CN111710886B - Method for prolonging service life of metal-air battery - Google Patents
Method for prolonging service life of metal-air battery Download PDFInfo
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Abstract
The invention provides a method for prolonging the service life of a metal-air battery, which comprises the following steps of discharging the metal-air battery, then charging the metal-air battery, and then continuously carrying out overcharging to obtain the metal-air battery with prolonged service life; the metal-air battery includes a used metal-air battery or a metal-air battery that exhibits an end-of-life signal. The method for prolonging the service life of the metal-air battery can completely decompose the discharge product, so that the cycle life of the metal-air battery is prolonged; and the overcharge can fully exert the advantage of large capacity of the metal-air battery, and even under deep discharge, discharge products can be completely decomposed after the overcharge of the battery. Thus, the long cycle life under large capacity is realized, and the performance of the metal-air battery is fully exerted. The method provided by the invention is simple and easy to implement, mild in condition, easy to control and suitable for popularization and application on an industrial level.
Description
Technical Field
The invention relates to the technical field of metal-air battery materials, in particular to a method for prolonging the service life of a metal-air battery.
Background
With the continuous improvement of the requirement of the electric automobile on the endurance mileage, the mainstream lithium ion battery in the current market cannot meet the requirement. Metal-air batteries have received much attention due to their ultra-high energy density, which is ten times that of lithium ion batteries. The air battery is one of chemical batteries, and is constructed in a similar principle to a dry battery except that its positive active material is taken from oxygen in the air or pure oxygen, also called an oxygen battery, and may include metal air batteries such as lithium-air batteries, potassium-air batteries, sodium-air batteries, zinc-air batteries, aluminum-air batteries, magnesium-air batteries, and the like, classified by negative electrode materials. The metal-air battery consists of a positive electrode, an electrolyte and a negative electrode. Because of the wide attention paid to the extremely high energy density of the metal-air battery, theoretically, the metal-air battery can be smaller and lighter, has the advantages of ultrahigh specific energy, convenience in use, low cost and the like, and is considered as a promising next-generation energy storage device in the field.
Although metal-air batteries have many advantages, many studies are required before they are put into practical production, and many critical problems, such as cyclicity, still need to be solved. The metal-air battery comprises a negative electrode, an electrolyte and a positive electrode. The negative electrode is a metallic material and the positive electrode is predominantly a carbon material, e.g. commercially availableCarbon (KB carbon, Super P, XC-72), carbon nanotubes, graphene, etc. can be loaded with a catalyst (e.g., noble metal, transition metal oxide, etc.) on a carbon material to improve the cycle life, charge-discharge efficiency, specific surface area of the positive electrode, etc. of the battery, which determines the discharge capacity of the battery. During the discharge process, lithium metal atoms lose electrons to become lithium ions, oxygen in the positive electrode is reduced, and the lithium ions are combined to generate lithium peroxide (Li)2O2) Solid, deposited on the surface of the positive electrode. During charging, lithium peroxide (Li)2O2) Then decomposed into Li and O again2And the reversibility of the battery is realized.
Therefore, how to find a suitable way to further improve the cycle performance of the metal-air battery and prolong the service life of the metal-air battery has become one of the focuses of extensive attention of many researchers in the field.
Disclosure of Invention
In view of the above, the technical problem to be solved by the present invention is to provide a method for prolonging the service life of a metal-air battery, which is simple and easy to implement, has mild conditions, and can completely decompose a discharge product deposited on the positive electrode of the metal-air battery, so that the cycle life of the lithium-air battery is increased, and the advantage of large capacity of the lithium-air battery is fully exerted.
The invention provides a method for prolonging the service life of a metal-air battery, which comprises the following steps:
A) after discharging, charging the metal-air battery, and then continuously performing overcharging to obtain the metal-air battery with the service life prolonged;
the metal-air battery includes a used metal-air battery or a metal-air battery that exhibits an end-of-life signal.
Preferably, the discharge mode comprises constant current discharging in a fixed voltage window and/or constant current constant capacitance discharging;
the charging mode comprises one or more of constant current charging under a fixed voltage window, constant current and constant capacitance charging, non-constant current charging and constant voltage charging;
the discharging current and the charging current are independent in numerical value and can be the same or different;
the discharge capacity generated in the discharge process of the metal-air battery is less than or equal to the charge capacity charged into the metal-air battery after the metal-air battery is charged and is continuously overcharged.
Preferably, the discharge cut-off voltage of the constant current discharging under a fixed voltage window is 1.0-2.5V;
the current value of the constant current discharged in a fixed voltage window is 0.01-10 mA cm-2；
The charging cut-off voltage of the constant current charged under a fixed voltage window is 3.5-6.0V;
the constant current is charged under a fixed voltage window, and the current value is 0.01-10 mA cm-2。
Preferably, the discharge time of the constant-current and constant-capacity discharge is 1-100 hours;
the current value of constant current and constant capacity discharge is 0.01-10 mA cm-2；
The discharge voltage of the constant-current and constant-capacitance discharge is 1.5-2.9V.
