Patent Application
20230198070
This application relates to the technical field of energy storage devices, and in particular, to an electrochemical apparatus and an electronic device.
Lithium-ion batteries are a type of rechargeable secondary battery, during working of which lithium ions migrate between positive and negative electrodes, and are intercalated into or deintercalated from the electrodes to generate electrical energy. Specifically, during charging, lithium ions are deintercalated from the positive electrode and intercalated into the negative electrode through the electrolyte. During discharging, lithium ions are deintercalated from the negative electrode and intercalated into the positive electrode through the electrolyte. Lithium-ion batteries are prone to generate gas under conditions such as short circuit, high temperature, and overcharge, causing the battery to swell. When the generated gas cannot be discharged, the battery will malfunction, deform, or even explode, endangering personal safety of users.
This application provides an electrochemical apparatus and an electronic device, to improve safety of the electrochemical apparatus.
A first aspect of this application provides an electrochemical apparatus, where the electrochemical apparatus includes:
a housing having a cavity, and the housing includes a wall;
where the wall is provided with a stress-weak zone.
In a possible design, the stress-weak zone is a continuous structure or a discontinuous structure.
In a possible design, a total length of the stress-weak zone arranged on the wall is greater than or equal to 3 mm.
In a possible design, H is a depth of the stress-weak zone, and H is 30% to 90% of a thickness of the wall.
In a possible design, W is a width of the stress-weak zone, and W is 50% to 110% of a thickness of the wall.
In a possible design, the wall is provided with one or more stress-weak zones.
In a possible design, the wall is a wall with the largest area of the housing.
In a possible design, the stress-weak zone is arranged on at least one of an interior surface and an exterior surface of the wall.
In a possible design, an elastic modulus of the wall is greater than or equal to 1000 MPa.
In a possible design, the stress-weak zone includes at least one of an indentation, a groove, or a zone with a material strength lower than that of surrounding zones.
In a possible design, the wall has an outer end edge, and a curvature of the stress-weak zone is the same as a curvature of the outer end edge closest to the stress-weak zone.
In a possible design, the wall has an outer end edge and a first zone, where the first zone has a first outer edge, the first outer edge coincides with the outer end edge, and the stress-weak zone is arranged in the first zone; and a ratio of an area of the first zone to an area of the wall ranges from 30% to 50%.
In a possible design, the outer end edge deviates inwardly by a first distance L1 to form the first zone, the first zone is an annular structure, the first zone has a first inner edge and a first outer edge, and the first outer edge coincides with the outer end edge.
In a possible design, the first zone is an annular structure, the first zone has a first inner edge, and the first inner edge is a circle formed by connecting line segments, where the line segments are formed by extension of points on the first outer edge toward the inside of the wall by a same first distance L1 in a direction of normal line or perpendicular line of the first outer edge.
In a possible design, the first zone is an annular structure, the first zone has a first inner edge, and the first inner edge is a circle formed by connecting line segments, where the line segments are formed by extension of points on the first outer edge toward the inside of the wall by a same first distance L1 in a direction of normal line or perpendicular line of the first outer edge, where the line segments have a non-connected part, and two of the line segments that are adjacent to the non-connected part further extend to intersect with each other based on a same curvature as the first outer edge that forms the two line segments.
In a possible design, there is a second distance L2 between the outer end edge and a geometric center of the wall, where the first distance L1 and the second distance L2 satisfy 0.1≤L1/L2 ≤0.4.
In a possible design, the outer end edge and the first inner edge are both circular-shaped or arc-shaped; and
a distance between the first inner edge and the geometric center is R1, a radius of the outer end edge is R, and 0.7≤R1/R≤0.8.
In a possible design, the wall is circular, and the first zone is annular; and
the first zone has an inner radius of R1 and an outer radius of R;
where R1=√{square root over (0.55)}R.
