Current collector and preparation method thereof

A current collector and graphene technology, applied in the direction of electrode carrier/current collector, etc., can solve the problems such as the expansion and separation of active material and current collector, the influence of cycle life battery safety performance, the influence of interface resistance and bonding strength, etc., to achieve interaction Strong force, strong adhesion, and the effect of enhancing conductivity

Active Publication Date: 2014-11-05
NINGBO INST OF MATERIALS TECH & ENG CHINESE ACADEMY OF SCI
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Problems solved by technology

However, such a structural design has the following two defects: 1) The contact area between the rigid metal current collector and the active material particles is limited, and the interface resistance is large, which causes an increase in the internal resistance of the battery. There is a negative impact on the performance under discharge conditions; 2) The bond strength of the binder is limited. During the continuous charge and discharge process, it is easy to cause the expansion and separation between the active material and the current collector, which leads to a further increase in the internal resistance of the battery, making the The cycle life and safety performance of the battery are affected
However, due to the three-dimensional structure of graphite or carbon black, the contact between graphite or carbon black and copper foil constitutes a point contact, so that the formed conductive coating is not dense and easy to fall off, which affects the interface resistance and bonding strength to a certain extent. battery performance

Method used

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  • Current collector and preparation method thereof
  • Current collector and preparation method thereof
  • Current collector and preparation method thereof

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preparation example Construction

[0031] The present invention also provides a method for preparing a current collector of a secondary battery, comprising: dispersing graphene and a binder in a solvent to form a slurry; coating the slurry on at least one surface of a current collector foil On, a coating layer containing graphene and a binder is formed; and then dried.

[0032] In order to make the coating have good electrical conductivity, as a preferred solution, the mass ratio of the graphene to the binder is (1-49): 1; the number of layers of the graphene is preferably between a single layer or 1-30 layers room, the layer is sp 2 Hybridized carbon atoms hexagonally closely packed, thin-layer carbon materials bonded by π bonds between layers; the carbon content of graphene is >95wt%, and the bulk conductivity is >100S / cm. The binder is preferably one or more of sodium carboxymethylcellulose, polyvinylidene fluoride, polytetrafluoroethylene, styrene-butadiene rubber and LA series binders.

[0033] In the pr...

Embodiment 1

[0039] Weigh 2g of sodium carboxymethyl cellulose and add it to 1000g of deionized water, mix evenly with a mixer, then add 40g of graphene slurry and stir to mix evenly, the graphene slurry contains 8g of graphene, add 2000g of deionized water to adjust the slurry Material viscosity, the viscosity is controlled to 800mPa·s, and finally add 30g of ethanol to carry out low-speed vacuum stirring and defoaming treatment, and pass through a 150 mesh screen to obtain the slurry; the slurry is evenly coated on the surface of the aluminum foil by a transfer coating machine, and Dried in a blast oven to obtain a graphene conductive coating with a single-side coating thickness of 500 nanometers.

[0040] Using the peel strength tester to measure the peel strength of the current collector prepared above, the peel strength is 0.5N, and the resistivity of the pole piece is 4.553E by using the four-probe method. -6 ohm.cm.

[0041] figure 1 A schematic diagram of the structure of the cur...

Embodiment 2

[0044] Take by weighing 1.5g sodium carboxymethyl cellulose and join in 1000g deionized water, use a stirrer to mix uniformly, then add 30g graphene slurry and 0.5g conductive carbon black (Super P) and stir and mix uniformly, the graphene slurry contains 8g graphene, add 2000g deionized water to adjust the viscosity of the slurry, the viscosity is controlled to 600mPa s, finally add 30g ethanol to carry out low-speed vacuum stirring and defoaming treatment, pass through a 150 mesh screen to obtain the slurry; pass the slurry through a transfer coating The cloth machine is evenly coated on the surface of the aluminum foil, and dried in a blast drying oven to obtain a graphene conductive coating with a coating thickness of 200 nanometers on one side.

[0045] Using the peel strength tester to measure the peel strength of the current collector prepared above, the peel strength is 0.5N, and the resistivity of the pole piece is 4.761E by using the four-probe method. -6 ohm.cm.

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Abstract

The invention provides a current collector and a preparation method thereof. The current collector comprises a current collector foil and at least one surface of the current collector foil is coated with coating layers containing graphene and a binder. The preparation method comprises the following steps of dispersing graphene and the binder in a solvent to obtain slurry, coating the slurry on at least one surface of the current collector foil and drying. Graphene of the coating layer has a two-dimensional sheet structure and thus the graphene forms a uniform and compact coating on the surface of the current collector foil so that a contact area of the graphene and the surface of the current collector is greatly improved; a conductive contact between an active material and the current collector is improved; the interface resistance of the current collector and the active material is effectively reduced; and internal resistance of a cell is reduced. Contact areas of graphene layers paved on the surface of the current collector and contact areas of the graphene layers and the current collector are large and thus interactional forces are strong; falling off is difficult; adhesive forces are strong; separation of the active material and the current collector is avoided in charging and discharging; and internal resistance reduction is promoted.

Description

technical field [0001] The invention relates to the field of lithium secondary batteries, in particular to a current collector and a preparation method thereof. Background technique [0002] As a high-capacity, long-life energy storage system, lithium secondary batteries have been widely used in small portable electronic products, and their application prospects in high-power power batteries and large-capacity energy storage batteries have attracted the attention of the world. gaze. The development of high-performance lithium-ion batteries is an important task in the field of electrochemical energy storage. [0003] In lithium secondary batteries, the active material is evenly coated on the surface of the current collector of aluminum foil or copper foil. The current collector collects and exports the electrons generated by the electrochemical reaction to the external circuit through physical contact with the active material, thereby realizing the conversion of chemical ene...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/66
CPCY02E60/10
Inventor 周旭峰刘兆平胡华胜曾永锋唐长林
Owner NINGBO INST OF MATERIALS TECH & ENG CHINESE ACADEMY OF SCI
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