Energy storage device

1. An energy storage device, comprising:

a housing;

a plurality of battery packs in the housing;

a first set of fluid passages, the first set of fluid passages including:

a plurality of first fluid passages, wherein each first fluid passage has an inlet; and

a plurality of second fluid passages, wherein each second fluid passage has an outlet,

each second fluid passage separated from a first fluid passage by battery packs,

each second fluid passage in fluid communication with each adjacent first fluid passage,

the fluid that enters into the first fluid passage via the inlet flowing through the battery pack between the first and second fluid passages and leaving from the outlet of the second fluid passage, and

the battery packs being thermally insulated from fluid in the first set of fluid passages,

wherein each battery pack comprises:

a pair of heat insulating plates disposed at two ends of the battery pack; and

a plurality of battery cells interposed between the pair of the heat insulating plates,

wherein each of the heat insulating plates comprises:

a base portion made of a thermally insulating material;

a plurality of grooves each accommodating an end of one of the battery cells; and

a plurality of via-holes configured to allow the fluid flowing through the via-holes on the base portion between the two neighboring grooves.

2. The energy storage device of claim 1 , wherein the battery packs are separated from each other in a first direction, and the first set of fluid passages extend in a second direction, and wherein the second direction is perpendicular to the first direction.

3. The energy storage device of claim 1 , further comprising:

a second set of fluid passages between the battery cells, the fluid passages of the second set being in fluid communication with adjacent fluid passages of the first set.

4. The energy storage device of claim 2 , wherein each of the via-holes has a rectangular shape, and

a width of a via-hole in the second direction is substantially equal to a width of a fluid passage of the second set in the second direction.

5. The energy storage device of claim 4 , wherein the width of the via-hole is about 5 to about 20 mm.

6. The energy storage device of claim 1 , wherein the housing includes slide grooves configured to allow the battery packs to be inserted into the housing by sliding edges of the heat insulating plates along the slide grooves.

7. The energy storage device of claim 1 , wherein the battery packs include two sides covered by a heat insulating material.

8. The energy storage device of claim 1 , wherein the first fluid passage of the first set is provided with a first fluid guide.

9. The energy storage device of claim 8 , wherein the first fluid guide has a substantially V-shape with a vertex facing the inlet of the first fluid passage.

10. The energy storage device of claim 1 , wherein the second fluid passage of the first set is provided with a second fluid guide.

11. The energy storage device of claim 10 , wherein the second fluid guide has a substantially V-shape with a vertex facing the outlet of the second fluid passage.

12. The energy storage device of claim 1 , wherein the inlet of the first fluid passage is positioned at an end of the first fluid passage, and the outlet of the second passage is positioned at an end of the second fluid passage that is opposite to the end of the first fluid passage that has the inlet.

13. The energy storage device of claim 1 , wherein each of the fluid passages of the first set has an aspect ratio of length to height of about 5:1 to about 10:1.