Piezoelectric activation treatment method for dead lithium of lithium battery

Abstract

The invention discloses a dead lithium piezoelectric activation method of a metal lithium negative electrode. The method comprises the following steps: measuring the initial first discharge capacity of a metal lithium battery; circularly discharging the metal lithium battery until the metal lithium battery is attenuated to a preset discharge capacity; fixing the metal lithium battery attenuated to the preset discharge capacity on the piezoelectric ceramic, applying vibration to the piezoelectric ceramic through a vibration device, vibrating for a set time at a set frequency, and activating dead lithium generated on the surface of a metal lithium negative electrode in the metal lithium battery; after the dead lithium generated on the surface of the metal negative electrode is activated, carrying out a charge and discharge test on the metal lithium battery, comparing the first discharge capacity of the metal lithium battery after the dead lithium is activated with the initial first discharge capacity, and verifying the piezoelectric activation effect of the dead lithium; the metal lithium negative electrode is vibrated by setting frequency and time, dead lithium generated on the surface of the metal lithium negative electrode in the cyclic discharge process is activated, the specific capacity of the metal lithium battery is improved, and the cycle life of the metal lithium battery is prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of metal lithium batteries, and more specifically to a piezoelectric activation processing method for dead lithium in lithium batteries. Background Art

[0002] Metal lithium anode is considered to be the most ideal next-generation anode material due to its high theoretical specific capacity (3860mAh / g) and lowest standard electrode potential (-3.045V), which is superior to the theoretical specific capacity of graphite anode in lithium-ion batteries (372mAh / g). However, the stability of highly active metal lithium anode is poor. During the long-term cycle of lithium anode, active lithium is easily converted into "dead lithium", which significantly reduces the coulombic efficiency and cycle life of metal lithium batteries. Studies have shown that metal lithium oxides such as Li2O and Li2O2 are the main components of "dead lithium". These electronically insulating inert oxides cover the surface of metal lithium anode, hindering charge transfer, mass transfer and diffusion reactions during battery charging and discharging, resulting in battery capacity attenuation and reduced cycle life.

[0003] Chinese invention patent CN113782815B discloses a method for activating "dead lithium" in lithium-ion batteries through light-assisted activation. This method is applicable to a transparent soft-pack lithium-ion battery. First, the soft-pack battery is charged and discharged, and then a light source is used to illuminate one side of the transparent semiconductor layer of the battery to activate the "dead lithium". In addition, Chinese invention patent CN102185365B discloses a method for charging a multi-cell lithium-ion battery pack in series through an industrial frequency transformer to activate the "dead lithium".

[0004] The piezoelectric effect refers to the deformation of certain dielectrics when subjected to external forces in a specific direction, which results in polarization inside the dielectric, and then forms opposite positive and negative charges on the two opposite surfaces of the dielectric. Compared with the existing methods of activating "dead lithium" in lithium batteries, using the instantaneous voltage generated by the piezoelectric effect to activate the "dead lithium" generated by the metal lithium negative electrode during the charge and discharge cycle may be a simple and effective industrial means to increase the cycle life of the metal lithium negative electrode. However, there are currently no reports on the commercial application of using the piezoelectric effect to activate "dead lithium". Summary of the invention

[0005] The purpose of the present invention is to provide a piezoelectric activation treatment method for dead lithium in a lithium battery, which vibrates the metal lithium negative electrode at a set frequency and time to activate the dead lithium generated on the surface of the metal lithium negative electrode during the cycle process, thereby increasing the specific capacity of the metal lithium battery and improving the cycle life of the metal lithium battery.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A piezoelectric activation treatment method for dead lithium in a lithium battery comprises the following steps:

[0008] Measure the initial first discharge capacity of metal lithium batteries;

[0009] Discharging the metal lithium battery in a cycle until it decays to a predetermined discharge capacity;

[0010] The metal lithium battery that has decayed to a predetermined discharge capacity is fixed to the piezoelectric ceramic, and the piezoelectric ceramic is vibrated by a vibration device, and vibrated at a set frequency for a set time to activate the dead lithium generated on the surface of the metal lithium negative electrode in the metal lithium battery;

[0011] After activating the dead lithium produced on the surface of the metal negative electrode, the metal lithium battery is subjected to charge and discharge tests. The first discharge capacity of the metal lithium battery after activating the dead lithium is compared with the initial first discharge capacity to verify the piezoelectric activation effect of the dead lithium.