In a possible design, the wall is rectangular, and the first zone is a rectangular ring; and
under the condition that side lengths of the wall are t1 and t2 respectively, the first distance L1, t1, and t2 satisfy the relation (t1 −2L1)×(t2 −2L1)=0.55t1×t2.
In a possible design, the wall is in an asymmetric shape, and the first zone is an asymmetric ring.
In a possible design, the wall is L-shaped, and the first zone is an L-shaped ring;
under the condition that side lengths of the wall are t1, t2, t3, t4, t5, and t6 respectively and that t2=t4+t6 and t3=t1+t5, the first distance L1, t1, t2, t3, t4, t5, and t6 satisfy the relation: 0.45×(t2×t3−t5×t6)=(t2×t3−(t2 −2L1)×(t3 −2L1)).
In a possible design, the first zone is an asymmetric L-shaped ring.
In a possible design, the wall has an outer end edge and a second zone, the stress-weak zone is arranged in the second zone, the second zone has a second outer edge, and the second outer edge is a circle formed by connecting line segments, where the line segments are formed by extension of points on the first outer edge toward the inside of the wall by a same third distance L3 in a direction of normal line or perpendicular line of the first outer edge.
In a possible design, the wall has an outer end edge and a second zone, and the stress-weak zone is arranged in the second zone; the second zone has a second outer edge, and the second outer edge is a circle formed by connecting line segments, where the line segments are formed by extension of points on the first outer edge toward the inside of the wall by a same third distance L3 in a direction of normal line or perpendicular line of the first outer edge, where the line segments have a non-connected part, and two of the line segments that are adjacent to the non-connected part further extend to intersect with each other based on a same curvature as the first outer edge that forms the two line segments; and a ratio of an area of the second zone to an area of the wall ranges from 10% to 22%.
In a possible design, the wall has an outer end edge, the outer end edge deviates inwardly by a third distance L3 to form a second outer edge, and the second outer edge encloses the second zone; and a ratio of an area of the second zone to an area of the wall ranges from 10% to 22%.
In a possible design, there is a second distance L2 between the outer end edge and a geometric center of the wall, where the third distance L3 and the second distance L2 satisfy 0.2≤L3/L2 ≤0.5.
In a possible design, the outer end edge and the second outer edge are both circular-shaped or arc-shaped; and a distance between the second outer edge and the geometric center is R2, a radius of the outer end edge is R, and 0.3≤R2/R≤0.5.
In a possible design, the wall and the second zone are both circular;
where R2=√{square root over (0.2)}R.
In a possible design, the wall and the second zone are both rectangular; and under the condition that side lengths of the wall are t1 and t2 respectively, the third distance L3, t1, and t2 satisfy the relation (t1 −2L3)×(t2 −2L3)=0.2t1×t2.
In a possible design, the wall and the second zone are both L-shaped; and under the condition that side lengths of the wall are t1, t2, t3, t4, t5, and t6 respectively and that t2=t4+t6 and t3−t1+t5, the third distance L3, t1, t2, t3, t4, t5, and t6 satisfy the relation: (t3 −2L3)×(t4 −2L3)+t6×(t1 −2L3)=0.2×(t2×t3−t5×t6).
Another aspect of this application provides an electronic device, where the electronic device includes:
a housing;
a screen, installed on the housing; and
an electrochemical apparatus, located in an inner cavity of the housing;
where the electrochemical apparatus is the foregoing electrochemical apparatus.
In this application, the stress-weak zone arranged on the wall of the housing of the electrochemical apparatus is a weak part of the housing. When the electrochemical apparatus generates gas under conditions such as short circuit, high temperature, and overcharge, a pressure inside the housing increases. Under the action of the pressure, the stress-weak zone can form an opening, and the opening allows the inner cavity of the housing to communicate with the external environment in which the electrochemical apparatus is located, so as to discharge the gas in the inner cavity of the housing. This reduces risks of expansion, deformation, or even explosion of the electrochemical apparatus caused by gas generation inside the electrochemical apparatus, and improves safety of the electrochemical apparatus.
