Battery module including pressure drop sheet
The present disclosure relates to a battery module including: a battery cell stack in which a plurality of battery cells are stacked; and a pressure drop sheet on one side of the battery cell stack, in which the pressure drop sheet includes: a ventilation layer including ceramic fiber; and a sacrificial layer on at least one surface of the ventilation layer, the sacrificial layer is disposed in a direction facing the battery cell stack, and the pressure drop sheet exhibits gas permeability at a critical temperature.
1 . A battery module, comprising: a battery cell stack in which a plurality of battery cells are stacked; and a pressure drop sheet formed as a flat rectangular sheet and positioned on one side of the battery cell stack, wherein the pressure drop sheet covers the plurality of battery cells and extends across substantially an entire surface of the battery cell stack on the one side of the battery cell stack, wherein the pressure drop sheet includes a ventilation layer and a sacrificial layer on a surface of the ventilation layer, and directly faces the battery cell stack, wherein, before reaching a critical temperature, the sacrificial layer is maintained and the sacrificial layer is exposed to the battery cell stack, and after reaching the critical temperature, the sacrificial layer is lost and the ventilation layer is exposed to the battery cell stack so that gas generated from the battery cell stack is released across substantially an entire area of the pressure drop sheet, wherein the pressure drop sheet has a ratio of gas permeability A before reaching the critical temperature and gas permeability B after reaching the critical temperature that satisfies Equation 1 below:
B/A>2 [Equation 1.]
2 . The battery module of claim 1 ,
wherein the ventilation layer is permeable to gas and the sacrificial layer is non-permeable to gas,
wherein the sacrificial layer is lost upon reaching a critical temperature, such that the gas permeability after reaching the critical temperature of the pressure drop sheet is higher than the gas permeability before reaching the critical temperature.
3 . The battery module of claim 1 ,
wherein the ventilation layer includes a ceramic fiber.
4 . A battery module, comprising:
a battery cell stack in which a plurality of battery cells are stacked; and
a pressure drop sheet on one side of the battery cell stack,
wherein the pressure drop sheet includes a ventilation layer and a sacrificial layer on a surface of the ventilation layer and directly facing the battery cell stack,
wherein, before reaching a critical temperature, the sacrificial layer is maintained and the sacrificial layer is exposed to the battery cell stack, and after reaching the critical temperature, the sacrificial layer is lost and the ventilation layer is exposed to the battery cell stack,
wherein the ventilation layer includes a ceramic fiber, and
wherein the ceramic fiber has about 45 to 75 wt % of alumina and about 25 to 55 wt % of silica.
5 . The battery module of claim 3 ,
wherein the density of the ceramic fiber is 0.5 g/cm3 or less.
6 . The battery module of claim 3 ,
wherein the average length of the ceramic fiber is 1 to 50 mm.
7 . The battery module of claim 1 ,
wherein the ventilation layer includes the inorganic particles, wherein the inorganic particles include TiO2, SiO2, BaTiO3, PbS, ZrO2, SiC, NaF, and LiF particles.