What are the safety issues of lithium battery?

Jun 12, 2019   Pageview:74

The “no charge” on the packaging of a lithium battery is fully scientifically based on the protection of consumers from a safety perspective. In fact, lithium manganese batteries are not completely unchargeable. From the principle of electrochemistry: metal lithium is used as the negative electrode of the battery, and manganese dioxide is used as the positive electrode of the battery, both of which participate in the chemical reaction inside the lithium battery. The reaction when the battery is discharged is Li+MnO2-R1nOOLi. During the discharge process, metallic lithium is continuously consumed to form the compound MnOOLi. When the metal lithium is safely consumed, the discharge ends and the open circuit voltage of the battery is also reduced from 3.3V to 2.8V. If the battery is charged by an external power source, a reverse reaction of the discharge reaction occurs in the battery, and some MnOOLi starts to decompose and regenerate Li and MnO. As the charging continues, the open circuit voltage of the battery also starts to rise, up to 4.2V. After the fully charged battery is left for a period of time, the internal balance of the battery is reached, and the open circuit voltage of the battery can be restored to the normal 3.2-3.5V. Since the microstructures of MnO2 and Li generated during the charging process are not exactly the same as the original pure substances, their activities are also different. When the charged battery is discharged, it will find that its capacity is much lower than the new battery. Taking the common CR123A battery as an example, a new battery is continuously discharged with 50 resistors, and the capacity of the child can reach 110mAh, about 130 minutes. A new battery is used for camera photography, continuous flashing and rewinding, at least 10 volumes can be taken. . For the first-time battery, the battery is continuously discharged with a 5Ω resistor. The capacity is less than 400mAh, which is about 40 minutes. It is used for camera photography, continuous flashing and rewinding, and can shoot up to 4 rolls at most. As the number of times of charging increases, the conversion rate of MnOOLi becomes lower and lower, and after about 10 times, the battery is difficult to recharge.

 

In the professional textbook, the chargeability of lithium-manganese battery is not discussed, because both theory and facts prove that lithium manganese can be charged, but because of the poor reversibility of its active material MnOOLi, the number of cycles cannot meet the requirements of rechargeable batteries. It is a secondary battery. By the same token, alkaline manganese batteries and silver oxide batteries are not completely unchargeable. In fact, alkaline manganese rechargeable batteries have been produced in small quantities by manufacturers.

 

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