阅读说明：本技术 废旧锂电池的放电方法 (Discharge method of waste lithium battery ) 是由 张刚 李松贤 缪永华 陈佳杰 田忠良 黄勇 薛驰 杨声海 张凯 于 2018-06-22 设计创作，主要内容包括：本发明提供的一种废旧锂电池的放电方法,首先将废旧锂电池与牺牲阳极直接接触得到预处理系统；然后将预处理系统浸没于导电盐溶液中放电；最后引出所述电池的正负极,分别连接铜片后将铜片置于导电盐溶液中,测量所述电池的电压直至电压值趋于稳定,则放电结束。本发明中牺牲阳极可稳定存在于中性或碱性溶液中,受光照、温度等影响较小,放电条件易控制；牺牲阳极在放电过程优先发生氧化溶解避免氯气的析出从而有效解决电解液泄露污染的问题；不仅如此,由于牺牲阳极与导电盐的阳离子相对应,牺牲阳极溶解后导电盐溶液的离子浓度变大,加快放电速率的同时可以实现导电盐溶液的循环使用,节约放电成本。本发明工艺简单易操作,适用于规模化应用。(The invention provides a discharge method of waste lithium batteries, which comprises the steps of firstly, directly contacting the waste lithium batteries with a sacrificial anode to obtain a pretreatment system; then, immersing the pretreatment system in a conductive salt solution for discharging; and finally, leading out the positive electrode and the negative electrode of the battery, respectively connecting the copper sheets, then placing the copper sheets in a conductive salt solution, measuring the voltage of the battery until the voltage value tends to be stable, and ending the discharge. The sacrificial anode can stably exist in neutral or alkaline solution, is less influenced by illumination, temperature and the like, and has easily controlled discharge conditions; the sacrificial anode is preferentially oxidized and dissolved in the discharging process to avoid the precipitation of chlorine, so that the problem of electrolyte leakage pollution is effectively solved; moreover, because the sacrificial anode corresponds to the positive ions of the conductive salt, the ion concentration of the conductive salt solution after the sacrificial anode is dissolved is increased, the discharge rate is accelerated, the cyclic use of the conductive salt solution can be realized, and the discharge cost is saved. The method has simple process and easy operation, and is suitable for large-scale application.)

1. A discharging method of a waste lithium battery is characterized by comprising the following steps:

directly contacting a waste lithium battery with a sacrificial anode to obtain a pretreatment system;

immersing the pretreatment system in a first conductive salt solution for discharging;

and leading out the positive electrode and the negative electrode of the battery, respectively connecting the copper sheets, then placing the copper sheets in a second conductive salt solution, measuring the voltage of the battery until the voltage value tends to be stable, and ending the discharge.

2. The method of discharging spent lithium batteries according to claim 1, wherein: and the sacrificial anode is directly contacted with a positive terminal or a positive electrode tab of the waste lithium battery.

3. The method of discharging spent lithium batteries according to claim 1, wherein: the mass ratio of the sacrificial anode to the battery is 1:100 to 1: 500.

4. The method of discharging spent lithium batteries according to claim 1, wherein: the sacrificial anode comprises one or any combination of magnesium, titanium, manganese, zinc, chromium, iron and cadmium.

5. The method of discharging spent lithium batteries according to claim 1, wherein: the sacrificial anode is in one of a hollow circular ring shape, a block shape, a silk shape, a net shape, a spherical shape and a spiral shape.

6. The method of discharging spent lithium batteries according to claim 1, wherein: the first conductive salt solution or the second conductive salt solution is a chloride solution of the sacrificial anode.

7. The method of discharging spent lithium batteries according to claim 6, wherein: the mass percentage concentration of the chloride is 5-15%.

8. The method of discharging spent lithium batteries according to claim 1, wherein: the discharge time of the system is 12 hours to 24 hours.

9. The method of discharging spent lithium batteries according to claim 1, wherein: and the discharge is ended when the measured voltage has no change in value within half an hour.

