Nanostructured silicon electrodes for solid-state 3-d rechargeable lithium batteries

This paper presents 3-D MEMS-fabricated lithium rechargeable batteries relying on structured silicon rods as anodes in order to increase the effective electrode surface area. A new method of fabricating silicon micro/nano rod arrays with controllable diameters in the range of 300–8000 nm is proposed. Different sizes of silicon rod-arrays as anodes were successfully incorporated into an all-solid-state battery construction. The structured architecture of the silicon electrodes allowed for a heightened surface area as well as improvement in cycle life and capacity over comparable planar electrodes. Structured rod array electrodes showed a first cycle coulombic efficiency over 80% which is more than double that of conventional powder composite silicon electrodes. Galvanostatic cycling of structured silicon rod electrodes showed highly reversible capacity for high current densities. Variation of rod diameter and current density revealed that decreasing the rod diameter leads to higher capacity and more stable cycling of batteries.