Preferably, the charging time of the constant-current and constant-capacity charging is 1-200 hours;
the constant current and constant capacity charging current value is 0.01-10 mA cm-2；
The charging voltage of the constant-current constant-capacitance charging is 3.5-6.0V.
Preferably, the initial voltage of the constant current discharging in the fixed voltage window is the same as the charge cut-off voltage of the constant current charging in the fixed voltage window;
the discharging time of the constant-current constant-capacitance discharging is the same as the charging time of the constant-current constant-capacitance charging.
Preferably, the non-constant current charging comprises gradient current charging;
the charging current for constant voltage charging is 0.01-10 mA cm-2；
The charging voltage of the constant-voltage charging is 3.2-6.0V;
when the charging mode is constant-voltage charging and constant-current constant-capacitance charging, the voltage of the constant-voltage charging is 3.2-6.0V, and the current of the constant-current constant-capacitance charging is 0.01-10 mA cm-2；
The step a) may be performed every time the metal-air battery is cycled, or may be performed separately after the metal-air battery is cycled for a certain number of times.
Preferably, after the metal-air battery is recharged and overcharged continuously, the total charging capacity charged into the metal-air battery is 100-300% of the discharging capacity generated in the discharging process of the metal-air battery;
the overcharge time is 0.01-5000% of the discharge time;
the electric energy charged by the overcharge is used for decomposing the discharge products which are deposited on the anode of the metal-air battery and cannot be decomposed after charging.
Preferably, the overcharged current is 10-200% of the discharge current;
the voltage of the overcharge is 3.5-6.0V;
the overcharge cut-off voltage is 4.5-6.0V.
Preferably, the end-of-life signal comprises a voltage drop condition of the metal-air battery during discharging after a plurality of cycles;
the voltage drop comprises that the discharge voltage drops below 2.0V and/or the difference between the discharge final voltage and the discharge final voltage of the previous cycle is more than 0.1V;
in the process that the discharge voltage is reduced to be below 2.0V, the average reduction rate of the discharge voltage is 0.1-0.5V/hour;
the negative electrode metal element in the metal-air battery comprises one or more of lithium, sodium and potassium;
the positive working gas of the metal-air battery comprises one or more of oxygen, nitrogen, carbon dioxide and argon in different proportions.
The invention provides a method for prolonging the service life of a metal-air battery, which comprises the following stepsDischarging the metal-air battery, then charging, and then continuously overcharging to obtain the metal-air battery with prolonged service life; the metal-air battery includes a used metal-air battery or a metal-air battery that exhibits an end-of-life signal. Compared with the prior art, the invention aims at the problem that the cycle life of the existing metal-air battery is short, starts from the mechanism direction of metal air, and particularly selects the deposit Li of the anode in the discharging process2O2As a direction of improvement, it is considered that Li is attributable to2O2Is less conductive, is difficult to completely decompose during charging, and can hinder Li in subsequent cycles2O2And therefore results in a relatively short cycle life of the metal-air battery.
The invention selects the charging process of the improved metal-air battery more creatively, and the conventional charging process is considered to be mainly divided into two types, wherein the first type is charging and discharging under a fixed voltage window by using constant current, generally within 2.0-5.0V, namely, the first type is discharging to 2.0V and then charging to 4.5V, namely, a cycle. But cycling through the voltage window, the capacity to charge is unpredictable, and typically less than the capacity to discharge, which makes Li2O2It cannot be completely decomposed.
Referring to fig. 1, fig. 1 is a charge-discharge curve for charging and discharging at a fixed voltage window using a constant current.
From the results of the typical constant voltage window charging and discharging of fig. 1, it can be seen that the charge capacity is significantly lower than the discharge capacity, the more cycles, the lower the discharge capacity, which is due to the incomplete decomposition of the discharge product.
And the second is constant current and constant capacity charging, that is, under constant current, discharging for a certain time, and then charging for the same time with the same current. But the charging efficiency is not 100%, there will be some Li2O2It is not completely decomposed and covers the surface of the positive electrode, which affects the subsequent cycle, as in the case of the first charging method.
Referring to fig. 2, fig. 2 is a charge and discharge curve using constant current and constant capacity charge and discharge. Wherein the constant capacity of the battery is 1000 ma-hr per gram, it can be seen from fig. 2 that after 35 circles, the voltage of the battery is reduced rapidly, and the battery life is over, which is also caused by the deposition of discharge products of the positive electrode. The consequences are low capacity and short cycle life. In this charging and discharging mode, the most advantage of the lithium-air battery, that is, the large capacity is not fully exerted, and the lithium-air battery is difficult to compete with the lithium-ion battery.
