Toward High-performance Lithium-ion Batteries via A New Germanium-based Anode Material

In comparison to traditional and single metal oxides, multielement metal oxides exhibit enhanced specific capacity, buffer the volume expansion, and facilitate charge transfer or ion diffusion, which are regarded as promising anode materials for lithium-ion batteries (LIBs). Herein, we present a new carbon coating multielement metal oxide calcium titanium germanate (CaTiGeO5@C, donated as CTGO@C) with proper elemental composition. The CTGO@C anode exhibits an initial discharge specific capacity of 864.8 mAh g–1, corresponding to an initial Coulombic efficiency of 62% at 50 mA g–1. Moreover, the capacity retention rate is 55% after 100 cycles at 200 mA g–1. Importantly, the CTGO@C anode maintains its functionality under both low temperature (−20 °C) and high temperature (60 °C) conditions. When assembled into a CTGO@C||LiNi0.5Mn1.5O4 full cell, the energy density of the full cell is 352.8 Wh kg–1 with a maximum power density of 1149.2 W kg–1. The electronic properties of CTGO@C nanoparticles were investigated using density functional theory (DFT) calculations. Ex-situ X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and extended X-ray absorption fine structure (EXAFS) measurements elucidate a synergistic combination of conversion and alloying reaction mechanism in CTGO@C. The work provides a new avenue for designing metal oxide anodes for high-energy density, wide-temperature range LIBs.