10. The method of discharging spent lithium batteries according to claim 1, wherein: when the discharge is finished, the voltage of the battery is less than 1V, the total discharge time is less than 40 hours, and the positive terminal post or the positive electrode lug is not corroded.

Technical Field

The invention relates to the technical field of lithium batteries, in particular to a safe discharge method of waste lithium batteries.

Background

This section is intended to provide a background or context to the embodiments of the invention that are recited in the claims. The description herein is not admitted to be prior art by inclusion in this section.

The lithium ion battery has the advantages of large specific capacity, high voltage, long service life and no memory effect, and the demand of the lithium ion battery in the fields of electronic products, electric automobiles and the like is gradually increased year by year. With the development of electric vehicles and hybrid electric vehicles, the demand of lithium ion batteries at home and abroad increases year by year, and the service life of the lithium ion batteries is generally 3-5 years, so that a large amount of waste batteries can be generated. The lithium ion battery contains a lot of metal elements, volatile organic electrolyte, binder and the like, if the lithium ion battery is not recycled, serious waste is inevitably caused, and meanwhile, the lithium ion battery has great potential harm to the environment and human bodies.

The waste lithium ion batteries are recycled, the waste lithium ion batteries need to be subjected to early discharge treatment, the residual voltage in the waste batteries is reduced to below about 1V, and then the subsequent disassembling process can be carried out, otherwise, the short circuit of the positive electrode and the negative electrode is easy to occur in the battery disassembling process, and the fire is caused. At present, the mainstream discharge method is to immerse the waste lithium ion battery in a sodium chloride solution, take the anode and cathode metals of the battery as the anode and cathode, take the sodium chloride solution as the electrolyte, and consume the electric quantity of the battery through the electrolysis process. The method is simple to operate and low in cost, but chlorine is generated by discharging chlorine ions on the surface of the battery positive terminal during discharging, a passivation film on the surface of an aluminum positive terminal/positive electrode lug is damaged, and then exposed aluminum is discharged as an active metal anode to cause the dissolution of the battery positive terminal, so that on one hand, the leakage of electrolyte can occur to pollute the operating environment, and meanwhile, the discharged salt solution flows into the battery to pollute the recovered product. The prior art also discloses a safe discharge method of the waste battery by taking copper sulfate and ascorbic acid as discharge solution, which solves the problem of dissolution loss of the battery shell in the discharge process and can realize safe discharge. However, the ascorbic acid used in this method is very unstable in neutral or alkaline solution, easily oxidized by light, and also very easily deactivated by the influence of temperature, pH and metal ions, especially Cu in this method²⁺The metal ion has obvious catalytic action on the oxidation inactivation of the ascorbic acid, and in order to ensure that the metal ion and the ascorbic acid can stably coexist, the discharge condition must be strictly controlled, so that the scale application is difficult to realize.

Disclosure of Invention

In view of the above, there is a need to provide an improved method for discharging waste lithium batteries, which is safe in discharging, avoids the problem of electrolyte leakage and pollution caused by corrosion of the positive terminal of the battery, and has stable discharging solution and recycling use; the method has high discharge efficiency, long discharge time and full discharge.

The technical scheme provided by the invention is as follows: a discharging method of a waste lithium battery comprises the following steps:

directly contacting a waste lithium battery with a sacrificial anode to obtain a pretreatment system;

immersing the pretreatment system in a first conductive salt solution for discharging;

and leading out the positive electrode and the negative electrode of the battery, respectively connecting the copper sheets, then placing the copper sheets in a second conductive salt solution, measuring the voltage of the battery until the voltage value tends to be stable, and ending the discharge.

Further, the sacrificial anode is in direct contact with a positive terminal or a positive electrode tab of the waste lithium battery.

Further, the mass ratio of the sacrificial anode to the battery is 1:100 to 1: 500.