Therefore, the invention is experimentally considered that the conventional charging mode cannot realize complete reversibility of the battery, so the invention creatively provides an overcharging concept aiming at the charging process of the metal-air battery, and prolongs the charging time on the basis of the original charging process of the metal-air battery, so that after charging, a discharge product can be completely decomposed, and the subsequent discharge capacity can be maintained unchanged.
The method for prolonging the service life of the metal-air battery with the overcharging step can completely decompose a discharge product, so that the cycle life of the metal-air battery is prolonged; and the overcharge can fully exert the advantage of large capacity of the metal-air battery, and even under deep discharge, discharge products can be completely decomposed after the overcharge of the battery. Thus, the long cycle life under large capacity is realized, and the performance of the metal-air battery is fully exerted. The method provided by the invention is simple and easy to implement, mild in condition, easy to control and suitable for popularization and application on an industrial level.
Experimental results show that the discharge capacity of the battery circulating within the fixed voltage range of 2.0-4.5V can be remarkably improved by about one third compared with the discharge capacity of the battery without over-charging after the over-charging is carried out for 2 hours, and the effect is very remarkable. Especially for the dead battery, through overcharging, the battery can discharge again, realizes the reviving of battery, and is very practical to the emergency of coping with.
Drawings
FIG. 1 is a charge-discharge curve for charging and discharging at a fixed voltage window using a constant current;
FIG. 2 is a charge-discharge curve using constant current and constant capacity charge-discharge;
FIG. 3 is a schematic diagram of a lithium-air battery according to the present invention;
fig. 4 is a schematic diagram illustrating a comparison between a charging method provided in embodiment 1 of the present invention and a conventional charging method;
FIG. 5 is a comparison curve of capacity retention rates of lithium air batteries according to the charging method provided in example 1 of the present invention and the conventional charging method;
FIG. 6 is a graph showing the cycle curve of a constant current overcharge applied to a lithium oxygen battery according to example 2 of the present invention;
fig. 7 is a graph showing a cycle curve of a lithium-air battery according to example 3 of the present invention using constant current overcharge;
fig. 8 is a graph showing a cycle curve of a lithium-air battery according to example 4 of the present invention using constant current overcharge.
Detailed Description
For a further understanding of the invention, preferred embodiments of the invention are described below in conjunction with the examples, but it should be understood that these descriptions are included merely to further illustrate the features and advantages of the invention and are not intended to limit the invention to the claims.
All of the starting materials of the present invention, without particular limitation as to their source, may be purchased commercially or prepared according to conventional methods well known to those skilled in the art.
All the raw materials of the present invention are not particularly limited in purity, and the present invention preferably employs purity commonly used in the field of analytical purification or metal air batteries.
The invention provides a method for prolonging the service life of a metal-air battery, which comprises the following steps:
A) and discharging the metal-air battery, then charging, and then continuously overcharging to obtain the metal-air battery with the service life prolonged.
The specific definition of the metal-air battery is not particularly limited in principle, and may be selected and adjusted by those skilled in the art according to the actual battery condition, charge and discharge condition and battery performance, and the negative electrode metal element in the metal-air battery preferably includes one or more of lithium, sodium and potassium, and more preferably lithium, sodium or potassium. The positive working gas of the metal-air battery preferably comprises one or more of oxygen, nitrogen, carbon dioxide and argon in different proportions, and more preferably is oxygen or a mixed gas containing oxygen in any proportion. Specifically, for example, a lithium oxygen battery, a lithium-oxygen/carbon dioxide battery (gas ratio 1: 1).
The conditions of the metal-air battery are not particularly limited in principle, and a person skilled in the art can select and adjust the conditions according to the actual battery condition, the charge and discharge condition and the battery performance. In the present invention, if the battery is an unused battery, it is not subjected to a conventional charge and discharge operation, and it is theoretically free from deposits during discharge on the positive electrode, so the method for extending the service life of a metal-air battery provided by the present invention is not suitable for an unused metal-air battery, i.e., a metal-air battery that has not been subjected to a conventional discharge process.
The definition of overcharge in the present invention preferably means that the charge capacity is larger than the discharge capacity, and may be understood as a complementary charge or a compensation charge, etc., which is different from the definition of other overcharge, such as the concept of the lithium ion battery and the formation step thereof.
