g, which is close to 10 times the specific capacity of conventional carbon negative electrodes (372 mAh / g for graphite), which has a good development prospect. However, the lithium negative electrode is continuously dissolved and deposited during the charging and discharging process, which is prone to produce dendrites, resulting in a decrease in cycle performance. In severe cases, the dendrites will pierce the separator and contact the positive electrode, resulting in internal short circuit, and even safety accidents such as fire or explosion. [0003] In order to...

Claims

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Application Information

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IPC IPC(8): H01M4/66H01M4/139H01M4/13H01M10/0525
CPCY02E60/10
Inventor 刘雯
Owner SHANGHAI INST OF SPACE POWER SOURCES
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