Patent Application
20180337432
The subject matter generally relates to an electrode material, an electrode plate, an electrolyte, and a lithium ion secondary battery.
Lithium ion secondary batteries are rechargeable batteries widely used in electric vehicles. In order to satisfy requirements of the electric vehicle to travel a long time, a discharge rate, an energy density, and a cycle life of the lithium ion secondary battery need to be increased. Improvement in the art is preferred.
Implementations of the present disclosure will now be described, by way of example only, with reference to the attached figures.
It will be appreciated that for simplicity and clarity of illustration, where appropriate, reference numerals have been repeated among the different figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein can be practiced without these specific details. In other instances, methods, procedures, and components have not been described in detail so as not to obscure the related relevant feature being described. Also, the description is not to be considered as limiting the scope of the embodiments described herein. The drawings are not necessarily to scale, and the proportions of certain parts may be exaggerated to illustrate details and features of the present disclosure better.
The disclosure is illustrated by way of example and not by way of limitation in the figures of the accompanying drawings, in which like references indicate similar elements. It should be noted that references to “an” or “one” embodiment in this disclosure are not necessarily to the same embodiment, and such references mean at least one.
The term “comprising,” when utilized, means “including, but not necessarily limited to”; it specifically indicates open-ended inclusion or membership in the so-described combination, group, series and the like.
The positive electrode plate 1 includes a conducting collector (not shown) and a positive electrode active layer (not shown) coated on the conducting collector. The positive electrode active layer includes a positive electrode material. The positive electrode material includes a positive electrode active material, a conductive agent, an adhesive, and at least one additive.
In at least one exemplary embodiment, the additive has a mass percentage of about 0.5% to about 5% of a total mass of the positive electrode material.
In at least one exemplary embodiment, the negative electrode plate 2 includes a conducting collector (not shown) and a negative electrode active layer (not shown) coated on the conducting collector. The negative electrode active layer includes a negative electrode material. The negative electrode material includes a negative electrode active material, a conductive agent, an adhesive, and at least one additive.
The conducting collector of the positive electrode plate can be an electrolytic aluminum foil. In at least one exemplary embodiment, the electrolytic aluminum foil has a thickness of about 10 μm to about 20 μm.
The conducting collector of the negative electrode plate can be an electrolytic copper foil. In at least one exemplary embodiment, the electrolytic copper foil has a thickness of about 7 μm to about 15 μm.
The positive electrode active material is a lithium transition metal oxide, such as LiCoO2, LiMn2O4, LiMnO2, Li2MnO4, LiFePO4, Li1+aMn1−xMxO2, LiCo1−xMxO2, LiFe1−xMxPO4, LiMn2−yMyO4, and Li2Mn1−xO4. Wherein, M can be nickel (Ni), cobalt (Co), manganese (Mn), aluminum (Al), chromium (Cr), magnesium (Mg), zirconium (Zr), molybdenum (Mo), vanadium (V), titanium (Ti) bismuth (B), fluorine (F), and yttrium (Y), or any combination thereof, 0<x<1 , 0<y<1, and 0≤a<0.2.
The negative electrode active material can be natural graphite, synthetic graphite, soft carbon, hard carbon, lithium titanate, silicon, and silicon carbide, or any combination thereof.
The conductive agent can be a carbon black conductive agent, a graphite conductive agent, a graphene conductive agent, or any combination thereof.
In at least one exemplary embodiment, the carbon black conductive agent includes acetylene black, Super P, Super S, 350G, carbon fiber(VGCF), carbon nanotube (CNT), and Ketjenblack (such as Ketjenblack EC300J, KetjenblackEC600JD, Carbon ECP, Carbon ECP600JD), or any combination thereof.
In at least one exemplary embodiment, the graphite conductive agent includes KS-6, KS-15, SFG-6, SFG-15 (trade name), or any combination thereof
The adhesive includes fluorine-containing resin, polyolefine compounds, cellulosic compounds, or any combination thereof.
The additive is a Prussian Blue analogue, which has a molecular formula of AxMy(FeCN6).nH2O, where A denotes an alkali element, M denotes a transition metal element. In at least one exemplary embodiment, A is potassium (K) or sodium (Na), M is iron (Fe), 0<x<2, y=1+(1−x)/3.
Referring to
In at least one exemplary embodiment, the diameter of the Prussian Blue analogue is about 100 nm.
The isolation membrane 3 is a porous polymer film, which allows lithium ions or alkali metal ions to pass through but prevents electrons from passing through.
In at least one exemplary embodiment, the isolation membrane 3 can be made of polypropylene or polyethylene.
In at least one exemplary embodiment, the electrolyte 4 includes a non-aqueous organic solvent and lithium salts dissolved in the non-aqueous organic solvent.
The non-aqueous organic solvent includes at least one of cyclic carbonate and chain carbonate.
The cyclic carbonate includes vinyl carbonate, propylene carbonate, and gamma-butyl ester, or any combination thereof.
The chain carbonate includes dimethyl carbonate, butene carbonate, diethyl carbonate, propyl carbonate, methyl ethyl carbonate, carbonate propyl ester, ethylene propylene carbonate, methyl formate, formic acid ethyl ester, propyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl acrylic acid, propionic acid ethyl ester, and propyl propionate, or any combination thereof.
