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NSFC [2093110426, 21003102, 21021002, 20833005]; "973" program [209CB220102]; "863" program [2011AA11A254]; Solid State and Materials Chemistry Program of the Division of Materials Research at the U.S. National Science Foundation

NSFC [2093110426, 21003102, 21021002, 20833005]; "973" program [209CB220102]; "863" program [2011AA11A254]

Three-dimensional porous Cu film is prepared for the first time by electroless plating. Sn–Co alloy is electrodeposited on the porous Cu film to fabricate porous Sn–Co alloy electrode. SEM images evidence that porous Sn–Co alloy electrode presents a three-dimensional porous structure. XRD results show that the Sn–Co alloy electrode comprises pure Sn and CoSn 2 phases. Electrochemical discharge/charge results show that the three-dimensional porous Sn–Co alloy electrode exhibits much better cycleability than planar Sn–Co alloy electrode, with first discharge capacity and charge capacity of 636.3 and 528.7 mAh g −1 , respectively. After 70th cycling, capacity retention is 83.1% with 529.5 mAh g −1 . The lithiation and delithiation processes during first discharge and charge were investigated by electrochemical impedance spectroscopy (EIS). EIS results together with differential capacity curves describe the process of SEI formation, charge transfer and phase transformation in the alloy electrode in the first discharge, and phase transformation during charge at delithiation potential.

Major State Basic Research Development Program of China [2009CB220102]; NSFC [20773102, 20833005]; Xiamen University [J0630429]

A novel ternary Sb–Co–P alloy electrode was prepared by electroplating on copper current collector as a promising negative electrode material for lithium-ion batteries. The structural and morphological features of the Sb–Co–P alloy were characterized by powder X-ray diffraction (XRD) and scanning electron microscope (SEM). The as-prepared alloy electrode exhibits a high specific capacity and an excellent cycleability. The initial discharge and charge capacities of the Sb–Co–P alloy anode were measured 700 and 539 mA h g−1, respectively. The results suggest that the Sb–Co–P alloy material obtained by the electrodeposition shows a good candidate anode material for lithium-ion batteries. Keywords: Sb–Co–P alloy, Anode, Electroplating, Lithium-ion batteries, Electrodeposition

Porous Cu was fabricated by electrodeposition through a kinetic template of hydrogen bubbles. The product was subsequently annealed to increase its structural stability. The Cu-Sn alloy was then electrodeposited onto porous Cu which served as a current collector. X-ray diffraction (XRD) studies ascertained that the composition of the Cu-Sn alloy was Cu6Sn5 and scanning electron microscopy (SEM) investigations showed a three-dimensional (3D) porous structure of the electrode. The first charge/discharge capacities of the Cu6Sn5 alloy electrode were measured respectively at 735 and 571 mAh·g-1, and a good retention of the capacities has been determined. Interfacial properties of the Cu6Sn5 alloy electrode in a commercial electrolyte were also studied by electrochemical impedance spectroscopy (EIS).

The formation process of solid electrolyte interphase(SEI) film on spinel LiMn2O4 electrode surface was studied by electrochemical impedance spectroscopy(EIS) during the initial storage in 1 mol/L LiPF6-EC:DMC:DEC electrolyte and in the subsequent first charge-discharge cycle. It has been demonstrated that the SEI film thickness increased with the increase of storage time,and spontaneous reactions occurring between spinel LiMn2O4 electrode and electrolyte can be prevented by the SEI film. In the first charge-discharge cycle succeeding the storage, the electrolyte oxidation coupled with Li-ion insertion is evidenced as the main origin to increase the resistance of SEI film. The results also confirm that the variations of the charge transfer resistance(Rct) with the electrode potential(E) can be well described using a classical equation. Keywords Li-ion batteries; SEI film; Electrochemical impedance spectroscopy; Spinel LiMn2O4

The storage behavior and the first delithiation of LiCoO2 electrode in 1 mol/L LiPF6-EC:DMC:DEC electrolyte were investigated by electrochemical impedance spectroscopy (EIS). It has found that, along with the increase of storage time, the thickness of SEI film increases, and some organic carbonate lithium compounds are formed due to spontaneous reactions occurring between the LiCoO2 electrode and the electrolyte. When electrode potential is changed from 3.8 to 3.95 V, the reversible breakdown of the resistive SEI film occurs, which is attributed to the reversible dissolution of the SEI film component. With the increase of electrode potential, the thickness of SEI film increases rapidly above 4.2 V, due to overcharge reactions. The inductive loop observed in impedance spectra of the LiCoO2 electrode in Li/LiCoO2 cells is attributed to the formation of a Li1−x CoO2/LiCoO2 concentration cell. Moreover, it has been demonstrated that the lithium-ion insertion-deinsertion in LiCoO2 hosts can be well described by both Langmuir and Frumkin insertion isotherms, and the symmetry factor of charge transfer has been evaluated at 0.5.

A novel nanoarchitectured Sn–Sb–Co alloy electrode is reported, which was prepared by direct electrodeposition on a Cu nanoribbon array in order to target the rapidly fading capacity and the poor rate-capability issues of Sn based materials for Li-ion batteries. The SEM images indicate a three-dimensional (3D) nanoarchitectured Sn–Sb–Co alloy with an array structure. Electrochemical measurements show that the 3D nanoarchitectured Sn54Sb41Co5 alloy electrode exhibits a reversible capacity as high as 512.8 mA h g−1 at 0.2 C (1 C = 650 mA g−1) after 150 cycles. Furthermore, the 3D nanoarchitectured Sn54Sb41Co5 anode can deliver a high reversible capacity (275 mA h g−1) up to the 80th cycle at a high discharge–charge rate of 23 C (∼15 A g−1). These outstanding electrochemical properties are attributed to the unique nanoarchitectures of the Sn54Sb41Co5 electrodes, making them an excellent anode material.