It should be understood that the foregoing general description and the following detailed description are only exemplary and are not intended to limit this application.
The accompanying drawings herein are incorporated into this specification and form a part of this specification, illustrate the embodiments conforming to this application, and are intended to explain the principles of this application together with this specification.
To help better understand the technical solutions of this application, the following describes the embodiments of this application with reference to the accompanying drawings.
Apparently, the described embodiments are merely some but not all of the embodiments of this application. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments of this application shall fall within the protection scope of this application.
The terms used in the embodiments of this application are merely intended to describe specific embodiments, but not intended to limit this application. The terms “a/an”, “the” and “this” of singular forms used in the embodiments and the appended claims of this application are also intended to include plural forms, unless otherwise specified in the context clearly.
It should be understood that in this specification, a term “and/or” is only an associative relationship for describing associated objects, indicating that three relationships may exist. For example, A and/or B may indicate three situations: A exists independently; A and B exist simultaneously; and B exists independently. In addition, a character “/” in this specification generally indicates an “or” relationship between contextually associated objects.
It should be noted that the directional terms such as “above”, “under”, “left”, and “right” described in the embodiments of this application are described as seen from the angles shown in the accompanying drawings, and should not be understood as limitations to the embodiments of this application. In addition, in the context, it should be further understood that when an element is referred to as being “above” or “under” another element, the element can not only be directly connected “above” or “under” the another element, but also be indirectly connected “above” or “under” the another element through an intermediate element.
An embodiment of this application provides an electrochemical apparatus. The electrochemical apparatus includes a housing and an electrode assembly located inside the housing, where the electrode assembly includes a terminal, the terminal is configured to transport electrical energy generated by the electrode assembly, at least part of the electrode assembly is located in a cavity of the housing, and the housing is configured to protect the electrode assembly. The housing may be in various shapes such as circular, square, rectangular, L-shaped, and irregular shapes. The wall of the housing encloses one of the above-mentioned shapes. A plurality of walls of the housing includes a wall 1. The wall 1 may be in various shapes such as circular, square, rectangular, L-shaped, and irregular shapes. As shown in
In this embodiment, the stress-weak zone 2 arranged on the wall 1 of the housing of the electrochemical apparatus is a weak part of the housing. When the electrochemical apparatus generates gas under conditions such as short circuit, high temperature, and overcharge, a pressure inside the housing increases. Under the action of the pressure, the stress-weak zone 2 can form an opening, and the opening allows the inner cavity of the housing to communicate with the external environment in which the electrochemical apparatus is located, so as to discharge the gas in the inner cavity of the housing. This reduces risks of expansion, deformation, or even explosion of the electrochemical apparatus caused by gas generation inside the electrochemical apparatus, and improves safety of the electrochemical apparatus.
Specifically, the stress-weak zone 2 in this embodiment of this application may include at least one of an indentation, a groove, or a zone with a material strength lower than that of its surrounding zones. The zone with a material strength lower than that of its surrounding zones means that: a material strength of the stress-weak zone 2 is lower than that of other zones of the wall 1. When the wall 1 is under stress, the material in the stress-weak zone 2 is easily deformed, thus forming an opening. In addition, both the groove and the indentation are zones with lower strength in the wall 1, namely, the zones that are easily broken to form an opening when under stress. The following description uses an example in which the stress-weak zone 2 is a groove or an indentation.
Specifically, as shown in
In this embodiment, when a pressure in the housing increases due to gas generation of the electrochemical apparatus, the wall 1 is subjected to the pressure, and a position of the wall 1 that is close to the outer end edge 11 (the first zone 12) is subjected to a greater pressure, in other words, the position is more likely to break under the action of pressure than other positions. Therefore, compared with that the stress-weak zone 2 is arranged in other positions of the wall 1, when the stress-weak zone 2 is arranged in the first zone 12, the stress-weak zone 2 is subjected to a greater pressure under the action of the gas generated in the housing. In other words, the stress-weak zone 2 at this position is easier to form an opening to discharge the gas in the housing, thereby further reducing risks of expansion, deformation, and even explosion of the electrochemical apparatus.