The specific definition of the end-of-life signal is not particularly limited in principle, and may be selected and adjusted by those skilled in the art according to the actual battery condition, the charge and discharge condition and the battery performance, and the end-of-life signal preferably includes a voltage drop situation occurring during discharge after the metal-air battery is cycled for several times. Specifically, the voltage dip of the present invention preferably includes a discharge voltage drop of 2.0V or less and/or a difference between the discharge end voltage and the discharge end voltage of the previous cycle of 0.1V or more, more preferably a discharge voltage drop of 2.0V or less (or 1.8V or less, or 1.5V or less), or a difference between the discharge end voltage and the discharge end voltage of the previous cycle of 0.1V or more (or 0.2V or more, or 0.3V or more). Further, in the process that the discharge voltage is reduced to be less than 2.0V, the average rate of reduction of the discharge voltage can be 0.1-0.5V/hour, also can be 0.15-0.45V/hour, also can be 0.2-0.4V/hour, also can be 0.25-0.35V/hour.
It should be noted that the concept of overcharge is not equivalent to that of overcharge in lithium ion batteries, and the present invention is only a term defined to distinguish it from the conventional charging process of lithium air batteries. In the present invention, it may be named complementary or compensatory charging based on the mechanism and the corresponding description.
The specific discharge mode is not particularly limited in principle, and can be selected and adjusted by a person skilled in the art according to the actual battery condition, the charge and discharge condition and the battery performance, the metal-air battery provided by the invention has the advantages of better complete decomposition of discharge products, improvement of cycle performance, prolongation of cycle life and full play of large capacity of the metal-air battery, and the discharge mode preferably comprises constant current discharge in a fixed voltage window and/or constant current constant capacitance discharge, and more preferably constant current discharge in a fixed voltage window or constant current constant capacitance discharge.
The invention has no special limitation on the specific parameters of the constant current discharging in the fixed voltage window in principle, and the technicians in the field can select and adjust the parameters according to the actual battery condition, the charging and discharging condition and the battery performanceThe discharge cut-off voltage is preferably 1.0 to 2.5V, more preferably 1.2 to 2.3V, and still more preferably 1.5 to 2.0V. The current value of the constant current discharging in a fixed voltage window is preferably 0.01-10 mA cm-2More preferably 0.05 to 8mA cm-2More preferably 0.1 to 6mA cm-2More preferably 0.5 to 4mA cm-2More preferably 1 to 3mA cm-2。
The specific parameters of the constant-current and constant-capacity discharge are not particularly limited in principle, and a person skilled in the art can select and adjust the parameters according to the actual battery condition, the charge and discharge condition and the battery performance, the discharge product is completely decomposed better, the cycle performance is improved, the cycle life is prolonged, and the advantage of the large capacity of the metal-air battery is fully exerted, and the discharge time of the constant-current and constant-capacity discharge is preferably 1-100 hours, more preferably 10-90 hours, more preferably 30-70 hours, and more preferably 40-60 hours. The discharge voltage of the constant-current and constant-capacitance discharge is preferably 1.5-2.9V, more preferably 1.7-2.7V, more preferably 1.9-2.5V, and more preferably 2.1-2.3V. The current value of constant current and constant capacity discharge is preferably 0.01-10 mA cm-2More preferably 0.05 to 8mA cm-2More preferably 0.1 to 6mA cm-2More preferably 0.5 to 4mA cm-2More preferably 1 to 3mA cm-2。
The specific charging mode is not particularly limited in principle, and can be selected and adjusted by a person skilled in the art according to the actual battery condition, the charge and discharge condition and the battery performance, the metal-air battery can be completely decomposed for better discharge products, the cycle performance is improved, the cycle life is prolonged, and the advantage of large capacity of the metal-air battery is fully exerted, and the charging mode preferably comprises one or more of constant-current charging under a fixed voltage window, constant-current constant-capacitance charging, non-constant-current charging and constant-voltage charging, and more preferably, constant-current charging under a fixed voltage window, constant-current constant-capacitance charging, non-constant-current charging or constant-voltage charging.
The invention is in principle not particularly limited to the specific parameters of the constant current charging at a fixed voltage window, and the person skilled in the art can useAccording to the method, the discharge product is completely decomposed, the cycle performance is improved, the cycle life is prolonged, and the advantage of large capacity of the metal-air battery is fully exerted, wherein the charge cut-off voltage of the constant current charging under a fixed voltage window is preferably 3.5-6.0V, more preferably 4.0-5.5V, and more preferably 4.5-5.0V. The current value of the constant current charged in a fixed voltage window is preferably 0.01-10 mA cm-2More preferably 0.05 to 8mA cm-2More preferably 0.1 to 6mA cm-2More preferably 0.5 to 4mA cm-2More preferably 1 to 3mA cm-2。
The specific parameters of the constant-current and constant-capacity charging are not particularly limited in principle, and a person skilled in the art can select and adjust the parameters according to the actual battery condition, the charging and discharging condition and the battery performance, the constant-current and constant-capacity charging method is used for completely decomposing a better discharging product, improving the cycle performance, prolonging the cycle life and fully playing the advantage of large capacity of the metal-air battery, and the charging time of the constant-current and constant-capacity charging is preferably 1-200 hours, more preferably 10-150 hours, more preferably 50-100 hours, and more preferably 60-90 hours. The charging voltage of the constant-current and constant-capacity charging is preferably 3.5-6.0V, more preferably 4.0-5.5V, and more preferably 4.5-5.0V. The current value of constant current and constant capacity charging is preferably 0.01-10 mA cm-2More preferably 0.05 to 8mA cm-2More preferably 0.1 to 6mA cm-2More preferably 0.5 to 4mA cm-2More preferably 1 to 3mA cm-2。
The specific mode of the non-constant current charging is not particularly limited in principle, and a person skilled in the art can select and adjust the non-constant current charging according to the actual battery condition, the charging and discharging condition and the battery performance.
