CN102868003A - Device and method for detecting internal gas pressure of lithium ion battery - Google Patents

Abstract

The invention discloses a device and method for detecting the internal gas pressure of a lithium-ion battery. The detection of the internal gas pressure of the lithium-ion battery is based on the Boyle's theorem to set the equation P ₁ ×V ₁ =P ₂ ×(V ₁ +△V), In the formula: P ₁ and V ₁ are the original internal pressure and volume of the battery, P ₂ and △V are the air pressure and gas volume change after the battery is exhausted respectively, and P ₂ and △V are measured by the device provided by the invention, and then measured From V ₁ , P ₁ can be calculated. The invention realizes the detection of the internal air pressure of the battery through the structure of the U-shaped tube, the structure is simple, the measurement is convenient, and the real-time and effective detection of the internal gas pressure of the lithium-ion battery is realized, which guides the design of the lithium-ion battery body structure and safety valve , Play an important role in eliminating hidden dangers of lithium-ion batteries.

Description

Lithium-ion battery internal gas pressure detection device and method

technical field

The present invention relates to the field of lithium-ion batteries, in particular to a device and method for detecting gas pressure inside a lithium-ion battery.

Background technique

With the problems caused by energy shortage and environmental pressure, lithium-ion batteries will be widely used, especially in the electric vehicle industry, lithium-ion batteries will be widely used, so their safety performance is particularly important. Lithium-ion battery is a closed reaction container. There are decomposition reactions of electrolyte, electrolyte and negative electrode reaction, electrolyte and positive electrode reaction inside the battery. Especially under some abuse conditions and special environments, these reactions will be intensified, such as overcharge , over-discharge, short-circuit and high-temperature environment, these reactions will intensify, and a large amount of gas will be generated. The accumulation of gas will cause the internal pressure of the battery to rise. If it cannot be discharged in time, an explosion will occur and a safety accident will occur. At present, explosion-proof valves are used in the industry to solve this problem, but the limit pressure design of the explosion-proof valve must be within a safe range. If the limit pressure is too high, the gas inside the battery will not be discharged in time, causing the battery to explode. If the limit pressure is too low, it will cause the battery to explode. Premature failure reduces battery life. Therefore, it is very important to measure the gas pressure inside the battery.

Contents of the invention

The object of the present invention is to provide a device and method for detecting gas pressure inside a lithium-ion battery in order to remedy the defects of the prior art.

The present invention is achieved through the following technical solutions:

A device for detecting gas pressure inside a lithium-ion battery, including a U-shaped tube with liquid inside and a gas release device, the gas release device includes upper and lower battery splints, and the battery to be tested is placed between the two battery splints Between the two battery splints, the two battery splints are fixed by screw rods, and a gas release cavity is fixed above the battery to be tested, and the gas discharge cavity passes through the upper battery splint and is sealed and connected with the upper battery splint. The bottom of the cavity is an air inlet, the side is provided with an air outlet, and the top is sealed. The air outlet is connected to the right cavity of the U-shaped tube through a trachea. A piston is placed on the upper side of the air outlet in the deflation cavity. There is also a piercing needle, the tip of the piercing needle contacts the upper part of the battery to be tested, and is used to pierce holes on the battery to be tested, and the other end of the piercing needle passes through the top of the piston and the venting cavity and is fixed on the handle. The handle is supported by the support frame and drives the piercing needle to move up and down.

