In line with an increase in the price of energy sources due to the depletion of fossil fuels and amplification of interests in environmental pollution, environmentally-friendly alternative energy sources have become an indispensable factor for the future life. Accordingly, research has been continued on various power production technologies, such as atomic energy, solar energy, wind energy, tidal energy, and power storage devices for more efficiently using energy produced as such have also continuously drawn interests.
In particular, as the technological development and demand for mobile apparatuses increase, the demand for batteries as an energy source rapidly has increased, and recently, applications of secondary batteries as power sources for electric vehicles (EV), hybrid electric vehicles (HEV), and the like have been realized, and application fields have been expanded to an auxiliary power source and the like through gridding, and thus, various research on batteries capable of meeting various demands are being carried out.
Meanwhile, while one, two, three, or four battery cells are used for one device in small-size mobile apparatuses, a battery pack including a medium and large-size battery module in which a plurality of battery cells are electrically connected is used for medium and large-size devices such as vehicles.
In the case of such a battery pack, devices exposed to various operation environments such as electric bicycles, electric vehicles have components which constitute a battery pack and which should be safely protected against external environment, and a high output and a large capacity should be achieved by using a plurality of batteries. Therefore, safety aspects have also acquired greater importance.
Representatively, moisture or foreign substances may easily penetrate into a battery pack in a high humidity condition, such as the rainy season, and in various environments, and may therefore deteriorate the safety of the battery pack such that a malfunction of a battery pack module constituting the battery pack or an electrical connection device is caused thereby.
Accordingly, in the case of a general battery pack, the above limitations have been solved by interposing gaskets in coupling portions of case members constituting the battery pack.
However, gaskets are generally made of materials with predetermined elasticity so as to exert desired sealing capability due to coupling strengths of case members, and thus portions, which deviate from desired portions and are pushed and thereby bent, may occur and therefore cause the deterioration of the coupling strengths between the case members and the safety of the battery pack.
In addition, since the gasket is formed of an elastic material and may therefore deviate from a normal position, metal bushings have been conventionally used by being inserted into fastening holes of the gasket.
However, a step of inserting metal bushings into the fastening holes of the gasket may cause not only an increase in manufacturing time but also a remarkable increase in manufacturing costs.
Thus, the development of a technique which can basically solve the above limitations is highly demanded.