[0012] Further, the metal lithium battery that has reached a predetermined discharge capacity is vibrated at a first set frequency for a first set time until the dead lithium generated on the surface of the metal lithium negative electrode in the metal lithium battery is activated, specifically:

[0013] After the metal lithium battery decays to a predetermined discharge capacity, the metal lithium negative electrode in the metal lithium battery is taken out, and the metal lithium negative electrode is fixed on a piezoelectric ceramic, and the piezoelectric ceramic is vibrated at a frequency of 20-150 Hz for 10-90 minutes until the piezoelectric ceramic produces a piezoelectric effect to activate the dead lithium generated on the surface of the metal lithium negative electrode;

[0014] The metal lithium negative electrode, metal lithium positive electrode and lithium battery separator after activating the dead lithium are reassembled into a metal lithium battery, the electrolyte is dripped into it and sealed, and the charge and discharge test is carried out.

[0015] Furthermore, the process of causing the piezoelectric ceramic to produce a piezoelectric effect to activate the dead lithium produced on the surface of the metallic lithium negative electrode is specifically as follows:

[0016] The piezoelectric effect generated by piezoelectric ceramics can activate the dead lithium generated during the charge and discharge cycle of the metal lithium negative electrode with a thickness of 0.1 to 3 mm.

[0017] Furthermore, the piezoelectric ceramics include: barium titanate piezoelectric ceramics, lead titanate piezoelectric ceramics or lead zirconate titanate piezoelectric ceramics.

[0018] Furthermore, the material of the metal lithium positive electrode includes: lithium nickel oxide, lithium manganese oxide or lithium iron phosphate.

[0019] Furthermore, the material of the lithium battery separator includes: polyethylene or polypropylene.

[0020] Furthermore, the lithium battery electrolyte includes: ethylene carbonate, propylene carbonate and diethyl carbonate.

[0021] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0022] The present invention discharges the metal lithium battery cyclically to a predetermined discharge capacity, and after reaching the predetermined discharge capacity, vibrates the metal lithium negative electrode at a set frequency and time to activate the dead lithium generated on the surface of the metal lithium negative electrode during the cycle, thereby increasing the specific capacity of the metal lithium battery and improving the cycle life of the metal lithium battery. The method aims to make these dead lithiums re-participate in the charge and discharge reaction, thereby increasing the overall capacity of the metal lithium battery.

[0023] The present invention can slow down the capacity decay caused by the accumulation of dead lithium during long-term use of the battery, thereby extending the cycle life of the battery. The metal lithium battery can be charged and discharged to verify the effect of the activation method, ensuring that the metal lithium battery can recover or improve its performance after vibration activation. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0025] The piezoelectric activation treatment method for dead lithium in a lithium battery of the present invention is further described below in conjunction with the accompanying drawings;

[0026] Figure 1 It is a schematic diagram of the overall process of the piezoelectric activation treatment method for dead lithium in a lithium battery provided by the present invention;

[0027] Figure 2 It is the discharge capacity of the lithium battery before and after the "dead lithium" is activated by the barium titanate piezoelectric ceramic in the piezoelectric activation treatment method for dead lithium of the lithium battery provided by the present invention;

[0028] Figure 3 It is the discharge capacity of the lithium battery before and after the lead titanate piezoelectric ceramic activates the "dead lithium" in the piezoelectric activation treatment method for dead lithium in the lithium battery provided by the present invention;

[0029] Figure 4 It is the discharge capacity before and after the lead zirconate titanate piezoelectric ceramic activates the "dead lithium" of the lithium battery in the piezoelectric activation treatment method for dead lithium of the lithium battery provided by the present invention. DETAILED DESCRIPTION

[0030] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0031] In order to better understand the purpose, structure and function of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings.

