Dynamic Metal-Ligand Coordinated Self-Healing Polymer Electrolytes for Lithium-Ion Batteries: Correlating Coordination Mechanisms with Electrochemical Properties

It is a big challenge for polymer electrolyte-based lithium-ion batteries (LIBs) because poor interfacial contact induces low conductivity and uncontrolled lithium dendrite growth. Herein, metal-ligand coordination strategy with metal ions, including Zr⁴⁺, Cu²⁺, and Zn²⁺, is demonstrated to formulate polymer electrolytes with dynamic cross-link sites for high-performance LIBs. It is investigated that how the metal ions with specified outer electron configurations and charge transfer behavior affect the transport of lithium ions and the electrochemical stability of the polymer electrolytes. As compared to Cu²⁺ and Zn²⁺, Zr⁴⁺-coordinated electrolytes not only exhibit superior electrochemical stability due to their high-coordination-number and chemo-stability, but also show more uniform lithium (Li) deposition to prevent dendrite growth owing to their ligand-to-metal charge transfer mechanism and uniform electron distribution. Notably, Zr⁴⁺-coordinated electrolyte-based Li//Li cells achieve a stable long-term cycle (>4000 h under 0.1 mA cm⁻²), and form stable solid–electrolyte interphase with excellent electronic insulation and enhanced ionic conductivity. Furthermore, Zr⁴⁺-coordinated electrolyte enables over 500 cycles at 3 C in Li//LiNi_0.8Co_0.1Mn_0.1O₂, and maintains 81.3% capacity retention after 3000 cycles in Li//LiFePO₄. This study offers a new design strategy for interfacial polymer electrolytes for LIBs with high safety and energy density.