Enhancing Lithium-Ion Diffusion Kinetics in a 3D Lithium Metal Host through Surface Modification with Hierarchical Multimetal Oxides.

Lithium metal is a promising anode candidate to achieve high-energy-density lithium metal batteries (LMBs) due to its ultrahigh theoretical capacity (3860 mA h g-1) and low electrochemical potential (-3.04 V vs S.H.E). Unfortunately, the commercialization of lithium metal anodes is hindered by the growth of Li dendrites and the infinite Li volume changes during the cycling process. Herein, we introduce a 3D hierarchical multimetal oxide nanowire framework as a current collector for Li metal anodes. The hierarchical metal oxide layers of CoO and CuxO provide abundant Li nucleation sites and thus offer uniform Li plating and regulate Li nucleation during the charge/discharge process. As a result, half cells present a prolonging Coulombic efficiency of 97% at 1 mA cm-2 with a capacity of 1 mA h cm-2 for over 300 cycles. A stable cyclability of symmetric cells is demonstrated under 1 mA cm-2 with a capacity of 1 mA h cm-2 for 1500 h. Full cells paired with an LFP cathode show a stable capacity of 131.5 mA h g-1 with a capacity retention of 92% for 200 cycles. These results will shed insights into the design of 3D Cu current collectors for high-performance composite Li metal anodes.

Wrapping silicon microparticles by using well-dispersed single-walled carbon nanotubes for the preparation of high-performance lithium-ion battery anode.

Silicon microparticles (SiMPs) show considerable promise as an anode material in high-performance lithium-ion batteries (LIBs) because of their low-cost starting material and high capacity. The failure issues associated with the intrinsically low conductivity and significant volume expansion of Si have largely been resolved by designing silicon/carbon composites using carbon nanotubes (CNTs). The CNTs are important in terms of stress dissipation and the conductive network in Si/CNT composites. Here, we synthesized a SiMP/2D CNT sheet wrapping composite (SiMP/CNT wrapping) via a facile freeze-drying method with the use of highly dispersed single-walled CNTs. In this work, the well-dispersed CNTs are easily mixed with Si, resulting in effective CNT wrapping on the SiMP surface. During freeze-drying, the CNTs are self-assembled into a segregated 2D CNT sheet morphology via van der Waals interactions. The resulting CNT wrapping shows a unique wide range of conductive networks and mesh-like CNT sheets with void spaces. The SiMP/CNT wrapping 9 : 1 electrode exhibits good rate and cycle performance. The first charge/discharge capacity of SiMP/CNT wrapping 9 : 1 is 3160.7 mA h g-1/3469.1 mA h g-1 at 0.1 A g-1 with superior initial coulombic efficiency of 91.11%. After cycling, the SiMP/CNT wrapping electrode shows good structural integrity with preserved electrical conductivity. The superior electrochemical performance of the SiMP/CNT wrapping composite can be explained by an extensive conductive CNT network on the SiMPs and facile lithium-ion diffusion via mesh-like CNT wrapping.