LG Energy Solution said on the 7th that it has secured a key technology to improve the stability of lithium-manganese-rich (LMR) batteries through joint research with a team led by Professor Lim Jong-woo in the Department of Chemistry at Seoul National University.
The research results, recognized for technical achievement and academic value, were published in the internationally renowned journal Nature Communications.
The joint research team identified the causes of gas generation and capacity fade that occur during LMR battery charging and discharging, and developed optimal operating conditions for large cells to control them.
LMR is a next-generation cathode material that can drastically reduce material expense by using low-cost manganese as the main raw material without cobalt. It also uses not only transition metals such as nickel and manganese but oxygen inside the material for energy storage, enabling high energy density.
On the other hand, if the oxygen oxidized during charging does not fully recover during discharge, it can cause internal structural damage and gas generation, which, in large cells for electric vehicles with limited internal free space, leads to increased internal pressure and performance degradation and has long been considered the biggest challenge to commercializing LMR.
The joint research team precisely analyzed the redox behavior of oxygen under different charge-discharge conditions and found that the key variables governing oxygen recovery include not only the upper cutoff voltage for charging but also the lower cutoff voltage for discharging.
In fact, when the upper cutoff voltage for charging was lowered from 4.6 volts (V) to 4.3 V, the reduction rate of oxidized oxygen improved significantly from 86% to 97%. They also confirmed that when discharging proceeded to 2.0 V instead of the conventional 3.0 V, the oxygen recovered to nearly its original state.
Based on this analysis, researchers at LG Energy Solution redesigned the operating voltage range and activation (formation) process conditions for a 40 Ah-class LMR large cell. In particular, they applied a process that lowers the temperature during the activation stage to effectively suppress gas generation characteristic of large cells.
As a result, the 40 Ah-class LMR large cell with optimized conditions maintained 92.2% of its initial energy even after 883 charge-discharge cycles. This demonstrated the commercial potential of LMR materials at the large-cell level suitable for installation in actual electric vehicles, beyond small cells.
Lim Jong-woo, a professor at Seoul National University, said, "This study identified the causes of LMR battery degradation from the perspective of oxygen reversibility and showed that cell stability can be improved by electrochemical protocol design alone," adding, "We confirmed that to ensure the long-term stability of LMR batteries, discharge conditions as well as charge conditions must be considered comprehensively."
An LG Energy Solution official said, "This study effectively suppresses gas generation, a key challenge for LMR batteries, showing that stable battery life can be secured even in large cells," adding, "This has laid an important foundation to accelerate growth in the next-generation LMR battery market."