LLO materials provide a 20% increase in energy density over traditional nickel-based cathodes by substituting nickel and cobalt with lithium and manganese. This makes them a cost-effective and eco-friendly alternative for electric vehicles and energy storage systems (ESS). However, widespread adoption has been hindered by capacity fading and voltage decay during repeated charge-discharge cycles.
Addressing these challenges, the POSTECH researchers focused on the destabilizing effect of oxygen release during battery operation. By improving the chemical stability of the cathode-electrolyte interface, they minimized oxygen release, a primary cause of structural instability. Enhancing the electrolyte composition, they achieved an 84.3% energy retention rate after 700 cycles, compared to just 37.1% retention after 300 cycles with conventional electrolytes.
The team also identified structural surface changes in LLO as critical to stability and lifespan. By targeting these changes, they reduced detrimental reactions such as electrolyte decomposition, further improving battery performance.
"Using synchrotron radiation, we analyzed chemical and structural differences between the cathode surface and its interior," said Professor Jihyun Hong. "We discovered that surface stability is essential for maintaining the material's structural integrity and performance. This work opens new pathways for developing advanced cathode materials."
The research highlights the critical importance of optimizing both electrolyte composition and cathode surface structure to overcome the limitations of LLO materials, paving the way for longer-lasting, high-performance lithium-ion batteries.
Research Report:Decoupling capacity fade and voltage decay of Li-rich Mn-rich cathodes by tailoring surface reconstruction pathways
