The safety and reliability of lithium-ion batteries have always been the most important issue in the new energy industry.

However, when communicating with some netizens and even many industry insiders about the safety of lithium-ion batteries, the author discovered a common understanding difference that no one had noticed for a long time.

The safety that people talk about in daily life refers to whether the battery will spontaneously encounter safety issues during normal use (including abuse within normal range), such as spontaneous combustion, sudden explosion, or sudden power loss, leakage, and other abnormal usage.

From a technical perspective, safety refers to the severity of the battery's failure response under abuse conditions. The abuse conditions are carried out in accordance with the national standard GBT31485-2015 Safety Requirements and Experimental Methods for Power Batteries for Electric Vehicles, including over discharge, over charging, external short circuit, squeezing, and falling; Failure reactions include night leakage, fire, and explosion.

There is a certain correlation between these two, but they are not entirely the same. It is generally difficult for ordinary media professionals to distinguish the differences between the two. They extract paragraphs from some textbooks or academic reports, randomly piece them together, and publish them, causing serious misleading effects on ordinary consumers and even many industry insiders.

So, the author has specially compiled this article in an attempt to explain the differences between the two. (If you are interested, you can continue reading. If you are not interested, you can turn it off because the following discussion is technical and a bit boring, but I will try to explain it in a simpler way.)

We can divide the concept of "safety" into two definitions: "reliability" and "severity of failure response". "Reliability" refers to the risk level of normal use; The severity of the failure reaction refers to the severity of the reaction when tested according to the national standard experiment. This article will first introduce the composition and failure reaction mechanism of lithium-ion power batteries, and then provide a detailed analysis of the above two concepts.