Dual-Descriptor Tailoring: Rational Solvent Molecule Tuning Enables High-Voltage Li-Ion Batteries

Abstract

Electrolyte engineering to enhance the cathode-electrolyte interface stability is widely recognized as a promising strategy for achieving high-voltage lithium-ion batteries, which are currently hindered by the meta-stable surface of lithium-rich layered oxides. Despite significant progress in electrolyte development, clear design guidelines for high-voltage electrolytes remain lacking, making solvent selection unpredictable. Here, a dual-descriptor tailoring concept based on Mulliken charge (adsorption) and Laplacian bond order (antioxidation) to identify ideal solvent molecules for high-voltage electrolytes is proposed. This concept stabilizes meta-stable transition metal atoms in surface tetrahedral interstices through interactions between bottom solvent molecules and cathode dangling bonds. Acetonitrile (AN) is eventually selected as a promising bottom solvent that interacts strongly with unstable surface bonds, improving interfacial stability. Consequently, the prepared 0.6 Ah graphite||LCO pouch cell using AN-based electrolyte maintained a remarkable 80% capacity retention after 900 cycles with an average Coulombic efficiency of 99.92% at high cut-off voltage. This work revisits the interfacial stability mechanism across different electrolyte classes, where strong solvent adsorption mitigates the instability of the meta-stable Co spin state, reduces surface band overlap, and alleviates the instability of lattice oxygen at the interface. This dual-descriptor-guided design opens a new avenue for high-voltage Li-ion batteries is believed.