Spatially heterogeneous carbon-fiber papers as surface dendrite-free current collectors for lithium deposition

SummaryDespite the high energy density, the lithium metal electrode has been plagued for decades with a dendrite growth problem that can result in a battery thermal runaway. Here, we introduce anisotropic spatially heterogeneous three dimensional (3D) current collectors that prevent lithium deposition on the insulating electrolyte-facing surface and accommodate lithium deposition inside the spacious voids. The anisotropic spatial heterogeneity was introduced by a line-of-sight deposition of a thin SiO2 layer onto a carbon-fiber paper. The deposited SiO2 was later converted into SiC by a magnesiothermic reaction. The SiO2 and SiC decorated 3D current collectors were confirmed dendrite-free by ex situ SEM observation after a deep lithium deposition of 28.8 C cm−2 at a high current density of 4 mA cm−2. A high lithium cycling efficiency of 94% was achieved over deep deposition (14.4 C cm−2) and stripping cycles in a carbonate based organic electrolyte, demonstrating the superiority of the novel current collector for dendrite control and lithium cycling. This strategy opens new avenues to address the dendrite problem by rationally designed current collectors and for the creation of a high energy density electrode.

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► Dendrite free lithium deposition is facilitated in spatially heterogeneous current collectors.
► Spatial heterogeneity was created by a line-of-sight SiO2 deposition.
► No dendrites grow on insulated electrolyte-facing surface of the current collectors.
► High lithium cycling efficiency is achieved with the novel current collector.