A kind of aqueous phosphate lithium iron battery positive plate coating waste water method
[technical field]
The present invention relates to a kind of aqueous phosphate lithium iron battery positive plate coating waste water method; The coated face density more particularly relating to a kind of positive and negative two sides is 200 ~ 600g/m
2the coating waste water method of aqueous lithium battery anode slice.
[background technology]
In various battery systems universal at present, lithium ion battery, due to the characteristic of its high-energy-density, has been widely used in digital product, electronic toy, and the field such as electric tool, electric automobile; And how to improve the emphasis that its energy density is also research always further.
Lithium battery interior is generally made up of positive electrode and the part such as collector, negative material and collector thereof, electrolyte, barrier film, shell thereof.Wherein positive electrode content and negative material content match by a certain percentage, the common capacity determining battery, and other part only plays the effect forming battery system, and itself does not provide capacity.Under the prerequisite that lithium battery each component has all been determined, improve its energy density, unique channel is exactly improve positive electrode and negative material ratio in the battery, then improve the dressing amount of positive and negative electrode material unit are on its collector respectively, the namely coated face density of positive and negative plate.
In Production Process of Lithium Battery, the coating of positive and negative plate is the processing step of wherein most critical.According to current technical merit, relative to negative plate, the difficulty improving positive plate coated face density is larger.For positive plate, existing conventional coating techniques is, two at collector are coated with respectively, dries.Under this technique, the coated face density of positive plate substantially close to the upper limit, as after degree improve, in coating, pole piece process, in the use procedure that even lithium battery is later, all very easily there is shedding phenomenon, have a strong impact on the process reliability of battery and various serviceability.If can coating method be changed, under the prerequisite not occurring shedding phenomenon, improve the surface density of positive plate significantly, then greatly can improve the energy density of lithium battery.
[summary of the invention]
The object of the invention is to overcome the deficiencies in the prior art part, a kind of coating auxiliary material amount that can improve positive plate is provided, improves the surface density of positive plate significantly, greatly can improve the positive plate of lithium battery coating waste water method of the energy density of lithium battery.
The object of the present invention is achieved like this:
A kind of aqueous phosphate lithium iron battery positive plate coating waste water method, is characterized in that step is as follows:
The preparation of step one, anode sizing agent;
Anode sizing agent is mixed by LiFePO4, conductive agent, aqueous binders and the water as solvent; Wherein, the mass ratio of described LiFePO4 is 90 ~ 97%, and the mass ratio of described conductive agent is 1 ~ 7%, and the mass ratio of described aqueous binders is 1.5 ~ 6%;
The one side coating in step 2, first front;
Regulate the discharging width of coating mouth, prepared anode sizing agent is uniformly coated on the front of collector, then dries, then test surfaces density, the one side coated face density of target is 100g/m
2;
The one side coating of step 3, first reverse side;
The discharging width of fixing coating mouth, the collector that upset front has been coated with, is uniformly coated on the reverse side of collector, then dries by prepared anode sizing agent;
The successive of step 4, coated face density increases;
The positive plate of above-mentioned steps gained is turn to front again, and anode sizing agent prepared on even spread, then dries; Positive plate turn to reverse side again afterwards, and even spread anode sizing agent again, dry; To repeat in this step in obverse and reverse coating sizing-agent step until the coated face density on positive and negative two sides is equal, and coated face density is at 200 ~ 600g/m
2in scope.
A kind of aqueous phosphate lithium iron battery positive plate coating waste water method as above, it is characterized in that the mass ratio of the LiFePO4 described in described step one is 94.5%, described conductive agent mass ratio is 2.5%, and described aqueous binders mass ratio is 3%.
A kind of aqueous phosphate lithium iron battery positive plate coating waste water method as above, it is characterized in that in described step 4, often upset is coated with once, the surface density of coating increases 100g/m
2.
A kind of aqueous phosphate lithium iron battery positive plate coating waste water method as above, is characterized in that the target coated face density of collector reverse side in described step 3 is 180-200g/m
2.
