Source: https://patents.google.com/patent/US20040209156A1/en
Timestamp: 2019-04-21 16:54:21+00:00

Document:
2018-11-05 First worldwide family litigation filed litigation Critical https://patents.darts-ip.com/?family=4676280&utm_source=google_patent&utm_medium=platform_link&utm_campaign=public_patent_search&patent=US20040209156(A1) "Global patent litigation dataset” by Darts-ip is licensed under a Creative Commons Attribution 4.0 International License.
The present invention provides a new method for improving capacity, average operating voltage and specific energy of a secondary lithium ion cell or battery. This method is achieved by means of properly adjusting the ratio between a positive material and negative material, which is calculated by theoretical specific energy, and properly increasing charge cut-off voltage. The present method can greatly increasing specific energy and average operating voltage of a secondary lithium ion cell without influence on recycle property of the cell. The present invention also provides a secondary lithium ion cell or battery practicing the method, a protecting circuit adapted for the secondary lithium ion cell or battery, a electronic device using said protecting circuit and said secondary lithium ion cell or battery, and a charging device for the secondary lithium ion cell or battery.
In addition, Lei Yongquan, “Materials for New Energy” (in Chinese), 2000, p136, discloses that the decomposition voltage of electrolyte solution using LiPF 6 as electrolyte and EC/DMC as mixture solvent is 4.2 V, and thus deems that the electrolyte solution will be decomposed and the recycle life will be affected when the charge cut-off voltage is above 4.2 V.
Yet another object of the present invention is to provide a charging device for the secondary lithium ion cell or battery, said charging device controlling an charge cut-off voltage for the single lithium ion cell within the range of greater than 4.3 V but less than 5.8 V, preferably within the range from 4.3 V to 5.2 V, and more preferably from 4.3 V to 4,8 V.
2. Within a certain range of charge cut-off voltage, the decomposition of little electrolyte solution brings about negligible effect on the recycle property of cell. The electrolyte having a high decomposition potential or an additive increasing the decomposition potential of electrolyte solution may bring about better performance. The decomposition of electrolyte solution mainly occurs on the positive electrode. Although prior documents disclosed that the decomposition voltage of the electrolyte solution comprising LiPF 6 as electrolyte and the mixture of EC/DMC as solvent on the surface of aluminum foil is 4.2 V, according to the results of experiments, this factor essentially does not affect the recycle life of the currently commercialized lithium ion cell. Namely, even though the electrolyte solution decomposes under a voltage higher than 4.2 V, the electric energy is mainly converted into chemical energy and the electric energy involved in the decomposition of electrolyte is very little, thus, this decomposition of electrolyte can hardly affect the recycle life of the lithium ion cell. As to the voltages above the decomposition voltage, such as above 5.0 V, the substance A can be added into the electrolyte solution, or the electrolyte solution B having a higher decomposition voltage can be used. The decomposition potentials of the components of electrolyte solution commonly used in the art are depicted in Table 1. It can be seen that the lowest decomposition voltage of solvent is above 4.5 V.
Without limitation, the following contents more concretely introduce the secondary lithium ion cell used in the present method. Generally, a secondary lithium ion cell comprises a positive electrode, a negative electrode, a non-aqueous electrolyte, and a separator the positive electrode and the negative electrode. The non-aqueous electrolyte can be obtained by dissolving lithium-containing metal salt, such as LiPF 6, as electrolyte into a non-aqueous solvent, such as ethylene carbonate or dimethyl carbonate. The separator can be insoluble in said non-aqueous solvent, and is a porous membrane made of polyethylene or polypropylene resin. The ratio of positive electrode material to negative electrode material is calculated by theoretical capacity under the charge cut-off voltage of 4.2 V.
The positive electrode active substance used in the present invention is lithium-containing compound. Although the examples use lithium cobalt oxides (lithium cobalt composite oxides), lithium manganese oxides and lithium nickel oxides as positive electrode material, it is understood that the practice of the present invention is not limited to the specific properties of said lithium-containing composite oxides, rather a wide range of positive electrode active substance can be used in the present invention. The common feature of these oxides is that their specific energy increases with the increase of voltage, and the experiments (see the examples) prove that the capacity of cell is greatly elevated when the charge cut-off voltage is above 4.20 V, while the other properties of cell are not affected. The present invention can also be used to lithium ion cells having doped lithium-containing compound as positive electrode active material, such as various positive electrode active materials containing various oxides and sulfides, such as lithium cobalt composite oxides, lithium manganese composite oxides, lithium nickel composite oxides, lithium nickel cobalt composite oxides, lithium manganese cobalt composite oxides, and vanadium oxides. Among these positive electrode materials, lithium cobalt composite oxides (such as LiCoO 2), lithium manganese composite oxides (such as LiMn2O4), lithium nickel composite oxides (such as LiNiO2), lithium nickel cobalt composite oxides (such as LiNi1-xCoxO2), and lithium manganese cobalt composite oxides (such as LiMnxCo1-xO2), which have higher cell voltage, are preferably used. In addition, the present invention can use conventional conducting agent and binder, and the mixture ratio for each components in the positive electrode active material can be those well known in the art.
