A Composite Structure of Cu₃Ge/Ge/C Anode Promise Better Rate Property for Lithium Battery

Abstract

Much effort has been made to search for high energy and high power density electrode materials for lithium ion batteries. Here, a composite structure among Ge, C and Cu3Ge in Cu3Ge/Ge/C materials with a high rate performance of lithium batteries has been reported. Such Cu3Ge/Ge/C composite is synthesized through the in-situ formation of Ge, C and Cu3Ge by one-pot reaction. Density function theory (DFT) calculations and electrochemical impedance spectroscopy (EIS) suggest a higher electron mobility of the hibrid Cu3Ge/Ge/C composites through the in-situ preparation. As a result, remarkable charge rate over 300 C (fast delithiated capability) and outstanding cycling stability (≈0.02% capacity decay per cycle for 500 cycles at 0.5 C) are achieved for the Cu3Ge/Ge/C composites anode. These Cu3Ge/Ge/C composites demonstrate another perspective to explore the energy storage materials and should provide a new pathway for the design of advanced electrode materials.

Facile Synthesis of Peapod‐Like Cu3Ge/Ge@C as a High‐Capacity and Long‐Life Anode for Li‐Ion Batteries

“…It is worth noting that Cu 3 Ge is an inactive phase that does not have Li‐ion storage capacity, in other words, it does not provide a capacity contribution during charge and discharge cycles in the current Cu 3 Ge/Ge@C anode. The previous work used in situ XRD technology to prove the presence of the Cu 3 Ge phase during one or more cycles, indicating that it is an inert phase . For the purpose of making this conclusion more convincing and direct, home‐made Cu 3 Ge was used to mix with conductive carbon and sodium alginate, and assembled into a half‐cell in the same way as the Cu 3 Ge/Ge@C composite.…”

“…The addition of an electrochemically inert phase to aG ea node has been considered to enhance its performance for LIBs. [30][31][32] Some inactive elements in these GeÀM( M: metal) alloys not only increase the electric conductivity of the Ge anode (e.g.,c ompared with the value of 1.45 Scm À1 for pure Ge, Cu 3 Ge has ar ather high electric conductivity of 1.0-1.67 10 7 Scm À1 ), but can also act as ab arrier, which can reduce the volume expansion in the charginga nd discharging processes. [33] Herein, through introductiono ft he inactive alloyinge lement Cu and ag ood conductive carbonm atrix, an ovel structure of ap eapod-like Cu 3 Ge/Ge@C anode was designed and synthesizedt hrough facile annealingo fC uGeO 3 @dopamine in the H 2 /Ar atmosphere.…”

“…The previousw ork used in situ XRD technology to prove the presence of the Cu 3 Ge phase during one or more cycles,i ndicating that it is an inert phase. [30] For the purpose of making this conclusion more convincing and direct, home-made Cu 3 Ge was used to mix with conductive carbon and sodium alginate, and assembled into ah alf-cell in the same waya st he Cu 3 Ge/Ge@Cc omposite. The XRD pattern shown in Figure S5 (Supporting Information) indicates that pure Cu 3 Ge was indeeds ynthesized.…”

“…Recently, the alloying strategy of group IV elements has attracted much attention owing to its effective action on enhancing electrochemical performance, for example, NiSi 2 /Si/C, FeSi 2 @Si, and so on. The addition of an electrochemically inert phase to a Ge anode has been considered to enhance its performance for LIBs . Some inactive elements in these Ge−M (M: metal) alloys not only increase the electric conductivity of the Ge anode (e.g., compared with the value of 1.45 S cm −1 for pure Ge, Cu 3 Ge has a rather high electric conductivity of 1.0–1.67×10 7 S cm −1 ), but can also act as a barrier, which can reduce the volume expansion in the charging and discharging processes .…”

Improving the Performance of Micro‐Silicon Anodes in Lithium‐Ion Batteries with a Functional Carbon Nanotube Interlayer

“…Raman spectroscopy was performed to determine the composition and bond structure of the soft MWCNTs membrane at a wavelength of 514 nm (Figure c). The broad peak located at near 1580 cm −1 is related to typical vibration mode of the graphite G‐band and near 1350 cm −1 related to the D‐band of carbon ,. The strong Raman signals of the D and G bands are thought to stem from MWCNTs, which are randomly distributed in the surface of the membrane.…”