Is it true that lithium-ion batteries explode?
With the rapid development of lithium-ion battery packs and new energy devices, while improving our lives, problems have also arisen. The Samsung Note 7 and iPhone battery explosion incidents, as well as the recent series of fires on the Crab Island bus, have raised concerns about new energy technologies.
I. External Short Circuit
External short circuits may be caused by improper operation or misuse. Due to an external short circuit, the battery discharge current is very large, which will cause the battery cell to heat up. The high temperature will cause the diaphragm inside the battery cell to shrink or completely break down, resulting in an internal short circuit and thus an explosion.
II. Internal Short Circuit
Due to an internal short circuit, the battery cell discharges a large current, generating a lot of heat that burns the diaphragm, causing an even larger short circuit. This results in the battery cell reaching high temperatures, causing the electrolyte to decompose into gas and creating excessive internal pressure. When the battery cell's casing can no longer withstand this pressure, the battery cell will explode.
3. Overcharge
When a battery cell is overcharged, excessive lithium release from the positive electrode can alter its structure. Excessive lithium release can also prevent it from inserting into the negative electrode, leading to lithium deposition on the negative electrode surface. Furthermore, when the voltage reaches 4.5V or higher, the electrolyte decomposes, producing a large amount of gas. All of these factors can potentially cause an explosion.
IV. Excessive moisture content
Moisture can react with the electrolyte in the battery cell to produce gas. During charging, it can react with the generated lithium to form lithium oxide, causing capacity loss in the battery cell and making it prone to overcharging and gas generation. Moisture has a low decomposition voltage, so it easily decomposes and generates gas during charging. When this series of generated gases increases the internal pressure of the battery cell, the battery cell will explode when the outer casing cannot withstand it.
5. Insufficient negative electrode capacity
When the capacity of the negative electrode opposite the positive electrode is insufficient or non-existent, some or all of the lithium generated during charging cannot be inserted into the interlayer structure of the negative electrode graphite and will precipitate on the surface of the negative electrode, forming protruding dendrites. During the next charge, this protrusion is more likely to cause lithium precipitation. After dozens to hundreds of charge-discharge cycles, the dendrites will grow and eventually pierce the separator paper, causing a short circuit inside.
These are all reasons why lithium-ion battery packs can explode. Many factors contribute to the safety issues of lithium-ion batteries, and we cannot generalize. We must consider multiple aspects and minimize external factors that cause lithium battery problems. We hope relevant companies will improve their technology and testing capabilities. Users should also pay attention during use.
Why do lithium-ion batteries explode?
While lithium-ion batteries are generally very safe, they occasionally catch fire or explode. When this happens, such as the disastrous Samsung Galaxy Note 7 crash or HP's recent laptop recall, it's always big news. So what exactly happens, and why do batteries sometimes explode with a bang? Let's find out. Rechargeable lithium-ion batteries are widely used in laptops, mobile phones, tablets, and almost every modern device you own, as well as electric vehicles and airplanes, and are a vital component supporting the development of portable devices. Without lithium-ion batteries, I probably couldn't be writing this article in a coffee shop unless I kept my laptop plugged in. To understand why lithium-ion batteries sometimes fail, you need to understand what's happening under the cover. In every lithium-ion battery, there are two electrodes: a positively charged cathode and a negatively charged anode, separated by a thin layer of microplastics, preventing the two electrodes from contacting each other. When a lithium-ion battery is charged, lithium ions travel from the cathode through a separator and micropores filled with a conductive fluid to the anode. When the battery discharges, the reverse happens as lithium ions flow from the anode to the cathode. This is the reaction that powers a laptop.
Small batteries, like those in smartphones, typically have only one lithium-ion cell. Larger batteries, such as those in laptops, usually have six to twelve lithium-ion cells. Batteries in electric vehicles and airplanes can have hundreds of cells. What makes lithium-ion batteries so useful is also their ability to catch fire or explode. Lithium is excellent at storing energy. When released as a trickle, it can power your phone all day. But when it's released all at once, the battery explodes. Most lithium-ion battery fires and explosions are caused by short circuits. This happens when the plastic separator fails, allowing the anode and cathode to come into direct contact. Once these two electrodes come together, the battery begins to overheat.
