Clean Solid-Electrolyte/Electrode Interfaces Double the Capacity of Solid-State Lithium Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Solid-state lithium batteries are crucial for advanced energy storage solutions.
• Spinel-oxide cathode materials like LiNi0.5Mn1.5O4 offer high potential for high-performance batteries.
• Achieving stable and high-capacity cycling in these batteries is a key challenge.

Purpose of the Study:

• To investigate the impact of a clean Li3PO4/LiNi0.5Mn1.5O4 interface on solid-state lithium battery performance.
• To explore stable battery cycling between Li0Ni0.5Mn1.5O4 and Li2Ni0.5Mn1.5O4 phases.
• To understand the structural changes and Li migration within the electrode during cycling.

Main Methods:

• Fabrication of solid-state lithium batteries utilizing LiNi0.5Mn1.5O4 electrodes.
• Electrochemical cycling experiments to assess battery performance and stability.
• Interface characterization to confirm the presence and cleanliness of the Li3PO4/LiNi0.5Mn1.5O4 interface.
• Structural analysis to investigate phase changes and lithium distribution during cycling.

Main Results:

• Demonstrated stable battery cycling between Li0Ni0.5Mn1.5O4 and Li2Ni0.5Mn1.5O4 phases at 2.9 and 4.7 V vs Li/Li+.
• Achieved a doubling of battery capacity compared to conventional cycling between Li0Ni0.5Mn1.5O4 and Li1Ni0.5Mn1.5O4 phases.
• Observed an inhomogeneous distribution of the Li2Ni0.5Mn1.5O4 phase due to spontaneous Li migration post-interface formation.
• Confirmed the critical role of a contamination-free Li3PO4/LiNi0.5Mn1.5O4 interface.

Conclusions:

• A contamination-free Li3PO4/LiNi0.5Mn1.5O4 interface is essential for enhancing solid-state lithium battery capacity.
• Stable cycling between higher-order lithiation states (up to Li2) is achievable with a clean interface.
• Understanding Li migration dynamics is crucial for optimizing electrode design and battery performance.