A kind of aqueous phosphate lithium iron battery positive plate coating waste water method as above, it is characterized in that in described step 4, often upset is coated with once, the surface density of coating increases 180-200g/m
2, the positive plate of gained is turn to front again; Before last coating, readjust the discharging width of coating mouth, anode sizing agent is uniformly coated on the front of collector, then dries, and test thickness, until the coated face density in front is 400-540g/m
2, the coated face density of reverse side is 400-540g/m
2.
A kind of aqueous phosphate lithium iron battery positive plate coating waste water method as above, is characterized in that described binding agent is the wherein one in Kynoar organic binder bond, sodium carboxymethylcellulose binding agent, butadiene-styrene rubber binding agent.
A kind of aqueous phosphate lithium iron battery positive plate coating waste water method as above, is characterized in that described collector is the wherein one in aluminium foil, aluminium net, nickel screen.
The present invention repeatedly overturns the mode of coating owing to have employed, while raising positive plate coated face density, prevent pole piece from occurring shedding phenomenon well, so can under the prerequisite not changing lithium battery key property, improve the surface density of positive plate significantly, the coating auxiliary material amount of positive plate can be improved, effectively improve its energy density.
[detailed description of the invention]
The coated face density on the positive and negative two sides of embodiment 1. is 400g/m
2the repeatedly upset uniform thickness coating waste water method of aqueous phosphate iron lithium positive plate.
The preparation of step one anode sizing agent:
Be that 3% aqueous binders is dissolved in appropriate pure water by mass ratio, then add that mass ratio is 94.5% LiFePO4, mass ratio is 2.5% conductive agent, uniform slurry can be stirred in mixer high speed;
The one side coating in step 2, first front:
Regulate the discharging width of coating mouth, prepared anode sizing agent is uniformly coated on the front of collector, under 80 DEG C of constant temperature ovens, then shelves oven dry in 5 minutes, then test surfaces density, the one side coated face density of target is 100g/m
2if surface density does not reach requirement, readjust the discharging width of coating mouth, repeat above-mentioned coating, baking step, until surface density meets the requirements;
The one side coating of step 3, first reverse side:
The discharging width of fixing coating mouth, the collector that upset front has been coated with, is uniformly coated on the reverse side of collector, then dries by prepared anode sizing agent;
The successive of step 4, coated face density increases:
The positive plate of gained is above turn to front again, and anode sizing agent prepared on even spread, then dries; Positive plate turn to reverse side again afterwards, and even spread anode sizing agent again, dry ... often overturn and be coated with once, the surface density of this coated face increases 100g/m
2, until the coated face density on positive and negative two sides is 400g/m
2, coating completes.
The coated face density on the positive and negative two sides of embodiment 2. is 400g/m
2the non-uniform thickness coating process of repeatedly upset of aqueous phosphate iron lithium positive plate.
The preparation of step one, anode sizing agent:
Be that 3% aqueous binders is dissolved in appropriate pure water by mass ratio, then add that mass ratio is 94.5% LiFePO4, mass ratio is 2.5% conductive agent, uniform slurry can be stirred in mixer high speed;
The one side coating in step 2, first front:
Regulate the discharging width of coating mouth, prepared anode sizing agent is uniformly coated on the front of collector, then under 80 DEG C of constant temperature ovens, shelve oven dry in 5 minutes (hereinafter referred to as oven dry), then test surfaces density, the one side coated face density of target is 100g/m
2if surface density does not reach requirement, readjust the discharging width of coating mouth, repeat above-mentioned coating, baking step, until surface density meets the requirements;
The one side coating of step 3, first reverse side:
Regulate the discharging width of coating mouth, the collector that upset front has been coated with, prepared anode sizing agent is uniformly coated on the reverse side of collector, then dries, then test thickness, the target coated face density of reverse side is 200g/m
2if surface density does not reach requirement, readjust the discharging width of coating mouth, repeat above-mentioned coating, baking step, until surface density meets the requirements;
The successive of step 4, coated face density increases:
The discharging width of fixing coating mouth, the positive plate of gained is above turn to front again, and anode sizing agent prepared on even spread, then dries; Positive plate turn to reverse side again afterwards, and even spread anode sizing agent again, dry; Often overturn and be coated with once, the surface density of this coated face increases 200g/m
2, until the coated face density on positive and negative two sides is respectively 300g/m
2, 400g/m
2; The positive plate of gained is above turn to front again; Before last coating, readjust the discharging width of coating mouth, anode sizing agent is uniformly coated on the front of collector, then dries, and test thickness, the target one side coated face density in front is 400g/m
2if surface density does not reach requirement, readjust the discharging width of coating mouth, repeat above-mentioned coating, baking step, until surface density meets the requirements.
