CN103344920A - Method and equipment for detecting state of health of battery - Google Patents

Abstract

The invention provides a method for detecting the state of health of a battery. The method comprises the steps that the internal pressure of the battery is detected; the SOH of the battery is obtained from a corresponding relation generated in advance according to the internal pressure of the battery; the corresponding relation is the corresponding relation between the SOH and the internal pressure of the battery. The invention further provides equipment for detecting the state of health of the battery. According to the technical scheme, the improvement of detection accuracy of the SOH of the battery is achieved.

Description

A method and device for detecting the state of health of a battery

【Technical field】

The invention relates to the field of battery detection, in particular to a method and equipment for detecting the health state of a battery.

【Background technique】

With the maturity of lithium-ion battery technology and the advantages of long cycle life, fast charging and discharging, and good safety performance, lithium-ion batteries are becoming more and more widely used, mainly in the fields of transportation and communication, such as Cars, mobile phones, laptops, etc.

Lithium-ion batteries are used as energy storage units. The State of Health (SOH) of lithium-ion batteries plays an important role in the maintenance, replacement and maintenance of products in actual use. Proper application is very important.

The current method of estimating the state of health of the battery is to establish the correspondence between battery internal resistance, battery state of charge (SOC, State of Charge), temperature, and SOH. When a request for SOH estimation is made, temperature measurement and SOC estimation are performed. , and detect the internal resistance value of the battery, and read the SOH value corresponding to the measured temperature, the estimated battery SOC and the detected internal resistance value of the battery from the corresponding relationship.

The above method of estimating the state of health of a battery has a certain degree of accuracy for a specific battery, but in many cases the internal resistance of a lithium-ion battery does not change or changes without obvious rules, and the interaction between temperature, current, and batteries during actual use It is more significant, so the error of the SOH value of the battery obtained by this method is very large; at the same time, this method needs to deal with the relationship between internal resistance, SOC, temperature and SOH parameters, so the estimation process is more cumbersome, and the implementation process is relatively Complicated, when the battery is abnormal, it will not be able to give a warning of battery abnormality in time; when the battery is overcharged or overdischarged, the change of SOH cannot be analyzed through internal resistance, but it may give an indication of battery health.

【Content of invention】

In view of this, an embodiment of the present invention provides a method and device for detecting the state of health of a battery, so as to improve the detection accuracy of the SOH of the battery.

In the first aspect, the embodiment of the present invention provides a method for detecting the state of health of a battery, including:

Detect the battery internal pressure of the battery;

The battery state of health SOH of the battery is obtained from a pre-generated correspondence according to the internal pressure of the battery; the correspondence is a correspondence between the SOH of the battery and the internal pressure of the battery.

In a first possible implementation manner of the first aspect, before the detection of the battery internal pressure of the battery, the method further includes:

Carrying out a charge-discharge test at a preset temperature on the battery;

Obtain the SOH of the battery according to the discharge capacity and initial capacity of the battery after the charge and discharge test, and generate the corresponding relationship between the SOH and time;

Detect the battery internal pressure of the battery during the charge and discharge test, and generate the curve characteristics of the battery internal pressure and time;

According to the corresponding relationship between the SOH of the battery and the time and the curve characteristics of the battery internal pressure and time, the corresponding relationship between the SOH of the battery and the internal pressure of the battery is obtained.

In combination with the first aspect or in a first possible implementation manner of the first aspect, the battery is a lithium ion battery.

In the second aspect, an embodiment of the present invention provides a device for detecting the state of health of a battery, including:

A pressure sensor for detecting the battery internal pressure of the battery;

The detection device is used to obtain the battery state of health SOH of the battery from the pre-generated correspondence according to the battery internal pressure detected by the pressure sensor; the correspondence is the correspondence between the battery SOH and the battery internal pressure.

In a first possible implementation manner of the second aspect, the device includes:

The corresponding relationship generating device is used to perform a charge and discharge test on the battery at a preset temperature, obtain the SOH of the battery according to the discharge capacity and initial capacity of the battery after the charge and discharge test, and generate the correspondence between the SOH and time relationship; detect the battery internal pressure of the battery during the charge and discharge test, and generate the curve characteristics of the battery internal pressure and time; according to the corresponding relationship between the SOH of the battery and the time and the curve characteristics of the battery internal pressure and time, obtain the battery's Correspondence between SOH and battery internal pressure.

In combination with the second aspect or in a first possible implementation manner of the second aspect, the battery is a lithium ion battery.

As can be seen from the above technical solutions, the present invention has the following beneficial effects:

When it is necessary to obtain the SOH of the battery, it is only necessary to detect the internal pressure of the battery, and then according to the internal pressure of the battery and the corresponding relationship between the SOH of the battery and the internal pressure of the battery, the SOH of the battery can be obtained. Therefore, the detection process of SOH is simple. The detected SOH is less affected by external factors such as temperature and magnification, so that the accuracy of the detected SOH of the battery is relatively high; moreover, when the battery is abnormal, it can be accurately judged in time based on the detected SOH, and timely Give early warning of battery abnormality, high reliability.