[0032] like Figure 1 As shown, the present invention provides a piezoelectric activation treatment method for dead lithium in a lithium battery, comprising the following steps: assembling a button battery with a metal lithium negative electrode, a lithium iron phosphate positive electrode, and a diaphragm, cycling it multiple times to a lower capacity, then taking out the lithium negative electrode in the battery, activating the "dead lithium" through the piezoelectric effect, and then reassembling the battery with the activated lithium negative electrode for charge and discharge testing, specifically:

[0033] Measure the initial first discharge capacity of metal lithium batteries;

[0034] Discharging the metal lithium battery in a cycle until it decays to a predetermined discharge capacity;

[0035] A metal lithium battery that has decayed to a predetermined discharge capacity is placed on a piezoelectric ceramic, and the piezoelectric ceramic is vibrated by a vibration device at a set frequency for a set time to activate dead lithium generated on the surface of the metal lithium negative electrode in the metal lithium battery;

[0036] After activating the dead lithium produced on the surface of the metal negative electrode, the metal lithium battery is subjected to charge and discharge tests. The first discharge capacity of the metal lithium battery after activating the dead lithium is compared with the initial first discharge capacity to verify the piezoelectric activation effect of the dead lithium.

[0037] The metal lithium battery having reached a predetermined discharge capacity is vibrated at a first set frequency for a first set time until dead lithium generated on the surface of the metal lithium negative electrode of the metal lithium battery is activated, specifically:

[0038] After the metal lithium battery decays to a predetermined discharge capacity, the metal lithium negative electrode in the metal lithium battery is taken out, and the metal lithium negative electrode is fixed on a piezoelectric ceramic, and the piezoelectric ceramic is vibrated at a frequency of 20-150 Hz for 10-90 minutes until the piezoelectric ceramic produces a piezoelectric effect to activate the dead lithium generated on the surface of the metal lithium negative electrode;

[0039] The metal lithium negative electrode, metal lithium positive electrode and lithium battery separator after activating the dead lithium are reassembled into a metal lithium battery, the electrolyte is dripped into it and sealed, and the charge and discharge test is carried out.

[0040] It should be noted that the metal lithium negative electrode is a metal lithium foil with a thickness of 0.1 to 3 mm.

[0041] The process of activating the dead lithium generated on the surface of the metal lithium negative electrode by the piezoelectric ceramics is as follows:

[0042] The piezoelectric effect generated by piezoelectric ceramics can activate the dead lithium generated during the charge and discharge cycle of the metal lithium negative electrode with a thickness of 0.1 to 3 mm.

[0043] The dielectrics that activate the "dead lithium" of metal lithium batteries through the piezoelectric effect are piezoelectric ceramics such as barium titanate, lead titanate, and lead zirconate titanate.

[0044] The metal lithium positive electrode includes materials such as lithium nickel oxide, lithium manganese oxide, and lithium iron phosphate.

[0045] The lithium battery separator is made of polyolefin materials such as polyethylene and polypropylene.

[0046] Lithium battery electrolyte is mainly composed of ethylene carbonate, propylene carbonate, diethyl carbonate, etc.

[0047] The present invention also provides the following specific embodiments:

[0048] Example 1

[0049] (1) A metal lithium battery is assembled with a 1.5 mm thick metal lithium foil, a lithium iron phosphate positive electrode, and a polypropylene separator, and an electrolyte is dripped into the battery.

[0050] (2) The charge and discharge performance of the metal lithium battery was tested using a blue battery tester. The initial discharge capacity of the metal lithium battery was 3.1 mAh. After 100 cycles, the capacity decayed to less than 0.1 mAh. Figure 2 shown.

[0051] (3) A metal lithium negative electrode with a capacity of less than 0.1 mAh is fixed together with a small vibrator and barium titanate piezoelectric ceramics, and vibrated at a frequency of 70 Hz for 15 minutes to activate the "dead lithium" produced on the surface of the metal lithium negative electrode.

[0052] (4) The charge and discharge performance of the metal lithium battery was tested using a blue battery tester, and the initial discharge capacity of the metal lithium battery reached 6.2 mAh.

[0053] Example 2

[0054] (1) A metal lithium foil with a thickness of 0.5 mm was assembled with a lithium iron phosphate positive electrode and a polypropylene separator to form a metal lithium battery, and an electrolyte was dripped into the battery.

[0055] (2) The charge and discharge performance of the metal lithium battery was tested using a blue battery tester. The initial discharge capacity of the metal lithium battery was 1.4 mAh. After 100 cycles of charge and discharge, the capacity of the metal lithium battery decayed to less than 0.2 mAh. Figure 3 shown.

[0056] (3) A metal lithium negative electrode with a capacity of less than 0.2 mAh is fixed together with a small vibrator and lead titanate piezoelectric ceramics, and vibrated at a frequency of 50 Hz for 30 minutes to activate the "dead lithium" produced on the surface of the metal lithium negative electrode.

