BATTERY PACK
A battery pack includes a battery assembly including battery cells parallel to one another and an outer case. Each battery cell includes a discharge valve provided on an end surface thereof, and an end-surface electrode provided at an end portion thereof. A welding surface of the lead plate is connected to the end-surface electrode arranged on the same plane. The battery pack includes a backflow-restricting layer disposed on a non-welding surface of the lead plate in the outer case. The lead plate has a gas permeation gap therein allowing a gas discharged from the discharge valve to pass in a discharge direction of the backflow-restricting layer. The backflow-restricting layer includes a resistance part configured to allow the gas passing through gas permeation gap to pass in the discharge direction, and to suppress or prevent the exhaust gas from passing in a direction opposite to the discharge direction.
1 . A battery pack comprising:
a battery assembly including
a plurality of battery cells arranged parallel to one another, each of the plurality of battery cells including a discharge valve and an end-surface electrode, the discharge valve being provided on an end surface of the each of the plurality of battery cells, the end-surface electrode being provided at an end portion of the each of the plurality of battery cells and being arranged on a same plane, and
a lead plate having a welding surface connected to the end-surface electrode of the each of the plurality of battery cells arranged on the same plane;
an outer case housing the battery assembly therein; and
a backflow-restricting layer disposed in the outer case, the backflow-restricting layer being disposed on a non-welding surface of the lead plate, wherein
the lead plate has a gas permeation gap therein allowing an exhaust gas discharged from the discharge valve to pass through the gas permeation gap in a discharge direction of the backflow-restricting layer from the each of the plurality of battery cells, and
the backflow-restricting layer includes a resistance part configured to:
allow the exhaust gas passing through the gas permeation gap to pass in the discharge direction; and
suppress or prevent the exhaust gas from passing in a direction opposite to the discharge direction.
2 . The battery pack according to claim 1 , wherein
the battery assembly further includes a battery holder allowing the plurality of battery cells to be arranged in fixed positions,
the battery holder includes a surface plate allowing the lead plate to be disposed at a fixed position,
the surface plate has an electrode window therein that exposes, through the electrode window, the end-surface electrode of the each of the plurality of battery cells disposed in the fixed positions, and
the lead plate is connected to the end-surface electrode of the each of the plurality of battery cells in the electrode window.
3 . The battery pack according to claim 2 , wherein the lead plate disposed at the fixed position of the surface plate has a plurality of gas permeation gaps therein each of the plurality of gas permeation gaps being the gas permeation gap.
4 . The battery pack according to claim 1 , wherein
the backflow-restricting layer has a through-hole configured to the exhaust gas to pass through the through-hole, and
the backflow-restricting layer includes a resistance part around near the through-hole, the resistance part closing a position facing the gas permeation gap.
5 . The battery pack according to claim 4 , wherein
the gas permeation gap of the lead plate is a slit opening having an annular shape, and
the through-hole of the backflow-restricting layer opens and faces an inside of the slit to constitute the resistance part.
6 . The battery pack according to claim 4 , wherein the backflow-restricting layer has a cutout therein extended radially from the through-hole.
7 . The battery pack according to claim 1 , wherein
the backflow-restricting layer has a cutout therein extended radially, the cutout allowing the exhaust gas to pass through the cutout, and
the cutout has a resistance part closing a position facing the gas permeation gap.
8 . The battery pack according to claim 1 , wherein the backflow-restricting layer is made of rubber material.
9 . The battery pack according to claim 1 , wherein the backflow-restricting layer is made of foamed material.
10 . The battery pack according to claim 1 , wherein
the each of the plurality of battery cells includes a protrusion electrode provided on an end surface thereof, and
the discharge valve has an exhaust port opening at an outer periphery of the protrusion electrode.
11 . The battery pack according to claim 10 , wherein the each of the plurality of battery cells is a cylindrical battery.
12 . The battery pack according to claim 1 , wherein
the lead plate includes:
a plate part having a flat shape and constituting the non-welding surface; and
an electrode connecting tongue connected to the end-surface electrode of the each of the plurality of battery cells, the electrode connecting tongue constituting the welding surface, and
the lead plate having a slit opening provided therein along an outer periphery of the electrode connecting tongue, the slit opening constituting the gas permeation gap.
13 . The battery pack according to claim 1 , wherein the backflow-restricting layer is bonded to a surface of the lead plate.