Electrodeposited Three-Dimensional Porous Silicon Nanostructure with Excellent Stability and High Rate Performance for Lithium-Ion Batteries

Recently, rechargeable lithium ion batteries with higher energy/power densities and better rate performance have been widely developed to be used for powering future portable electronic devices and for application to renewable energy storage facilities and in electric vehicles (EVs)[1]. Silicon is one of the most promising anode candidates owing to its extremely high theoretical capacity of 4200 mAh/g (with the formation of the Li_4.2Si alloy), which is more than 10 times higher than the capacity of graphitic carbon (372 mAh/g) and other Li alloys.[2] Due to a major volume change (300-400%) of Si during the lithiation/delithiation processes, the resulting pulverization and a loss of electrical connection between the active materials and the electrode framework cause serious irreversible capacity loss and poor cyclability. In order to solve the pulverization issues of Si, we have fabricated 3D porous Si/metal (copper or nickel) film by an electrodeposition method using two types of template; one is a hydrogen gas bubble template and the other is inverse opal template. Compared with chemical vapor deposition or etching method for porous 3D Si anode, electrodepostion method is a simple and low-cost method which is used for large scale operation in industry.[3] Our 3D porous silicon/metal anode with a well-defined configuration for lithium ion batteries consists of interconnected metal film, which not only allows for robustness during the charge and discharge process with the volume expansion but enables the formation of a large area for silicon electrodeposition at a high capacity in lithium ion batteries. The resulting self-supported 3D porous Si/metal electrodes exhibit a high reversible capacity (2824 mAh/g), remarkable cycling stability (1628 mAh/g after 100 cycles) and superior rate capability without any binder or conductive additives. The results using the 3D porous Si/metal anode in our study represent a promising approach for high-performance silicon-based anodes which are compatible with scaled-up manufacturing process for next-generation lithium-ion batteries due to their simple and rapid fabrication process.