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Silicon-Few Layer Graphene (Si-FLG) composite electrodes are investigated using a scalable electrode manufacturing method. A comprehensive study on the electrochemical performance and the impedance response is measured using electrochemical impedance spectroscopy. The study demonstrates that the incorporation of few-layer graphene (FLG) results in significant improvement in terms of cyclability, electrode resistance and diffusion properties. Additionally, the diffusion impedance responses that occur during the phase changes in silicon is elucidated through Staircase Potentio Electrochemical Impedance Spectroscopy (SPEIS): a more comprehensive and straightforward approach than previous state-of-charge based diffusion studies.

Polymer binders are a key component for long-lasting silicon (Si)-based electrodes, and they should be mechanically robust and electrochemically stable, with the ability to accommodate the large volume expansion of Si during the lithiation/delithiation process. The combination of poly(acrylic acid) (PAA) and poly(vinyl alcohol) (PVA) utilizes the strong adhesion properties of PAA and mechanical robustness of PVA, which can potentially overcome the current technical challenges faced by the traditional polyvinylidene-fluoride-based binder systems, e.g., poor interfacial adhesion, brittleness, and short service life. This study has investigated the PAA/PVA (60/40 wt %) blend for Si anodes and compared its performance with the effects of PAA and partially neutralized PAA/PVA (60/40 wt %). The PAA/PVA blends were further thermally cross-linked in order to improve the mechanical properties. The PAA/PVA binder shows higher stiffness, adhesion strength, and electrochemical performance (100 cycles with 240 mA/g and 40 cycles with 400 mA/g) compared with those of unmodified PAA (38 cycles with 240 mA/g and 25 cycles with 400 mA/g). The partially neutralized PAA/PVA blend shows further improved performance (over 140 cycles with 240 mA/g and over 60 cycles with 400 mA/g). The working mechanism of the partially neutralized PAA/PVA binder is discussed.

Copies of full items can be used for personal research or study, educational, or not-for-profit purposes without prior permission or charge. Provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way. Publisher statement:First published by Royal Society of Chemistry 2016 http://dx.doi.org/10.1039/C6CP06788C A note on versions:The version presented here may differ from the published version or, version of record, if you wish to cite this item you are advised to consult the publisher's version. Please see the 'permanent WRAP URL' above for details on accessing the published version and note that access may require a subscription. Hybrid anode materials consisting of micro-sized silicon (Si) interconnected with few-layer graphene (FLG) nanoplatelets and sodium-modified poly (acrylic acid) (PAA) as a binder were evaluated for Li-ion batteries. The hybrid film has demonstrated a reversible discharge capacity of ~1800 mAh/g 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 functionalized polymer binder. Furthermore, improved SEI stability is achieved from the electrolyte additives, due to the formation of a kinetically stable film on the surface of the Si.