The invention is not limited in principle to the specific parameters of the constant voltage charging, and the technique in the fieldPersonnel can select and adjust the discharge current according to the actual battery condition, the charge and discharge condition and the battery performance, the constant-voltage charging device can completely decompose discharge products, improve the cycle performance, prolong the cycle life and fully play the advantage of large capacity of the metal-air battery, and the charging current of the constant-voltage charging is preferably 0.01-10 mA cm-2More preferably 0.05 to 8mA cm-2More preferably 0.1 to 6mA cm-2More preferably 0.5 to 4mA cm-2More preferably 1 to 3mA cm-2. The charging voltage of the constant voltage charging is preferably 3.5-6.0V, more preferably 4.0-5.5V, and more preferably 4.5-5.0V.
In the invention, the charging mode can also be a charging mode combining constant voltage charging and constant current and constant capacitance charging. In the constant voltage charging stage, the charging voltage is preferably 3.2-6.0V, more preferably 4.0-5.5V, and more preferably 4.5-5.0V. In the constant-current and constant-capacity charging stage, the charging current is preferably 0.01-10 mA cm-2More preferably 0.05 to 8mA cm-2More preferably 0.1 to 6mA cm-2More preferably 0.5 to 4mA cm-2More preferably 1 to 3mA cm-2。
In the invention, the method for integrally refining and prolonging the service life is better to completely decompose the discharge product, improve the cycle performance, prolong the cycle life and fully exert the advantage of large capacity of the metal-air battery, and the discharge current and the charge current are independent in numerical value and can be the same or different. Further, the initial voltage at which the constant current is discharged in the fixed voltage window is preferably the same as the charge cut-off voltage at which the constant current is charged in the fixed voltage window. The discharge time of the constant current and constant capacity discharge is preferably the same as the charge time of the constant current and constant capacity charge.
In the invention, in order to complete and refine the whole method for prolonging the service life, the discharge product is better and completely decomposed, the cycle performance is improved, the cycle life is prolonged, the advantage of large capacity of the metal-air battery is fully exerted, and the discharge capacity generated in the discharge process of the metal-air battery is preferably less than or equal to that of the metal-air battery which is then chargedAnd charging capacity of the metal-air battery after the overcharge is continued. That is, the discharge capacity generated in the discharge process of the metal-air battery is larger than the charge capacity charged in the metal-air battery during the charging process after the metal-air battery is discharged, and the overcharge is continued in the invention, so that the total capacity charged in the metal-air battery after the overcharge is larger than or equal to the discharge capacity before the current charging. Specifically, after the metal-air battery is recharged and overcharged, the total charging capacity charged in the metal-air battery is preferably 100% to 300%, more preferably 150% to 300%, and still more preferably 200% to 250% of the discharge capacity generated during the discharge of the metal-air battery. In the present invention, the overcharged electric energy is used to decompose the undecomposed deposited discharge product (Li) on the positive electrode of the metal-air battery after charging2O2)。
The specific parameters of the overcharge are not particularly limited in principle, and a person skilled in the art can select and adjust the specific parameters according to the actual battery condition, the charge and discharge condition and the battery performance, the overcharge time can be 0.01-5000%, 0.05-1000%, 0.1-500%, 0.5-100%, 1-80% and 10-50% of the discharge time, the cycle performance is improved, the cycle life is prolonged, and the advantage of large capacity of the metal-air battery is fully exerted. In the invention, the overcharge time can be long because the charge current of the overcharge can be set to be very small based on actual conditions, such as 1mA in normal discharge, so that in order to enable the discharge product to be decomposed more completely, the discharge product can be decomposed very slowly by using a small current, so that the decomposition is more complete and the effect is better.
The overcharge current in the present invention is preferably 10% to 200%, more preferably 30% to 180%, more preferably 50% to 150%, and more preferably 80% to 130% of the discharge current. The voltage of the overcharge is preferably 3.5-6.0V, more preferably 4.0-5.5V, and more preferably 4.5-5.0V. The over-charging cut-off voltage is preferably 4.5-6.0V, more preferably 4.7-5.8V, and more preferably 5.0-5.5V.
