Suppression of battery thermal runaway
Thermal runaway in battery packs is suppressed by inserting packages of hydrated hydrogel at physical interfaces between groups of one or more cells. The hydrogel acts to diffuse and absorb thermal energy released by the cells in the event of a cell failure. During extreme overheating of a battery cell, the water stored by the hydrogel will undergo phase change, that is, begin to vaporize, thus absorbing large amounts of thermal energy and preventing thermal runaway.
1 . A thermal runaway suppression element for interposition between the cells of a multiple-cell battery pack, comprising:
a container conforming to the external surfaces of said cells, such that the container is in good thermal conductive relation with the cells, and
a phase change material consisting essentially of a quantity of water in hydrogel form, disposed in said container,
whereby in the event one of said cells overheats, heat is transferred to the hydrogel, heating the water, such that the water absorbs the heat given off by the overheated cell, and whereby said water can undergo a phase change and be vaporized if sufficiently heated.
2 . The thermal runaway suppression element of claim 1 , wherein said hydrogel is a lightly cross linked, partially neutralized polyacrylic acid.
3 . The thermal runaway suppression element of claim 1 , wherein said hydrogel is a superabsorbent polymer.
4 . The thermal runaway suppression element of claim 1 , wherein said hydrogel is an acrylic or acrylic derivative polymer crosslinked by a polyamine crosslinking agent.
5 . The thermal runaway suppression element of claim 1 , wherein said hydrogel is a polyacrylate of sodium or potassium.
6 . The thermal runaway suppression element of claim 1 , wherein said hydrogel is selected from the group consisting of sodium and potassium polyacrylate.
7 . The thermal runaway suppression element of claim 1 , wherein said container is fabricated of a sheet of material comprising a heat-bondable polymer film.
8 . The thermal runaway suppression element of claim 7 , wherein said sheet of material further comprises a metallic layer.
9 . The thermal runaway suppression element of claim 8 , wherein the metal of said metallic layer is aluminum.
10 . The thermal runaway suppression element of claim 1 , wherein distilled water is used to prepare said hydrogel.
11 . A battery pack made up of a plurality of individual cells, comprising circuit components connecting the cells in a desired configuration, and further comprising thermal runaway suppression elements in good thermal contact with each of said cells, wherein each said thermal runaway suppression element comprises:
a container conforming to the external surfaces of one or more of said cells, such that the container is in good thermal conductive relation with the cells, and
a phase change material consisting essentially of a quantity of water in hydrogel form, disposed in said container,
whereby in the event one of said cells overheats, heat is transferred to the hydrogel, heating the water, such that the water absorbs the heat given off by the overheated cell, and whereby said water can undergo a phase change and be vaporized if sufficiently heated.
12 . The battery pack of claim 11 , wherein said hydrogel is a lightly cross linked, partially neutralized polyacrylic acid.
13 . The battery pack of claim 11 , wherein said hydrogel is a superabsorbent polymer.
14 . The battery pack of claim 11 , wherein said hydrogel is an acrylic or acrylic derivative polymer crosslinked by a polyamine crosslinking agent.
15 . The battery pack of claim 11 , wherein said hydrogel is a polyacrylate of sodium or potassium.
16 . The battery pack of claim 11 , wherein said hydrogel is selected from the group consisting of sodium and potassium polyacrylate.
17 . The battery pack of claim 11 , wherein said container is fabricated of a sheet of material comprising a heat-bondable polymer film.
18 . The battery pack of claim 17 , wherein said sheet of material further comprises a metallic layer.
19 . The battery pack of claim 18 , wherein the metal of said metallic layer is aluminum.
20 . The battery pack of claim 11 , wherein distilled water is used to prepare said hydrogel.
21 . The battery pack of claim 11 , wherein the cells each comprise an internal supply of oxygen and combustible fuel.
22 . The battery pack of claim 21 , wherein the cells are of Li-ion battery chemistry with at least one metal oxide electrode.
23 . A method of suppressing thermal runaway of a battery pack made up of a plurality of individual cells, said battery pack further comprising circuit components connecting the cells in a desired configuration, said method comprising the step of providing thermal runaway suppression elements in good thermal contact with each of said cells, wherein each said thermal runaway suppression element comprises:
a container conforming to the external surfaces of one or more of said cells, such that the container is in good thermal conductive relation with the cells, and
a phase change material consisting essentially of a quantity of water in hydrogel form, disposed in said container,
whereby in the event one of said cells overheats, heat is transferred to the hydrogel, heating the water, such that the water absorbs the heat given off by the overheated cell, and whereby said water can undergo a phase change and be vaporized if sufficiently heated.
24 . The method of claim 23 , wherein said hydrogel is a lightly cross linked, partially neutralized polyacrylic acid.
25 . The method of claim 23 , wherein said hydrogel is a superabsorbent polymer.
26 . The method of claim 23 , wherein said hydrogel is an acrylic or acrylic derivative polymer crosslinked by a polyamine crosslinking agent.
27 . The method of claim 23 , wherein said hydrogel is a polyacrylate of sodium or potassium.
28 . The method of claim 23 , wherein said hydrogel is selected from the group consisting of sodium and potassium polyacrylate.
29 . The method of claim 23 , wherein said container is fabricated of a sheet of material comprising a heat-bondable polymer film.
30 . The method of claim 29 , wherein said sheet of material further comprises a metallic layer.
31 . The method of claim 30 , wherein the metal of said metallic layer is aluminum.
32 . The method of claim 23 , wherein distilled water is used to prepare said hydrogel.