Synthesis And Electrochemical Performance Of CoGeO₃ Hybrids,MnGeO₃ Hybrids,CoSnO₃ Hybrids As Anode Materials For Lithium Ion Battery

In this paper, we focus our attention on ternary transitional oxides, such as CoGeO₃, MnGeO₃, CoSnO₃ via solid-state methods and coprecipitation reaction. As a result, sharp capacity fading occurred during the Li-cycling process due to huge volume expansion. Herein we introduced graphene and Arabic gum into Co GeO₃ to fabricate hybrids in the hope of improving electrochemical performance. A various methods such as XRD, TEM, XPS, Raman, FT-IR have been utilized to inspect the compositions and microstructures of these materials. What’s more, galvanostatic cycling test, CV, EIS are also used to examine the electrochemical performance of those mentioned materials.In this work, a facile route to dually-protected CoGeO₃ nanoparticle hybrids has been established. Graphene-covered and carbon-encapsulated CoGeO₃ nanoparticles were utilized as Li ion battery anode materials. Such a rationally designed structure could effectively accommodate the volume expansion of CoGeO₃ nanoparticles during Li-cycling. As a consequence, remarkable electrochemical performances, i.e. high first discharge capacity（2000 mAh g-1）, favorable cyclic performances（782 mAh g-1 after 50 cycles and 638.7 mAh g-1 after 100 cycles, respectively, under 200 mA g-1）, have been garnered for CoGCs/C-4 composite electrodes, whose electrochemically active materials contained 20.3 wt% graphene and 4.2 wt% pyrolytic carbon. These advantageous attributes make dually-protected CoGeO₃ particles the potential anode materials for LIBs.MnGeO₃ powders were synthesized via solid-state methods under 1100 ℃ for 12 h using Mn（CH3COO）2 and GeO2 powder as raw materials. Subsequently, MnGeO₃ powder reacted with graphene oxide via hydrothermal methods to yield MnGeO₃ and graphene hybrids. MnGeO₃/G-16 nanocomposites（compring 15.88% graphene） exhibited excellent electrochemical peformances, i.e. high capacity of 1570 mAh g-1 at the first cycle under the current density of 200 m A g-1. When cycled to 50 th, the discharge specific capacity decreased to 532 mAh g-1 and charge specific capacity decreased to 524 mAh g-1. The coulombic efficiency was about 98.5%, close to 100%.CoSO4·7H2O powder was mixed with Na2SnO₃·3H2O powder under constant stirring to gain pink precipitation, namely precursor CoSn（OH）₆. CoSn（OH）₆ powder afterward reacted with graphene oxide via hydrothermal methods to get the hybrids of CoSn（OH）₆ and graphene. After removing water in the the hybrid under 350 ℃ in nitrogen atmosphere, CoSnO₃ and graphene composites have been gathered. Electrochemical capacity of CoSnG-C（compring 17.01% graphene and 3.27% pyrolysis carbon from Arabic gum） had largely been improved. CoSnG-C composites delivered a discharge specific capacity of 647 mAh g-1 and charge specific capacity of to 630 mAh g-1 when cycled to 50 th under the current density of 200 mA g-1, with about 97.4% coulombic efficiency.