Si–Ni-alloy-assisted very high-areal-capacity silicon-based anode on Ni foam for lithium ion battery

Silicon is investigated as an active material for the anode of lithium-ion battery (LIB) because of the 10 times higher specific capacity of silicon than graphite. In order to achieve a low internal resistance and high areal capacity of a silicon-based anode, metal foams are used as three-dimensional current collectors. However, unless the foam is densely compressed, active materials adhere loosely to the foam and suffer from loss of electrical contacts with the current collector. A densely compressed anode suffers from poor physical integrity without spare room for large volume expansion of silicon. By means of pyrolysis at 800 °C in argon of a mixture of silicon nanoparticles, phenolic resin binder, and Super P conductivity agent on the nickel foam, silicon reacts with nickel to form nickel silicide while the specially selected binder is graphitized to form a conductive and porous anode with a nickel foam current collector. We report 80-nm-silicon-based anode with a nickel foam, exhibiting excellent cycling performance and a high retained areal capacity of 6.5 mAh/cm² after 50 cycles under a discharge/charge current density of 4 mA/cm². For anode area of 1 cm², it stores 23.4 C of charges at a current rate of 4 mA.