Scientists Uncover the Mystery of Battery Degradation

Over time, battery capacity gradually decreases, which is why the battery life of old phones deteriorates. However, the mechanism behind this phenomenon has long remained incompletely understood.

An international research team from the University of Colorado Boulder in the United States has uncovered the potential mechanism of battery degradation, aiding scientists in designing longer-lasting, more efficient batteries. This breakthrough could extend the range of electric vehicles and drive the application of clean energy.

The research findings have been published in the journal Science.

Engineers have been striving for years to design cobalt-free lithium-ion batteries. So far, scientists have attempted to replace cobalt in lithium-ion batteries with other elements like nickel and magnesium. However, these batteries exhibit even higher self-discharge rates. Self-discharge refers to the reduction in stored energy within the battery due to internal chemical reactions, leading to a decrease in capacity over time. Due to self-discharge, the lifespan of most electric vehicle batteries is typically 7 to 10 years.

Previously, scientists believed that self-discharge in batteries occurred because not all lithium ions returned to the anode during charging, thereby reducing the number of charged ions available to generate current and provide power.

Using X-ray equipment at the Argonne National Laboratory, researchers discovered that hydrogen molecules in the battery electrolyte migrate to the cathode, occupying the positions of lithium ions. This reduces the space available for lithium ion binding, consequently weakening the battery's current and capacity.

With a deeper understanding of this mechanism, engineers can explore new methods to prevent battery self-discharge, such as coating the cathode with special materials to block hydrogen molecules or employing different electrolyte designs.