CN101071847A - High power lithiumion cell positive electrode and its manufacturing method - Google Patents

Abstract

This invention involves two power sources which may be duplicatedly used, specially a high power lithium ion battery positive electrode and its manufacture method. It takes the iron phosphate lithium as the negative pole material; Water is used as solvent for manufactures of the positive electrode pulp the; Poly-ethylene oxide and and butyl benzene rubber is used as binder for making positive pulp and electrode piece. It mainly solves the limitation of lithium ion cell using existing negative pole material in safety and high multiplying discharge and the prolem of difficult binding of iron phosphate lithium used as pole plate material as specific surface area is large. A t the same time it has good toughness and can bear the effect of pole piece expansion and contraction impaction, thus it has longer service life.

Description

A kind of positive pole of high power lithium ion cell and manufacture method thereof

Technical field:

The present invention relates to the positive pole and the manufacture method thereof of reusable secondary power supply (rechargeable battery) technical field, particularly a kind of high power lithium ion cell.

Background technology:

Lithium ion battery is the development of nineteen nineties Japan Sony Corporation and begins to realize commercial that its appearance is the once leap on the secondary cell development history.Lithium ion battery is in light weight with it, capacity is high, operating voltage is high, long service life and characteristics such as pollution-free and developed rapidly, and its global marketing volume has surpassed the summation of ni-mh, nickel-cadmium cell.There had been significant progress in China aspect the lithium ion battery industrialization in recent years, and 2003 gross annual output amounts have surpassed 2.5 hundred million, reach 600,000,000 production scale in 2005, caught up with and surpassed the advanced world level.

Electric tool in the past mainly uses NI-G, Ni-MH battery, and electric bicycle uses plumbic acid and Ni-MH battery, does not all use lithium ion battery, mainly is subjected to undesirable restriction of big multiplying power discharging property of lithium ion battery.

Following table is various battery performance contrasts:

Performance	Lithium ion battery		Ni-H cell	Ickel-cadmium cell	Lead-acid battery
						Square	Cylinder
	Gravimetric specific energy (Wh/Kg)	100～120						110～114	70	58	30
Volumetric specific energy			280～300	380	200	100	40

(Wh/L)
						Average voltage (V)	3.7	3.7	1.2	1.2	2
Multiplying power discharging property	Bad	Bad	Good	Very good	Good
						Serviceability temperature (℃)	-20～60	-20～60	-20～40	-40～60	-20～50
Memory effect	Do not have	Do not have	Do not have	Have	Do not have
						Self discharge	≤10％	≤10％	≤20％	≤20％	≥10％
Shell	Aluminium, stainless steel, nickel plating	The nickel plating shell	The nickel plating shell	The nickel plating shell	Resin
						Security performance	Safety	Safety	Safety	Safety	Safety
Environmental protection	Pollution-free	Pollution-free	Pollution-free	Pollution is arranged	Pollution is arranged

The lithium ion battery that is used for the high-multiplying power discharge field of employment only accounts for few quantity at present, also is in research and development and experimental stage, and cathode material is with cobalt acid lithium, LiMn2O4 and nickel-cobalt-manganese ternary system (Li (NiCoMn) ₁O ₂) in the majority, LiFePO4 then is a focus in 2005, plants material in the limitation aspect safety and the high-multiplying power discharge because of first three, causes the research of LiFePO4 and application work to launch rapidly.The advantage of LiFePO 4 material performance is significantly, but its specific area is big, and unmanageable characteristics become the greatest difficulty of its application.At present, famous in the world company all begins to carry out the application study of LiFePO4, comprises Valence and A123 System etc.

Summary of the invention:

The object of the present invention is to provide a kind of positive pole and manufacture method thereof of high power lithium ion cell, mainly solve existing cathode material with cobalt acid lithium, LiMn2O4 and nickle cobalt lithium manganate are the main limitation of lithium ion battery aspect safety and high-multiplying power discharge, overcome LiFePO 4 material simultaneously because specific area is big, the technical problem that as plate material the time, is difficult to bond, this pole piece has good pliability simultaneously, can bear the influence that pole piece expands and contraction is impacted in the large current density electric process, have the longer life-span, be more suitable for doing high power, the chemical cell power supply of high-multiplying power discharge.

