Small highly mesoporous silicon nanoparticles for high performance lithium ion based

Highly mesoporous silicon nanoparticles of sizes less than 150 nm and porosity greater than 50% were successfully synthesized and composited with N-doped carbon (m-Si@NDC) as high performance anode materials for lithium ion based energy storage. The small size, large porosity, and composition with N-doped carbon coating layer of the highly mesoporous silicon nanoparticles offer much improved cycling volume expansion/ shrinkage stability and overall conductivities, and create nano-sized reservoirs for lithium ions to enable local, fast lithiation/delithiation for much enhanced lithium ion based energy storage performances. The m-Si@NDC anode delivered a high specific capacity of 2,482 mAh g(-1) at 0.2 A g(-1) and maintained a decent specific capacity of 797 mAh g(-1) at a high current density of 8 A g(-1). The lithium ion capacitor, assembled by coupling the m-Si@NDC anode with a glucose derived carbon nanosphere (GCNS) cathode of an ultrahigh specific surface area of 1,451 m(2) g(-1), m-Si@NDC//GCNS, delivered a high energy density of 210 Wh kg(-1) at a power density of 0.32 kW kg(-1), and maintained a decent energy density of 70.1 Wh kg(-1) at a high power density of 36.1 kW kg(-1). The stability of m-Si@NDC//GCNS is also outstanding, exhibiting an energy density retention of 89% after a 20,000 cycle operation at a current density of 8 A g(-1). The N-doped carbon coated small highly mesoporous silicon nanoparticles prove to be an outstanding nanostructure for anodes of lithium ion based energy storage.