[0057] (4) The charge and discharge performance of the metal lithium battery was tested using a blue battery tester, and the initial discharge capacity of the metal lithium battery was found to be 2.3 mAh.

[0058] Example 3

[0059] (1) A metal lithium foil with a thickness of 1.0 mm was assembled with a lithium iron phosphate positive electrode and a polypropylene separator to form a metal lithium battery, and an electrolyte was dripped into the battery.

[0060] (2) The charge and discharge performance of the metal lithium battery was tested using a blue battery tester. The initial discharge capacity of the metal lithium battery was 5.5 mAh. After 100 cycles, the capacity of the metal lithium battery decayed to less than 0.2 mAh. Figure 4 shown.

[0061] (3) A metal lithium negative electrode with a capacity of less than 0.2 mAh is fixed together with a small vibrator and lead zirconate titanate piezoelectric ceramics, and vibrated at a frequency of 50 Hz for 30 minutes to activate the "dead lithium" produced on the surface of the metal lithium negative electrode.

[0062] (4) The charge and discharge performance of the metal lithium battery was tested using a blue battery tester. The initial discharge capacity of the metal lithium battery was 6.2 mAh.

[0063] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A dead lithium piezoelectric activation method for a metallic lithium negative electrode, characterized in that: The following steps are involved: Measure the initial first discharge capacity of metal lithium batteries; Discharging the metal lithium battery in a cycle until it decays to a predetermined discharge capacity; The metal lithium battery that has decayed to a predetermined discharge capacity is fixed to the piezoelectric ceramic, and the piezoelectric ceramic is vibrated by a vibration device, and vibrated at a set frequency for a set time to activate the dead lithium generated on the surface of the metal lithium negative electrode in the metal lithium battery; After activating the dead lithium produced on the surface of the metal negative electrode, the metal lithium battery is subjected to charge and discharge tests. The first discharge capacity of the metal lithium battery after activating the dead lithium is compared with the initial first discharge capacity to verify the piezoelectric activation effect of the dead lithium.

2. The dead lithium piezoelectric activation method of the metallic lithium negative electrode according to claim 1, characterized in that: The metal lithium battery having reached a predetermined discharge capacity is vibrated at a first set frequency for a first set time until dead lithium generated on the surface of the metal lithium negative electrode of the metal lithium battery is activated, specifically: After the metal lithium battery decays to a predetermined discharge capacity, the metal lithium negative electrode in the metal lithium battery is taken out, and the metal lithium negative electrode is fixed on a piezoelectric ceramic, and the piezoelectric ceramic is vibrated at a frequency of 20-150 Hz for 10-90 minutes until the piezoelectric ceramic produces a piezoelectric effect to activate the dead lithium generated on the surface of the metal lithium negative electrode; The metal lithium negative electrode, metal lithium positive electrode and lithium battery separator after activating the dead lithium are reassembled into a metal lithium battery, the electrolyte is dripped into it and sealed, and the charge and discharge test is carried out.

3. The dead lithium piezoelectric activation method of the metallic lithium negative electrode according to claim 2, characterized in that: The process of activating the dead lithium generated on the surface of the metal lithium negative electrode by the piezoelectric ceramics is as follows: The piezoelectric effect generated by piezoelectric ceramics can activate the dead lithium generated during the charge and discharge cycle of the metal lithium negative electrode with a thickness of 0.1 to 3 mm.

4. The dead lithium piezoelectric activation method of the metallic lithium negative electrode according to claim 2, characterized in that: The piezoelectric ceramics include: barium titanate piezoelectric ceramics, lead titanate piezoelectric ceramics or lead zirconate titanate piezoelectric ceramics.

5. The dead lithium piezoelectric activation method of the metallic lithium negative electrode according to claim 2, characterized in that: The material of the metal lithium positive electrode includes: lithium nickelate, lithium manganate or lithium iron phosphate.

6. The dead lithium piezoelectric activation method of the metallic lithium negative electrode according to claim 2, characterized in that: The material of the lithium battery separator includes polyethylene or polypropylene.

7. The dead lithium piezoelectric activation method of a metallic lithium negative electrode according to claim 2, characterized in that: The lithium battery electrolyte includes ethylene carbonate, propylene carbonate and diethyl carbonate.

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