The present invention discloses an exhaust filter system for a battery pack, including an explosion-proof valve and a filter apparatus. One end of the explosion-proof valve is connected to a battery pack. The other end of the explosion-proof valve is connected to the filter apparatus. The filter apparatus includes an introduction port, a discharge port, a housing, and a filter mechanism. The introduction port and the discharge port are separately disposed at two ends of the housing. The filter mechanism is disposed inside the housing. The filter mechanism is provided with a plurality of filter holes. The present invention has the following beneficial effects: by optimal design of a novel explosion-proof valve and a novel filter apparatus, the applicability of technical solutions of this application is made more extensive. The problem of fire induced by thermal runaway can be satisfactorily solved for both high-capacity batteries and small-capacity batteries. Combustion gas is exhausted more smoothly, and a better filtering effect and a better effect on post handling for thermal runaway in a battery pack are obtained.

A ventilation device for a secondary battery includes a frame including a first frame and a second frame, and a connector connecting the first frame and the second frame to each other and including a slit portion formed therein. Each of the first frame and the second frame has a facing surface that faces each other, and at least one of the first frame and the second frame includes a ventilation guiding portion recessed from the facing surface, and a ventilation control portion is formed to provide a space between the first frame and the second frame and to be connected to the ventilation guiding portion.

A ventilation device for a secondary battery includes a frame including a first frame and a second frame, and a connector connecting the first frame and the second frame to each other and including a slit portion formed therein. Each of the first frame and the second frame has a facing surface that faces each other, and at least one of the first frame and the second frame includes a ventilation guiding portion recessed from the facing surface, and a ventilation control portion is formed to provide a space between the first frame and the second frame and to be connected to the ventilation guiding portion.

A cell module includes a plurality of battery cells each having a safety valve at a first end in a height direction, a first current collector plate including a main body having a through hole that at least partly overlaps the safety valve when viewed along the height direction and a lead extending into the through hole from the main body and being electrically connected to a first terminal of each of the battery cells, an exhaust duct disposed over a surface of the first current collector plate remote from the battery cells, and an insulating film being made of an insulating material and covering an area of the first current collector plate facing the exhaust duct. The safety valve opens when an internal pressure of any of the battery cells reaches or exceeds a predetermined level.

A cell module includes a plurality of battery cells each having a safety valve at a first end in a height direction, a first current collector plate including a main body having a through hole that at least partly overlaps the safety valve when viewed along the height direction and a lead extending into the through hole from the main body and being electrically connected to a first terminal of each of the battery cells, an exhaust duct disposed over a surface of the first current collector plate remote from the battery cells, and an insulating film being made of an insulating material and covering an area of the first current collector plate facing the exhaust duct. The safety valve opens when an internal pressure of any of the battery cells reaches or exceeds a predetermined level.

Some embodiments of the present disclosure relate to a battery comprising a housing. In some embodiments, the housing comprises an opening. In some embodiments, the battery comprises at least one fluoropolymer membrane. In some embodiments, the at least one fluoropolymer membrane covers the opening of the housing. In some embodiments, the at least one fluoropolymer membrane has a crystallinity of 85% to 100%. In some embodiments, the at least one fluoropolymer membrane has a density of 2.0 g/cm.sup.3 to 2.2 g/cm.sup.3. In some embodiments, the at least one fluoropolymer membrane has a CO.sub.2 permeability to moisture permeability ratio of more than 0.5. A polytetrafluoroethylene film for electronic components, characterized in that the polytetrafluoroethylene film can have a density of 1.40 g/cm.sup.3 or higher and an air impermeability of 3,000 seconds or higher.

A battery module for an electric vehicle includes a case and a plurality of rechargeable battery cells stored inside the case and connected in series, wherein the plurality of rechargeable battery cells is stored in a parallel configuration inside the case in a plurality of rows, and at least one of the plurality of rechargeable battery cells is stored in each of the plurality of rows. The battery module further includes an overcharge protection circuit having a voltage threshold for each of the plurality of rechargeable battery cells to prevent overcharging. Each of the plurality of rechargeable battery cells has a nominal voltage and a maximum voltage. The voltage threshold is larger than the nominal voltage and smaller than the maximum voltage. All of the plurality of rechargeable battery cells are comprised of lithium iron phosphate LiFePO.sub.4, and a number of the plurality of rechargeable battery cells is five.

A battery module for an electric vehicle includes a case and a plurality of rechargeable battery cells stored inside the case and connected in series, wherein the plurality of rechargeable battery cells is stored in a parallel configuration inside the case in a plurality of rows, and at least one of the plurality of rechargeable battery cells is stored in each of the plurality of rows. The battery module further includes an overcharge protection circuit having a voltage threshold for each of the plurality of rechargeable battery cells to prevent overcharging. Each of the plurality of rechargeable battery cells has a nominal voltage and a maximum voltage. The voltage threshold is larger than the nominal voltage and smaller than the maximum voltage. All of the plurality of rechargeable battery cells are comprised of lithium iron phosphate LiFePO.sub.4, and a number of the plurality of rechargeable battery cells is five.

A rechargeable battery cell a casing and first and second electrode materials separately positioned in the casing. A mechanical impulse element is positioned to mechanically move and dislodge gas bubbles from at least one of the first and second electrode materials in response to activation. In some embodiments the mechanical impulse element can include a vibratory piezoelectric element. In other embodiments, a gas vent in the battery cell can be used to release dislodged gas bubbles.

A rechargeable battery cell a casing and first and second electrode materials separately positioned in the casing. A mechanical impulse element is positioned to mechanically move and dislodge gas bubbles from at least one of the first and second electrode materials in response to activation. In some embodiments the mechanical impulse element can include a vibratory piezoelectric element. In other embodiments, a gas vent in the battery cell can be used to release dislodged gas bubbles.