How to determine anode and cathode of lithium-ion batteries—Useful Tips

In electronic products, it is necessary to use batteries for power supply. When using, the correct anode and cathode connection of the battery is very critical. However, rare people know how to determine anode and cathode of lithium-ion batteries, especially when we encounter multiple batteries supplying power at the same time, we need to arrange them side by side and connect the positive and negative poles separately, so that multiple batteries can be supplied together.

In this process, it should be noted that the positive pole of the batteries cannot be connected together, otherwise the batteries will be damaged. In order to avoid getting the polarity wrong and causing electrical system failures, it is necessary to accurately know how to determine anode and cathode of the batteries.

1. Ordinary lithium-ion battery

Usually, the manufacturer will clearly mark the positive and negative of battery terminals. The positive pole of a new battery is marked with a "+" sign or "POS" or painted in red; the negative pole is marked with a "-" sign or "NEG" or painted in green for better identification. The protruding head of the lithium-ion battery, like 21700 battery, is the positive electrode, and the flat bottom is the negative electrode; some manufacturers also make the diameter of the positive pole slightly larger than that of the negative pole.

2. Spring design batteries

Many electronic devices use a spring design to help us determine cathode and anode of the battery more easily. So, which side is connected to the spring corresponding to the positive and negative poles? This needs to be determined according to the specific equipment. Normally, if there are one or more springs inside the device that are in contact with the battery, then the positive terminal of the battery should be in contact with the springs. Because in a circuit, current flows from positive to negative, this means that the terminal the spring is touching should be the positive terminal.

The spring is usually located at the bottom of the battery compartment, and its function is to make the connection between the battery and the electronic product more tightly and reliably. If there are multiple springs in the battery compartment, usually only one spring corresponds to the positive terminal of the battery, while the other springs correspond to the negative terminal of the battery.

We only need to align the positive and negative poles of the battery with the corresponding springs in the battery compartment, and then press in gently until a firm connection is formed between the battery and the spring. The positive pole of the battery should face the corresponding spring in the battery compartment, otherwise the electronic product may not work properly.

However, not all devices use a spring design, and some devices may use other methods to differentiate the positive and negative terminals of the battery. In this case, how to determine anode and cathode of lithium-ion batteries?

We can look for the positive and negative symbols or color codes in the device and the battery, which will help us connect the battery correctly.

3. For batteries after long-term use

How to determine anode and cathode for batteries that are not clearly marked or have no obvious marks after long-term use? Here are 6 useful tips.

① Color recognition method

Since the active material on the positive plate of the battery is lead dioxide (PbO2), which is brown-red; the active material on the negative plate is spongy pure lead (Pb), which is blue-gray. Therefore, the positive and negative poles can be distinguished from the color of the plate: the positive pole is brown-red, dark in color; the negative pole is blue-gray, light in color.

② Voltage measurement identification method

Use the DC 50V voltage block of the multimeter, and use its red and black test leads to measure the two poles of the battery respectively. If the pointer turns correctly and the voltage value is displayed, the pole connected to the red test lead is the positive pole of the battery, and the pole connected to the black test lead is the negative pole of the battery.

③ Current measurement identification method

Touch the connection line of the "+" terminal of the vehicle ammeter with any pole, and instantly wipe the other terminal with the other pole of the single cell battery, and at the same time quickly observe the direction of the pointer of the ammeter: if the pointer swings to the "+" direction, the pole that the ammeter "+" terminal touches is the "+" pole; if the pointer swings to the "-" direction, the pole that the ammeter "+" terminal touches is the "-"pole.

④ Bubble recognition method

There is a wire on each of the two poles of the battery, insert the other ends of the two wires into dilute sulfuric acid solution or salt water, keep a proper distance, and observe the bubbles generated at the ends of the wires: the wire with more bubbles is connected to the pole of the battery. Negative electrode, the one with less air bubbles is the positive electrode of the battery.

⑤ Position recognition method

The polarity of the battery pole can also be judged according to the position relative to the brand name. When the poles are arranged front and back, the positive pole is close to the front of the label, and the negative pole is close to the reverse side of the label; when the poles are arranged left and right, the left side of the label is the positive pole, and the one on the right side of the label is the negative pole.

⑥ High rate discharge meter identification method

When using a high-rate discharge meter to distinguish the positive and negative poles of the battery, compare it with the battery with obvious polarity marks. According to the swing direction of the pointer, the positive and negative polarities of the battery poles can also be accurately judged.

4. FAQs about the anode and cathode of lithium-ion batteries

① What are the anode and cathode of lithium-ion batteries

Common positive electrode materials for lithium-ion batteries include lithium manganese oxide, lithium cobalt oxide, lithium iron phosphate, and ternary materials. Commonly used negative electrode materials include carbon materials and silicon-based materials.

In lithium-ion battery materials, positive and negative electrode materials are important components, which can have a great impact on the performance of the overall battery.

② 18650 lithium-ion battery: How to determine anode and cathode

• Look at the screen printing: the one with the screen printing is facing the screen printing, usually the left is positive and the right is negative;
• Look at the shape of both ends: the protruding end is positive, and the flat bottom is negative;
• Look at the shape, the remodeled battery is generally the original shape, look at the insulation guarantee at both ends, one end has a concave ring, the other end does not, some are positive, and none are negative;
• Some manufacturers do not produce according to battery standards and labels, so actually measure and consult the manufacturers to obtain specifications.

How to determine anode and cathode properly of lithium-ion batteries is very important to the life and safety of your electronics. We should operate in the correct way, carefully read the equipment instructions or seek help from professionals to avoid unnecessary trouble and loss.

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