In addition, a ratio of an area of the first zone 12 to an area of the wall 1 ranges from 30% to 50%. For example, the ratio of the two areas may be 30%, 35%, 38%, 45%, or 50%. In an embodiment, the ratio of the area of the first zone 12 to the area of the wall 1 is 45%. In this case, the stress-weak zone 2 provided in the first zone 12 can well meet the pressure relief requirements.
More specifically, as shown in
Therefore, as shown in
In some embodiments, the wall 1 may be in an asymmetric shape, and the first zone 12 is an asymmetric ring.
In this embodiment, as shown in
Further, as shown in
In this embodiment, when the ratio of the first distance L1 to the second distance L2 satisfies the above relation, the ratio of the area of the first zone 12 to the area of the wall 1 ranges from 30% to 50%. In this case, the stress-weak zone 2 is arranged in the first zone 12, and when gas is generated inside the electrochemical apparatus, the stress-weak zone 2 can quickly form an opening to discharge the gas inside the electrochemical apparatus, thereby improving the safety of the electrochemical apparatus.
In an embodiment, as shown in
In this embodiment, as shown in
Specifically, as shown in
In this embodiment, the area of the first zone 12 is S1=πR2−πR12=0.45πR2. In this case, the ratio of the area S1 of the first zone 12 to the area S of the wall 1 satisfies S1/S=0.45.
In this embodiment, when the wall 1 is a regular circle, the first zone 12 configured to arrange the stress-weak zone 2 is a regular annular structure, making it easy to determine the position of the stress-weak zone 2.
For example, when R=3 mm, R1 may be 2.22 mm. In this case, the inner radius of the first zone 12 is R1=2.22 mm, the outer radius is R=3 mm, and S1/S=0.4524.
In another embodiment, as shown in
In this embodiment, the area S of the wall 1 satisfies S=t1×t2, and the area S1 of the first zone 12 satisfies: S1=S−(t1 −2L1)×(t2 −2L1)=0.45t1×t2. Therefore, the ratio of the area of the first zone 12 to the area of the wall 1 satisfies S1/S=0.45.
For example, when t1=60 mm and t2=40 mm, L1 may be 6 mm. In this case, the area of the first zone 12 is S1=1056 mm2, the area of the wall 1 is S=2400 mm2, and S1/S=0.44.
In this embodiment, when the wall 1 is a regular rectangle, the first zone 12 configured to arrange the stress-weak zone 2 is a regular rectangular structure, making it easy to determine the position of the stress-weak zone 2.
In another embodiment, as shown in
In this embodiment, the area S of the wall 1 satisfies S=t2×t3−t5×t6, and the area S1 of the first zone 12 satisfies: S1=t2×t3−(t2 −2L1)(t3 −2L1). Therefore, the ratio of the area of the first zone 12 to the area of the wall 1 satisfies S1/S=0.45.
For example, when t1=25 mm, t2=60 mm, t3=50 mm, t4=20 mm, t5=25 mm, and t6=40 mm, the first distance L1 may be 4.32 mm. In this case, the area of the first zone 12 is S1=875.75 mm2, the area of the wall 1 is S=2000 mm2, and S1/S=0.438.
