CN210576303U - Low-temperature charging and discharging protection device for lithium battery - Google Patents

Abstract

Lithium cell low temperature charge-discharge protection device. The low-temperature discharge capacity of the lithium ion battery can be reduced, but the lithium ion battery can be recovered after normal-temperature charge and discharge, and is reversible capacity loss; however, low temperature charging causes lithium precipitation and is a permanent capacity loss. The utility model discloses the constitution includes: the lithium battery low-temperature charge and discharge protection device comprises a charging circuit (9) and a discharging circuit (8), wherein the charging circuit (9) is connected between a charge and discharge plug (7) and a battery pack electric core (6) in series, the discharging circuit is used for correspondingly connecting the charge and discharge plug and the positive electrode and the negative electrode of the battery pack electric core, the charging circuit comprises a normally open temperature control switch (3) and a normally closed temperature control switch (4) which are connected in parallel, the normally closed temperature control switch is connected with a heating device (5) in series, and the heating device is connected to. The utility model is used for lithium cell low temperature charge-discharge protection and battery self-heating.

Description

Low-temperature charging and discharging protection device for lithium battery

The technical field is as follows:

the utility model relates to a lithium cell low temperature charge-discharge protection device belongs to new forms of energy lithium cell technical field.

Background art:

for lithium ion batteries, no matter national standards or enterprise standards, the lower limit temperature of discharge is strictly limited: not lower than-20 ℃. In contrast, the charging temperature not only specifies the minimum temperature as in the case of discharge, but also clearly specifies that charging is possible only at a low rate and not at full charge (for example, charging is possible only at 0.2C at 0 to 15 degrees and the upper limit voltage is 4.0V) at a low temperature, which is feared that the user is more likely to be in a half-step state.

The working principle of the lithium ion battery is that potential difference occurs between the positive electrode and the negative electrode through the change of chemical reaction of internal electrolyte, so that current is generated. The electrolyte moves quite slowly in a low-temperature environment, so that the transfer activity of lithium ions between the positive electrode and the negative electrode is influenced, and the charge and discharge performance of the battery is reduced.

First, the discharge performance of the lithium ion battery at low temperature is described. For discharge at the same rate, the lower the outside temperature, the lower the discharge voltage of the lithium ion battery will be. When the temperature is reduced, the discharge voltage of the battery is also greatly reduced, so that the battery can reach the discharge cut-off voltage more quickly during low-temperature discharge, and the low-temperature discharge capacity is obviously lower than the normal-temperature capacity. The capacity of the lithium ion battery at low temperature does not disappear, but the lithium ion battery cannot be fully discharged in the normal voltage range (more than or equal to 3.0V), and if the discharge cut-off voltage can be continued to be lowered, the remaining capacity can be discharged.

Because the temperature is needed for charging and discharging, battery products of many enterprises can realize normal discharging at low temperature, but normal charging is more strenuous or even impossible at the same temperature, and when Li & lt + & gt is embedded into a graphite material, desolvation is firstly carried out, so that certain energy is consumed in the process, and Li & lt + & gt is prevented from diffusing into the graphite; in contrast, Li + can be rapidly extracted from graphite by a solvation process without consuming energy when the Li + is extracted from the graphite material into solution. Therefore, the charge acceptance of graphite materials is significantly inferior to the discharge acceptance.

In a low temperature environment, there is a certain risk of battery charging. As the dynamic characteristics of the graphite cathode are improved and worsened along with the reduction of the temperature, the electrochemical polarization of the cathode is obviously intensified in the charging process, and the precipitated metal lithium is easy to form lithium dendrites to break through a diaphragm and cause short circuit of the anode and the cathode, thereby causing safety accidents.

The low-temperature discharge capacity of the lithium ion battery can be reduced, but the lithium ion battery can be recovered after normal-temperature charge and discharge, and is reversible capacity loss; however, low temperature charging causes lithium precipitation and is a permanent capacity loss.

By above can derive, the lithium cell receives the temperature to influence very greatly, with power lithium cell application field and the great application environment of temperature influence, need carry out temperature management to the lithium cell, could improve the safety in application of lithium cell, improves the availability factor, extension lithium cell life.

