In Situ Polymerized Polysiloxane Enables Cohesive Solid-Electrolyte Interphase for Practical Lithium-Metal Batteries.

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Mechanical instability of the nanostructured solid-electrolyte interphase (SEI) on lithium (Li)-metal anodes limits battery cycle life.
• SEI cracking and regeneration occur due to Li-metal anode volume fluctuations during cycling.

Purpose of the Study:

• To develop a cohesive SEI nanostructure to enhance mechanical stability.
• To improve the cycle life and practical applicability of Li-metal batteries.

Main Methods:

• In situ formation of polysiloxane from hexamethylcyclotrisiloxane (CTS) electrolyte additive to glue inorganic nanoparticles in SEI.
• Characterization of SEI mechanical properties, including elastic modulus.
• Electrochemical cycling of Li-metal coin and pouch cells.

Main Results:

• The cohesive SEI demonstrated a 109% increase in elastic modulus, improving tolerance to anode volume fluctuations.
• Li-metal coin cells with glued SEI achieved 320 cycles, compared to 183 cycles for routine SEI.
• A prototype Li-metal pouch cell achieved 175 cycles and demonstrated high-rate discharge capabilities.

Conclusions:

• The proposed strategy effectively reinforces the SEI, enhancing mechanical stability and battery performance.
• This generalizable approach advances the development of high-energy-density Li-metal batteries for practical applications.
• The reinforced SEI enables superior cycling stability and high-rate discharge, powering devices like micro-unmanned aerial vehicles.