Aliphatic Hyperbranched Polycarbonates Solid Polymer Electrolytes with High Li-Ion Transference Number for Lithium...

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Solid polymer electrolytes (SPEs) are crucial for safer lithium-ion batteries.
• Traditional poly(ethylene oxide) (PEO)-based electrolytes face challenges in conductivity and electrochemical stability.

Purpose of the Study:

• To synthesize novel hyperbranched polycarbonate-poly(ethylene oxide) (HBPC-SEs) as advanced solid polymer electrolytes.
• To investigate the impact of polymer structure and salt concentration on ionic conductivity and electrochemical properties.
• To evaluate the performance of HBPC-SEs in lithium-ion battery applications.

Main Methods:

• Organo-catalyzed "A1"+"B2"-ring-opening polymerization for HBPC-SE synthesis.
• Temperature-dependent ionic conductivity measurements.
• Electrochemical stability window and Li+ transference number determination.
• Fabrication and testing of LiFePO4/HBPC1-SE-3/Li battery cells.

Main Results:

• HBPC-SEs with ether-carbonate alternating structures demonstrated superior ionic conductivity.
• The HBPC1-SE with 30 wt% LiTFSI achieved high ionic conductivities (e.g., 6.07 × 10-4 S cm-1 at 80 °C).
• Enhanced electrochemical stability (5 V) and Li+ transference number (0.53) were observed compared to traditional PEO electrolytes.
• The LiFePO4/HBPC1-SE-3/Li cell showed excellent rate capability and long-cycling performance (95% retention after 300 cycles).

Conclusions:

• Hyperbranched polycarbonate-poly(ethylene oxide) solid polymer electrolytes offer a promising alternative for high-performance lithium-ion batteries.
• The tailored polymer structure significantly enhances ionic conductivity and electrochemical stability.
• These HBPC-SEs enable batteries with improved safety, rate capability, and cycle life.