For solving the problems of the technologies described above, the present invention is achieved in that

A kind of positive pole of high power lithium ion cell is characterized in that: be cathode material with the LiFePO4; Water is as the solvent of making anode sizing agent; Polyethylene glycol oxide (PEO) and butadiene-styrene rubber (SBR) are for making the binding agent of anode sizing agent, pole piece.

A kind of method of making the positive pole of aforesaid high power lithium ion cell is characterized in that: its procedure of processing is the aqueous solution that at first PEO is configured to 1-3%, the method that adopts low speed slowly to add, and the limit edged stirs, and seals up for safekeeping the solution that configures stand-by; Simultaneously LiFePO4 and conductive agent are carried out mechanical mixture, mix (also conductive agent and LiFePO4 substep can be added respectively) after mixing again with the PEO solution that configures, adopt high speed shear to disperse 1-5 hour, the SBR emulsion that adds again through dilution stirs more than 0.5 hour, place slurry more than 1 hour, slurry is coated on the aluminium foil uniformly, adopts a large amount of hot air circulation of 80～130 degrees centigrade, make the pole piece oven dry.

A kind of high power lithium ion cell uses aforesaid manufacturing method for anode, it is characterized in that: also comprise the steps: in the manufacture process

1. the pole piece after will being coated with is rolled into bulk density 1.6～2.5g/cm3, and 100～150 degrees centigrade of oven dry are to be spooled;

2. the pole piece coiling after will drying becomes electric core, in the battery case of packing into.

Embodiment:

The invention provides a kind of manufacture method of positive pole and lithium ion battery of high power lithium ion cell, detailed step is as follows:

1. making slurry

At first PEO is configured to the aqueous solution of 1-3%, the method that adopts low speed slowly to add, the limit edged stirs, and seals up for safekeeping the solution that configures stand-by; Simultaneously LiFePO4 and conductive agent are carried out mechanical mixture, mix with the PEO solution that configures again after mixing, adopt high speed shear to disperse 1-5 hour, the SBR emulsion that adds again through dilution stirred more than 0.5 hour, slurry was placed can be coated with more than 1 hour.

2. coating

Slurry is coated on the thick aluminium foil of thickness 0.015～0.025mm uniformly, adopts a large amount of hot air circulation of 80～130 degrees centigrade, make the pole piece oven dry.

3. roll extrusion

Pole piece after the coating is rolled into bulk density 1.6～2.5g/cm3, and 100～150 degrees centigrade of oven dry are to be spooled.

4. reel

Pole piece coiling after the oven dry is become electric core, in the battery case of packing into.

5. fluid injection is sealed

Add EC/DME/EMC, the electrolyte of LiPF6 series adopts machinery to divide the mode of mouth to seal, and guarantees sealing.

6. change into, partial volume

Battery is carried out the charging and discharging activation, control voltage between 3.65～4.2V, minimum 2.5V, and carry out the capacity sorting.

7. performance test

For 18650 type batteries, can accomplish capacity 1000～1400mAh, the 10C discharge capacity is 85～96% of a 0.5C discharge capacity, 1C cycle life can reach more than 1000 times.Security performance test (comprise overcharge, short circuit, acupuncture, extruding, heavy impact, hot case etc.) is all passed through, these performance index have reached the requirement of electrokinetic cell fully, and because its good security performance, be particularly suitable for making battery pack work, overcome other batteries and done safety defect when being used in combination.

