阅读说明：本技术 一种高能电源的电成型方法 (Electroforming method of high-energy power supply ) 是由 谈益 于 2019-11-06 设计创作，主要内容包括：本发明提供了一种高能电源的电成型方法,通过在电成型的过程中的递进式充电方式,可以形成多层SEI膜对电池表面形成增强的保护能力,通过方波交流充电方式,可以使SEI膜不易破损,有效提高了电池的使用寿命。本发明提供的方法,提高了高能电源的循环稳定性和循环寿命,降低了生产成本。(The invention provides an electroforming method of a high-energy power supply, which can form a plurality of SEI films to form enhanced protection capability on the surface of a battery through a progressive charging mode in the electroforming process, and can ensure that the SEI films are not easy to damage through a square wave alternating current charging mode, thereby effectively prolonging the service life of the battery. The method provided by the invention improves the cycle stability and the cycle life of the high-energy power supply and reduces the production cost.)

1. A method of electroforming a high energy power supply, comprising the steps of:

(1) charging the battery to 2.7V at a constant current of 0.2-0.3C;

(2) stopping charging, and standing for 3-5 hours;

(3) charging at a constant voltage of 2.7V until the charging current becomes a trickle or less, wherein the trickle charging current is 0.03 mu A;

(4) stopping charging, and standing for 2.5-3.5 hours;

(5) carrying out square wave alternating current charging at the frequency of 35-50Hz and the square wave alternating current voltage of 3.3-3.6V, wherein the charging time is 2.5-3.5 hours;

(6) stopping charging, and standing for 5-7 hours;

(7) charging with a current of 0.55-0.65C until the final voltage is 4.0-4.2V;

(8) stopping charging, and standing for 0.5-1.5 hours;

(9) and (4) charging at constant voltage by using the termination voltage of the step (7) until the charging current is below trickle, wherein the trickle charging current is 0.02 mu A;

(10) carrying out square wave alternating current charging at a frequency of 55-65Hz and a square wave alternating current voltage of 4.1-4.5V for 3.5-4.5 hours;

(11) stopping charging, and standing for 2-3 hours;

(12) charging the battery to a stop voltage of 5V by a constant current of 0.75-0.85C;

(13) stopping charging, and standing for 0.5-1 hour;

(14) discharging with 0.3-0.5C discharge current until the battery voltage is 2.3V;

(15) repeating the steps (1) to (14) for 3 to 4 times;

(16) charging the battery to 5V with a charging current of 0.8C, and finally charging the battery for 5-6 hours at a constant voltage of 5V.

2. The method of claim 1, wherein the frequency in step 5 is 35 Hz.

3. The method of claim 1, wherein the frequency in step 10 is 65 Hz.

4. The method of claim 1, wherein the discharge current in step 14 is 0.3C.

5. The method of claim 1, wherein the step 15 is repeated 3 times.

6. The method of claim 1, wherein the high energy power source is selected from at least one of a carbon-based lithium ion battery, a lithium sulfur battery, a silicon-based lithium ion battery, or a lithium polymer battery.

7. The method of claim 1, wherein the electroforming process is a multi-level molding process.

Technical Field

The invention relates to the technical field of high-energy power supplies, in particular to an electroforming method of a high-energy power supply.

Background

With the rapid development of high-energy power supplies, especially lithium power supplies (such as lithium ion batteries) technologies, high-energy power supplies are also beginning to be widely used as power supplies and energy storage power supplies. For a high-power supply, a plurality of single batteries are usually connected in series or in parallel to form a battery pack and work together, and functional failure of any single battery in the battery pack can cause functional failure of the whole battery pack, and even can cause the problems of out-of-control safety of the battery and the like. Research shows that the deterioration of a lithium battery system in the prior art depends on the molding condition of an SEI film on the surface of an electrode when the battery is subjected to factory electroforming, a cobalt system, a nickel system, an iron system and/or a manganese system are/is mostly adopted as a battery anode material, graphite or a silicon-containing material is adopted as a battery cathode material, and the SEI film is formed on the surface of the electrode in a low-current continuous charging electroforming mode.

Disclosure of Invention

The invention provides an electroforming method of a high-energy power supply, which can form a plurality of SEI films to form enhanced protection capability on the surface of a battery through a progressive charging mode in the electroforming process, and can ensure that the SEI films are not easy to damage through a square wave alternating current charging mode, thereby effectively prolonging the service life of the battery. The method provided by the invention improves the cycle stability and the cycle life of the high-energy power supply and reduces the production cost.

