There may be three reasons for the bulging battery:

1. The problem of battery manufacturing level, the electrode coating is not uniform, and the production process is relatively rough;

2. The violent reaction of the short circuit generates a lot of heat, which in turn causes the electrolyte to decompose and vaporize, and the battery bulges. ；

3. In addition, if the battery is not used for a long time, bulging will occur, because the air is conductive to a certain extent. Therefore, if the battery is left for too long, it is equivalent to direct contact between the positive and negative electrodes of the battery, causing a chronic short circuit.

Generally, batteries containing lithium elements are used as electrodes, and graphite is the most used negative electrode at this stage. In fact, lithium batteries mainly rely on the movement of lithium ions between the positive electrode and the negative electrode to work. During the charging and discharging process, Li+ intercalates and deintercalates back and forth between the two electrodes: when recharging the battery, Li+ deintercalates from the positive electrode and inserts into the negative electrode through the electrolyte, and the negative electrode is in a lithium-rich state; the opposite is true during discharge.

The electrodes of lead-acid batteries are mainly made of lead and its oxides, and the electrolyte is a sulfuric acid solution. In the charged state of a lead-acid battery, the main component of the positive electrode is lead dioxide and the main component of the negative electrode is lead; in the discharged state, the main component of the positive and negative electrodes are lead sulfate.

The production cost of lithium batteries is high. The expensive production equipment and labor costs account for about 40% of the production cost, and the price is about three times that of lead-acid batteries.

How long is the service life of lithium batteries for electric vehicles? Many people are entangled in the life of lithium batteries for electric vehicles. How long can a set of lithium batteries for electric vehicles last? Why do some people's lithium batteries can be used for 2 to 3 years, and some can even be used for 3 to 5 years? In fact, the service life of most lithium batteries is designed to be around 1,000 times (ordinary ternary lithium battery materials), which is 3 to 4 years.