A method for detecting the internal gas pressure of a lithium-ion battery by using the above-mentioned device, comprising the steps of:

(1) The handle drives the piercing needle to move downward, and the piercing hole is pierced with a small hole on the battery to be tested. The gas in the battery to be tested enters the venting cavity and enters the trachea from the gas outlet into the U-shaped tube. In the right cavity, until the liquid surface on both sides of the U-shaped tube is still, record the difference in liquid level as h, after the battery to be tested is exhausted, the internal air pressure P2=P0+ρgh, the gas volume change in the battery ΔV=1/2hS, Among them, P0 is the atmospheric pressure, ρ is the liquid density in the U-shaped tube, and S is the cross-sectional area of the U-shaped tube;

(2) Take out the exhausted battery to be tested and weigh it, record it as W1, put the battery to be tested into a container filled with organic solvent, and completely submerge it, put the container into a vacuum box, and continuously evacuate it. The organic solvent fills the volume of gas discharged from the battery to be tested. Take out the battery to be tested to remove the organic solvent on the surface and weigh it as W2. The volume of gas discharged from the battery to be tested is V1=(W2-W1)/ρ1, ρ1 is the organic solvent density;

(3) According to Boyle's law P1V1=P2(V1+ΔV), calculate the internal pressure P1 of the gas to be measured.

The device for detecting gas pressure inside the lithium-ion battery is characterized in that: upper and lower gaskets are respectively provided between the upper and lower surfaces of the battery to be tested and the upper and lower battery splints.

The gas pressure detection device inside the lithium-ion battery is characterized in that: the diameter of the deflation cavity is 10 to 30 mm, and the material is stainless steel; the diameter of the piercing needle is 1 to 2 mm, and the material is stainless steel.

The gas pressure detection device inside the lithium-ion battery is characterized in that the liquid in the U-shaped tube is ethanol or ethyl acetate.

The advantages of the present invention are: the present invention realizes the detection of the internal pressure of the battery through the structure of the U-shaped tube. The design of structure and safety valve plays an important role in eliminating hidden dangers of lithium-ion batteries.

Description of drawings

Fig. 1 is a structural schematic diagram of the present invention.

Fig. 2 is an enlarged view of the deflation device in the present invention.

Detailed ways

As shown in Figures 1 and 2, a gas pressure detection device inside a lithium-ion battery includes a U-shaped tube 3 with liquid inside and a deflation device 1, and the deflation device 1 includes upper and lower battery splints 5, 6, put the battery to be tested 4 between the two battery splints, the two battery splints are fixed by the screw 7, the air release cavity 8 is fixed above the battery to be tested 4, and the air release cavity 8 passes through The upper battery splint 5 is sealed and connected with the upper battery splint 5, the bottom of the deflation cavity 8 is an air inlet, the side is provided with an air outlet, and the top is sealed, and the air outlet is connected to the U through the air pipe 2. The right cavity of the type tube 3 is connected, a piston 9 is placed on the upper side of the air outlet in the deflation cavity 8, and a piercing needle 10 is also placed in the deflation chamber 8, and the tip of the piercing needle 10 contacts the battery to be tested 4 The upper part is used for piercing holes on the battery 4 to be tested. The other end of the piercing needle 10 passes through the top of the piston 9 and the deflation cavity 8 and is fixed on the handle 11. The handle 11 is supported by the support frame 12 and drives the piercing. The hole needle 10 moves up and down.

A method for detecting the internal gas pressure of a lithium-ion battery by using the above-mentioned device, comprising the steps of:

(1) The handle 11 drives the piercing needle 10 to move downward, and the piercing hole 10 has a small hole in the battery 4 to be tested, and the gas in the battery 4 to be tested enters the deflation cavity 8 and enters the trachea from the gas outlet 2 into the right chamber of the U-shaped tube 3 until the liquid surface on both sides of the U-shaped tube 3 is still, record the difference in liquid level as h, and the internal air pressure P2=P0+ρgh after the battery 4 to be tested is exhausted, The volume change of the gas inside the battery ΔV=1/2hS, where P0 is the atmospheric pressure, ρ is the liquid density in the U-shaped tube, and S is the cross-sectional area of the U-shaped tube;

(2) Take out the exhausted battery to be tested and weigh it, record it as W1, put the battery to be tested 4 into a container filled with organic solvent, and completely submerge it, put the container into a vacuum box, and continuously evacuate it , the organic solvent fills the volume of gas discharged from the battery to be tested, take out the battery to be tested, remove the organic solvent on the surface and weigh it as W2, the volume of gas discharged from the battery to be tested is V1=(W2-W1)/ρ1, ρ1 is the organic solvent density;

(3) According to Boyle's law P1V1=P2(V1+ΔV), calculate the internal pressure P1 of the gas to be measured.

