Toward High-performance\nLithium-ion Batteries via\nA New Germanium-based Anode Material

Abstract

In comparison to traditional and single metal oxides,\nmultielement\nmetal oxides exhibit enhanced specific capacity, buffer the volume\nexpansion, and facilitate charge transfer or ion diffusion, which\nare regarded as promising anode materials for lithium-ion batteries\n(LIBs). Herein, we present a new carbon coating multielement metal\noxide calcium titanium germanate (CaTiGeO₅@C, donated as\nCTGO@C) with proper elemental composition. The CTGO@C anode exhibits\nan initial discharge specific capacity of 864.8 mAh g^–1, corresponding to an initial Coulombic efficiency of 62% at 50 mA\ng^–1. Moreover, the capacity retention rate is 55%\nafter 100 cycles at 200 mA g^–1. Importantly, the\nCTGO@C anode maintains its functionality under both low temperature\n(−20 °C) and high temperature (60 °C) conditions.\nWhen assembled into a CTGO@C||LiNi_0.5Mn_1.5O₄ full cell, the energy density of the full cell is 352.8 Wh\nkg^–1 with a maximum power density of 1149.2 W kg^–1. The electronic properties of CTGO@C nanoparticles\nwere investigated using density functional theory (DFT) calculations.\nEx-situ X-ray diffraction (XRD), X-ray photoelectron spectroscopy\n(XPS), and extended X-ray absorption fine structure (EXAFS) measurements\nelucidate a synergistic combination of conversion and alloying reaction\nmechanism in CTGO@C. The work provides a new avenue for designing\nmetal oxide anodes for high-energy density, wide-temperature range\nLIBs.