The utility model has the following contents:

the utility model aims to solve the problem that the lithium precipitation is caused by the low-temperature charging of the current lithium battery and the permanent capacity loss is caused, and provides a low-temperature charging and discharging protection device of the lithium battery, which can heat and insulate the lithium battery,

the above purpose is realized by the following technical scheme:

the utility model provides a lithium cell low temperature charge-discharge protection device, this lithium cell low temperature charge-discharge protection device and battery self-heating system are including establishing ties the charging circuit between charge-discharge plug and group battery electricity core and inciting somebody to action the charge-discharge plug with the group battery electricity core positive negative pole correspond the discharge circuit who connects, the charging circuit include parallel connection's normally open temperature detect switch and normally closed temperature detect switch, normally closed temperature detect switch establish ties with heating device, heating device connect the negative pole end of group battery electricity core.

The lithium battery low-temperature charging and discharging protection device is characterized in that a charging diode is installed on a charging circuit.

In the low-temperature charging and discharging protection device for the lithium battery, a charging and discharging plug of a discharging circuit is provided with a discharging diode on a positive connecting line of a battery cell of a battery pack.

The lithium battery low-temperature charging and discharging protection device is characterized in that the heating device is a carbon fiber heating wire wound outside the battery cell or a carbon fiber heating film wrapped outside the battery cell.

In the low-temperature charging and discharging protection device for the lithium battery, the normally open temperature control switch is a kick type 15 ℃ normally open temperature control switch.

In the low-temperature charging and discharging protection device for the lithium battery, the normally closed temperature control switch is a kick type 20 ℃ normally closed temperature control switch.

Has the advantages that:

1. the utility model discloses low temperature charging protection, the electric current can only get into charging circuit when charging, through the diode that charges, through normally opening temperature detect switch, charges, and the fruit temperature is less than normally opening temperature detect switch jumping temperature 15 ℃, then normally opening temperature detect switch automatic disconnection can't charge, and the heating system device starts, to the lithium cell heating, when the temperature is higher than normally opening temperature detect switch jumping temperature 15 ℃, then normally opening temperature detect switch is automatic closed, and the switch-on charging circuit charges to the lithium cell. The lithium battery is heated and then charged in a low-temperature environment, the charging safety of the lithium battery is guaranteed, and the capacity is not damaged. The heating device continues heating, and when the temperature reaches 25 ℃, the heating is stopped.

The utility model discloses install self-heating system additional, lithium cell group uses under autumn winter low temperature environment in the north, when lithium cell group inside temperature is less than 20 ℃, normally closed temperature control switch is automatic closed, start heating device utilizes group battery self electric quantity to heat, when the temperature reaches 25 ℃, normally closed temperature control switch automatic disconnection, heating device stop heating guarantees that lithium cell group discharges at an optimum ambient temperature 20-25 degrees to this improves group battery low temperature environment and discharges the electric quantity.

The utility model discloses when environmental temperature-20 ℃ after test lithium cell group installs additional the heat preservation, the electric quantity that the freezing self-heating of process 12 hours starts the loss is less than 8% of lithium cell group total electric quantity, and lithium cell group can emit and exceed 92% electric quantity. If the lithium battery pack normally travels on the electric vehicle, the electric core in the discharging process of the lithium battery pack can automatically release heat, the internal temperature of the lithium battery pack is lowered more slowly, the electric quantity consumed by self-discharging heating is lower, and the lithium battery pack can emit more electric quantity. Therefore, the problem that the discharge performance of the lithium battery is reduced in a low-temperature environment is solved.

Description of the drawings:

FIG. 1 is a schematic circuit diagram of the present invention;

in the figure: 1. a discharge diode; 2. a charging diode; 3. a normally open temperature control switch; 4. a normally closed temperature control switch; 5. a heating device; 6. a battery cell; 7. a charge-discharge plug; 8. a discharge circuit; 9. a charging circuit.

The specific implementation mode is as follows:

example 1:

the utility model provides a lithium cell low temperature charge-discharge protection device, this lithium cell low temperature charge-discharge protection device and battery self-heating system are including establishing ties charging circuit 9 between charge-discharge plug 7 and group battery electricity core 6 and inciting somebody to action the charge-discharge plug with the positive negative pole of group battery electricity core correspond the discharging circuit 8 of connecting, charging circuit include parallel connection's normally open temperature detect switch 3 and normally closed temperature detect switch 4, normally closed temperature detect switch and heating device 5 establish ties, heating device connect the negative pole end of group battery electricity core.