The specific scheme is as follows:

a method of electroforming a high energy power supply, comprising the steps of:

(1) charging the battery to 2.7V at a constant current of 0.2-0.3C;

(2) stopping charging, and standing for 3-5 hours;

(3) charging at a constant voltage of 2.7V until the charging current becomes a trickle or less, wherein the trickle charging current is 0.03 mu A;

(4) stopping charging, and standing for 2.5-3.5 hours;

(5) square wave alternating current charging is carried out at the frequency of 35-50Hz with the square wave alternating current voltage of 3.3-3.6V (optional current of 0.05-0.25C), and the charging time is 2.5-3.5 hours;

(6) stopping charging, and standing for 5-7 hours;

(7) charging with a current of 0.55-0.65C until the final voltage is 4.0-4.2V;

(8) stopping charging, and standing for 0.5-1.5 hours;

(9) and (4) charging at constant voltage by using the termination voltage of the step (7) until the charging current is below trickle, wherein the trickle charging current is 0.02 mu A;

(10) carrying out square wave alternating current charging at a frequency of 55-65Hz and a square wave alternating voltage of 4.2V (optionally, a current of 0.1-0.5C), wherein the charging time is 3.5-4.5 hours;

(11) stopping charging, and standing for 2-3 hours;

(12) charging the battery to a stop voltage of 5V by a constant current of 0.75-0.85C;

(13) stopping charging, and standing for 0.5-1 hour;

(14) discharging with 0.3-0.5C discharge current until the battery voltage is 2.3V;

(15) repeating the steps (1) to (14) for 3 to 4 times;

(16) charging the battery to 5V with a charging current of 0.8C, and finally charging the battery for 5-6 hours at a constant voltage of 5V.

Further, the charging current in the step 1 is 0.2C.

Further, the frequency in the step 5 is 35 Hz.

Further, the frequency in the step 10 is 65 Hz.

Further, the discharge current in step 14 is 0.3C.

Further, the step 15 is cycled for 3 times.

Preferably, the high energy power source is selected from at least one of a carbon-based lithium ion battery, a lithium sulfur battery, a silicon-based lithium ion battery, or a lithium polymer battery.

In particular, the electroforming process of the present invention may also be referred to as a multi-level formation process for high energy lithium batteries.

The invention has the following beneficial effects:

1. in the electroforming method, the SEI films which are layered and have different densities can be formed by the progressive low-rate constant current charging in the steps (1), (7) and (12), so that the insertion and extraction of lithium ions are controlled, the degradation of an electrode material structure is inhibited, and the service life of the battery is prolonged.

2. In the electroforming method, the form of the SEI film can be further perfected by the progressive constant voltage charging in the steps (3) and (9), and a multi-layer complete SEI film structure can be formed by matching with the progressive low-rate constant current charging.

3. In the electroforming method, the self-perfection of the SEI film can be promoted and the compatibility of the electrolyte and the SEI film can be improved by the sectional standing mode of the steps (2), (4), (6), (8), (11) and (13), so that the internal structure of the battery is stabilized.

4. In the electroforming method, the square wave alternating current charging mode in the steps (5) and (10) is adopted, and the direction change of current is adopted, so that the oxidation-reduction mode of the electrode material is changed under variable current, the flexibility of an SEI film on the surface of the electrode material is improved, the SEI film is not easy to damage under the working condition of high-frequency charging use, the structure of the electrode material is stably protected, and the service life of a battery is prolonged.

5. According to the electroforming method, the density of the SEI film is improved and the compactness is enhanced through the cyclic multiple electroforming process in the step (15), so that the complete film structure is still maintained after thousands of cyclic processes, the battery is guaranteed to have high reversible capacity, and the high cycle life is guaranteed.

Through the scheme, the obtained battery can still ensure the reversible capacity of at least 85 percent under the working condition of frequent charging and high-frequency charging use, such as more than 1000 times of circulation.

Detailed Description

The present invention will be described in more detail below with reference to specific examples, but the scope of the present invention is not limited to these examples.

Test example:

the semi-finished lithium secondary battery comprises a positive electrode, a negative electrode and a diaphragm arranged between the positive electrode and the negative electrode, wherein the positive electrode comprises a positive electrode active material, a conductive agent and a binder in a weight ratio of 90:5:5, and the negative electrode comprises a negative electrode active material and a binder in a weight ratio of 95: 5. The diaphragm comprises a polypropylene/polyethylene composite film; the anode active material is lithium iron phosphate, and the cathode active material is artificial graphite; the conductive agent is superconducting carbon black, and the binder is PVDF; the electrolyte includes EC: PC: DEC-2: 1:1 and the lithium salt is 1M lithium hexafluorophosphate.

After the above-described semi-finished secondary battery was assembled, the conventional commercial electroforming process was not performed, but an electroforming (formation) process was performed in the manner of the following example.

The batteries used in the examples and comparative examples of the present invention were the batteries of the above-described test examples.