The lithium salts can be Li(FSO2)2N, LiPF6, LiBF4, LiBOB, LiODFB, LiAsF6, Li(CF3SO2)2N, LiCF3SO3, and LiClO4, or any combination thereof.
In another exemplary embodiment, it is only the negative electrode material that includes the additive. The additive has a mass percentage of about 0.5% to about 5% of a total mass of the negative electrode material.
In other exemplary embodiments, only the electrolyte includes the additive. The additive has a mass percentage of about 0.5% to about 5% of a total mass of the electrolyte.
In other exemplary embodiments, at least two of the positive electrode material, the negative electrode material, and the electrolyte further include the additive. When the positive electrode material includes the additive, the additive has a mass percentage of about 0.5% to about 5% of a total mass of the positive electrode material. When the negative electrode material includes the additive, the additive has a mass percentage of about 0.5% to about 5% of a total mass of the negative electrode material. When the electrolyte includes the additive, the additive has a mass percentage of about 0.5% to about 5% of a total mass of the electrolyte.
The following equations illustrate the chemical reaction of the Prussian Blue analogue when the lithium ion secondary battery 100 is charging.
The chemical reaction in the positive electrode 1 is:
AxMny[FeII(CN)6]-e−→Ax−1Mny[FeIII(CN)6]+A−;
The chemical reaction in the negative electrode 2 is:
Ax−1Mny[FeIII(CN)6]+e−+A+→AxMny[FeII(CN)6];
The following equations illustrate the chemical reaction of the Prussian Blue analogue when the lithium ion secondary battery 100 is discharging.
The chemical reaction in the positive electrode 1 is:
Ax−1Mny[FeIII(CN)6]e−+A+→AxMny[FeII(CN)6];
The chemical reaction in the negative electrode 2 is:
AxMny[FeII(CN)6]-e−→Ax−1Mny[FeIII(CN)6]+A+º
“Example” is the battery of the instant disclosure, and “comparative example” is regular battery.
A positive electrode active material, a conductive agent, an adhesive, and at least one additive are mixed to form a positive electrode material. The positive electrode material forms a positive electrode plate of the lithium ion secondary battery 100. The positive electrode active material has a mass percentage of about 95% to about 98% of a total mass of the positive electrode material. The conductive agent has a mass percentage of about 0.5% to about 3% of the total mass of the positive electrode material. The adhesive has a mass percentage of about 0.5% to about 2% of the total mass of the positive electrode material. The additive has a mass percentage of about 0.5% to about 5% of the total mass of the positive electrode material.
A positive electrode active material, a conductive agent, and an adhesive are mixed to form a positive electrode material. The positive electrode material is used to form a positive electrode plate of a regular battery. The positive electrode active material has a mass percentage of about 95% to about 98% of a total mass of the positive electrode material. The conductive agent has a mass percentage of about 0.5% to about 3% of the total mass of the positive electrode material. The adhesive has a mass percentage of about 0.5% to about 2% of the total mass of the positive electrode material.
A lithium ion secondary battery 100 is made by the positive electrode plate in the example, and a battery is made by the positive electrode plate in the comparative example. An energy density, a discharge rate, and a cycle life of each of the lithium ion secondary battery 100 and the battery are tested. Wherein, the cycle life is tested under normal temperature of 25° C. when the charge rate and the discharge rate are 0.7 C/0.7 C. The test results are shown in
Referring to
Referring to
Referring to
With the above configuration, the additive is added into at least one of the positive electrode plate, a negative electrode plate, and an electrolyte, and the additive is a Prussian Blue analogue. Thus, when the electrical potential of the lithium ion secondary battery 100 changes, the transition metal elements M undergoes an oxidation-reduction reaction, and the alkali ions A+ can flow back and forth between the positive electrode plate 1 to the negative electrode plate 2. Thus, the electric capacity and the average energy density of the lithium ion secondary battery 100 can be increased. Furthermore, when the alkali ions A+ flow away from the Prussian Blue analogue, the space for the alkali element A is empty, forming a channel to allow the lithium ions to pass through. This channel can improve ionic conductivity of the lithium ion secondary battery 100, and then the discharge rate can be improved. Moreover, the Prussian Blue analogue in the positive electrode plate or the negative electrode plate can reduce collision rates between the electrolyte and the positive electrode plate or the negative electrode plate thus can reduce irreversible reactions in the electrolyte, which would reduce the cycle life of the lithium ion secondary battery. The amount of the additive is small, so the additive cannot affect the working potential of the lithium ion secondary battery 100. Then, the additive can be applied to nearly all kinds of positive active materials, negative active materials, and electrolytes. Thus, the additive can be easily added into the lithium ion secondary battery 100.
It is to be understood, even though information and advantages of the present embodiments have been set forth in the foregoing description, together with details of the structures and functions of the present embodiments, the disclosure is illustrative only; changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the present embodiments to the full extent indicated by the plain meaning of the terms in which the appended claims are expressed.
| Number | Date | Country | Kind |
|---|---|---|---|
| 106116316 | May 2017 | TW | national |
