Microstructure Controlled Porous Silicon Particles as a High Capacity Lithium Storage Material via Dual Step Pore Engineering

To overcome the lithium storage barriers of current lithium‐ion batteries, it is imperative that conventional low capacity graphite anodes be replaced with other higher capacity anode materials. Silicon is a promising alternative anode material due to its huge energy densities; however, its lithium‐concentration‐dependent volumetric changes can induce severely adverse effects that lead to drastic degradations in capacity during cycling. The dealloying of Si–metal alloys is recently suggested as a scalable approach to fabricate high‐performance porous Si anode materials. Herein, a microstructure controlled porous Si is developed by the dealloying in conjunction with wet alkaline chemical etching. The resulting 3D networked structure enables enhancement in lithium storage properties when the Si‐based material is applied not only as a single active material but also in a graphite‐blended electrode. A microstructure‐controlled 3D porous Si material is fabricated by dual chemical etching of a designed Si‐alloy in which Si and the metal‐alloy are entangled. Benefiting from the enlarged pore volume and reduced Si domain size, the resulting 3D porous Si anode shows improvement in lithium‐storage properties in terms of cyclability and energy density.