Low Resistance and High Stable Solid-Liquid Electrolyte Interphases Enable High-Voltage Solid-State Lithium Metal Batteries

Solid-state batteries (SSBs) with addition of liquid electrolytes are considered to possibly replace the current lithium-ion batteries (LIBs) because they combine the advantages of benign interfacial contact and strong barriers for unwanted redox shuttles. However, solid electrolyte and liquid electrolyte are generally (electro)-chemically incompatible and the resistance of the newly formed solid-liquid electrolyte interphase (SLEI) appears as an additional contribution to the overall battery resistance. Herein, a boron, fluorine-donating liquid electrolyte (B, F-LE) is introduced into the interface between the high-voltage cathode and ultrathin composite solid electrolyte (CSE), which is fabricated by adhering a high content of nanosized Li6.4La3Zr1.4Ta0.6O12 (LLZTO) with poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), to generate a low resistance and high stable SLEI in situ, giving a stable high-voltage output with a reinforced cathode|CSE interface. B, F-LE, consisting of a highly fluorinated electrolyte with a lithium bis(oxalato)borate additive, exhibits good chemical compatibility with CSE and enables rapid and uniform transportation of Li+, with its electrochemically and chemically stable interface for high-voltage cathode. Eventually, the B, F-LE assisted LiNi0.6Co0.2Mn0.2O2|Li battery displays the enhanced rate capability and high voltage cycling stability. The findings provide an interfacial engineering strategy to turn SLEI from a real culprit into the savior that may pave a brand-new way to manipulate SLEI chemistry in hybrid solid-liquid devices.

Automated summary

The study introduced a boron, fluorine-donating liquid electrolyte to enhance the performance of solid-state batteries, providing a new interfacial engineering strategy to improve the stability and resistance of solid-liquid electrolyte interfaces.