A lithium ion battery

Abstract

The invention provides a lithium ion battery, which includes a shell, and an electrode group and an electrolyte solution sealed in the shell. The electrode group comprises an anode, a cathode, and a diaphragm between the anode and the cathode. The anode includes an anode conductive substrate and an anode material layer attached to the anode conductive substrate. The anode material layer includes a lithium iron phosphate anode active material, iron phosphate, a conductive agent and an anode binder. The minimum particle size of the iron phosphate is not less than 20 micrometers. The cathode includes a cathode conductive substrate and a cathode material layer attached to the cathode conductive substrate. The cathode material layer includes a cathode active material layer, which comprises lithium and / or lithium alloy, a cathode active material and a cathode binder; or the cathode material layer includes a cathode active material layer and lithium and / or lithium alloy attached to the cathode active material layer. The prepared lithium ion battery itself has excellent anti-over discharge capacity.

Description

technical field

[0001] The invention relates to a lithium ion battery. Background technique

[0002] Compared with other chemical power sources, lithium-ion batteries have many excellent properties, such as high energy density, long cycle life, high open circuit voltage, no memory effect, safety and pollution-free, etc. After nearly two decades of rapid development, lithium-ion batteries have been widely used in mobile phones, notebook computers, digital cameras and other fields. With the rise of global oil prices and the enhancement of people's awareness of environmental protection, both research institutions and enterprises are paying attention to the development of electric vehicles. Researchers generally believe that lithium-ion batteries are one of the most promising chemical power sources for electric vehicles. Compared with other mobile devices, electric vehicles have higher requirements on the performance of batteries such as cycle life, energy density, consistency...

Examples

preparation example Construction

[0031] The preparation of the negative electrode can be that first lithium and / or lithium alloy, negative electrode active material and negative electrode binder are configured together to form a slurry and attached to the negative electrode conductive substrate, for example, lithium and / or lithium alloy, negative electrode active material and negative electrode binder can be After dry mixing of the binder, etc., it is attached to the negative electrode conductive substrate by spraying. It is also possible to wet mix lithium and / or lithium alloy, negative electrode active material, negative electrode binder, etc. with solvents and selectively add dispersants, etc., It is attached to the negative electrode conductive substrate by slurry coating and other methods. Generally, the solvent used at this time is an oily solvent, and the binder is an oily binder. Then drying, calendering, etc., wherein, the steps of drying and calendering are the same as the prior art, that is, drying ...

Embodiment approach

[0033] Among them, the separator can be selected from various separators used in lithium-ion batteries known to those skilled in the art, such as polyolefin microporous membrane (PP), polyethylene felt (PE), glass fiber felt or ultrafine glass fiber paper or PP / PE / PP. As a preferred embodiment, the separator is PP / PE / PP.

[0034] The electrolyte contains lithium salt and non-aqueous solvent. The lithium salt can be lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium perchlorate, lithium trifluoromethanesulfonate, lithium perfluorobutylsulfonate, aluminate One or more of lithium, lithium chloroaluminate, lithium fluorosulfonyl imide, lithium chloride and lithium iodide; the non-aqueous solvent can be γ-butyrolactone, ethyl methyl carbonate, methyl propyl carbonate , dipropyl carbonate, acid anhydride, N-methylpyrrolidone, N-methylformamide, N-methylacetamide, acetonitrile, N,N-dimethylformamide, sulfolane, dimethylsulfoxide, disulfite ...

Embodiment 1

[0040] (1) Preparation of positive electrode:

[0041] 90g of lithium iron phosphate (D 50 =0.3 microns), 10g of iron phosphate with a minimum primary particle size of 30 microns (D 50 =35 microns), 4g of binder polyvinylidene fluoride (PVDF), 5g of conductive agent SP (super conductive carbon black), 0.5g of dispersant polyvinylpyrrolidone (PVP) and 120g of N-methylpyrrolidone were added Stir in a vacuum mixer to form a uniform positive electrode slurry. The positive electrode slurry was evenly coated on both sides of an aluminum foil with a thickness of 16 μm, and then dried at 150° C. After rolling and cutting, a positive electrode sheet with a size of 453*40 mm is obtained.