In addition, as shown in
Specifically, as shown in
In this embodiment, as shown in
When the pressure in the housing increases due to the gas generation of the electrochemical apparatus, the wall 1 is subjected to the pressure. Under the action of the pressure, the wall 1 undergoes a specific degree of deformation, and the deformation of the wall 1 in the second zone 13 is relatively large, meaning that compared with other positions, this position is more likely to break and form an opening under the action of pressure. Therefore, compared with that the stress-weak zone 2 is arranged in other positions of the wall 1, when the stress-weak zone 2 is arranged in the second zone 13, the stress-weak zone 2 deforms greatly under the pressure of the gas generated in the housing, meaning that the stress-weak zone 2 at this position is easy to form an opening, to discharge the gas in the housing more easily, thereby further reducing risks of expansion, deformation, and even explosion of the electrochemical apparatus.
Furthermore, a ratio of an area of the second zone 13 to an area of the wall 1 ranges from 10% to 22%. For example, the ratio of the two may be 10%, 15%, 20%, 22%, or the like. In an embodiment, the ratio of the area of the second zone 13 to the area of the wall 1 may be 20%. In this case, the stress-weak zone 2 provided in the second zone 13 can well meet the pressure relief requirements.
Specifically, as shown in
In this embodiment, when the ratio of the third distance L3 to the second distance L2 satisfies the above relation, the ratio of the area of the second zone 13 to the area of the wall 1 ranges from 10% to 22%. In this case, the stress-weak zone 2 is arranged in the second zone 13, and when gas is generated inside the electrochemical apparatus, the position of the wall 1 in where the stress-weak zone 2 is located deforms greatly, so that the stress-weak zone 2 can quickly form an opening to discharge the gas inside the electrochemical apparatus, thereby improving the safety of the electrochemical apparatus.
In an embodiment, as shown in
In this embodiment, when 0.3≤R2/R≤0.5, the ratio of the area of the second zone 13 to the area of the wall 1 may range from 10% to 22%.
Specifically, as shown in
In this embodiment, the area of the second zone 13 is S2=πR22=0.2πR2. In this case, the ratio of the area S2 of the second zone 13 to the area S of the wall 1 satisfies S2/S=0.2.
In this embodiment, when the wall 1 is a regular circle, the second zone 13 configured to arrange the stress-weak zone 2 is a regular circular structure, making it easy to determine the position of the stress-weak zone 2.
To verify the pressure relief effect of the wall 1 being provided with the stress-weak zone 2 (using the groove as an example), a pressure relief comparison test is carried out. In the test, the stress-weak zone 2 is arranged as the embodiment shown in
r in the table represents the distance between the groove and the geometric center of the wall 1, that is, the radius of the position of the groove, and r can represent the position of the groove. For example, when R=3 mm, R2 may be 1.34 mm. In the test, the groove is located at the first inner edge 121 of the first zone 12 when r=2.12 mm, and the groove is located at the second outer edge 131 of the second zone 13 when r=1.34 mm. The upper and lower limits of the battery pressure are required to be (0.1 MPa, 4 MPa). It can be seen from the test results that when r=1.6 mm, that is, the groove was not within the range of the first zone 12 and the second zone 13, the groove did not release pressure effectively, the average relief pressure was higher than the upper limit, and most batteries exploded. When the groove was located in the first zone 12 and the second zone 13 (r≥2.12 mm or r≤1.34 mm), the groove could effectively release the pressure and prevent the battery from exploding. Further, when the groove was located in the zone in which the ratio of the area S1 of the first zone 12 to the area S of the wall 1 was 45% (that is, r≥2.22 mm), the average relief pressure further reduced, and no battery exploded.
In another embodiment, the wall 1 is rectangular, that is, the outer end edge 11 of the wall 1 encloses a rectangular wireframe. In this case, the first zone 12 is a rectangular ring, side lengths of the wall 1 are t1 and t2 (the length and width of the rectangular wireframe) respectively, and the first distance L1, t1 and t2 satisfy the relation S1=t1×t2−(t1 −2L1)×(t2 −2L1)=0.5t1×t2.
In this embodiment, the area S of the wall 1 satisfies S=t1×t2, and the area S2 of the second zone 13 satisfies: S2=(t1 −2L1)×(t2 −2L1)=0.2t1×t2. Therefore, the ratio of the area S2 of the second zone 13 to the area of the wall 1 satisfies S2/S=0.2.