The present invention is compared with the prior art table:

Contrast	Prior art	The present invention
			Solvent	NMP	Water
Binding agent	PVDF	PEO and SBR
			Cathode material	LiMn2O4 or Li (NiCoMn) 1O 2	LiFePO4 (LiFePO 4)
The solvent contrast
			Contrast	NMP	Water
Environmental protection	Dealt with pollution improperly	Do not have
			Price	30,000/ton	250 yuan/ton
The source	Petrochemical industry	Wide material sources

The binding agent contrast

Contrast	PVDF	PEO	SBR
				Molecular weight	30-60 ten thousand	100-600 ten thousand	20
Heat decomposition temperature (℃)	316	423-425	350-390
				Polarity	Oleophylic	Hydrophilic	Hydrophilic
Fusing point (℃)	170	66-70	105-110
				Brittle point (℃)	-62	-50	-60
Price (unit/kilogram)	200	170	50

The cathode material contrast

Contrast	Cobalt acid lithium	LiMn2O4	Lithiated nickel dioxide cobalt manganese	LiFePO4
					Molecular formula	LiCoO2	LiMn2O4	Li(NiCoMn ) 1O 2	LFePO 4
Specific capacity	140	120	170	140
					The high magnification charging	Bad	Bad	Generally	Good
High-multiplying power discharge	Good	Good	Good	Very good
					Resource	Scarce resource	Extensively	Generally	Extensively
Price	High	In	In	Low
					Manufacture difficulty	High	The highest	High	High
Conductivity	Good	Good	Good	Bad
					Difficulty as electrokinetic cell	Security performance	High rate capability	Suction easily	Be difficult to bonding

The electrokinetic cell adaptability

No

Generally

Generally

Good

This shows that the optimal material that uses as electrical source of power is LiFePO4, and the characteristics that it is difficult to bond cause it to be difficult to make the pole plate of battery.Of the present invention one big advantage addresses this problem exactly, can find that by the performance comparison of binding agent the characteristics that this binding agent molecular weight is big just are being suitable for the binding agent as this material, makes the application of LiFePO4 become possibility.Generally speaking, the bond effect of use 15%PVDF only is equivalent to use the bond effect of 1%PEO, simultaneously, owing to use a high proportion of binding agent can cause volume of battery and gravimetric specific energy to reduce, also can cause security performance to reduce, cause cost to increase, cause the internal resistance of cell to increase, can't realize high power discharge, simultaneously, the electric conductivity of LiFePO4 self is just bad, and so way will cause battery can not carry out powerful discharge at all.The above characteristics of bond material, the present invention will improve the LiFePO4 Application feasibility effectively.

Being preferred embodiment of the present invention only in sum, is not to be used for limiting practical range of the present invention.Be that all equivalences of doing according to the content of the present patent application claim change and modification, all should be technology category of the present invention.

Claims (3)

1, a kind of positive pole of high power lithium ion cell is characterized in that: be cathode material with the LiFePO4; Water is as the solvent of making anode sizing agent; Polyethylene glycol oxide and butadiene-styrene rubber are for making the binding agent of anode sizing agent, pole piece.

2, a kind of method of positive pole of manufacturing high power lithium ion cell as claimed in claim 1, it is characterized in that: its procedure of processing is the aqueous solution that at first polyethylene glycol oxide is configured to 1-3%, the method that adopts low speed slowly to add, the limit edged stirs, and seals up for safekeeping the solution that configures stand-by; Simultaneously LiFePO4 and conductive agent are carried out mechanical mixture, mix (also conductive agent and LiFePO4 substep can be added respectively) after mixing again with the polyethylene oxide solutions that configures, adopt high speed shear to disperse 1-5 hour, the butadiene-styrene rubber emulsion that adds again through dilution stirs more than 0.5 hour, be coated on slurry on the aluminium foil uniformly after placing slurry more than 1 hour, adopt a large amount of hot air circulation of 80～130 degrees centigrade, make the pole piece oven dry.

3, a kind of high power lithium ion cell uses manufacturing method for anode as claimed in claim 2, it is characterized in that: also comprise the steps: in the manufacture process

1. the pole piece after will being coated with is rolled into bulk density 1.6～2.5g/cm3, and 100～150 degrees centigrade of oven dry are to be spooled;

2. the pole piece coiling after will drying becomes electric core, in the battery case of packing into.