Facile synthesis of novel Si nanoparticles–graphene composites as high-performance anode materials for Li-ion batteries

Abstract

Improving the Li storage properties of a Si negative electrode is of great significance for Li-ion batteries. A major challenge is to fabricate Si-based active materials with good electronic conduction and structural integrity in the process of discharging and charging. In this study, novel Si nanoparticles-graphene composites have been synthesized by hybrid electrostatic assembly between positively charged aminopropyltriethoxysilane modified Si nanoparticles and negatively charged graphene oxide, followed by thermal reduction. Commercially available Si nanoparticles are well embedded and uniformly dispersed into the graphene sheets, and the typically wrinkled graphene sheets form a network and cover the highly dispersed Si nanoparticles well. No any obvious aggregation of the Si nanoparticles can be found and many nanospaces exist around the Si nanoparticles, which provide buffering spaces needed for volume changes of Si nanoparticles during insertion/extraction of Li. High capacity and long cycle life (822 mA h g(-1) after 100 cycles at a current density of 0.1 A g(-1)) have been realized in the novel Si nanoparticles-graphene composites for Li-ion batteries. The excellent electrochemical performance is ascribed to the uniform distribution of Si nanoparticles and graphene, which effectively prevents aggregation and pulverization of Si nanoparticles, keeps the overall electrode highly conductive, and maintains the stability of the structure.

High-Performance Li-Ion Battery Anodes Based on Silicon-Graphene Self-Assemblies

“…For example, most self-assembled Si-graphene composites showed unsatisfactory cycling stability 25,27,29 even when operated in a shallow voltage range, 25 and low first-cycle Coulombic efficiencies (CEs) (48%-73%). 25,29,31 Even after the initial cycles, CEs above 99.5%, which is essential for a long cycle life, have seldom been reported for selfassembled Si-graphene composites. Furthermore, key information such as the material or electrode density and volumetric capacity in comparison with those of the state-of-the-art graphite anode is not provided.…”

“…However, the electrochemical reaction between nonconducting silicon and lithium ions is accompanied by a huge net volume expansion (∼300%) 15,17,18 followed by electrode pulverization, leading to rapid capacity fading due to loss of electrical contact, growth of a newly formed unstable solid-electrolyte interface (SEI), 19,20 electrolyte depletion, and so on. To address these issues associated with silicon, tremendous research efforts have been devoted z E-mail: jklee88@dau.ac.kr to rational designs of silicon-based composites in which the huge volume variation is effectively accommodated and thus the electrical network is well preserved to secure a long cycle life.Among many conducting carbonaceous platforms for the formation of silicon-based composites, graphene has been effectively incorporated in a variety of formats to enhance the cycling stability of silicon:11, 21-38 a self-supporting silicon nanoparticle (SiNP)-graphene paper composite prepared by simple membrane filtering of a homogeneous aqueous mixture of SiNPs or silicon nanowires and graphene oxide (GO), 21,22,28,32 crumpled-graphene-encapsulated SiNPs prepared by an aerosol-assisted capillary assembly method, 24 graphene granules or a graphene hybrid coated with nanosilicon by chemical vapor deposition, 23,30 Si/C composites internally wired with dispersed graphene networks prepared by a solution-based sol-gel process, 11,39 Si-graphene composites prepared by an electrostatic self-assembly method, 25,27,29,31,40 and conformal growth of graphene cages on the surface of silicon particles by a Ni-catalyzed dissolutionprecipitation mechanism. …”

“…11, 21-38 a self-supporting silicon nanoparticle (SiNP)-graphene paper composite prepared by simple membrane filtering of a homogeneous aqueous mixture of SiNPs or silicon nanowires and graphene oxide (GO), 21,22,28,32 crumpled-graphene-encapsulated SiNPs prepared by an aerosol-assisted capillary assembly method, 24 graphene granules or a graphene hybrid coated with nanosilicon by chemical vapor deposition, 23,30 Si/C composites internally wired with dispersed graphene networks prepared by a solution-based sol-gel process, 11,39 Si-graphene composites prepared by an electrostatic self-assembly method, 25,27,29,31,40 and conformal growth of graphene cages on the surface of silicon particles by a Ni-catalyzed dissolutionprecipitation mechanism.…”

Graphene‐Based Electrodes for Lithium Ion Batteries

“…Zhou and coworkers [51] synthesized Si/graphene composites by hybrid electrostatic assembly between negatively charged GO and positively charged aminopropyltriethoxysilane-modified Si nanoparticles, followed by heat treatment. The GSs formed a continuous conductive path and covered the highly dispersed Si nanoparticles well.…”

Solution plasma synthesis of Si nanoparticles

“…During the lithium insertion-extraction process, however, a large volume change (>280%) inevitably occurs, which leads to pulverization of the silicon anode and loss of electrical contact to the current collector, resulting in poor cycling performance [2,4]. To mitigate this volume-change issue, several strategies have been proposed, including reducing the particle size to nanoscale [5,6] and dispersing nano-Si in the conductive carbon matrix to form a Si-carbon composite [7][8][9][10]. Liu et al (2012) reported that the critical particle diameter needs to be below 150 nm to avoid the surface cracking and subsequent fracturing during lithiation [4].…”