Electrochemical characterization of silicon nanowires as an anode for lithium batteries

Thin Solid Films, 2019

Silicon (Si)-based anodes demonstrate great potential for the revolutionary enhancement in the energy storage of Li-ion cells. Unfortunately, these materials suffer from several shortcomings, such as high electrical resistivity, low Li diffusivity and significant volume change during operation, which limit their stability and power characteristics. To overcome these limitations, we fabricate Si-based anodes by deposition of Si thin film on multiwalled carbon nanotube (MWCNT) sheet using RF magnetron sputtering. The characterization of MWCNT-Si composites by spectroscopy techniques confirmed the deposition of amorphous Si nanofilms. The as-prepared MWCNT-Si nanocomposites were tested as anode material in half-cell using Li metal as counter and reference electrodes, and in full cell using LiFePO 4 as cathode. MWCNT-Si composites exhibited stable electrochemical performance during 50 cycles with specific reversible capacity greater than 2000 mAh/g for 130-nm Si film. MWCNT-Si//LiFePO 4 full cell delivered a voltage of 2.9 V and displayed satisfactory cycling performance during 50 cycles.

We report a silicon/graphene-sheet hybrid film prepared by combining electrophoretic deposition and radiofrequency magnetron deposition methods. The constructed hybrid film shows rough morphology with wrinkles and scrolling edges. As anode material for lithium ion batteries, the silicon/graphene-sheet hybrid film exhibits enhanced electrochemical performances with weaker polarization, higher capacity, better rate capability and cycling performance as compared to the bare silicon film. The silicon/graphene-sheet hybrid film delivers a high initial reversible capacity of 2204 mAh g −1 and quite good cycling life (capacity maintenance is 87.7%) after 150 cycles. The graphene-sheet in the hybrid film is responsible for the improvement of the electrochemical properties. The introduction of the graphene-sheet film not only enhances the adhesion between silicon and the current collector, but also alleviates the structure degradation caused by volume expansion and the shrinkage of silicon film during lithium-ion insertion/extraction, resulting in improved electrochemical performances.

Physical chemistry chemical physics : PCCP, 2016

Hybrid anode materials consisting of micro-sized silicon (Si) particles interconnected with few-layer graphene (FLG) nanoplatelets and sodium-neutralized poly(acrylic acid) as a binder were evaluated for Li-ion batteries. The hybrid film has demonstrated a reversible discharge capacity of ∼1800 mA h g(-1) with a capacity retention of 97% after 200 cycles. The superior electrochemical properties of the hybrid anodes are attributed to a durable, hierarchical conductive network formed between Si particles and the multi-scale carbon additives, with enhanced cohesion by the functional polymer binder. Furthermore, improved solid electrolyte interphase (SEI) stability is achieved from the electrolyte additives, due to the formation of a kinetically stable film on the surface of the Si.

Journal of Power Sources, 2004

Nano-silicon-based disordered carbon composites prepared by mechanical milling and pyrolysis have been examined as anodes of a lithium ion cell. Electrochemical measurements show that the charge-discharge capacity of disordered carbon composites incorporating both silicon-polyparaphenylene (Si-PPP) and silicon-polyvinyl chloride (Si-PVC) with differing silicon contents, decreases with increasing pyrolysis temperature. Si-PVC-based materials have a better cycle life than those based on Si-PPP at the same silicon content.

Journal of Solid State Electrochemistry, 2018

Silicon is considered to be a very attractive anode material for next-generation lithium-ion batteries due to its high theoretical capacity (4200 mAh g of silicon for a stoichiometry of Li 4.4 Si) and the abundance of silicon in the Earth's crust. To overcome some of the fundamental challenges of silicon anodes (such as conductivity and volume expansion effects in the anodes), multiwall carbon nanotubes (MWCNT) were added to the metallurgical silicon anode material. The superior properties of CNT, as well as their low density and enormous aspect ratio, make them ideal candidates for reinforcement and conductive additives for composite electrodes. The selection of appropriate binder and electrolyte solution is also very important for achieving good performance Li-Si anodes. Here, we report the use of micrometer-sized metallurgical Si particles as the anode material in Li-ion batteries, with MWCNT in the composite electrodes. With 5% MWCNT, the first cycle efficiency was 90%. These Si anodes demonstrated average cycling efficiency of 99.5% and reasonable capacity retention during prolonged cycling. Full cells with LiNi 0.8 Co 0.15 Al 0.05 O 2 cathodes were also demonstrated. We believe that upon optimization, such composite silicon electrodes based on relatively cheap and available materials, in terms of both additives (CNT) and binders, may be used as promising practical anodes for Li-ion batteries.