In this embodiment, as shown in
To verify the pressure relief effect of the wall 1 being provided with the stress-weak zone 2 (using the groove as an example), a pressure relief comparison test is carried out. In the test, the stress-weak zone 2 is arranged as the embodiment shown in
D in the table represents a shortest vertical distance between the groove and the outer end edge 11 of the wall surface 1, and D can represent the position of the groove. For example, when t1=60 mm and t2=40 mm, L3 may be 13 mm. In the test, when D=6 mm, the groove is located at the first inner edge 121 of the first zone 12, and when D=13 mm, the groove is located at the second outer edge 131 of the second zone 13. The upper and lower limits of the battery pressure are required to be (0.06 MPa, 2.4 MPa). It can be seen from the test results that when 8 mm≤D<13 mm, that is, the groove was not within the range of the first zone 12 and the second zone 13, the groove did not release pressure effectively, the average relief pressure was close to or even higher than the upper limit, and most batteries exploded. When the groove was located in the first zone 12 and the second zone 13 (D≥13 mm or D<8 mm), the groove could effectively release the pressure and prevent the battery from exploding.
In another embodiment, as shown in
In this embodiment, the area S of the wall 1 satisfies S=t2×t3−t5×t6, and the area S2 of the second zone 13 satisfies: S2=(t3 −2L3)×(t4 −2L3)+t6×(t1 −2L3). Therefore, the ratio of the area of the second zone 13 to the area of the wall 1 satisfies S2/S=0.2.
To verify the pressure relief effect of the wall 1 being provided with the stress-weak zone 2 (using the groove as an example), a pressure relief comparison test is carried out. In the test, the stress-weak zone 2 is arranged as the embodiment shown in
D in the table represents the distance between the groove and the outer end edge 11 of the wall 1, that is, D can represent the position of the groove. For example, when t1=25 mm, t2=60 mm, t3=50 mm, t4=20 mm, t5=25 mm, and t6=40 mm, the third distance L3 may be 7.67 mm. In the test, when D=5 mm, the groove is located at the first inner edge 121 of the first zone 12, and when D=8.63 mm, the groove is located at the second outer edge 131 of the second zone 13. The upper and lower limits of the battery pressure are required to be (0.04 MPa, 1.8 MPa). It can be seen from the test results that when 5 mm<D<8.63 mm, that is, the groove was not within the range of the first zone 12 and the second zone 13, the groove did not release pressure effectively, the average relief pressure was close to or even higher than the upper limit, and most batteries exploded. When the groove was located in the first zone 12 and the second zone 13 (D≥8.63 mm or D≤5 mm), the groove could effectively release the pressure and prevent the battery from exploding.
In an embodiment, as shown in
In the foregoing embodiments, the shape of the stress-weak zone 2 may be in various shapes such as arc, linear, broken-line, and curve. Three schemes shown in
Although the batteries in the three schemes shown in
Based on this, in the foregoing embodiments, a curvature of the stress-weak zone 2 is the same as a curvature of the outer end edge 11 closest to the stress-weak zone 2. For example, as shown in
In an embodiment, the stress-weak zone 2 may be a continuous structure or a discontinuous structure. As shown in
In an embodiment, the wall 1 may be provided with one or more stress-weak zones 2, and each stress-weak zone 2 may be a continuous structure or a discontinuous structure.
