High thermal stability thermal cutoff device pellet composition
Provided is a pellet composition having enhanced thermal stability for use in a thermally-actuated, current cutoff device. The solid thermal pellet composition comprises an organic compound have low ionization potential, such as dibenzosuberenone. The solid pellet maintains its structural rigidity up to a transition temperature (T f ), but further has improved overshoot temperature ranges. Therefore, the improved thermal pellets have a maximum dielectric capability temperature (T cap ), above which the pellet composition may lose substantial dielectric properties and conducts current that is at least 160° C. greater than the T f . The aging performance is further enhanced. Further, methods of enhanced processing and pelletizing are provided.
1. A pellet composition in a thermally-actuated, current cutoff device, the pellet composition comprising dibenzosuberenone is in a solid phase and maintains its structural rigidity up to a transition temperature (T f ) of greater than or equal to about 80° C. in the thermally-actuated, current cutoff device.
2. The pellet composition of claim 1 , wherein the pellet composition comprises dibenzosuberenone at greater than or equal to about 93% by weight of a total pellet composition.
3. The pellet composition of claim 1 , wherein the pellet composition has a maximum dielectric capability temperature (T cap ) above which the pellet composition loses substantial dielectric properties and conducts current, wherein the T cap is about 160° C. or greater than the T f .
4. The pellet composition of claim 3 , wherein the T f is greater than or equal to about 80° C. and less than or equal to about 90° C. and the T cap is greater than or equal to about 200° C. above the T f .
5. The pellet composition of claim 3 , wherein the T cap is greater than or equal to about 300° C. above the T f .
6. The pellet composition of claim 1 , further comprising one or more additive components selected from the group consisting of: binders, lubricants, press-aids, pigments, and combinations thereof, wherein the one or more additive components are cumulatively present at less than or equal to about 10% by weight.
7. The pellet composition of claim 6 , wherein the one or more additive components are cumulatively present at less than or equal to about 7% by weight of a total pellet composition and the dibenzosuberenone is present at greater than or equal to about 93% by weight of the total pellet composition.
8. The pellet composition of claim 1 , wherein the pellet composition comprises dibenzosuberenone at greater than or equal to about 98% by weight of a total pellet composition.
9. The pellet composition of claim 1 , wherein the pellet composition has a crush strength of greater than or equal to about 15 lbs.
10. A method for forming a thermally stable pellet composition in a thermally-actuated, current cutoff device, the method comprising:
admixing dibenzosuberenone and one or more additive components selected from the group consisting of: binders, lubricants, press-aids, pigments, and combinations thereof to form an admixture;
melting and then cooling the admixture;
grinding the admixture to form a powder; and
disposing the powder in a die and applying pressure to the powder to form a compacted solid pellet that maintains its structural rigidity up to a transition temperature (T f ) of greater than or equal to about 80° C.
11. The method of claim 10 , wherein the method is repeated to form a plurality of compacted solid pellets and a final yield of the method is greater than or equal to about 95%.
12. The method of claim 10 , wherein the compacted solid pellet has a crush strength of greater than or equal to about 15 lbs.
13. The method of claim 10 , wherein the compacted solid pellet comprises dibenzosuberenone at greater than or equal to about 93% by weight and the one or more additive components are cumulatively present at less than or equal to about 7% by weight of the compacted solid pellet.
14. The method of claim 10 , wherein a density of the compacted solid pellet is 29 pellets per gram to 50 pellets per gram.
15. A thermally-actuated, current cutoff pellet in a thermally-actuated, current cutoff device, the pellet comprising:
dibenzosuberenone; and
one or more additive components, wherein the pellet is a compacted solid that maintains its structural rigidity up to a transition temperature (T f ) of greater than or equal to about 80° C. in the thermally-actuated, current cutoff device.
16. The thermally-actuated, current cutoff pellet of claim 15 , wherein the pellet has a maximum dielectric capability temperature (T cap ) above which the pellet loses substantial dielectric properties and conducts current, wherein the T cap is about 160° C. or greater than the T f .
17. The thermally-actuated, current cutoff pellet of claim 16 , wherein the T f is greater than or equal to about 80° C. and less than or equal to about 90° C. and the T cap is greater than or equal to about 200° C. above the T f .
18. The thermally-actuated, current cutoff pellet of claim 15 , wherein the one or more additive components is selected from the group consisting of: binders, lubricants, press-aids, pigments, and combinations thereof, wherein the one or more additive components are cumulatively present at less than or equal to about 10% by weight of the pellet.
19. The thermally-actuated, current cutoff pellet of claim 15 , wherein the one or more additive components are cumulatively present at less than or equal to about 7% by weight of the pellet and the dibenzosuberenone is present at greater than or equal to about 93% by weight of the pellet.