Nitrogen-Doped Graphitic Layers Deposited on Silicon Nanowires for Efficient Lithium-Ion Battery Anodes

Abstract

Nitrogen (N)-doped graphitic layers were deposited as shells on pregrown silicon nanowires by chemical vapor deposition. Graphite-like and pyridine-like structures were selectively chosen for 3 and 10% N doping, respectively. Increasing the thickness of the undoped graphitic layers from 20 to 50 nm led to an increase in the charge capacity of the lithium ion battery from 800 to 1040 mA h/g after 45 cycles. Graphitelike 3% N-doping in the 50 nm-thick shell increases the charge capacity by 21% (i.e., to 1260 mA h/g), while pyridine-like 10% N-doping in the 20 nm-thick shell increases it by 36% (i.e., to 1090 mA h/g). This suggests that both pyridine-and graphitelike structures can be effective for lithium intercalation. First principles calculations of the graphene sheets show that the large storage capacity of both N-doping structures comes from the formation of dangling bonds around the pyridine-like local motives upon lithium intercalation.

Cycling strategies for optimizing silicon nanowires performance as negative electrode for lithium battery

“…However, a fast decline of this capacity is observed after only one hundred cycles. Therefore, improvements of SiNWs electrode cycle life were proposed by surface coatings [6][7][8][9] or use of electrolyte additives [10][11][12]. However, only a few papers deal with the influence of the cycling conditions and provide some indications to enhance the capacity retention, for instance by increasing the lower cut-off voltage above 100 mV [13][14][15][16].…”

Lithiation Behavior of High Capacity SiCO Anode Material for Lithium-ion Battery: A First Principle Study

“…Graphite has a capacity of 372 mA h g À1 and is commonly used as the anode material in commercial LIBs, while silicon has emerged as an attractive materials in replacing carbon-based anodes with approaching 10 times gravimetric capacity and cheaper cost than that of graphite [1,2]. However, the high capacity of silicon is associated with around 300% volume change during lithiation/delithiation cycling, and thus leads to mechanical failure, irreversible capacity and limited cycle life [3,4]. Therefore, seeking for new LIB anode materials with high capacities and longer life cycle is the most interest of researchers.…”

“…First principle method can give insights into the structure, electronic properties and lithiation characters of LIB electrode materials, and was successfully used in analyzing LIB electrodes such as Si [17], SiO [18], LiFePO 4 [19], BC 3 [20], porous graphene [21], Sodium hexatitanates [22], graphene sheets [4] and Sn nanowire encapsuled carbon nanotube [23]. In this work, first principle calculations are used to investigate the lithiation behavior of SiCO ceramics.…”

Alloy-Based Anode Materials

“…Once the electrostatic assembly performed in water-based solutions, the composites are dried and fired at high temperature (≧500°C) in a controlled reducing atmosphere. Sophisticated (and expensive) processes have also been developed for Si NWs, where they are first "wrapped" within a CVD graphene-like deposit and then further embedded within RGO sheets [69,70]. Having said this, inspection of Fig.…”