Ultrasmall metal (Fe, Co, Ni) nanoparticles strengthen silicon oxide embedded nitrogen-doped carbon superstructures for long-cycle-life Li-ion-battery anodes

Abstract

A universal electrospray-carbonization approach to prepare ternary metal/SiO x /nitrogen-doped carbon (NC) superstructures is proposed, where metal (Fe, Co, Ni, CoNi, FeNi, FeCo and FeCoNi) and small SiO x nanoparticles (NPs) are homogeneously distributed in NC matrix. Metal greatly promotes the electrochemical activity and stability of the SiO x system, which can be considered as high-performance Li-ion-battery anodes. • Metal/SiO x /nitrogen-doped carbon superstructures are designed as LIB anodes. • Nitrogen-doped carbon inhibits the gathering of SiO x and relieves its strain. • Ultrasmall Ni nanoparticles and nitrogen-doped carbon improve the kinetics of SiO x . • The strategy to prepare multiple SiO x - or metal-based composites is universal. For silicon oxides (SiO x ) as a prospective Li-ion-battery anode material, the low inherent conductivity and huge volume fluctuation during cycling immensely limit their electrochemical performance. Herein, a universal electrospray-carbonization approach to prepare ternary metal/SiO x /nitrogen-doped carbon (NC) superstructures is proposed. Accordingly, metal (Fe, Co, Ni, CoNi, FeNi, FeCo and FeCoNi) nanoparticles (NPs) and small SiO x NPs derived from rice husks (RHs) are homogeneously distributed in the NC matrix. Metal (Fe, Co, Ni) NP-embedded NC frameworks avoid the accumulation, increase the conductivity and accommodate adequent volume expansion of SiO x NPs. This results in an enhanced rate capability and excellent cycle stability upon cycling. Besides, Ni/SiO x /NC (NSC) superstructures with ultra-small Ni NPs can exhibit better electrochemical kinetics for fast diffusion of ions and charge transfer and cyclability than Co/SiO x /NC (CSC) and Fe/SiO x /NC (FSC) composites. When NSC superstructures are employed as lithium-ion battery (LIB) anodes, superior specific capacities of 757.5 mA h g −1 at the 200th cycle, as well as superb long cyclability with discharge capacities of 665.0 mA h g −1 for 500 cycles at 500 mA g −1 and 116.3 mA h g −1 at the 5000th cycle, even at 10 A g −1 , are achieved. Furthermore, the easy and general approach for preparing multiple SiO x -, metal- or alloy-based superstructures paves the way for designing high-performance rechargeable batteries and electrocatalysts.