The rapid development of energy storage technology provides a reliable solution for energy storage and promotes the large-scale application of renewable energy. However, as the scale and complexity of energy storage systems increases, so does the risk of safety incidents. These accidents can include battery failure, loss of energy, short circuits, etc., which are often accompanied by the production of carbon monoxide.
From the existing literature, it is not difficult to draw the following conclusions: the main gas products of lithium-ion batteries after thermal runaway are CO, CO2, H2, N2, hydrocarbons, etc. CO, CO2 and H2 are the three largest gases, accounting for more than 70% in general. Therefore, timely and accurate monitoring of carbon monoxide concentration changes is an important means to prevent safety accidents.
At the same time, the drive for technological innovation in the energy storage industry has also led to the development of carbon monoxide monitoring technology. Advanced monitoring technology can provide more accurate and real-time data, resulting in a more comprehensive understanding of the safety and performance of energy storage systems.
A carbon monoxide sensor is a type of gas sensor. The gas sensor is mainly composed of two parts: conduction and conversion system, and the carbon monoxide gas sensor can be detected based on CO gas, which can detect the concentration of CO, a dangerous gas exposed to the environment, and clearly read the gas concentration, peak and high and low concentration alarm levels. If the current high and low concentration values of the gas exceed the preset limit values, the alarm will alert the user by sound and light alarm.
At present, the sensors for detecting carbon monoxide are mainly divided into semiconductor, electrochemical, infrared and catalytic combustion according to the detection principle, and their main working principles and advantages and disadvantages are analyzed as follows:
1. Semiconductor type
The sensitivity of semiconductor sensors to gases depends on the temperature at which the sensitive element is heated. For the detection of carbon monoxide, the sensitive element is heated at a temperature of less than 100°C, which is much lower than the detection temperature of other gases (e.g. butane, methane, hydrogen, ethanol vapor, etc.). However, at such low temperatures, carbon monoxide responds less quickly and its sensitive properties are easily affected by water vapor in the atmosphere.
Advantages: low price, excellent performance, MEMS process can be adopted, small size, good seismic resistance, long life, simple application.
2. Electrochemical type
(1) Working principle and characteristic curve
The detection principle of an electrochemical gas sensor is shown in the figure below.
When a fixed voltage is applied to the positive and negative electrodes of the electrolyzer, the reaction occurs on the acting electrode and the counter electrode respectively, taking the carbon monoxide sensor as an example, the chemical reaction formula is:
This redox-reduction reversible reaction occurs consistently between the working and counter electrodes and creates a potential difference between the electrodes. However, because the reaction that occurs on both electrodes polarizes the electrodes, it is difficult to maintain a constant potential between the electrodes, thus limiting the range within which the carbon monoxide concentration can be detected.
The total reaction is the oxidation of carbon monoxide to carbon dioxide, the flow of electrons to form an external current, and the charge balance is done by the flow of carriers in the electrolyte.
The biggest feature of the electrochemical gas sensor is that the current is completely proportional to the carbon monoxide concentration, and the output signal has a good linear relationship with the gas concentration, so the signal processing and display are very convenient. Another feature is that because it is a normal temperature reaction, there is no need for a heater, so the voltage between the electrodes can be used in dry batteries, and there is no need for mains power, and it is a portable carbon monoxide alarm.
Advantages: zero power consumption, high sensitivity, good stability, good linearity, good repeatability, fast impact speed, resolution can generally reach 0.5ppm.
3. Infrared type
The detection principle of infrared sensors is that molecules made up of two different atoms have a so-called dipole moment (the product of the length of the dipole and the charge charge at the first end of the dipole), and when infrared light is irradiated on the gas, it absorbs light of a specific wavelength determined by the molecular structure of the gas.
The type of gas can be determined from the absorption wavelength of the absorption spectrum, and the concentration of the gas can be determined from the intensity of absorption. This sensor is very sensitive, selective, and especially very accurate, and is often used in meters, but its structure is complex, the cost is high, and it is rarely used in alarms.
Advantages: wide range, high precision, good selectivity, high reliability, no adsorption effect, no poisoning, no dependence on oxygen, less environmental interference factors, long life.
4. Catalytic combustion type
The sensor has a pair of catalytic combustion detection elements, one of which is very sensitive to carbon monoxide gas, which is coated with a multi-layer catalyst and the other is insensitive to compensate for ambient temperature changes. This pair of detection elements and another pair of high-precision resistors form the Wheatstone bridge.
Advantages: high linearity, accurate measurement, fast response, long life, anti-poisoning.
Relying on the R&D accumulation of various types of gas sensors, combined with its own manufacturing advantages of the whole industrial chain of intelligent sensors integrating design, manufacturing, packaging and testing, Huiwen Technology has developed and produced a variety of carbon monoxide sensors, which can escort the safety of the energy storage industry. These innovative products are part of our commitment to life safety and are designed to provide smarter, more reliable carbon monoxide monitoring solutions.