Trapping Lithium into Hollow Silica Microspheres with a Carbon Nanotube Core for Dendrite-Free Lithium Metal Anodes.

Li metal anodes, which have attracted much attention for their high specific capacity and low redox potential, face a great challenge in realizing their practical application. The fatal issue of dendrite formation gives rise to internal short circuit and safety hazards and needs to be addressed. Here we propose a rational strategy of trapping Li within microcages to confine the deposition morphology and suppress dendrite growth. Microcages with a carbon nanotube core and porous silica sheath were prepared and proved to be effective for controlling the electrodeposition behavior. In addition, the insulative coating layer prevents concentrated electron flow and decreases the possibility of "hot spots" formation. Because of the Li trapper and uniform electron distribution, the electrode with delicate structure exhibits a dendrite-free morphology after plating 2 mA h cm-2 of Li. As the dendrite growth is suppressed, the as-obtained electrode maintains a high plating/stripping efficiency of 99% over 200 cycles. This work delivers new insights into the design of rational Li metal anodes and hastens the practical application of Li metal batteries.