Secondary battery pack with improved thermal management

A combination for preparation of a silicone rubber syntactic foam, where the silicone rubber syntactic foam comprises hollow glass beads D, the combination comprising:

• (i) an organopolysiloxane A having at least two alkenyl groups bonded to silicon per molecule, the alkenyl groups each containing from 2 to 14 carbon atoms, wherein the organopolysiloxane A has a viscosity at 25° C. of about 5 mPa·s to about 5,000 mPa·s;
• (ii) a silicon compound B comprising:
• (a) a silicon chain extender B1 having two telechelic hydrogen atoms bonded to silicon per molecule with no pendent hydrogen atoms bonded to silicon per molecule, wherein the viscosity at 25° C. of the silicon chain extender B1 is between about 5 and about 100 mPa·s;
• and
• (b) a silicon crosslinker B2 having at least three hydrogen atoms bonded to silicon per molecule, wherein the viscosity at 25° C. of the silicon crosslinker B2 is between about 5 and about 2000 mPa·s;
• and
• (iii) a hydrosilylation catalyst C;
• and
• (iv) at least one cure rate controller G which slows the curing rate of the silicone foam combination;
• wherein the proportions in weight of the organopolysiloxane A (i) and the silicon compound B (ii) are such that the overall molar ratio of the hydrogen atoms bonded to the silicon to the overall alkenyl radicals bonded to the silicon is between about 0.4 to about 1.5;
• and
• wherein, upon inclusion of between about 9% to about 20% by weight of the hollow glass beads D in the combination, the combination has a viscosity at 25° C. between about 500 mPa·s and about 5,000 mPa·s and is capable of filling a battery module casing.

A kit of parts for preparation of a silicone rubber syntactic foam, wherein the silicone rubber syntactic foam comprises hollow glass beads D, the kit comprising two packages:

• the first package P1 comprising:
• 100 parts by weight of (i) an organopolysiloxane A, and
• from 4 to 150 ppm based on metal platinum of a platinum-based hydrosilylation catalyst C;
• and
• the second package P2 comprising:
• 100 parts by weight of (i) where the organopolysiloxane,
• from 10 to 70 parts by weight of a silicon chain extender B1,
• from 5 to 25 parts by weight of a silicon crosslinker B2, and
• optionally an effective amount of at least one cure rate controller G (iv) which slows the curing rate;
• (i) wherein the organopolysiloxane A has at least two alkenyl groups bonded to silicon per molecule, the alkenyl groups each containing from 2 to 14 carbon atoms, and wherein the organopolysiloxane A has a viscosity at 25° C. of from about 5 mPa·s to about 5,000 mPa·s;
• (ii) wherein the silicon chain extender B1 has two telechelic hydrogen atoms bonded to silicon per molecule with no pendent hydrogen atoms bonded to silicon per molecule and a viscosity at 25° C. of from about 5 to about 100 mPa·s;
• and
• (iii) wherein the silicon crosslinker B2 has at least three hydrogen atoms bonded to silicon per molecule and a viscosity at 25° C. of from about 5 mPa·s to about 2000 mPa·s;
• wherein the proportions in weight of the organopolysiloxane A, the silicon chain extender B1, and the silicon crosslinker B2 are such that the overall molar ratio of the hydrogen atoms bonded to the silicon to the overall alkenyl radicals bonded to the silicon is from about 0.4 to about 1.5;
• and
• wherein, upon inclusion of between about 9% to about 20% by weight of the hollow glass beads D to at least one of package P1 and P2, the combination of P1 and P2 provides a composition having a viscosity at 25° C. from 500 mPa·s to 5,000 mPa·s and is capable of filling a battery module casing.