Further, the sacrificial anode comprises one or any ratio of magnesium, titanium, manganese, zinc, chromium, iron and cadmium. When the waste lithium ion battery is discharged, the sacrificial anode is in contact with the positive electrode of the battery, so that the electrochemical reaction of the positive electrode of the battery is converted from the precipitation of chlorine gas to the oxidative dissolution of the sacrificial anode, the corrosion of the chlorine gas to a passive film on the surface of the positive electrode of the battery is avoided, and the problems of electrolyte leakage, product pollution recovery and the like caused by the dissolution of a binding post or a positive electrode lug of the positive electrode of the battery due to the traditional discharge by using a sodium chloride solution are effectively solved.

Further, the sacrificial anode has one of a hollow circular ring shape, a block shape, a filament shape, a net shape, a spherical shape and a spiral shape.

Further, the first conducting salt solution or the second conducting salt solution is a chloride solution of the sacrificial anode. Compared with copper sulfate and ascorbic acid conductive salt solution in the traditional waste battery discharging technology, the solid sacrificial metal/sacrificial alloy can stably exist in neutral or alkaline solution, is less influenced by illumination, temperature, pH value and other metal ions, and has easily controlled discharging conditions.

Further, the mass percentage concentration of the chloride is 5-15%. Because the sacrificial anode corresponds to metal cations in the conductive salt, the dissolved metal/alloy can improve the ion concentration in the conductive salt solution, accelerate the discharge rate, realize the recycling of the conductive salt solution and save the discharge cost.

Further, the discharge time period of the system is 12 hours to 24 hours.

Further, the discharge is ended when the measured voltage has no change in value within half an hour.

Further, when the discharging is finished, the voltage of the battery is less than 1 volt, the total discharging time is less than 40 hours, and the corrosion phenomenon does not occur on the positive terminal post or the positive electrode lug.

Compared with the prior art, the discharge method of the waste lithium battery provided by the invention comprises the following steps of firstly, directly contacting the waste lithium battery with a sacrificial anode to obtain a pretreatment system; then, immersing the pretreatment system in a conductive salt solution for discharging; and finally, leading out the positive electrode and the negative electrode of the battery, respectively connecting the copper sheets, then placing the copper sheets in a conductive salt solution, measuring the voltage of the battery until the voltage value tends to be stable, and ending the discharge. The sacrificial anode can stably exist in neutral or alkaline solution, is less influenced by illumination, temperature and the like, and has easily controlled discharge conditions; the sacrificial anode is preferentially oxidized and dissolved in the discharging process to avoid the precipitation of chlorine, so that the problem of electrolyte leakage pollution is effectively solved; moreover, because the sacrificial anode corresponds to the positive ions of the conductive salt, the ion concentration of the conductive salt solution after the sacrificial anode is dissolved is increased, the discharge rate is accelerated, the cyclic use of the conductive salt solution can be realized, and the discharge cost is saved. The method has simple process and easy operation, and is suitable for large-scale application.

Drawings

The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

Fig. 1 is a discharge flow chart of a waste lithium battery according to the present invention.

The following detailed description further illustrates embodiments of the invention in conjunction with the above-described figures.

Detailed Description

So that the manner in which the above recited objects, features and advantages of embodiments of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof which are illustrated in the appended drawings. In addition, the features of the embodiments of the present application may be combined with each other without conflict.

In the following description, numerous specific details are set forth to provide a thorough understanding of embodiments of the invention, and the described embodiments are merely a subset of embodiments of the invention, rather than a complete embodiment. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without any creative effort belong to the protection scope of the embodiments of the present invention.

The term "passivation film" as used herein means a very thin protective layer formed on the surface of the positive electrode metal material by strong anodic polarization under oxidizing conditions, and the protective layer has the effect of inhibiting corrosion. The term "sacrificial anode" as used herein refers to a sacrificial metal or a sacrificial alloy of a plurality of sacrificial metals, and the term "sacrificial metal" refers to an additional more active metal, which preferentially acts as a negative electrode and loses electrons to form cations when the waste battery is discharged, thereby protecting the positive electrode of the waste battery from corrosion.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which embodiments of the present invention belong. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the embodiments of the invention.