In another embodiment, the total length of the stress-weak zone 2 provided on the same wall 1 is greater than or equal to 3 mm. For the stress-weak zone 2 of a continuous structure, the total length is the length of the stress-weak zone 2. For the stress-weak of a discontinuous structure shown in
In this embodiment, if the total length of the stress-weak zone 2 of the same wall 1 is too large, the strength of the wall 1 is low, resulting in a low structural strength of the battery and reducing the service life of the battery; if the total length of the stress-weak zone 2 of the same wall 1 is too small, when the pressure inside the battery is too high due to gas generation, an area of an opening formed by the fracture of the stress-weak zone 2 is small, it takes a long time for the gas inside the battery to discharge, and the pressure cannot be released quickly, resulting in lower battery safety. In this embodiment, when the total length of the stress-weak zone 2 of the same wall 1 is greater than or equal to 3 mm, the housing of the battery has a higher strength and longer service life. In addition, the area of the opening formed by the stress-weak zone 2 is relatively large, allowing the gas inside the battery to be discharged quickly, reducing the risk of expansion, deformation, or even explosion of the battery, and improving the safety of the battery.
The embodiments shown in
It can be seen from the test results that when the total length of the stress-weak zone 2 was less than 3 mm, the stress-weak zone 2 did not have a pressure relief effect, and all the batteries exploded; and when the total length of the stress-weak zone 2 was greater than 3 mm, the battery could release pressure as required, effectively avoiding battery explosion.
In an embodiment, as shown in
Specifically, if the depth H of the stress-weak zone 2 is too large (for example, greater than 90% of the thickness of the wall 1), when the battery is operating properly without gas generation, the housing at the position of the stress-weak zone 2 has a low structural strength and is easily damaged, leading to battery failure, shortening battery life, and causing a risk of leakage from the position of the stress-weak zone 2; and if the depth H of the stress-weak zone 2 is too small (for example, less than 30% of the thickness of the wall 1), when gas is generated inside the battery, the stress-weak zone 2 with this depth H requires a relatively large pressure to break, that is, the stress-weak zone 2 can form an opening only when the internal pressure of the battery reaches a large value, making the gas inside the battery fail to be quickly discharged.
In this embodiment, when the depth H of the stress-weak zone 2 is 30% to 90% of the thickness of the wall 1, during normal operation of the battery, the stress-weak zone 2 will not significantly reduce the structural strength of the housing, thereby reducing the battery damage risk and prolonging the service life. In addition, the stress-weak zone 2 with this depth can quickly break to form an opening when gas is generated inside the battery, thereby quickly discharging the gas inside the battery, reducing the risk of expansion, deformation, or even explosion of the battery, and improving safety of the battery.
The embodiments shown in
It can be seen from the test results that when the depth H of the stress-weak zone 2 was greater than 70%, the relief pressure could not be stably controlled above the pressure relief lower limit, and there was a risk of liquid leakage in daily use; and when the depth H of the stress-weak zone 2 was less than 30%, the relief pressure could not be stably controlled below the pressure relief upper limit, and four batteries exploded. Therefore, in this embodiment, when the depth H of the stress-weak zone 2 is 30% to 70% of the thickness of the wall 1, better safety performance is provided.
Moreover, as shown in
Specifically, if the width W of the stress-weak zone 2 is too large (for example, greater than 110% of the thickness of the wall 1), the area of the wall surface 1 occupied by the stress-weak zone 2 is relatively large. When the battery is operating normally without gas generation, the housing at the position of the stress-weak zone 2 has a low structural strength, and is easily damaged, leading to battery failure and shortening the service life of the battery; if the width W of the stress-weak zone 2 is too small (for example, less than 50% of the thickness of the wall 1), an area of the wall surface 1 occupied by the stress-weak zone 2 is too small. When gas is generated inside the battery, the opening formed by the fracture of the stress-weak zone 2 is too small, making the gas inside the battery fail to be quickly discharged.
In this embodiment, when the width W of the stress-weak zone 2 is 50% to 110% of the thickness of the wall 1, during normal operation of the battery, the stress-weak zone 2 will not significantly reduce the structural strength of the housing, thereby reducing the battery damage risk and prolonging the service life. In addition, the stress-weak zone 2 with this width W forms a larger opening when gas is generated inside the battery, allowing the gas inside the battery to be quickly discharged, reducing the risk of expansion, deformation, or even explosion of the battery, and improving safety of the battery.
