Arc analysis to the CID of li-ion battery cells in high-current applications

Abstract

This paper focus on the prevention and risk management of DC arcs in batteries. Indeed some commercial Liion batteries include Positive Temperature Coefficient (PTC) and Current Interrupt Device (CID) to manage safety concerns. PTC is used to prevent too high currents inside the cell. CID is used to manage cell over-charge by opening the cell circuitry by internal pressure increase. Analysis will be used to improve the Li-ion batteries safety in high voltage applications. The experimental test bench is composed of a 48 V DC battery pack and a variable resistor which can deliver a continuous current up to 1000 A. Two configurations are considered to initiate the arc. In the first configuration, the CID opens dynamically by contact release. The second configuration consists in igniting an arc between the electrodes with a copper wire in a confined space. Arc voltage and current are measured. Arc image is recorded using a high speed video camera which allows an analysis of the physical phenomena. Arcing analysis leads to solution proposal to reduce arcing risk.

Reliability of Cylindrical Li-ion Battery Safety Vents

“…However, the PTC thermistor cannot prevent an internal short circuit, such as one caused by an internal defect [14]. Moreover, a PTC thermistor alone may not stop thermal runaway propagation in a battery pack, which contains multiple cells in series and/or parallel [15], [16]. In these cases, if the series-connected cells are shorted, the first PTC thermistor that trips in the series configuration can induce a voltage drop that exceeds its voltage rating and may result in failure.…”

“…In these cases, if the series-connected cells are shorted, the first PTC thermistor that trips in the series configuration can induce a voltage drop that exceeds its voltage rating and may result in failure. Once the first PTC thermistor fails in a large series of cells, the short can transmit this failure and cause the next PTC thermistor to fail until all the cells short [15]. Fire and explosion can then occur.…”

“…The CID can be activated by pressure, temperature, or a circuit monitoring the battery status. In most 18650 cylindrical batteries, the activation method is pressure, and the critical pressure for a CID is around 1000 kPa [15], [17]. Once this threshold value is reached, the structure of the CID is destroyed and the battery can no longer operate.…”

“…Once this threshold value is reached, the structure of the CID is destroyed and the battery can no longer operate. While a CID is a reliable method for single cells, for a battery pack having voltages over 20 V, Augeard et al [15], [18] found that the CID opening can generate and maintain an arc that could result in thermal runaway. NASA researchers [16] reported the CID arcing could be ignited at 55 V and 110 V for Moli batteries and Sony HC batteries, respectively.…”

Consumer-Based Evaluation of Commercially Available Protected 18650 Cells

“…These packs, containing multiple cells assembled in series and parallel, generally contain ancillary equipment to monitor individual cell properties such as voltage and temperature. This equipment accompanies standard internal cell safety designs, such as positive temperature coefficient (PTC) devices and current interrupting devices (CID) [8]. PTCs are resettable devices in which cell resistance increases rapidly when a set temperature is reached, lowering cell current to acceptable levels [9].…”