In recent years, electronic products such as mobile phones, computers, cameras and the like are continuously updated, a large number of waste lithium batteries appear, and the existing treatment modes are roughly three types: the curing is deeply buried, stored in a waste mine and recycled, the former two modes need a special landfill site, and consume large environmental resources (difficult degradation occupies large space, more toxic and harmful substances easily cause environmental pollution, and the sealing treatment engineering is difficult and high in cost and the like), and the recycling of a large amount of waste lithium batteries not only can obtain high-value metals such as lithium, cobalt and the like, but also can solve a series of environmental problems caused by the waste lithium batteries. The first key step of recycling is to perform thorough discharge treatment on the waste lithium battery, and only the uncharged waste lithium battery can be obtained to continue the subsequent treatment process (such as pyrolysis, crushing and dissociation, screening treatment and the like).

Referring to fig. 1, fig. 1 illustrates a method for discharging a waste lithium battery according to an embodiment, including the following steps:

step 1: directly contacting a waste lithium battery with a sacrificial anode to obtain a pretreatment system; and the sacrificial anode is directly contacted with a positive terminal or a positive electrode tab of the waste lithium battery. When the waste lithium ion battery is discharged, the sacrificial anode is in contact with the positive electrode of the battery, so that the electrochemical reaction of the positive electrode of the battery is converted from the precipitation of chlorine gas to the oxidative dissolution of the sacrificial anode, the corrosion of the chlorine gas to a passive film on the surface of the positive electrode of the battery is avoided, and the problems of electrolyte leakage, product pollution recovery and the like caused by the dissolution of a binding post or a positive electrode lug of the positive electrode of the battery due to the traditional discharge by using a sodium chloride solution are effectively solved.

Wherein:

the mass ratio of the sacrificial anode to the battery is 1:100 to 1: 500;

the sacrificial anode comprises one or any ratio of magnesium, titanium, manganese, zinc, chromium, iron and cadmium;

the sacrificial anode is in one of a hollow circular ring shape, a block shape, a silk shape, a net shape, a spherical shape and a spiral shape.

Step 2: immersing the pretreatment system in a first conductive salt solution for discharging;

wherein:

the first conductive salt solution is a chloride solution of one or more elements of the sacrificial anode; the sacrificial anode comprises one or any ratio of magnesium, titanium, manganese, zinc, chromium, iron and cadmium; compared with copper sulfate and ascorbic acid conductive salt solution in the traditional waste battery discharging technology, the solid sacrificial metal/sacrificial alloy can stably exist in neutral or alkaline solution, is less influenced by illumination, temperature, pH value and other metal ions, and has easily controlled discharging conditions.

The solvent adopted by the solution is water;

the mass percentage concentration of the chloride is 5-15%;

the discharge time of the system is 12 hours to 24 hours.

And step 3: and leading out the positive electrode and the negative electrode of the battery, respectively connecting the copper sheets, then placing the copper sheets in a second conductive salt solution, measuring the voltage of the battery until the voltage value tends to be stable, and ending the discharge.

Wherein:

the second conductive salt solution is a chloride solution of the sacrificial anode; because the sacrificial anode corresponds to metal cations in the conductive salt, the dissolved metal/alloy can improve the ion concentration in the conductive salt solution, accelerate the discharge rate, realize the recycling of the conductive salt solution and save the discharge cost;

and the discharge is ended when the measured voltage has no change in value within half an hour.

At the end of the discharge, the discharge was completed,

the battery voltage is less than 1 volt;

the total discharge time is less than 40 hours;

and the positive wiring terminal or the positive electrode lug is not corroded.

The method for discharging the waste lithium battery according to the present invention will be described with reference to the following embodiments.