Formula for improving overcharge performance of battery cell and improving safety

Abstract

The invention relates to the technical field of lithium batteries, and discloses a formula for improving overcharge performance and safety of a battery cell, the formula comprises 80-90% of lithium cobalt oxide, 0-5% of a conductive agent, 0-5% of a binder, and 0.1-10% of a mixture of lithium oxide and lithium titanium aluminum phosphate, the chemical formula of the lithium titanium aluminum phosphate is Li < 1.5 > Al < 0.5 > Ti < 1.5 > (PO4) 3, and the chemical formula of the lithium oxide is Li2O. According to the formula for improving the overcharge performance of the battery cell and improving the safety, lithium oxide and lithium titanium aluminum phosphate are specifically added into a positive electrode formula, and the lithium titanium aluminum phosphate has good high-temperature and high-voltage stability, so that an electrolyte can be prevented from being oxidized on the surface of a high-voltage positive electrode, side reactions are reduced, the overcharge temperature rise is reduced, and the overcharge performance of the battery is improved; and lithium oxide can provide lithium atoms to ensure the battery capacity and make up the capacity loss caused by the titanium aluminum lithium phosphate, so that the high energy density and the safety are ensured, and the problems in the prior art are solved.

Description

Technical Field

[0001] The invention relates to the technical field of lithium batteries, and in particular to a formula for improving overcharge performance of a battery cell and enhancing safety. Background Art

[0002] As a secondary battery (rechargeable battery), lithium-ion battery mainly relies on the movement of lithium ions between the positive electrode and the negative electrode to work. For example, in the specific charging and discharging process, Li+ is embedded and de-embedded between the two electrodes: when charging, Li+ is de-embedded from the positive electrode and embedded into the negative electrode through the electrolyte, and the negative electrode is in a lithium-rich state; when discharging, the opposite is true, so the power supply needs to be met, and compared with traditional batteries, lithium-ion batteries have high energy density and high average output voltage. The self-discharge is small, and for good batteries, it is less than 2% per month (recoverable), there is no memory effect, and the operating temperature range is wide from -20℃ to 60℃. It has excellent cycle performance, can be charged and discharged quickly, and the charging efficiency is as high as 100%. It also has high output power, long service life, and does not contain toxic and harmful substances, so it is also called a green battery.

[0003] However, the secondary lithium-ion batteries used in reality have the characteristics of high energy density and high voltage, and their safety against overcharging is relatively low. There is a certain probability of dangerous accidents such as fire and explosion. Therefore, how to improve the stability of the positive electrode of secondary lithium-ion batteries during the production stage has become a research focus in this field. Summary of the invention

[0004] 1. Technical issues to be solved

[0005] The invention provides a formula for improving the overcharge performance of a battery cell and enhancing safety, thereby solving the problems raised in the background technology.

[0006] (II) Technical solution

[0007] The present invention provides the following technical solution: a formula for improving the overcharge performance and safety of a battery cell, comprising 80-90% lithium cobalt oxide, 0-5% conductive agent, 0-5% binder, and 0.1%-10% of a mixture of lithium oxide and lithium aluminum titanium phosphate, wherein the chemical formula of the lithium aluminum titanium phosphate is Li 1.5 Al 0.5 Ti 1.5 (PO4)3, the chemical formula of the lithium oxide is Li2O.

[0008] Preferably, the conductive agent is a graphite material or an acetylene carbon black material.

[0009] Preferably, the binder is polyvinylidene fluoride material or polymethyl methacrylate material.

[0010] Preferably, the formula ratio of the lithium oxide and lithium aluminum titanium phosphate mixture can be further reduced to between 1% and 5%.

[0011] A preparation method for improving the overcharge performance and safety of a battery cell comprises the following steps:

[0012] The first step is to place a certain amount of binder in a stirring container of a designated stirring device, then add a conductive agent into the stirring container according to the formula ratio, and then use the stirring device to stir the mixed solution in the stirring container until it is evenly dispersed;

[0013] The second step is to add a corresponding proportion of lithium cobalt oxide into the stirring container according to the formula ratio and use a stirring device to stir the lithium cobalt oxide in the mixed solution until it is evenly dispersed;

[0014] The third step is to add lithium oxide and lithium aluminum titanium phosphate in a corresponding proportion into a stirring container according to the formula ratio, and then use a stirring device to fully stir and mix the total mixed solution in the stirring container to prepare a suspension;

[0015] The fourth step is to evenly coat the prepared suspension on the existing current collector, and then completely evaporate the suspension on the current collector to obtain a positive electrode sheet of a lithium-ion battery.

