锂电池绝缘缺陷检测

中文概述：本文说明为何以及如何在锂电池生产线上检测绝缘缺陷——通过在应绝缘的部位施加电压、观察是否漏电，来判断金属屑或隔膜划伤等早期缺陷。正文为英文原文。

Detection of Insulation Defects in Lithium-ion Batteries

By measuring the insulation resistance of lithium-ion battery cells before electrolyte is poured in, it is possible to detect metallic foreign matter and separator damage at an early stage of production.

Problem

For LIBs, insufficient insulation resistance means areas that should be insulated are not, reducing battery life and raising combustion risk. The main causes are metallic foreign contaminants and separator damage. Metal slivers from electrode cutting act like fine needles piercing the electrode and separator, while scratches or cuts from production reduce insulation. Both create paths where current should not flow, and the resulting heat can lead to ignition.

Solution

One simple way to check is to see how electricity flows: apply a voltage across areas that should be insulated; if current flows too readily, a defect exists. This is the insulation resistance test. From a manufacturer's view, finding defects early avoids wasting good parts on faulty ones; the earliest effective step is after cell assembly but before electrolyte filling (applying voltage afterward damages the battery).

Testing points

On a prismatic cell, the two electrode sheets are stacked with a separator, rolled, tab-welded, and enclosed. Insulation resistance must be measured at three points: between the two electrodes (before electrolyte filling) and between the enclosure and each electrode (after filling).