【Description of drawings】

FIG. 1 is a functional block diagram of a device for detecting the state of health of a battery provided by an embodiment of the present invention;

Fig. 2 is a schematic flowchart of a method for detecting a battery health state provided by an embodiment of the present invention.

【Detailed ways】

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

During the use of lithium-ion batteries, the battery capacity will gradually decrease, that is, the battery health will gradually deteriorate. The main reason is that the chemical side reactions generated during the use of the battery will consume active lithium ions, and the chemical side reactions will produce Gas, with the reduction of active lithium ions in the lithium-ion battery, more and more gas is generated inside the battery, and the battery shell is deformed by the pressure of the internal gas. Therefore, the internal pressure of the battery gradually increases during the cycle of charging and discharging The SOH of the battery is obtained by testing the internal pressure of the battery; the SOH of the battery is equal to the discharge capacity of the battery divided by the initial capacity of the battery, and the initial capacity of the battery refers to the new battery When the total capacity of the battery, as the number of cycles increases, the discharge capacity of the battery gradually decreases, which will be less than the initial capacity of the battery.

The embodiment of the present invention provides a device for detecting the state of health of the battery. FIG. 1 is a functional block diagram of the device for detecting the state of health of the battery provided by the embodiment of the present invention. As shown in FIG. 1 , the device includes:

A pressure sensor 101, used to detect the battery internal pressure of the battery;

The detection device 102 is configured to obtain the battery state of health SOH of the battery from a pre-generated correspondence according to the internal pressure of the battery detected by the pressure sensor 101; the correspondence is the correspondence between the SOH of the battery and the internal pressure of the battery.

The equipment includes:

The corresponding relationship generating device 103 is used to perform a charge-discharge test on the battery at a preset temperature, obtain the SOH of the battery according to the discharge capacity and initial capacity of the battery after the charge-discharge test, and generate a relationship between the SOH and time Correspondence; detect the battery internal pressure of the battery during the charge and discharge test, and generate the curve characteristics of the battery internal pressure and time; according to the corresponding relationship between the SOH of the battery and time and the curve characteristics of the battery internal pressure and time, obtain the battery The corresponding relationship between the SOH and the internal pressure of the battery.

Wherein, the battery is a lithium ion battery.

The embodiment of the present invention also provides a method for detecting the state of health of the battery. FIG. 2 is a schematic flowchart of the method for detecting the state of health of the battery provided by the embodiment of the present invention. As shown in FIG. 2 , the method includes the following steps:

Step S201, detecting the battery internal pressure of the battery.

Specifically, when it is necessary to obtain the SOH of a certain battery, a pressure sensor is installed on the surface of the battery, and the pressure sensor periodically detects the battery internal pressure of the battery according to a preset cycle, and then sends the detected internal pressure of the battery to the detection device.

Step S202, obtaining the battery state of health SOH of the battery from a pre-generated correspondence according to the internal pressure of the battery; the correspondence is a correspondence between the SOH of the battery and the internal pressure of the battery.

Specifically, after receiving the internal pressure of the battery from the pressure sensor, the detection device obtains the SOH corresponding to the internal pressure of the battery according to the correspondence between the SOH of the battery and the internal pressure of the battery pre-stored in the storage device.

In the above technical solution of the embodiment of the present invention, the battery is a lithium ion battery.

Wherein, the method for generating the corresponding relationship between the SOH of the battery and the internal pressure of the battery by the corresponding relationship generating device is as follows:

Install a pressure sensor on the surface of the battery, and then use the charging and discharging device to perform a cycle test on the battery at a preset temperature. After the cycle test is completed, the charging and discharging device subtracts the remaining capacity of the battery from the initial capacity of the battery to obtain the discharge capacity of the battery. Then divide the discharge capacity of the battery by the initial capacity of the battery to obtain the SOH of the battery after the cycle test, and generate the corresponding relationship between SOH and time according to the SOH and the current time; Carry out a cycle test on the battery, and after each cycle test, the corresponding relationship between SOH and time will be obtained. After all cycle tests are completed, a series of corresponding relationships between SOH and time will be obtained.

At the same time, the pressure sensor installed on the surface of the battery detects the internal pressure of the battery in real time. After all the cycle tests are completed, the pressure sensor outputs the curve characteristics of the internal pressure of the battery and time.

According to the corresponding relationship between the SOH of the battery and time, use the time in the corresponding relationship to obtain the internal pressure of the battery corresponding to the time from the curve characteristics of the internal pressure of the battery and time, so as to obtain the corresponding relationship between the SOH of the battery and the internal pressure of the battery at this time , saving the generated correspondence between the SOH of the battery and the internal pressure of the battery to a storage device.

Cyclic tests can be carried out for different batteries to obtain the corresponding relationship between the SOH of the battery and the internal pressure of the battery. In this way, when detecting the SOH of a certain battery, it is only necessary to obtain the corresponding relationship between the SOH of the battery and the internal pressure of the battery. SOH will do.

