Melamine-Regulated Ceramic/Polymer Electrolyte Interface Promotes High Stability in Lithium-Metal Battery

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Composite electrolytes combine organic and inorganic materials for all-solid-state Li-metal batteries.
• Interfacial energy mismatch between ceramic (LAGP) and polymer (PEO) electrolytes causes poor contact and space charge layer formation.
• This limits the performance of solid-state batteries.

Purpose of the Study:

• To develop a transition layer to improve interfacial contact and electrochemical properties of LAGP/PEO composite electrolytes.
• To enhance the performance and stability of all-solid-state Li-metal batteries.

Main Methods:

• A melamine (MA) transition layer was introduced between LAGP and PEO.
• Electron transfer from LAGP to MA's triazine ring was analyzed.
• The effect of MA on Li-salt anion stabilization and Li+ dissociation was investigated.
• Fabrication and testing of symmetric Li/Li cells and full cells (Li|PEO-MA@LAGP|LFP and Li|PEO-MA@LAGP|NCM523).

Main Results:

• Melamine layer formation via electron transfer ensures intimate contact and mechanical stability between LAGP and PEO.
• MA stabilizes Li-salt anions, reduces interfacial decomposition, and promotes Li+ dissociation.
• Superior ionic conductivity and interfacial stability were achieved.
• Symmetric Li/Li cells demonstrated stable Li plating/stripping for over 1300 hours.
• All-solid-state cells showed improved cycling stability, with one configuration lasting 5 times longer than controls.

Conclusions:

• The melamine transition layer effectively addresses interfacial challenges in LAGP/PEO composite electrolytes.
• This strategy significantly enhances ionic conductivity, interfacial stability, and overall battery performance.
• The developed composite electrolyte is a promising candidate for high-performance all-solid-state Li-metal batteries.