Secondary battery internal pressure measurement method
In order to more accurately measure internal pressure of a secondary battery, the present disclosure provides a measurement method including (a) interposing the secondary battery between an upper plate and a lower plate, (b) increasing internal pressure of the secondary battery by injecting a gas into the inside of the secondary battery, (c) monitoring surface pressure of the secondary battery at a measuring member which is in contact with the lower plate, and (d) measuring a value of the surface pressure from the measuring member at a point in time when at least one sealing portion of the secondary battery is vented.
1 . A method of measuring an internal pressure of a secondary battery comprising:
(a) interposing the secondary battery between an upper plate and a lower plate;
(b) increasing the internal pressure of the secondary battery by injecting a gas into the inside of the secondary battery;
(c) monitoring surface pressure of the secondary battery at a measuring member which is in contact with the lower plate; and
(d) measuring a value of the surface pressure from the measuring member at a point in time when at least one sealing portion of the secondary battery is vented,
wherein the gas in step (b) is injected at a predetermined time interval, and the internal pressure in step (b) is constantly increased to a desired level,
wherein the gas in step (b) is injected through a hole into the inside of the secondary battery,
wherein the secondary battery includes a first area at the lower plate where the surface pressure is measured and a second area comprising a space at the hole where the gas is injected into the inside of the secondary battery, and
wherein the first area where the surface pressure is measured is separated from the second area where the internal pressure is measured.
2 . The method of claim 1 , wherein the secondary battery comprises an electrode assembly and an external material for accommodating the electrode assembly.
3 . The method of claim 1 , wherein the upper plate and the lower plate in step (a) fix the first area.
4 . The method of claim 1 , wherein the internal pressure in step (b) is pressure of the gas injected into the secondary battery.
5 . The method of claim 1 , wherein the internal pressure in step (b) is increased using a regulator.
6 . The method of claim 1 , wherein step (b) further comprises monitoring the internal pressure of the secondary battery.
7 . The method of claim 1 , wherein the measuring member in step (c) is in contact with a bottom surface of the lower plate.
8 . The method of claim 1 , wherein the measuring member in step (c) is a load cell.
9 . The method of claim 1 , wherein the surface pressure in step (c) is a value monitored in a pressure display unit indicating pressure applied to the measuring member.
10 . The method of claim 1 , wherein step (c) further comprises comparing a value of the internal pressure of the secondary battery and a value of the surface pressure of the secondary battery.
11 . The method of claim 1 , wherein the sealing portion in step (d) is formed on an outer periphery where an electrode tab is present.
12 . The method of claim 1 , wherein step (d) further comprises calculating the value of the surface pressure as a maximum value of the internal pressure of the secondary battery.