Silicon Nanoparticles Within the Carbonized SU-8 Cages as A Micro Lithium-Ion Battery Anode

Silicon as the anode materials for lithium batteries has over tenfold higher specific capacity than that of the commercial graphite. However, it suffers from poor recyclability and large volume expansion (~400%) during the lithiation and delithiation processes. Here, we develop an effective approach to fabricate a novel silicon/void/carbon (Si/void/C) anode used in micro lithium-ion batteries. The silicon nanoparticles (SiNPs) in the anode materials enable the high capacity, while the carbonized SU-8 provides a structural support and also facilitates the fast lithium-ions transport between the electrolyte and the silicon. The nano-void space between SiNPs and carbon scaffold provides enough space for the expansion of SiNPs during intercalation and de-intercalation of lithium-ions into the anode; moreover, it is also very helpful to reduce the damage of the carbon structure and offer high cycle life. To balance the specific capacity and the stability, the Si/void/C nanocomposite with the weight ratio of 60/0/40 shows the highest specific capacity retention of 1200 mAh/g after 80 cycles with 2200 mAh/g as the initial specific capacity. In the future, the micro lithium-ion batteries can be directly prototyped on chip by the lithography techniques.