Lithium Borate Polycarbonates for High-Capacity Solid-State Composite Cathodes

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Solid-state batteries require advanced composite cathodes for improved performance.
• Polymeric binders are crucial for maintaining ionic conductivity and chemo-mechanical stability in composite cathodes.

Purpose of the Study:

• To develop and evaluate novel block copolymer networks as binders for solid-state battery composite cathodes.
• To enhance the capacity, capacity retention, and ionic conductivity of composite cathodes.

Main Methods:

• Synthesis of block copolymer networks comprising lithium borate polycarbonates and poly(ethylene oxide).
• Fabrication and electrochemical testing of all-solid-state composite cathodes using nickel-rich LiNi0.8Co0.1Mn0.1O2, Li6PS5Cl, and carbon.
• Characterization of ionic conductivity and Li-ion transference numbers.

Main Results:

• The block copolymer binders improved cathode capacity to 200 mAh g-1 at 1.75 mA cm-2 and capacity retention to 94% over 300 cycles.
• The binders exhibited high Li-ion conductivities (0.2 mS cm-1 at 30°C) and Li-ion transference numbers close to unity (tLi+ ~0.94).
• Tetrahedral anions provided hydrogen-bonding crosslinking and selective Li-ion conductivity.

Conclusions:

• Block copolymer networks are effective binders for enhancing solid-state battery composite cathode performance.
• The developed binders offer a promising route for improving the processability and commercial viability of solid-state batteries.
• These findings can inform future binder designs for various battery configurations, including lithium-sulfur systems.