Example 2:

according to the low-temperature charging and discharging protection device for the lithium battery in the embodiment 1, the charging diode 2 is installed on the charging circuit, the unidirectional conductive characteristic of the rectifier diode is applied, and when the lithium battery pack normally discharges, current passes through the discharging circuit and passes through the discharging diode. When charging, the current can only enter the charging circuit, and the charging is carried out through the charging diode and the normally open temperature control switch, and the circuit independence of charging and discharging is realized under the condition of charging and discharging at the same port by applying the unidirectional conductivity of the rectifier diode. The charging circuit can be additionally provided with a temperature control switch and a heating system, so that the charging is realized after the heating is carried out at a low temperature.

Example 3:

according to the low-temperature charging and discharging protection device of the lithium battery in embodiment 1 or 2, the discharging diode 1 is installed on the connection line between the charging and discharging plug of the discharging circuit and the positive electrode of the battery cell.

Example 4:

according to embodiment 1 or 2 or 3, the lithium battery low-temperature charging and discharging protection device, the heating device is a carbon fiber heating wire wound outside the battery pack electric core or a carbon fiber heating film wrapped outside the battery pack electric core, and the heating wire is a silicon rubber carbon fiber heating wire or a flame-retardant Teflon heating wire. The carbon fiber heating film is also called a graphene electrothermal film. They are characterized in that: the working voltage (direct current 3-600V, alternating current 12-380V) has wide application range, uniform heating, adjustable length, low cost, good effect, no damage for years and more durability.

Example 5:

according to the lithium battery low-temperature charging and discharging protection device in the embodiment 1, 2, 3 or 4, the normally open temperature control switch is a kick type 15 ℃ normally open temperature control switch, and is switched off at a temperature lower than 15 ℃ and switched on at a temperature higher than 15 ℃.

Example 6:

according to the lithium battery low-temperature charging and discharging protection device in the embodiment 1, 2, 3, 4 or 5, the normally closed temperature control switch is a kick type 20 ℃ normally closed temperature control switch, and is switched on when the temperature is lower than 20 ℃ and switched off when the temperature is higher than 25 ℃.

Example 7:

for the group battery installs the heat preservation measure additional, adopt the thick fire-retardant XPS extrusion molding heated board of B1 level of high heat-insulating rate of 2cm (can be according to using region temperature increase and decrease heated board thickness) to assemble into sealed box body, place the group battery in the box body, guarantee lithium cell group internal temperature, can not cross low and rapid cooling because of outside temperature, can play the heat preservation effect.

Claims (6)

1. The utility model provides a lithium cell low temperature charge-discharge protection device which characterized by: the low-temperature charge-discharge protection device for the lithium battery comprises a charge circuit and a discharge circuit, wherein the charge circuit is connected in series between a charge-discharge plug and a battery pack cell, the charge-discharge plug is connected with the discharge circuit, the positive electrode and the negative electrode of the battery pack cell are correspondingly connected with the discharge circuit, the charge circuit comprises a normally open temperature control switch and a normally closed temperature control switch which are connected in parallel, the normally closed temperature control switch is connected with a heating device in series, and the heating device is connected with the negative electrode end of the battery pack cell.

2. The low-temperature charging and discharging protection device for the lithium battery as claimed in claim 1, wherein: and a charging diode is arranged on the charging circuit.

3. The low-temperature charging and discharging protection device for the lithium battery as claimed in claim 2, wherein: and a discharge diode is arranged on a charging and discharging plug of the discharge circuit and a positive electrode connecting wire of the battery cell.

4. The low-temperature charging and discharging protection device for the lithium battery as claimed in claim 3, wherein: the heating device is a carbon fiber heating wire wound outside the battery pack electric core or a carbon fiber heating film wrapped outside the battery pack electric core.

5. The lithium battery low-temperature charging and discharging protection device as claimed in claim 4, wherein: the normally open temperature control switch is a kick type 15 ℃ normally open temperature control switch.

6. The lithium battery low-temperature charging and discharging protection device as claimed in claim 5, wherein: the normally closed temperature control switch is a kick type 20 ℃ normally closed temperature control switch.

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