In the invention, in order to integrate and refine the whole method for prolonging the service life, the discharge product is better and completely decomposed, the cycle performance is improved, the cycle life is prolonged, and the advantage of large capacity of the metal-air battery is fully exerted, the step A) can be carried out in each cycle of the metal-air battery, and can also be carried out independently after the metal-air battery is cycled for a certain number of times. More specifically, the invention is based on the existing charging mode, such as constant current discharging until the voltage drops to 2.0V, and then charging to 4.5V under the same current, but experiments show that the battery cannot be completely reversible. The method for prolonging the service life of the invention specifically comprises the following steps:
the invention prolongs the charging time by 2 hours, firstly charges to 4.5V by constant current, and then charges for 2 hours by constant current, thus after charging, the discharge product is completely decomposed, and the following discharge capacity can be maintained unchanged.
The invention considers that the traditional charging mode of charging to 4.5V can not completely decompose the discharge product, and the influence is caused on the subsequent circulation. According to the charging mode provided by the invention, after the charging is carried out to 4.5V, the charging (overcharging) is carried out, the discharge product can be decomposed to the maximum extent, and powerful conditions are provided for the subsequent battery cycle, so that the energy density and the cycle can be remarkably improved.
The method for prolonging the service life of the metal-air battery aims to effectively solve the problem of the metal-air battery, and is not suitable for the lithium ion battery, otherwise, the lithium ion battery does not have corresponding revelation. The reason is that the lithium ion battery is based on the intercalation and deintercalation of lithium ions, when the lithium ion battery is charged to a certain capacity, the deintercalation of the lithium ions is complete, the overcharge further causes the deintercalation of transition metal ions and the decomposition of electrolyte, and the capacity is irreversible, so that the collapse of a positive electrode structure and the instability of a battery system are caused.
The steps of the invention provide a method for prolonging the service life of the metal-air battery, and the battery can not be completely charged based on the existing charging modeThe invention provides an overcharge concept aiming at the charging process of a metal-air battery, and prolongs the charging time on the basis of the original charging process of the metal-air battery, particularly a lithium-air battery, so that after charging, a discharge product Li2O2Can be completely decomposed, and the following discharge capacity can be maintained. The method for prolonging the service life of the metal-air battery with the overcharging step can decompose the discharge product to the maximum extent and provide powerful conditions for the subsequent battery cycle, so that the energy density and the cycle can be obviously improved, and the cycle life of the lithium-air battery is prolonged; and the overcharge can fully exert the advantage of large capacity of the lithium air battery, and even under deep discharge, the discharge product can be completely decomposed after the overcharge of the battery. This realizes a long cycle life at a large capacity, and gives full play to the performance of the lithium air battery.
The method provided by the invention is simple and easy to implement, mild in condition, easy to control and suitable for popularization and application on an industrial level.
Experimental results show that the discharge capacity of the battery circulating within the fixed voltage range of 2.0-4.5V can be remarkably improved by about one third compared with the discharge capacity of the battery without over-charging after the over-charging is carried out for 2 hours, and the effect is very remarkable. Especially for the dead battery, through overcharging, the battery can discharge again, realizes the reviving of battery, and is very practical to the emergency of coping with.
For further illustration of the present invention, the method for prolonging the service life of a metal-air battery provided by the present invention is described in detail with reference to the following examples, but it should be understood that the embodiments are implemented on the premise of the technical solution of the present invention, and the detailed embodiments and the specific operation procedures are given only for further illustration of the features and advantages of the present invention, not for limitation of the claims of the present invention, and the scope of protection of the present invention is not limited to the following examples.
Example 1
A carbon nano tube positive electrode, 1 mol/L lithium trifluoromethanesulfonate/tetraethylene glycol dimethyl ether solution are used as electrolyte, a lithium sheet is used as a negative electrode, a 2025 stainless steel battery shell, a glass fiber membrane is used as a diaphragm, foam nickel is used as a positive electrode current collector and other components are assembled into a lithium air battery, and then the battery is placed in sealed oxygen for testing. In this embodiment, the newly assembled battery is tested after being subjected to one or more normal charging and discharging operations, simulating a normally used battery.
Referring to fig. 3, fig. 3 is a schematic diagram of a lithium air battery according to the present invention.
Wherein, 1 is the positive pole shell, 2 is the hole on the positive pole shell, 3 is the mass flow body, 4 is the positive pole, 5 is the diaphragm, 6 is the sheetmetal, 7 is the negative pole shell.
Referring to fig. 4, fig. 4 is a schematic diagram illustrating a comparison between a charging method provided in embodiment 1 of the present invention and a conventional charging method.
At 0.1mA/cm-2The discharge is firstly carried out until 2.0V is stopped, and then the charge is carried out to 4.5V. The conventional charging method is that the charging is stopped when the charging is 4.5V, and the charging is continued for 2 hours after the charging is 4.5V in the embodiment 1 of the invention. Then, the discharge in one cycle is performed, and the cycle of the battery is repeated.
