Stabilizing High-Voltage Cathodes via Ball-Mill Coating with Flame-Made Nanopowder Electrolytes.

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• LiMn1.5Ni0.5O4 (LMNO) spinel is a promising cobalt-free cathode material due to its low cost and high discharge voltage (4.7 V).
• Conventional liquid electrolytes decompose on LMNO surfaces at high oxidation states, and Mn2+ dissolution limits its practical application.
• Addressing these challenges is crucial for advancing high-performance energy storage.

Purpose of the Study:

• To mitigate electrolyte decomposition and Mn2+ dissolution in LMNO cathodes.
• To enhance the electrochemical performance and stability of LMNO-based battery systems.
• To explore the potential of nanopowder coatings for next-generation battery materials.

Main Methods:

• Ball-mill coating of LMNO with flame-made nanopowders (NPs) including LiAlO2, LATSP, and LLZO (5-20 wt%).
• Characterization using Transmission Electron Microscopy (TEM) and X-ray Photoelectron Spectroscopy (XPS).
• Electrochemical testing including cycling performance, rate capability, and energy density measurements.

Main Results:

• Coated LMNO composites maintained a single cubic spinel phase with island-type NP coatings.
• Nanopowder coatings effectively suppressed electrolyte decomposition and Mn2+ dissolution.
• LMNO + 20 wt% LiAlO2 showed a two-order-of-magnitude increase in Li+ diffusivity, 136 mAh g-1 capacity after 100 cycles (98% retention).
• 10 wt% LiAlO2 achieved 110 mAh g-1 at 10C with an energy density of ~640 Wh kg-1.

Conclusions:

• Nanopowder coating is an effective strategy to improve the stability and performance of LMNO cathodes.
• The protective layers formed by NPs enhance Li+ diffusion and cycle life.
• These findings suggest potential applications in advanced batteries, including all-solid-state batteries (ASSBs).