Due to advanced PID Sensor technology, safety hazards associated with Li-ion battery storing and usage can be mitigated, allowing safety measures to be implemented.
Sensitive photoionisation detection (PID) sensors are able to detect potential problems before they occur in the manufacture and use of Li-ion batteries and the enormous variety of devices that use rechargeable batteries. With our ever-evolving digital age, the safe utilisation of Li-ion batteries is of paramount importance to manufacturers and customers.
The risks posed by Li-ion batteries have been highlighted by a number of high-profile incidents hitting mainstream media. Famously, in 2016, around 2.5 million mobile phones were recalled after complaints of overheating and exploding batteries. Extensive investigations revealed insufficient insulation material within the batteries and a design that did not provide sufficient space to safely accommodate the batteries’ electrodes were the main catalysts for these incidents. As a result of the magnitude of this problem, and the global publicity which ensued, demand grew for sensing technology that can detect faulty Li-ion batteries, both during production and operation.
The main safety concern associated with failing Li-ion batteries is the ignition of the battery cell. Not only does this pose an immediate acute (short-term) hazard to individuals, but over long periods of time can cause the emission of toxic gases. These gases include volatile organic compounds (VOCs), meaning sensitive VOC sensors can be used to check the condition of these batteries – either within portable detectors or in process/plant monitoring equipment.
The anode in rechargeable Li-ion batteries is typically graphite, the cathode is a metal oxide, and the electrolyte is usually a lithium salt in a (flammable) organic solvent. This electrolyte includes compounds such as ethyl methyl carbonate (EMC) which is known to be among the gases emitted by a faulty Li-ion battery. Conveniently, EMC can be detected by ION Science’s PID, so the developers of monitoring systems and equipment are able to design technologies that utilise ION’s MiniPID sensors.
The RFs for VOCs commonly used in Li-ion battery electrolytes are presented in Table 1: Evaluation of chemicals used in lithium-ion batteries.
| VOC | Boiling Point oC | RF | Sat. vapour pressure @ 25 oC bar | Prospective maximum response, ppm (IBE) | Measured spike response, ppm (IBE) |
| Dimethyl carbonate | 91 | 65 | 0.07 | 1000 | 80 |
| Ethyl methyl carbonate | 107 | 18 | 0.035 | 2000 | 240 |
| Diethyl carbonate | 127 | 7.5 | 0.015 | 2000 | 390 |
| Vinylene carbonate | 162 | 3.5 | 0.0033 | 1000 | 480 |
| Butylene carbonate 1,2- | 238 | 18 | 0.0002 | 1 | 10 |
| Propylene carbonate | 242 | 15 | 0.0002 | 1 | 80 |
| Ethylene carbonate | 243 | >50 | 0.0003 | 0.5 | <1 |
Due to their specificity, PID sensors are the most commonly employed technology for the detection of VOCs, and ION’s MiniPID range includes the most sensitive PID sensor in the world, which makes it ideal for the detection of trace leaks from faulty Li-ion batteries.
Summarising, Peter Morris from ION Science says:
“Prospective customers for our PID sensors in Li-ion battery applications include the developers of portable instruments, as well as the designers of monitoring systems for processes within battery manufacturing, as well as in the manufacture of EVs, e-bikes, laptops, tablets, phones and many others.”
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