[0016] (III) Beneficial effects

[0017] The present invention has the following beneficial effects:

[0018] The formula for improving the overcharge performance of the battery cell and enhancing safety is to add lithium oxide and lithium aluminum titanium phosphate to the positive electrode formula. Lithium aluminum titanium phosphate has excellent high temperature and high voltage stability, which can prevent the electrolyte from oxidizing on the surface of the high-voltage positive electrode, reduce side reactions, reduce overcharge temperature rise, and improve the overcharge performance of the battery. Lithium oxide can provide lithium atoms to ensure the battery capacity and make up for the loss of capacity caused by lithium aluminum titanium phosphate, thereby ensuring both high energy density and safety, and solving the problems existing in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a table diagram of overcharge test results of the present invention;

[0020] Figure 2 It is a data curve diagram of the overcharge test result of the present invention. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] See also Figure 1-2 A formula for improving the overcharge performance and safety of a battery cell, comprising 80-90% lithium cobalt oxide, 0-5% conductive agent, 0-5% binder, and 0.1%-10% of a mixture of lithium oxide and lithium aluminum titanium phosphate, wherein the chemical formula of the lithium aluminum titanium phosphate is Li 1.5 Al 0.5 Ti 1.5 (PO4)3, the chemical formula of the lithium oxide is Li2O;

[0023] The conductive agent is a graphite material or an acetylene carbon black material, the binder is a polyvinylidene fluoride material or a polymethyl methacrylate material, and the formula ratio of the lithium oxide and lithium aluminum titanium phosphate mixture can be further reduced to between 1% and 5%.

[0024] Embodiment 1

[0025] A preparation method for improving the overcharge performance and safety of a battery cell comprises the following steps:

[0026] The first step is to place 5% of the binder in a stirring container of a designated stirring device, then add 5% of the conductive agent into the stirring container according to the formula ratio, and then use the stirring device to stir the conductive agent and the binder until they are evenly dispersed;

[0027] The second step is to add 90% of lithium cobalt oxide into the stirring container according to the formula ratio and use a stirring device to stir the lithium cobalt oxide in the mixed solution until it is evenly dispersed;

[0028] The third step is to add 0.1% lithium oxide and 0.1% lithium aluminum titanium phosphate into the stirring container according to the formula ratio, and then use a stirring device to fully stir and mix the total mixed solution in the stirring container to prepare a suspension;

[0029] The fourth step is to evenly coat the prepared suspension on the existing current collector, and then completely evaporate the suspension on the current collector to obtain a positive electrode sheet of a lithium-ion battery.

[0030] Embodiment 2

[0031] A preparation method for improving the overcharge performance and safety of a battery cell comprises the following steps:

[0032] The first step is to place 5% of the binder in a stirring container of a designated stirring device, then add 5% of the conductive agent into the stirring container according to the formula ratio, and then use the stirring device to stir the conductive agent and the binder until they are evenly dispersed;

[0033] The second step is to add 85% of lithium cobalt oxide into the stirring container according to the formula ratio and use a stirring device to stir the lithium cobalt oxide in the mixed solution until it is evenly dispersed;

[0034] The third step is to add 1% lithium oxide and 1% lithium aluminum titanium phosphate into the stirring container according to the formula ratio, and then use a stirring device to fully stir and mix the total mixed solution in the stirring container to prepare a suspension;

[0035] The fourth step is to evenly coat the prepared suspension on the existing current collector, and then completely evaporate the suspension on the current collector to obtain a positive electrode sheet of a lithium-ion battery.