The device for detecting gas pressure inside the lithium-ion battery is characterized in that upper and lower gaskets 13 are provided between the upper and lower surfaces of the battery to be tested 4 and the upper and lower battery splints 5 and 6, respectively.

The device for detecting gas pressure inside the lithium-ion battery is characterized in that: the diameter of the degassing cavity 8 is 10 to 30 mm, and the material is stainless steel; the diameter of the needle head 10 is 1 to 2 mm, and the material is Stainless steel.

The gas pressure detection device inside the lithium-ion battery is characterized in that the liquid in the U-shaped tube 3 is ethanol or ethyl acetate.

Claims (5)

1. A lithium-ion battery internal gas pressure detection device is characterized in that: it includes a U-shaped tube and a gas release device with liquid inside, and the gas release device includes upper and lower battery splints, and the battery to be tested Placed between the two battery splints, the two battery splints are fixed by screws, and a venting cavity is fixed above the battery to be tested, and the venting cavity passes through the upper battery splint and is sealed and connected with the upper battery splint , the bottom end of the deflation chamber is an air inlet, the side is provided with an air outlet, and the top is sealed, and the air outlet is connected to the right cavity of the U-shaped tube through a trachea, and the upper side of the air outlet in the deflation chamber is placed Piston, there is also a piercing needle in the deflation chamber, the tip of the piercing needle contacts the upper part of the battery to be tested, the other end of the piercing needle passes through the piston and the top of the deflation chamber and is fixed on the handle, the handle It is supported by the support frame and drives the piercing needle to move up and down. 2. A method for detecting the internal gas pressure of a lithium-ion battery using the device according to claim 1, characterized in that: comprising the steps of: (1) The handle drives the piercing needle to move downward, and the piercing hole is pierced with a small hole on the battery to be tested. The gas in the battery to be tested enters the venting cavity and enters the trachea from the gas outlet into the U-shaped tube. In the right cavity, until the liquid surface on both sides of the U-shaped tube is still, record the difference in liquid level as h, after the battery to be tested is exhausted, the internal air pressure P2=P0+ρgh, the gas volume change in the battery ΔV=1/2hS, Among them, P0 is the atmospheric pressure, ρ is the liquid density in the U-shaped tube, and S is the cross-sectional area of the U-shaped tube; (2) Take out the exhausted battery to be tested and weigh it, record it as W1, put the battery to be tested into a container filled with organic solvent, and completely submerge it, put the container into a vacuum box, and continuously evacuate it. The organic solvent fills the volume of gas discharged from the battery to be tested. Take out the battery to be tested to remove the organic solvent on the surface and weigh it as W2. The volume of gas discharged from the battery to be tested is V1=(W2-W1)/ρ1, ρ1 is the organic solvent density; (3) According to Boyle's law P1V1=P2(V1+ΔV), calculate the internal pressure P1 of the gas to be measured. 3. The device for detecting gas pressure inside a lithium-ion battery according to claim 1, characterized in that: upper and lower gaskets are respectively provided between the upper and lower surfaces of the battery to be tested and the upper and lower battery splints. 4. The device for detecting gas pressure inside a lithium-ion battery according to claim 1, characterized in that: the diameter of the degassing cavity is 10 to 30 mm, and the material is stainless steel; the diameter of the needle head of the piercing needle is 1 to 30 mm. 2mm, made of stainless steel. 5. The device for detecting gas pressure inside a lithium-ion battery according to claim 1, wherein the liquid in the U-shaped tube is ethanol or ethyl acetate.

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