The embodiments shown in
It can be seen from the test results that when the width W of the stress-weak zone 2 was less than 50% of the thickness of the wall 1, the battery pressure could not be stably below the pressure upper limit, and six batteries exploded; when the width W of the stress-weak zone 2 was greater than 110% of the thickness of the wall 1, the relief pressure of the battery could not be stably controlled above the lower limit; and when the width W of the stress-weak zone 2 was between 50% and 110% of the thickness of the wall surface 1, the relief pressure could be stably controlled within a safe range, and no battery exploded.
In the foregoing embodiments, the wall 1 is a wall with the largest area in the housing or a wall with a second largest area, that is, the stress-weak zone 2 in this embodiment of this application is provided on the wall with the larger area in the housing. The area of the wall is larger, so that there is a larger space to arrange the stress-weak zone 2.
Specifically, the stress-weak zone 2 may be provided on at least one of an interior surface and an exterior surface of the wall 1, and the position, size, and shape of the stress-weak zone 2 are defined by the foregoing embodiments.
In the foregoing embodiments, an elastic modulus of the wall 1 is greater than or equal to 1000 MPa, meaning that the stress-weak zone 2 is arranged on the wall with greater hardness. The wall 1 with such hardness is not easy to be elastically deformed under the action of pressure, so that under the pressure of gas generated inside the housing, the stress-weak zone 2 breaks and forms an opening, to discharge the gas inside the housing.
Specifically, the material of the wall 1 may include one or more of a PC material, an aluminum plastic film, and a metal.
The processing method of the stress-weak zone 2 in this embodiment of this application may be laser cutting, which has the advantages of high processing accuracy, high efficiency, and little damage to other parts of the housing.
The electrochemical apparatus according to this application includes any apparatus in which electrochemical reactions take place. Specific examples of the apparatus include all kinds of primary batteries, secondary batteries, fuel batteries, solar batteries, or capacitors. Specially, the electrochemical apparatus is a lithium secondary battery, including a lithium metal secondary battery, a lithium-ion secondary battery, a lithium polymer secondary battery, or a lithium-ion polymer secondary battery.
The electrochemical apparatus in the embodiments of this application can be applied to various fields, and the electrochemical apparatus in the embodiments of this application can be used provided that a device can be powered by the electrochemical apparatus. For example, the electrochemical apparatus can be used for components such as electrochemical apparatus packages and electronic devices of electric vehicles. The electronic device may be a mobile phone, a tablet computer, a desktop computer, a laptop computer, a handheld computer, a notebook computer, an ultra-mobile personal computer (Ultra-mobile personal computer, UMPC), a netbook, as well as a cellular phone, a personal digital assistant (personal digital assistant, PDA), an augmented reality (augmented reality, AR) device, a virtual reality (virtual reality, VR) device, an artificial intelligence (artificial intelligence, AI) device, a wearable device, a vehicle-mounted device, a smart home device, and/or a smart city device. The embodiments of this application do not impose special restrictions on the specific types of electronic devices.
Specifically, the electronic device may include components such as a housing, a screen, a circuit board, and an electrochemical apparatus, where the screen, the circuit board, and the electrochemical apparatus are all installed in the housing, and the electrochemical apparatus is the electrochemical apparatus described in any of the foregoing embodiments.
The foregoing descriptions are merely preferred embodiments of this application, but are not intended to limit this application. Persons skilled in the art understand that this application may have various modifications and variations. Any modification, equivalent replacement, and improvement made without departing from the spirit and principle of this application shall fall within the protection scope of this application.
The present application is a continuation application of PCT application PCT/CN2020/108396, filed on Aug. 11, 2020, the disclosure of which is hereby incorporated by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/CN2020/108396 | Aug 2020 | US |
| Child | 18108268 | US |