The charging method provided in embodiment 1 of the present invention was examined.
Referring to fig. 5, fig. 5 is a graph comparing capacity retention rates of lithium air batteries according to the charging method provided in example 1 of the present invention and the conventional charging method.
The cycling results are shown in the figure, and the capacity retention of the battery after 2 hours of overcharge is significantly better than that of the battery without overcharge.
Example 2
The lithium oxygen battery is assembled by components of a carbon nano tube anode, 1 mol/L lithium trifluoromethanesulfonate/tetraethyleneglycol dimethyl ether solution as electrolyte, a lithium sheet as a cathode, a 2025 stainless steel battery shell, a glass fiber membrane as a diaphragm, foamed nickel as an anode current collector and the like.
The lithium oxygen cell prepared in the above step was placed in sealed oxygen for testing.
Referring to fig. 6, fig. 6 is a graph showing a cycle curve of the lithium oxygen battery according to example 2 of the present invention using constant current overcharge.
FIG. 6 is a cycle curve of the lithium-oxygen battery at a current of 0.05mA and a fixed capacity of 0.1 mAh. The conductivity of the positive electrode is reduced due to incomplete decomposition of discharge products, the discharge voltage is reduced continuously, and the battery is generally considered to be scrapped when the voltage of the battery is reduced to below 1.5V. However, by adopting the overcharge mode provided by the invention, the discharge is continued after the constant current is overcharged for 20 hours under the same current, the battery can normally operate, and as can be seen from fig. 6, the situation can be repeated for many times. This way a "rejuvenation" of the battery is achieved.
Example 3
The lithium air battery is assembled by components of a carbon nano tube anode, 1 mol/L lithium trifluoromethanesulfonate/tetraethylene glycol dimethyl ether solution as electrolyte, a lithium sheet as a cathode, a 2025 stainless steel battery shell, a glass fiber membrane as a diaphragm, foamed nickel as an anode current collector and the like.
The lithium oxygen cell prepared in the above procedure was tested in a sealed oxygen/carbon dioxide (1: 1).
Referring to fig. 7, fig. 7 is a graph showing a cycle curve of a lithium-air battery according to example 3 of the present invention using constant current overcharge.
Fig. 7 is a cycle curve of the lithium-air battery at a current of 0.05mA and a fixed capacity of 0.1 mAh. It is generally accepted that when the cell voltage drops below 1.5V, the cell is discarded. However, by adopting the overcharge mode provided by the invention, the discharge is continued after the constant current is overcharged for 20 hours under the same current, the battery can normally operate, and as can be seen from fig. 7, the situation can be repeated for many times. This also enables recycling of the battery.
Example 4
The lithium air battery is assembled by components of a carbon nano tube anode, 1 mol/L lithium trifluoromethanesulfonate/tetraethylene glycol dimethyl ether solution as electrolyte, a lithium sheet as a cathode, a 2025 stainless steel battery shell, a glass fiber membrane as a diaphragm, foamed nickel as an anode current collector and the like.
The lithium oxygen cell prepared in the above procedure was tested in a sealed oxygen/carbon dioxide (1: 1).
Referring to fig. 8, fig. 8 is a graph showing a cycle curve of a lithium-air battery according to example 4 of the present invention, which is overcharged with a constant current.
Fig. 8 is a cycle curve of the lithium-air battery at a current of 0.05mA with a fixed capacity of 0.5mAh (to fully exploit the advantage of the large capacity of the lithium-air battery, we set the battery capacity to 0.5mAh, compared with the previous 0.1 mAh). It is generally accepted that when the cell voltage drops below 1.5V, the cell is discarded. However, by adopting the overcharging mode provided by the invention, under the same current, the constant current is overcharged for 20 hours and then continues to discharge, the battery can normally operate, and when the voltage is reduced to 1.5V and is not overcharged, the next cycle voltage is quickly reduced, but after the voltage is overcharged by one time, the next cycle of the battery can have a stable discharging platform. Meanwhile, as can be seen from fig. 8, this case is repeatable a plurality of times.
It follows that cycling at high capacity, the overcharge mode herein can also significantly improve the cycle life of the battery.
The foregoing detailed description of the method for extending the service life of a lithium air battery provided by the present invention, and the principles and embodiments of the present invention as described herein, using specific examples, is provided merely to facilitate an understanding of the method and its core concepts, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention. The scope of the invention is defined by the claims and may include other embodiments that occur to those skilled in the art. Such other embodiments are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
Claims (10)
1. A method for prolonging the service life of a metal-air battery is characterized by comprising the following steps:
A) after discharging, charging the metal-air battery, and then continuously performing overcharging to obtain the metal-air battery with the service life prolonged;
the metal-air battery comprises a used metal-air battery or a metal-air battery with an end-of-life signal;
the overcharged electric energy is used for decomposing the discharge product lithium peroxide which is deposited on the anode of the metal-air battery and cannot be decomposed after charging.
