CN111584937A - Lithium ion battery lithium supplementing method - Google Patents

Abstract

The invention discloses a lithium ion battery lithium supplementing method, which comprises the steps of sampling different formation degrees in the formation process for discharging, measuring reversible electric quantity so as to determine the quantity of lithium ions, and calculating the proportion of the lithium ions consumed by SEI (solid electrolyte interphase) to the total formation electric quantity; converting the proportion of the SEI accounting for the total amount of the different formation degrees into the proportion of the current generated by the SEI film accounting for the total current; drawing a total current curve and a corresponding SEI film generation current curve in the formation process; three curves of formation total current, SEI film current and cathode current are used as formation process control parameters. According to the invention, the lithium is supplemented by using the third electrode of the metal lithium, so that accurate supplement is realized. The formation of dead lithium is avoided, and the potential safety hazard is eliminated.

Description

Lithium ion battery lithium supplementing method

Technical Field

The invention relates to the technical field of lithium ion batteries, in particular to a lithium ion battery lithium supplementing method.

Background

Since the advent of lithium ion batteries, lithium ion batteries have been rapidly developed and have been the subject of major development of rechargeable batteries. With the implementation of the new energy industry development planning of energy conservation in new energy automobile industry and the popularization of new energy industries such as energy storage, the requirements of power type and energy storage type lithium ion batteries are remarkably increased. The lithium ion battery mainly comprises a positive electrode, a negative electrode, a diaphragm, electrolyte, a shell, a lug and the like, and before lithium ions are reformed, the lithium ions are all stored in a positive electrode active material and the electrolyte serving as an ion conductor. The formation is to charge the battery cell for the first time after the battery is injected with liquid, activate active substances in the battery and activate the lithium ion battery. During the formation process, the solvent and lithium salt in the electrolyte can generate side reaction with the negative electrode to form a solid electrolyte interface film (SEI). A plurality of charge-discharge cycles are required for a complete formation process, and research shows that 10% of the initial capacity of the lithium ion battery is used as irreversible capacity loss to form an SEI film in the first charge-discharge cycle, and a small amount of SEI film is continuously formed in the subsequent cycles. Since lithium ions from the positive electrode are consumed in the formation process and cannot become active lithium capable of providing effective capacity for the battery cell, various lithium supplement technologies have been paid attention. Chinese patent 201610015441.8 developed a method for compounding a layer of lithium metal foil on the negative electrode to supplement lithium, chinese patent 201710438908.4 disclosed a method for supplementing lithium by using lithium metal vapor to evaporate a lithium layer with a thickness less than 1 micron, and patent application 201910452204.1 also used a method for evaporating metal lithium vapor to continuously heat the lithium vapor pipe, thereby avoiding deposition and improving the process. Chinese patent 201210351225.2 discloses a method of applying an organic lithium salt to the surface of a negative electrode sheet in an inert gas, so that lithium ions in the organic lithium salt are reduced to metallic lithium and inserted into the negative electrode sheet, and then drying the negative electrode sheet. Patent application 201910161302.X improves organic lithium salt into sodium bicarbonate solution, and the negative plate is dried after being contacted with the sodium bicarbonate solution, so that the toxicity of organic alkyl lithium is eliminated. Patent 201710343164.8 then injects the lithium-ion battery with the lithium-ion battery supplement electrolyte to carry out the pre-charging, and after accomplishing the pre-charging amount, goes out remaining lithium-ion battery supplement electrolyte, injects conventional electrolyte again, carries out the pre-formation to the battery afterwards. The existing lithium supplementing method using metal lithium does not consider that the metal lithium is accurately used for supplementing lithium ions, the metal lithium is directly attached to a negative electrode plate and is waited to be oxidized into lithium ions, so that a lot of dead lithium can be caused, the effect is equivalent to that of lithium dendrites, and even potential safety hazards can be caused.

