Case protection, in order to prevent air entry, lithium batteries are encapsulated in sealed containers, and in order to prevent external damage is usually equipped with stainless steel housing and aluminum alloy housing. For example, Tesla's electric car, even the use of titanium alloy protection plate, in order to prevent the use of the car, especially in traffic accidents on the battery container damage.

Diaphragm blocking protection prevents damage from external forces while at the same time preventing damage generated from inside the battery.

Usually, in order to prevent the positive and negative electrodes of the battery from directly touching and short-circuiting, there is a layer of diaphragm inside the battery, which separates the positive and negative electrodes on the one hand, and allows charged ions to pass through on the other.

However, in the lithium battery, the diaphragm also assumes another protective function. When the battery temperature is too high, the diaphragm gap will automatically close, so that lithium ions can not cross, thus terminating the entire battery reaction. This prevents the battery from being too hot, making the electrolyte in it vaporize to generate high pressure and destroy the sealed structure of the battery.

Overcharge voltage protection, not only air should be blocked out, but also prevent lithium metal from leaking out of the electrode.

Scientists through the electrode material nano-vacancy and material lattice mechanism to store and lock the lithium metal formed in the charge and discharge.

In this way, even if the battery shell ruptures and oxygen enters, the oxygen molecules will be too large to enter these tiny storage compartments and avoid spontaneous combustion.

However, charging with too high a voltage or continuing for too long after a full charge can produce very dangerous damage to the lithium battery.

After charging the lithium battery at a voltage higher than the rated voltage (usually 4.2V), if the charging continues, the subsequent lithium ions will accumulate on the surface of the negative electrode material because the storage compartment of the negative electrode has been filled with lithium atoms. These lithium ions will form electron transfer due to polarization, forming lithium metal and growing dendritic crystals from the surface of the negative electrode in the direction where the lithium ions come from.

These no electrode protection of lithium metal on the one hand is extremely active, prone to oxidation reactions and explosions. On the other hand, the formation of lithium metal crystals will penetrate the diaphragm, short-circuiting the positive and negative electrodes, thus triggering a short circuit and generating high temperatures. At high temperatures, the electrolyte and other materials will crack to produce gas, making the battery shell or pressure valve bulge rupture, allowing oxygen to enter and react with the lithium atoms accumulated on the surface of the negative electrode, and then explode.

When charging lithium batteries, set the upper voltage limit and overcharge protection. In the regular battery manufacturers produced in the lithium battery, are equipped with such a protection circuit. Automatic power off when the voltage exceeds the limit or when the power is full.