Simultaneous Perforation and Doping of Si Nanoparticles for Lithium-Ion Battery Anode

Abstract

Silicon nanostructures have served as promising building blocks for various applications, such as lithium-ion batteries, thermoelectrics, and solar energy conversions. Particularly, control of porosity and doping is critical for fine-tuning the mechanical, optical, and electrical properties of these silicon nanostructures. However, perforation and doping are usually separated processes, both of which are complicated and expensive. Here, we demonstrate that the porous nano-Si particles with controllable dopant can be massively produced through a facile and scalable method, combining ball-milling and acid-etching. Nano-Si with porosity as high as 45.8% can be achieved with 9 orders of magnitude of conductivity changes compared to intrinsic silicon. As an example for demonstration, the obtained nano-Si particles with 45.8% porosity and 3.7 atom % doping can serve as a promising anode for lithium-ion batteries with 2000 mA h/g retained over 100 cycles at the current density of 0.5 C, excellent rate performance with 1600 mA h/g at the current density of 5 C, and a stable cycling performance of above 1500 mA h/g retained over 940 cycles at the current density of 1 C with carbon coating.

Top‐Down Synthesis of Silicon/Carbon Composite Anode Materials for Lithium‐Ion Batteries: Mechanical Milling and Etching

“…Combining HEMM of cheap Si sources with etching, porous Si‐based anode materials for LIBs with excellent electrochemical properties can be fabricated at a large scale . Most of the reported electrochemical cycling performances of porous Si‐based anode materials prepared by combining HEMM of low‐cost Si sources and etching process were found to be stable with high reversible capacities above 1000 mAh g −1 . Several recently published review articles have largely discussed Si‐based anode materials for LIBs, but none of them focused mainly on low‐cost ball‐milling and etching routes for the synthesis of Si/C anodes for next‐generation LIBs.…”

“…Lv et al. successfully fabricated porous nano‐Si from low‐cost metallurgical Si powders (∼1 μ m , ∼98 wt %) mixed with P 2 O 5 (∼20 μ m ) through a simple and scalable method, combining ball‐milling and HF etching, (Figure ) . It was found that nanosized Si (particle size ∼150 nm) with different porosities and P‐dopant concentrations were produced by simply controlling the ratio of Si and P 2 O 5 .…”

“…(b) Optical image of P 2 O 5 particles, Si particles, and porous nano‐Si particles with P‐dopant. (c) P concentration, conductivity, and porosity of nano‐Si particles produced by different weight ratios of Si to P 2 O 5 . Reused with permission.…”

“…(d–f) SEM image and energy‐dispersive X‐ray spectroscopy (EDS) mapping of the porous nano‐Si particles with P‐dopant after acid‐etching (weight ratio Si/P 2 O 5 =10:2); the green (e) and blue (f) bright regions correspond to the elements of Si and P. (g) TEM image of porous nano‐Si particles with P‐dopant (weight ratio Si/P 2 O 5 =10:2). (h) Cycling performance of carbon‐coated porous nano‐Si particles with P‐dopant produced (weight ratio Si/P 2 O 5 =10:2; 0.1 C for the first 5 cycles and 1 C for the following cycles) . Reused with permission.…”

Interface Heteroatom‐doping: Emerging Solutions to Silicon‐based Anodes

“…In Figure f, the PSG55 (P‐doped Si/graphite at weight ratios of 5 : 5) electrode shows the best cycling stability (883.4 mA h g −1 after 200 cycles), which is attributed to the graphite shell improved the conductivity and help to form a stable SEI film on the electrode surface. In order to simultaneously control the porosity and doping of nano‐silicon particles, Lv et al . prepared the nano‐Si particles with controllable dopant by combining ball‐milling and acid‐etching process (Figure g).…”