Disclosure of Invention

The invention aims to provide a lithium ion battery lithium supplementing method, which comprises the following specific steps:

s1: the chemical process parameter determination method comprises the following steps:

(1) sampling from different formation degrees in the formation process for discharging, measuring reversible electric quantity so as to determine the quantity of lithium ions, and calculating the proportion of the lithium ions consumed by the SEI to the total formation electric quantity;

(2) converting the proportion of the SEI accounting for the total amount of the different formation degrees into the proportion of the current generated by the SEI film accounting for the total current;

(3) drawing a total current curve and a corresponding SEI film generation current curve in the formation process;

(4) three curves of total formation current, SEI film current and cathode current are used as control parameters of the formation process;

s2: the manufactured pole core is cased and is injected with excessive liquid;

s3: connecting a positive electrode, a negative electrode and a third lithium metal electrode on a formation station by adopting an opening formation process;

s4: using the total current curve in the step S1 to control the anode current, the SEI film current to control the metal lithium electrode current, and the cathode current to control the cathode plate current,

s5: and after formation is completed, removing the metal electrode, disconnecting the positive electrode and the negative electrode from the formation equipment, transferring to an electrolyte extraction process, and completing lithium supplement.

Compared with the prior art, the invention has the beneficial effects that: according to the invention, the lithium is supplemented by using the third electrode of the metal lithium, so that accurate supplement is realized. The formation of dead lithium is avoided, and the potential safety hazard is eliminated.

Drawings

FIG. 1 is a flow chart of an embodiment of a lithium supplementing method.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Example 1

A lithium ion battery lithium supplement method comprises the following specific steps:

s1: the chemical process parameter determination method comprises the following steps:

(1) sampling from different formation degrees in the formation process for discharging, measuring reversible electric quantity so as to determine the quantity of lithium ions, and calculating the proportion of the lithium ions consumed by the SEI to the total formation electric quantity;

(2) converting the proportion of the SEI accounting for the total amount of the different formation degrees into the proportion of the current generated by the SEI film accounting for the total current;

(3) drawing a total current curve and a corresponding SEI film generation current curve in the formation process;

(4) three curves of total formation current, SEI film current and cathode current are used as control parameters of the formation process;

s2: the manufactured pole core is cased and is injected with excessive liquid;

s3: connecting a positive electrode, a negative electrode and a third lithium metal electrode on a formation station by adopting an opening formation process;

s4: using the total current curve in the step S1 to control the anode current, the SEI film current to control the metal lithium electrode current, and the cathode current to control the cathode plate current,

s5: and after formation is completed, removing the metal electrode, disconnecting the positive electrode and the negative electrode from the formation equipment, transferring to an electrolyte extraction process, and completing lithium supplement.

According to the invention, the lithium is supplemented by using the third electrode of the metal lithium, so that accurate supplement is realized. The formation of dead lithium is avoided, and the potential safety hazard is eliminated.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.

Claims (1)

1. A lithium ion battery lithium supplementing method is characterized in that: the lithium ion battery lithium supplementing method specifically comprises the following steps:

s1: the chemical process parameter determination method comprises the following steps:

(1) sampling from different formation degrees in the formation process for discharging, measuring reversible electric quantity so as to determine the quantity of lithium ions, and calculating the proportion of the lithium ions consumed by the SEI to the total formation electric quantity;

(2) converting the proportion of the SEI accounting for the total amount of the different formation degrees into the proportion of the current generated by the SEI film accounting for the total current;

(3) drawing a total current curve and a corresponding SEI film generation current curve in the formation process;

(4) three curves of total formation current, SEI film current and cathode current are used as control parameters of the formation process;

s2: the manufactured pole core is cased and is injected with excessive liquid;

s3: connecting a positive electrode, a negative electrode and a third lithium metal electrode on a formation station by adopting an opening formation process;

s4: using the total current curve in the step S1 to control the anode current, the SEI film current to control the metal lithium electrode current, and the cathode current to control the cathode plate current,

s5: and after formation is completed, removing the metal electrode, disconnecting the positive electrode and the negative electrode from the formation equipment, transferring to an electrolyte extraction process, and completing lithium supplement.

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