Charging knowledge of cylindrical lithium manganese battery
2021 Dec 18 By admin 0 comment

1. Charging characteristics of cylindrical lithium manganese battery
If an external charger is used to charge the cylindrical lithium manganese battery, the reverse reaction of the discharge reaction will occur inside the battery, which will decompose part of the compound MnOOLi to regenerate Li and MnO2, and the battery voltage will also increase.

Charging knowledge of cylindrical lithium manganese battery
Charging characteristics of cylindrical lithium manganese battery

As the charging continues, the battery voltage will gradually increase, and the maximum charging voltage can reach 3.5V. When the charged battery is left to stand for a period of time to make its internal balance reach, the open circuit voltage of the battery can be restored to the normal 3.2V (the rated voltage is 3V when there is a load).

In the process of charging the cylindrical lithium manganese battery, the microstructure of the MnO2 and Li produced is not exactly the same as the original pure substance, and its activity becomes very poor. Therefore, when a charged battery is discharged, its capacity is much lower than that of a new battery.

As an example, if a new CR123A lithium-manganese battery is continuously discharged with a 5Q resistor to test its capacity, the capacity can reach 1300mAh, which can be discharged for more than 2h. Use the new battery to take pictures with the camera, continuous flashing and rewinding, at least 10 rolls of film can be taken.

For a fully charged CR123A lithium manganese battery, the capacity is still tested by continuous discharge with a 5Q resistor, the capacity does not exceed 400mA·h, and the continuous discharge does not exceed 1h. Used for camera photography, continuous flash and rewind, up to 4 rolls of film can be taken.

The above comparison shows that the conversion and reduction rate of the active material MnOOLi is very low during the charging process of the cylindrical lithium manganese battery. And as the number of recharges increases, the conversion rate of MnOOLi will be lower and lower. After about 10 recharges, the lithium manganese battery will be difficult to recharge. It can be seen that due to the poor reversibility of MnOOLi, the cylindrical lithium manganese battery is not suitable for charging.

2. The danger of charging cylindrical lithium manganese batteries
Commercially available cylindrical lithium manganese batteries are marked with the words “No Recharge” on the outside, emphasizing that these batteries are not rechargeable. In addition to the poor charging cycle performance described in the previous point, there are mainly the following problems.

Charging knowledge of cylindrical lithium manganese battery
The danger of charging cylindrical lithium manganese batteries

(1) Low-boiling organic solvents are used in the production of cylindrical lithium manganese batteries. Among them is an organic solvent called ethylene glycol dimethyl ether (DME), which has a lower lightning point temperature. If the lithium-manganese battery expands due to heat or is not properly sealed during charging, it is easy to cause ethylene glycol dimethyl ether to volatilize from the battery. If it encounters electric sparks or smoking sparks, it may cause burning and cause danger.

(2) During the charging process of cylindrical lithium-manganese batteries, the internal reaction will generate lithium (Li), which is an irregular crystal with a shape a bit like a tree branch, often called a dendrite. If the dendrites pierce the diaphragm during the growth process, it is easy to cause a short circuit inside the battery, which will cause combustion due to the high temperature generated by the short circuit and large current, and even cause an explosion and explosion accident. A CR123A lithium-manganese battery exploded, enough to blow the camera into pieces. It can be seen that non-professionals are not allowed to charge the cylindrical lithium manganese battery! We should comply with it.

It can be seen from the above that not only can the cylindrical lithium manganese battery not be charged, it can also not be disassembled or burned in a fire at will, not to mention the cylindrical lithium manganese battery should not be short-circuited or over-discharged to 0V. Doing so may cause danger.

In summary, both theory and practice have proved that the active material MnOOLi in cylindrical lithium-manganese batteries has poor reversibility, and the number of charging cycles cannot reach the level of batteries, and it is dangerous. This determines the charging of cylindrical lithium-manganese batteries. The advantages are small and the disadvantages are big, and it is not rechargeable.