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. 2021 Feb 17;21(4):1397. doi: 10.3390/s21041397

Table 2.

Comparative criteria of commercialized fiber optic sensors relative to other temperature measurement methods for Li-ion batteries.

Sensor Type Sensitivity 1 Accuracy 1 Base Cost (System + One Sensor) 2 Cost/Sensing Point 2 Robustness Multiple Parameters Interrogation Location Level of Impact for Internal Measurements 3
FBG sensor 10–13 pm/°C [43,44] ±0.05 °C [45] Over $10,000 $165/pt. (EV);
$31/pt. (ET);
$11/pt. (GES);		 Resistant to corrosion, EMI, RFI, high voltages Temperature, strain, pressure, etc. Capable of multi-parameter monitoring and signal discrimination External and internal measurements Level 2
Other fiber optic point sensor4 10 pm/°C [46] ±0.2 °C [47] ≈$4000 - Resistant to corrosion, EMI, RFI, high voltages Temperature, strain, chemicals, etc. Capable of multi-parameter monitoring and signal discrimination External and internal measurements Level 2
Thermistor 3–6%/°C [48,49] ±0.01–±0.05 °C
[50]		 $100~200 - Prone to electrical noises No Nonlinearity between temperature and resistance needs to be compensated External and internal measurements Level 3
Resistive temperature detector 0.38%/°C [42] ±0.01–±0.2 °C
[50]		 ≈$200 - Resistant to corrosion, but prone to electrical noises No Linear behavior between temperature and resistance enables simple interrogation Externally capable but requires thin-film fabrication for internal measures Level 3
Thermocouple 1–70 µV/°C [51] ±1–±2 °C [51] ≈$400 - Sensitive to corrosion, low long-term stability No Nonlinearity between temperature and voltage needs to be compensated Externally capable but requires thin-film fabrication for internal measures Level 3
Electrochemical impedance spectroscopy Depends on battery chemistries and measurement frequency ±0.17–±2.5 °C [52] Implementation dependent - Strongly interference sensitive Temperature,
other impedance-dependent cell state variables		 Interpreting temperature from impedance can be challenging due to the SOC and aging dependency of impedance [42] External
measurements		 Level 1
Infrared thermal imaging ≈0.05 °C [50] ±0.1–±5% [50] Implementation dependent - Delicate and non-practical for commercial purposes No Interfered by radiations from surrounding objects External and internal measurements Level 1

  1. Typical values of sensitivity and accuracy for each category of sensors are used, though actual values depend on specific types in that category.

  2. The costs presented are approximated from vendor provided pricing information on off-the-shelf products. Base costs are dominated by the interrogation cost, especially for fiber optic sensors. Calculation is shown in Equation (1) (EV = Electric Vehicle, ET = Electric Truck, GES = Grid-Scale Energy Storage).

  3. Potential level of impact of Li-ion batteries is classified into three levels: level 1: non-intrusive with no impact; level 2: minimal impact, capacity retention is comparable to original cell; level 3: negative impact, conventional size of sensors can cause increase in internal impedance and impedes ionic transport, which may result in lithium plating and lead to capacity loss or even internal short-circuit.

  4. Fiber optic point sensors other than FBGs includes Fabry–Perot interferometer, fluorescence-based, and evanescent wave field sensors.