The negative electrode active material used in the present invention is a carbonaceous or non-carbonaceous substance capable of doping and dedoping lithium ion, including, such as, lithium alloy (such as Li 4Ti5O12), metal oxide (such as amorphous tin oxide, WO2 and MoO2), TiS2 and carbonaceous substance capable of absorbing and desorbing lithium ions, and especially, the carbonaceous substance is the desired negative electrode active material.
The dried positive electrode and negative electrode are connected to a lead, and a separator made of PP is inserted between them. After being wrapped by a winder to form an assembly, and this assembly is mounted into a cell shell made of aluminum or steel material. The shell and the cover are soldered together by laser soldering. An electrolyte solution is injected into the cell under relative humidity less than 1.5%, wherein said electrolyte solution contains a mixture solvent of EC:DEC:DMC=1:1:1, and an electrolyte of 1M LiPF 6. The cell is immediately sealed after the injection.
added into the electrolyte solution.
1. A method for improving the capacity, average operating voltage and specific energy of a secondary lithium ion cell or battery, characterized in that the charge cut-off voltage of the singe cell is greater than 4.2 V but less than 5.8 V; and the ratio of positive electrode material to negative electrode material of the single cell is from 1:1.0 to 1:2.5, as calculated by the specific capacity with the charge voltage limited to 4.2 V.
2. A method according to claim 1, characterized in that the charge cut-off voltage of the singe cell is within a range from 4.3 V to 5.2 V.
3. A method according to claim 1, characterized in that the charge cut-off voltage of the singe cell is within a range from 4.3 V to 4.8 V.
4. A method according to claim 1, characterized in that the ratio of positive electrode material to negative electrode material of the single cell is from 1:1.15 to 1:2.5.
5. A secondary lithium ion cell or battery, characterized in that the single secondary lithium ion cell has a charge cut-off voltage of greater than 4.2 V but less than 5.8 V, and the ratio of positive electrode material to negative electrode material of the single cell is from 1:1.0 to 1:2.5. as calculated by the theoretic capacity with the charge cut-off voltage set at 4.2 V.
6. A secondary lithium ion cell or battery according to claim 5, characterized in that the single secondary lithium ion cell has a charge cut-off voltage within a range from 4.3 V to 5.2 V.
7. A secondary lithium ion cell or battery according to claim 5, characterized in that the single secondary lithium ion cell has a charge cut-off voltage within a range from 4.3 V to 4.8. V.
8. A secondary lithium ion cell or battery according to claim 5, characterized in that the ratio of positive electrode material to negative electrode material of the single cell is from 1:1.15 to 1:2.5.
9. A secondary lithium ion cell or battery according to claim 5, characterized in that the single lithium ion cell has a first overcharging protection voltage of greater than 4.35 V, and an overcharging protection release voltage of greater than 4.15 V.
10. A secondary lithium ion cell or battery according to claim 9, characterized in that the single lithium ion cell has a first overcharging protection voltage of greater than 4.45 V, and an overcharge protection release voltage of greater than 4.25 V.
11. A protecting circuit for the secondary lithium ion cell or battery according to claim 5, characterized in that the single lithium ion cell of said protecting circuit has a first overcharge protection voltage of greater than 4.35 V, and an overcharging protection release voltage of greater than 4.15 V.
12. A protecting circuit according to claim 11, characterized in that the single lithium ion cell of said protecting circuit has a first overcharge protection voltage of greater than 4.45 V, and an overcharge protection release voltage of greater than 4.25 V.
13. An electronic device using a secondary lithium ion cell or battery as energy source, characterized in that said electronic device comprises a protecting circuit, wherein the single lithium ion cell has a first overcharging protection voltage of greater than 4.35 V, and an overcharge protection release voltage of greater than 4.15 V.
14. An electronic device according to claim 13, characterized in that said electronic device comprises a protecting circuit, wherein the single lithium ion cell has a first overcharging protection voltage of greater than 4.45 V, and an overcharge protection release voltage of greater than 4.25 V.
15. A charging device for a secondary lithium ion cell or battery, characterized in that said charging device controls a charge cut-off voltage to the single lithium ion cell within the range of greater than 4.3 V but less than 5.8 V.
16. A charging device according to claim 15, characterized in that said charging device controls a charge cut-off voltage to the single lithium ion cell within the range from 4.3 V to 5.2 V.
17. A charging device according to claim 15, characterized in that said charging device controls a charge cut-off voltage to the single lithium ion cell within the range from 4.3 V to 4.8 V.

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