Embodiment 3: the coated face density on positive and negative two sides is 540g/m
2the non-uniform thickness coating process of repeatedly upset of aqueous phosphate iron lithium positive plate.
The preparation of step one, anode sizing agent:
Be that 4.5% aqueous binders is dissolved in appropriate pure water by mass ratio, then add that mass ratio is 93% LiFePO4, mass ratio is 2.5% conductive carbon, stir into uniform slurry in mixer high speed;
The one side coating in step 2, first front:
Regulate the discharging width of coating mouth, prepared anode sizing agent is uniformly coated on the front of collector, under 80 DEG C of constant temperature ovens, then shelve oven dry in 5 minutes (hereinafter referred to as oven dry), then test surfaces density, the one side coated face density of target is 90g/m
2if surface density does not reach requirement, readjust the discharging width of coating mouth, repeat above-mentioned coating, baking step, until surface density meets the requirements;
The one side coating of step 3, first reverse side:
Regulate the discharging width of coating mouth, the collector that upset front has been coated with, prepared anode sizing agent is uniformly coated on the reverse side of collector, then dries, then test thickness, the target coated face density of reverse side is 180g/m
2if surface density does not reach requirement, readjust the discharging width of coating mouth, repeat above-mentioned coating, baking step, until surface density meets the requirements;
The successive of step 4, coated face density increases:
The discharging width of fixing coating mouth, the positive plate of gained is above turn to front again, and anode sizing agent prepared on even spread, then dries; Positive plate turn to reverse side again afterwards, and even spread anode sizing agent again, dry; Often overturn and be coated with once, the surface density of this coated face increases 180g/m
2, until the coated face density on positive and negative two sides is respectively 450g/m
2, 540g/m
2; The positive plate of gained is above turn to front again; Before last coating, readjust the discharging width of coating mouth, anode sizing agent is uniformly coated on the front of collector, then dries, and test thickness, the target one side coated face density in front is 540g/m
2if surface density does not reach requirement, readjust the discharging width of coating mouth, repeat above-mentioned coating, baking step, until surface density meets the requirements.
Be coated with in the present invention, the surface density that positive pole increases can be equal at every turn, also can be unequal.Its key is that the difference of the surface density of the double-edged coating of collector can not be excessive, otherwise just there will be shedding phenomenon after being once coated with arbitrarily.After all coatings complete, the surface density of the positive electrode on collector two sides must be equal or approximately equalised.
Binding agent in the present invention can be the water-soluble binders such as Kynoar organic binder bond, sodium carboxymethylcellulose binding agent, butadiene-styrene rubber binding agent; The degree of Kynoar organic binder bond, sodium carboxymethylcellulose binding agent, butadiene-styrene rubber binding agent is all in 1.5 ~ 6% scopes.Correspondingly, solvent also can be organic solvent, also can be water.Adopting any one binding agent above-mentioned, can be all equal or approximately equalised by the coated face density that any one coating waste water method of above-described embodiment one, two, three makes positive and negative two sides, and coated face density be at 200 ~ 600g/m
2positive level sheet in scope.
Collector in the present invention can be aluminium foil, the metal sheet being applicable to lithium battery anode coating used such as aluminium net, nickel screen.
By the positive plate that the inventive method is made, can be used for the lithium battery making the form of ownerships such as Soft Roll, aluminum hull, cylinder further.
The energy density of lithium battery equals the gross energy stored by it divided by the quality (mass energy density) of this battery or volume (volume energy density).Gross energy is determined by the kind of the positive and negative pole material of lithium battery and content.Under the prerequisite that mentioned kind and content all remain unchanged, improve the coated face density of positive plate, then the coated face density of corresponding negative plate also can improve, then the collector, barrier film, electrolyte etc. of the positive/negative plate of inside battery do not provide the component of energy to reduce, the gross mass of battery and cumulative volume also just correspondingly reduce, and the energy density of battery just can improve.