[0036] Embodiment 3

[0037] A preparation method for improving the overcharge performance and safety of a battery cell comprises the following steps:

[0038] The first step is to place 5% of the binder in a stirring container of a designated stirring device, then add 5% of the conductive agent into the stirring container according to the formula ratio, and then use the stirring device to stir the conductive agent and the binder until they are evenly dispersed;

[0039] The second step is to add 83% of lithium cobalt oxide into the stirring container according to the formula ratio and use a stirring device to stir the lithium cobalt oxide in the mixed solution until it is evenly dispersed;

[0040] The third step is to add 3% lithium oxide and 3% lithium aluminum titanium phosphate into the stirring container according to the formula ratio, and then use a stirring device to fully stir and mix the total mixed solution in the stirring container to prepare a suspension;

[0041] The fourth step is to evenly coat the prepared suspension on the existing current collector, and then completely evaporate the suspension on the current collector to obtain a positive electrode sheet of a lithium-ion battery.

[0042] Embodiment 4

[0043] A preparation method for improving the overcharge performance and safety of a battery cell comprises the following steps:

[0044] The first step is to place 5% of the binder in a stirring container of a designated stirring device, then add 5% of the conductive agent into the stirring container according to the formula ratio, and then use the stirring device to stir the conductive agent and the binder until they are evenly dispersed;

[0045] The second step is to add 80% of lithium cobalt oxide into the stirring container according to the formula ratio and use a stirring device to stir the lithium cobalt oxide in the mixed solution until it is evenly dispersed;

[0046] The third step is to add 5% lithium oxide and 5% lithium aluminum titanium phosphate into the stirring container according to the formula ratio, and then use a stirring device to fully stir and mix the total mixed solution in the stirring container to prepare a suspension;

[0047] The fourth step is to evenly coat the prepared suspension on the existing current collector, and then completely evaporate the suspension on the current collector to obtain a positive electrode sheet of a lithium-ion battery.

[0048] In summary, as the content of lithium oxide and lithium aluminum titanium phosphate increases, the energy density decreases, and the monolayer overcharge resistance gradually increases. When the content reaches 1%, it has a significant effect. When the content further reaches 3%, the battery cell can completely pass the overcharge test and the temperature is low, and the temperature rise is small; when the content increases to 5%, the safety of the battery cell is greatly improved (temperature rise 55°C), but the energy density decreases a lot, affecting normal use. Therefore, the preferred content is 1%-5%.

[0049] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0050] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A formula for improving the overcharge performance and safety of a battery cell, comprising 80-90% lithium cobalt oxide, 0-5% conductive agent, 0-5% binder, and 0.1%-10% of a mixture of lithium oxide and lithium aluminum titanium phosphate, wherein the chemical formula of the lithium aluminum titanium phosphate is Li 1.5 Al 0.5 Ti 1.5 (PO4)3, the chemical formula of the lithium oxide is Li2O.

2. A formula for improving overcharge performance and safety of a battery cell according to claim 1, characterized in that: The conductive agent is graphite material or acetylene carbon black material.

3. A formula for improving overcharge performance and safety of a battery cell according to claim 1, characterized in that: The binder is specifically made of polyvinylidene fluoride material or polymethyl methacrylate material.

4. A formula for improving overcharge performance and safety of a battery cell according to claim 1, characterized in that: The formula ratio of the lithium oxide and lithium aluminum titanium phosphate mixture can be further reduced to between 1% and 5%.

5. A preparation of a formula for improving the overcharge performance and safety of a battery cell as claimed in any one of claims 1 to 4, characterized in that: The steps include: The first step is to place a certain amount of binder in a stirring container of a designated stirring device, then add a conductive agent into the stirring container according to the formula ratio, and then use the stirring device to stir the mixed solution in the stirring container until it is evenly dispersed; The second step is to add a corresponding proportion of lithium cobalt oxide into the stirring container according to the formula ratio and use a stirring device to stir the lithium cobalt oxide in the mixed solution until it is evenly dispersed; The third step is to add lithium oxide and lithium aluminum titanium phosphate in a corresponding proportion into the stirring container according to the formula ratio, and then use a stirring device to fully stir and mix the total mixed solution in the stirring container to prepare a suspension; The fourth step is to evenly coat the prepared suspension on the existing current collector, and then completely evaporate the suspension on the current collector to obtain a positive electrode sheet of a lithium-ion battery.

Images