2. The method according to claim 1, wherein the discharging comprises discharging at a constant current in a fixed voltage window and/or discharging at a constant current and constant capacitance;
the charging mode comprises one or more of constant current charging under a fixed voltage window, constant current and constant capacitance charging, non-constant current charging and constant voltage charging;
the discharging current and the charging current are independent in numerical value and can be the same or different;
the discharge capacity generated in the discharge process of the metal-air battery is less than or equal to the charge capacity charged into the metal-air battery after the metal-air battery is charged and is continuously overcharged.
3. The method according to claim 2, wherein the discharge cut-off voltage of the constant current discharge under a fixed voltage window is 1.0-2.5V;
the current value of the constant current discharged in a fixed voltage window is 0.01-10 mA cm-2；
The charging cut-off voltage of the constant current charged under a fixed voltage window is 3.5-6.0V;
the constant current is in a fixed voltage windowThe current value of the lower charging is 0.01-10 mA cm-2。
4. The method according to claim 2, wherein the constant current and constant volume discharge has a discharge time of 1 to 100 hours;
the current value of constant current and constant capacity discharge is 0.01-10 mA cm-2；
The discharge voltage of the constant-current and constant-capacitance discharge is 1.5-2.9V.
5. The method according to claim 2, wherein the constant current and constant capacity charging is carried out for a charging time of 1 to 200 hours;
the constant current and constant capacity charging current value is 0.01-10 mA cm-2；
The charging voltage of the constant-current constant-capacitance charging is 3.5-6.0V.
6. The method of claim 2, wherein the constant current is discharged at a fixed voltage window at a starting voltage that is the same as a charge cutoff voltage at which the constant current is charged at the fixed voltage window;
the discharging time of the constant-current constant-capacitance discharging is the same as the charging time of the constant-current constant-capacitance charging.
7. The method of claim 2, wherein the non-constant current charging comprises gradient current charging;
the charging current for constant voltage charging is 0.01-10 mA cm-2；
The charging voltage of the constant-voltage charging is 3.2-6.0V;
when the charging mode is constant-voltage charging and constant-current constant-capacitance charging, the voltage of the constant-voltage charging is 3.2-6.0V, and the current of the constant-current constant-capacitance charging is 0.01-10 mA cm-2；
The step a) may be performed every time the metal-air battery is cycled, or may be performed separately after the metal-air battery is cycled for a certain number of times.
8. The method according to any one of claims 1 to 7, wherein after the metal-air battery is recharged and overcharged continuously, the total charging capacity charged in the metal-air battery is 100% to 300% of the discharge capacity generated in the discharge process of the metal-air battery;
the overcharge time is 0.01-5000% of the discharge time.
9. The method according to any one of claims 1 to 7, wherein the overcharge current is 10% to 200% of the discharge current;
the voltage of the overcharge is 3.5-6.0V;
the overcharge cut-off voltage is 4.5-6.0V.
10. The method according to any one of claims 2 to 7, wherein the end-of-life signal comprises a voltage drop condition occurring in a discharge of the metal-air battery after a plurality of cycles;
the voltage drop comprises that the discharge voltage drops below 2.0V and/or the difference between the discharge final voltage and the discharge final voltage of the previous cycle is more than 0.1V;
in the process that the discharge voltage is reduced to be below 2.0V, the average reduction rate of the discharge voltage is 0.1-0.5V/hour;
the negative electrode metal element in the metal-air battery comprises one or more of lithium, sodium and potassium;
the positive working gas of the metal-air battery comprises one or more of oxygen, nitrogen, carbon dioxide and argon in different proportions.
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| JP5163709B2 (en) * | 2010-08-17 | 2013-03-13 | トヨタ自動車株式会社 | Liquid air electrode for metal-air battery, and metal-air battery provided with the liquid air electrode |
| KR101508128B1 (en) * | 2013-04-22 | 2015-04-08 | 한국에너지기술연구원 | Cathode For Lithium-Air Battery, Method Of Manufacturing The Same, And Lithium-Air Battery Comprising The Same |
| GB201512726D0 (en) * | 2015-07-20 | 2015-08-26 | Cambridge Entpr Ltd | Lithium-oxygen battery |
| CN105977508B (en) * | 2016-07-07 | 2018-06-05 | 北京科技大学 | A kind of lithium-air battery assisting electrode layer and its methods for making and using same |
| US10665867B2 (en) * | 2017-06-12 | 2020-05-26 | Panasonic Intellectual Property Management Co., Ltd. | Air battery including negative electrode, positive electrode, nonaqueous metal ion conductor, and oxygen evolving catalyst |
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