Abstract: Disclosed is an apparatus for protecting a secondary battery, in which, when the secondary battery such as a lithium-ion secondary battery is exposed to high temperature exceeding a working range due to a change in external environment, external impacts, and so on, or heated due to spontaneous generation of heat caused by internal defects, the secondary battery is discharged. The apparatus includes a thyristor or transistor having an anode and a cathode connected both terminals of the secondary battery respectively, and shorting both terminals of the secondary battery when gate current is supplied, and a temperature sensor detecting temperature of the secondary battery and supplying the gate current to the thyristor or transistor when the detected temperature is higher than predetermined temperature.

Abstract: Disclosed is a protection circuit for a secondary battery and a secondary battery having the same, which can interrupt electric current input into the secondary battery when the temperature of the secondary battery increases due to an overcharge, and also can protect the secondary battery in the case where the already charged secondary battery is exposed to a high temperature due to the increase of an external or internal temperature of the secondary battery. The protection circuit includes: means having one end connected to a first electrode of the secondary battery, for restricting electric current; switching means for connecting a second electrode of the secondary battery to a first outer electrode, or to the current restriction means in response to temperature; and a conducting wire for connecting the first electrode of the secondary battery to a second outer electrode.

Abstract: The present invention relates to an apparatus for protecting a secondary battery by preventing overcharge of the secondary battery. The apparatus for protecting a secondary battery includes: a secondary battery; a power supply, connected with both electrode terminals of the secondary battery, for providing a charging voltage and a charging current to the secondary battery to charge the secondary battery; and a secondary battery protection unit for shorting the power supply thereby to stop charging the secondary battery if a charging voltage of the secondary battery is above a predetermined voltage.

Abstract: Disclosed is a secondary battery. The secondary battery includes a battery can serving as a positive electrode terminal or a negative electrode terminal of the secondary battery, an electrically conductive substrate provided at an outer portion of the battery can, and a nonconductive film interposed between the battery can and the electrically conductive substrate in order to insulate the electrically conductive substrate from the battery can, wherein the electrically conductive substrate is electrically connected to an electrode terminal having polarity opposite to that of the battery can. Safety of the secondary battery is ensured even if the secondary battery is subject to external parameters, such as penetration of a sharp tool (e.g. a nail or a drill tip), pressing force of a tool (e.g. a nipper), external impact, and exposure to the high temperature.

Abstract: Disclosed are a safety device and a secondary battery using the same. The safety device includes a voltage sensitive heating device generating heat when a voltage difference between both ends thereof exceeds a predetermined voltage level and a temperature sensitive device having a reversible current ON/OFF function according to a temperature. The temperature sensitive device is coupled with the voltage sensitive heating device such that the temperature sensitive device detects the heat generated from the voltage sensitive heating device.

Abstract: An object of the present invention is to provide the device for protecting a secondary battery safely from overvoltage and overheating caused by the overcharge by using simple safety device, which provides a contacted safety device which connects between a constant voltage element showing a discharge characteristic in the state of overvoltage and a MIT (metal insulator transition) element showing a discharge characteristic in the state of overheating. Each of the constant voltage element and the MIT element are connected in parallel between a cathode lead and an anode lead of the secondary battery.

Abstract: Disclosed is a secondary battery having a constant-voltage device for preventing the secondary battery from being excessively overcharged. The breakdown voltage of the constant-voltage device is lower than the explosion or ignition voltage of the secondary battery, so the discharge operation may occur before the secondary battery is exploded or ignited even if the voltage of the secondary battery rises above the overcharge voltage, thereby protecting the secondary battery from explosion or ignition. The leakage current value of the constant-voltage device is less than 0.05% of the capacity value of the secondary battery under the maximum charge voltage of the secondary battery, or the breakdown voltage of the constant-voltage device is higher than the maximum charge voltage of the secondary battery. Thus, the constant-voltage device rarely generates the leakage current even if the secondary battery has been charged with the maximum charge voltage.

Abstract: Disclosed are a safety element for a battery, which is provided with material having a Metal-Insulator Transition (MIT) characteristic where resistance abruptly drops at or above a certain temperature, and a battery with such a safety element. This battery with an MIT safety element is turned into a stable discharged state when it is exposed to an elevated temperature or a battery temperature rises due to external impact, so that it can ensure its safety.

Abstract: Disclosed is a battery safety device adapted to form an electrical circuit when compressed by a predetermined pressure or higher and convert the charged state of a battery to the discharged state, a battery having the safety device, and a method for adjusting the safety of a battery by converting the charged state of the battery to the discharged state, before the battery is damaged by a pressure, through an electrical circuit formed on a safety device by means of the pressure. The safety device has a first metal plate, a second metal plate, and a pressure-sensitive conducting film interposed between both metal plates and adapted to exhibit electrical conductivity when a predetermined pressure or higher is applied. The first and second metal plates are electrically connected to the positive and negative electrodes of the battery, respectively.