Germanium-based materials possess promising potential as novel anode materials for high performance lithium-ion batteries (LIBs). However, the considerably huge volume change causes rapid capacity fade during the charge-discharge process. A simple strategy was devised to prepare porous GeO 2 nanoparticles via thermal decomposition of (Hbipy) 2 [Ge(C 2 O 4 ) 3 ]·2H 2 O in air atmosphere. As an anode material for LIBs, it shows superior electrochemical performance in comparison with commercial GeO 2 microparticles . The initial discharge capacity of porous GeO 2 nanoparticles is high to 2578.8 mA h/g, and it still retained 581.9 mA h/g after 100 cycles. Even at 2 A/g, a reversible discharge capacity of 184.2 mA h/g is yet obtained. The superior lithium storage performances should be chalked up to the positive synergism of nanoscale, porous structure and low crystalline nature, which effectively retard the huge volume change of GeO 2 and are beneficial for fast diffusion of lithium ions during cycling.
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.
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