ECS Journal of Solid State Science and Technology, 2013

The development of affordable and safe lithium-ion batteries (LIB) which feature high storage capacity represents one of the priority strategies toward further introduction of green technologies in our everyday life. This paper presents a study into the candidate composite anodes for high energy LIB; these utilize reversible high storage capacity of ions of lithium in the form of alloys of the latter with nano-sized silicon, imbedded in a soft-carbon matrix, which in turn, are deposited on a robust graphitic core. These structures allow an efficient contact between the constituents to be realized at the same time providing space for Si nano-particles during lithiation/de-lithiation process. The synthetic route described herein has a high potential for a cost-effective scale-up with the battery materials industry. Presented results demonstrate feasibility for creation of new active materials for the negative electrodes in LIB, which feature the storage capacity up to 700 mAh g −1 at C/2 and in excess of 1450 mAh g −1 at C/20 cycling rates, respectively. This work also shows that the use of acrylic binder has a positive effect on the overall system performance, as compared to state-of-the-art PVDF-based binder systems.

Batteries & Supercaps, 2018

The use of functional nanomaterials is a common strategy to improve the mechanical and electrochemical properties of silicon anodes for secondary lithium-ion cells. Here, we report the preparation of a structurally stable composite material with a unique morphology comprising small-size silicon particles and especially branched carbonaceous nanofibers and the analysis of its cycling performance by galvanostatic measurements. This two-phase composite was obtained from pyrolysis of blended silicon/cyanamide powders. The conversion of cyanamide to turbostratic carbon, rather than graphitic carbon nitride, was unexpected and appears to be catalyzed by accidental iron nanoparticles. Although the carbon content after pyrolysis was only about 7 %, half-cells using electrodes containing the silicon/carbon composite outperformed other silicon-based anode materials tested herein in terms of cyclability. After 300 cycles, they delivered two times higher capacity (> 1.7 A h g silicon À1 at C/10 and > 0.5 A h g silicon À1 at 1C in the 600-30 mV range when operated in constant current mode) than cells of similar loading with pristine silicon particles. The average fade rate per cycle was around 0.1 % between the 10th and 300th cycles, which is notable considering that the electrode structure and composition have not yet been optimized for battery applications.

Small, 2009

Rechargeable lithium ion batteries are integral to today's information-rich, mobile society. Currently they are one of the most popular types of battery used in portable electronics because of their high energy density and flexible design. Despite their increasing use at the present time, there is great continued commercial interest in developing new and improved electrode materials for lithium ion batteries that would lead to dramatically higher energy capacity and longer cycle life. Silicon is one of the most promising anode materials because it has the highest known theoretical charge capacity and is the second most abundant element on earth. However, silicon anodes have limited applications because of the huge volume change associated with the insertion and extraction of lithium. This causes cracking and pulverization of the anode, which leads to a loss of electrical contact and eventual fading of capacity. Nanostructured silicon anodes, as compared to the previously tested silicon film anodes, can help overcome the above issues. As arrays of silicon nanowires or nanorods, which help accommodate the volume changes, or as nanoscale compliant layers, which increase the stress resilience of silicon films, nanoengineered silicon anodes show potential to enable a new generation of lithium ion batteries with significantly higher reversible charge capacity and longer cycle life.

Journal of Power Sources, 2006

Composites comprising silicon (Si), graphite (C) and polyacrylonitrile-based disordered carbon (PAN-C), denoted as Si/C/PAN-C, have been synthesized by thermal treatment of mechanically milled silicon, graphite, and polyacrylonitrile (PAN) powder of nominal composition C-17.5 wt.% Si-30 wt.% PAN. PAN acts as a diffusion barrier to the interfacial diffusion reaction between graphite and Si to form the electrochemically inactive SiC during prolonged milling of graphite and Si, which could be easily formed in the absence of PAN. In addition, graphite, which contributes to the overall capacity of the composite and suppresses the irreversible loss, retains its graphitic structure during prolonged milling in the presence of PAN. The resultant Si/C/PAN-C based composites exhibit a reversible capacity of ∼660 mAh g −1 with an excellent capacity retention displaying almost no fade in capacity when cycled at a rate of ∼C/4. Scanning electron microscopy (SEM) analysis indicates that the structural integrity and microstructural stability of the composite during the alloying/dealloying process appear to be the main reasons contributing to the good cyclability observed in the above composites.

Journal of Materials Science, 2013

Composite anodes of Si nanoparticles (SiNPs) and reduced graphene oxide (RGO) sheets with highly dispersed SiNPs were synthesized to investigate the performance-related improvements that particle dispersion can impart. Three composites with varying degrees of particle dispersions were prepared using different ultrasonication, and a combination of ultrasonication and surfactant. With more dispersed SiNPs, the capacity retention and rate performance as evaluated by galvanostatic cycling using increasing current density rates (500-2500 mA/g) also improved compared with anodes that have poor particle dispersion. These results demonstrate that better nanoparticle dispersion (small clusters to mono-dispersed particles) between the stable and the highly conducting RGO layers, allows the carbonaceous matrix material to complement the SiNP-Li ? electrochemistry by becoming highly involved in the charge-discharge reaction mechanisms as indicated by chronopotentiometry and cyclic voltammetry (CV). Particle dispersion improvement was confirmed to be a key component in a composite anode design to maximize Si for high-performance lithium ion battery (LIB) application.