Lithium borate polycarbonates for high-capacity solid-state composite cathodes

Journal article

Improving composite cathode function is key to the success of the solid-state battery. Maximizing attainable cathode capacity and retention requires integrating suitable polymeric binders that retain a sufficiently high ionic conductivity and long-term chemo-mechanical stability of the cathode active material-solid-electrolyte-carbon mixture. Herein, we report block copolymer networks composed of lithium borate polycarbonates and poly(ethylene oxide) that improved the capacity (200 mAh g−1 at 1.75 mA cm−2) and capacity retention (94 % over 300 cycles) of all-solid-state composite cathodes with nickel-rich LiNi0.8Co0.1Mn0.1O2 cathode active material, Li6PS5Cl solid electrolyte, and carbon. Tetrahedral B(OR)2(OH)2− anions immobilized on the polycarbonate segments provide hydrogen-bonding chain crosslinking and selective Li-counterion conductivity, parameterized by Li-ion transference numbers close to unity (tLi+~0.94). With 90 wt % polycarbonate content and a flexible low glass transition temperature backbone, the single-ion conductors achieved high Li-ion conductivities of 0.2 mS cm−1 at 30 °C. The work should inform future binder design for improving the processability of cathode composites towards commercializing solid-state batteries, and allow use in other cell configurations, such as lithium-sulphur cathode designs.

Authors: Charlesworth, T; Yiamsawat, K; Gao, H; Rees, GJ; Williams, CK

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Wiley
• Journal: Angewandte Chemie International Edition
• Volume: 63
• Issue: 33
• Article number: e202408246
• Place of publication: Germany
• Publication date: 2024-07-11
• Acceptance date: 2024-05-31
• DOI: 10.1002/anie.202408246
• EISSN: 1521-3773
• ISSN: 1433-7851
• Pmid: 38819775
• Language: English
• Keywords: batteries; polymer electrolytes; ring-opening (co)polymerization; materials science; polymerization