Current interrupt device

CID current interrupter device activated by internal pressure. 

Other less prominent types of additives, also intended for overcharge protection, were termed shutdown additives in the battery industry based on their tendency at high potentials to release gas, which in turn would activate a current interrupter device (CID), or to polymerize and block the ion passage in the electrolyte. The former included such... 

Figure 10. Typical short-circuit behavior of a 18650 lithium-ion cell with shutdown separator and without PTC (positive temperature coefficient) and CID (current interrupt device). This test simulates an external short circuit of a cell.

A typical arrangement of components in a tensimetric titration is presented in Fig. 9.5, which shows the previously discussed tensimeter and a calibrated bulb attached to a vacuum line.2 The sample container on the tensimeter is fitted with a small reciprocating stirrer which consists of a thin glass rod connected to a glass-encased headless nail or glass-encased bundle of soft iron wire. This stirrer is driven by an external solenoid, the field of which is switched on and off by a current-interrupting device, the details of which are laid out in Fig 9.6. The size of the calibrated bulb is chosen so that it will contain the desired amount of gas for each addition at a pressure which is convenient and accurately measured (e.g., 100-500 torr). The calibration procedure and steps used dispensing gas from such a bulb are described in Section 5.3.G. 

A current interrupt device (CID) disconnects the electrodes from the cell terminal to stop current flow when the internal cell pressure reaches a predetermined pressure, usually the result of a high internal cell temperature. 

Fig. 20.15 Typical overcharge behavior of a 18,650 lithium-ion ceU with shutdown separator. The PTC (Positive Temperature Coefficient) and CID (Current Interrupt Device) were removed from the ceU header. Reprinted with permission from Chem. Rev. 104 (2004) 4419-4462, Copyright (2004) American Chemical Society...

The benefit of using small cells is that many of them have built-in safety features such as temperature-driven resettable thermal fuses and pressure-driven current interrupt devices and vents. The small cells may also reduce the impact of a single-cell failure... 

Commercial Li-ion cells are manufactured in cylindrical, prismatic metal can and prismatic pouch cell designs. Commercial Li-ion cells are typically fitted with one or more internal protection devices. Some of these are the positive temperature coefficient device (PTC), the current interrupt device (CID) and the shutdown separator. Both the PTC and CID are present in the header of the Li-ion cells as shown in Figure 17.1. 

To increase the safety, commercial Li-ion cells are usually equipped with safety devices that catch an abnormal behavior and shutdown or limit the ciurrent. The current interrupt device (CID) and the positive temperature coefficient (PTC) are representative of such safety devices. The CID functions as a circuit breaker for the overcharge mainly, disconnecting the positive lead from the circuit by using a concave and movable aluminum disk, when the internal pressure of a cell suddenly increases [36,37]. The PTC is a fuse-like device based on materials whose resistance increases dramatically with an increase in temperature. When a large current flow in the circuit and a violent temperature rise due to the Joule heat occms as a result of external shorting, the resistance of the PTC element can rapidly increase by several orders and limit the current to a relatively low and safe... 

Designing and testing of protective devices, such as PTC (positive temperature coefficient) current limiting devices, CID (current interrupt device) which shuts off power based on internal pressure, and vent system. 

To conduct proton conductivity measurements, Buchi et al. [3] designed a current interruption device that used an auxiliary current pulse method and an instrument for generating fast current pulses (i.e. currents > 10 A), and determined the time resolution for the appropriate required voltage acquisition by considering the relaxation processes in the membrane of a PEM fuel cell [3]. They estimated that the dielectric relaxation time, or the time constant for the spontaneous discharge of the double-layer capacitor, t, is about 1.4 x 10 ° s. They found that the potential of a dielectric relaxation process decreased to <1% of the initial value after 4.6r (6.4 x 10 s) and that the ohmic losses almost vanished about half a nanosecond after the current changes. Because there is presently no theory about the fastest electrochemical relaxation processes in PEM fuel cells, the authors assumed a conservative limit of 10 s, based on observations of water electrolysis membranes. They concluded that the time window for accurate current interruption measurements on a membrane is between 0.5 and 10 ns. Another typical application of the current interruption method was demonstrated by Mennola et al. [1], who used a PEM fuel cell stack and identified a poorly performing individual cell in the stack. 

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