Among them, when evaluating the application of batteries in the field of lithium batteries, the battery is mainly evaluated at room temperature and 45 degrees Celsius. Moreover, in the communication field of lithium battery applications, room temperature and 45 degrees Celsius are the most typical temperatures. At the same time, according to special application scenarios The cycle test of the battery is carried out at the temperature corresponding to the requirement definition, and the preset temperature in the present invention is normal temperature or 45 degrees Celsius.

Wherein, the cycle test refers to that the charging and discharging device first charges the battery, then discharges the battery, and repeats the process of charging and discharging the battery several times; for example, the charging and discharging device charges the battery to 3.6V with a constant current of 50A , and then leave the battery for 5 minutes, the charging and discharging device discharges the battery to 2.0V with a constant current of 50A, and after leaving the battery for 5 minutes, repeat the above process, the number of cycles is 3000 times.

It should be noted that during the use of the battery, side reactions will occur between the electrolyte of the battery and the raw materials of the positive and negative electrodes, which is the main reason for the attenuation of the battery life, and SOH is the parameter for evaluating the life of the battery; at the same time, the battery is a sealed whole, When the side reaction inside the battery consumes the active material in the battery, it will produce gas. These gases cannot be eliminated, which will cause the internal pressure of the battery to increase, so that the pressure on the surface of the battery will increase; by judging the gas generated inside the battery The amount is used to infer the amount of active material in the battery participating in the side reaction, so as to determine how much active material is available in the battery, that is, how much capacity the battery can release, that is, the SOH of the battery. When there is an abnormality in the battery, such as a short circuit, the active material will quickly decompose, thereby generating a large amount of gas in an instant, which will bring risks such as fire and explosion of the battery. At this time, the detection device can give early warning, and the safety factor is high.

The battery is a lithium-ion battery, and the lithium-ion battery includes a square lithium-ion battery and a soft-packed lithium-ion battery; the square lithium-ion battery is a rectangular lithium-ion battery or a square lithium-ion battery, such as a square 50Ah steel shell lithium-ion battery, Square 200Ah aluminum shell lithium-ion batteries, etc.; soft-packed lithium-ion batteries are lithium-ion batteries with hard plastic film materials, such as mobile phone batteries, polymer batteries, etc.

The technical solution of the present invention has the following beneficial effects:

When it is necessary to obtain the SOH of the battery, it is only necessary to detect the internal pressure of the battery, and then according to the internal pressure of the battery and the corresponding relationship between the SOH of the battery and the internal pressure of the battery, the SOH of the battery can be obtained. Therefore, the implementation process is simple and easy to operate. It is less affected by external factors such as temperature and magnification, so that the accuracy of the detected SOH of the battery is relatively high; moreover, when the battery is abnormal, it can be accurately judged in time based on the detected SOH, and the battery can be given in time. Abnormal early warning, high reliability.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the present invention. within the scope of protection.

Claims (6)

1. a method that detects cell health state is characterized in that, this method comprises:

Detect the inner pressure of battery of battery;

From the corresponding relation that generates in advance, obtain the cell health state SOH of battery according to described inner pressure of battery; Described corresponding relation is the SOH of battery and the corresponding relation of inner pressure of battery.

2. method according to claim 1 is characterized in that, before the inner pressure of battery of described detection battery, this method also comprises:

Described battery is carried out charge-discharge test under the preset temperature;

The SOH that behind described charge-discharge test, obtains battery according to discharge capacity and the initial capacity of battery, and generate the corresponding relation of described SOH and time;

The inner pressure of battery of battery when detecting charge-discharge test, and generate inner pressure of battery and the curvilinear characteristic of time;

SOH and the corresponding relation of time and the curvilinear characteristic of described inner pressure of battery and time according to described battery obtain the SOH of battery and the corresponding relation of inner pressure of battery.

3. method according to claim 1 and 2 is characterized in that, described battery is lithium ion battery.

4. an equipment that detects cell health state is characterized in that, this equipment comprises:

Pressure transducer is for detection of the inner pressure of battery of battery;

Pick-up unit is used for according to the cell health state SOH of the detected inner pressure of battery of described pressure transducer from the corresponding relation acquisition battery of generation in advance; Described corresponding relation is the SOH of battery and the corresponding relation of inner pressure of battery.

5. equipment according to claim 4 is characterized in that, this equipment comprises:

The corresponding relation generating apparatus is used for described battery is carried out charge-discharge test under the preset temperature, the SOH that behind described charge-discharge test, obtains battery according to discharge capacity and the initial capacity of battery, and generate the corresponding relation of described SOH and time; The inner pressure of battery of battery when detecting charge-discharge test, and generate inner pressure of battery and the curvilinear characteristic of time; SOH and the corresponding relation of time and the curvilinear characteristic of described inner pressure of battery and time according to described battery obtain the SOH of battery and the corresponding relation of inner pressure of battery.

6. according to claim 4 or 5 described equipment, it is characterized in that described battery is lithium ion battery.