Tuning Interphasial Chemistry with Titanium–Oxo Clusters for High-Energy-Density Lithium Metal Batteries

Trace amounts of water in commercial carbonate-based electrolytes produce hydrogen fluoride (HF), accelerating the corrosion of high-nickel cathodes and the dissolution of transition metal ions. This severely damages electrode-electrolyte interphase stability and intensifies electrolyte decomposition, causing rapid capacity degradation and failure of high-voltage lithium metal batteries (HVLMBs). Herein, we propose polycaprolactone diol-modified titanium-oxo clusters (TOC-PCL) as a multifunctional electrolyte additive to tune interphasial chemistry on high-nickel cathodes and Li anodes. Trace H₂O and HF are effectively eliminated via TOC-PCL hydrolysis in the electrolyte, followed by in situ construction of stable electrode-electrolyte interphase enriched with inorganic components (TiO₂, Li₂TiF₆, and LiF) during cycling, substantially inhibiting interphase chemical corrosion. As a result, the LiNi_0.8Co_0.1Mn_0.1O₂||Li cell (NCM811:12 mg cm^-2) with the TOC-PCL additive delivered over 1000 cycles at 1 C with 80.4% capacity retention, as well as even under ultrahigh cathode loading (41 mg cm^-2) and nickel content (96 wt %). The 1.6-Ah NCM811 pouch cell with a 50 μm Li thickness exhibited a high energy density (401.6 Wh kg^-1) over 150 cycles. This universal strategy of TOC-PCL multifunctional additives was extended to 3-Ah NCM811||silicon-carbon pouch cells, resulting in considerably prolonged cycling life of 500 cycles at 0.5 C. This study highlights the broad application prospects of metal-oxygen clusters, providing new insights for developing HVLMBs with high energy density and long cycle life.