[0042] (2) Preparation of negative electrode:

[0043] Add 50g of natural graphite, 1g of binder styrene-butadiene rubber latex (SBR), 0.5g of binder carboxymethylcellulose (CMC), 0.025g of lithium metal powder (purity 99.9%), and 125g of NMP into a vacuum mixer Stir to form a uniform negative el...

technical field

[0001] The invention relates to a lithium ion battery. Background technique

[0002] Compared with other chemical power sources, lithium-ion batteries have many excellent properties, such as high energy density, long cycle life, high open circuit voltage, no memory effect, safety and pollution-free, etc. After nearly two decades of rapid development, lithium-ion batteries have been widely used in mobile phones, notebook computers, digital cameras and other fields. With the rise of global oil prices and the enhancement of people's awareness of environmental protection, both research institutions and enterprises are paying attention to the development of electric vehicles. Researchers generally believe that lithium-ion batteries are one of the most promising chemical power sources for electric vehicles. Compared with other mobile devices, electric vehicles have higher requirements on the performance of batteries such as cycle life, energy density, consistency...

Examples

preparation example Construction

[0031] The preparation of the negative electrode can be that first lithium and / or lithium alloy, negative electrode active material and negative electrode binder are configured together to form a slurry and attached to the negative electrode conductive substrate, for example, lithium and / or lithium alloy, negative electrode active material and negative electrode binder can be After dry mixing of the binder, etc., it is attached to the negative electrode conductive substrate by spraying. It is also possible to wet mix lithium and / or lithium alloy, negative electrode active material, negative electrode binder, etc. with solvents and selectively add dispersants, etc., It is attached to the negative electrode conductive substrate by slurry coating and other methods. Generally, the solvent used at this time is an oily solvent, and the binder is an oily binder. Then drying, calendering, etc., wherein, the steps of drying and calendering are the same as the prior art, that is, drying ...

Embodiment approach

[0033] Among them, the separator can be selected from various separators used in lithium-ion batteries known to those skilled in the art, such as polyolefin microporous membrane (PP), polyethylene felt (PE), glass fiber felt or ultrafine glass fiber paper or PP / PE / PP. As a preferred embodiment, the separator is PP / PE / PP.

[0034] The electrolyte contains lithium salt and non-aqueous solvent. The lithium salt can be lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium perchlorate, lithium trifluoromethanesulfonate, lithium perfluorobutylsulfonate, aluminate One or more of lithium, lithium chloroaluminate, lithium fluorosulfonyl imide, lithium chloride and lithium iodide; the non-aqueous solvent can be γ-butyrolactone, ethyl methyl carbonate, methyl propyl carbonate , dipropyl carbonate, acid anhydride, N-methylpyrrolidone, N-methylformamide, N-methylacetamide, acetonitrile, N,N-dimethylformamide, sulfolane, dimethylsulfoxide, disulfite ...

Embodiment 1

[0040] (1) Preparation of positive electrode:

[0041] 90g of lithium iron phosphate (D 50 =0.3 microns), 10g of iron phosphate with a minimum primary particle size of 30 microns (D 50 =35 microns), 4g of binder polyvinylidene fluoride (PVDF), 5g of conductive agent SP (super conductive carbon black), 0.5g of dispersant polyvinylpyrrolidone (PVP) and 120g of N-methylpyrrolidone were added Stir in a vacuum mixer to form a uniform positive electrode slurry. The positive electrode slurry was evenly coated on both sides of an aluminum foil with a thickness of 16 μm, and then dried at 150° C. After rolling and cutting, a positive electrode sheet with a size of 453*40 mm is obtained.

[0042] (2) Preparation of negative electrode:

[0043] Add 50g of natural graphite, 1g of binder styrene-butadiene rubber latex (SBR), 0.5g of binder carboxymethylcellulose (CMC), 0.025g of lithium metal powder (purity 99.9%), and 125g of NMP into a vacuum mixer Stir to form a uniform negative el...

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