Directly grown Si nanowire arrays on Cu foam with a coral-like surface for lithium-ion batteries.

In order to mitigate the drastic volumetric expansion (>300%) of silicon (Si) during the lithiation process, we demonstrate the synthesis of novel Si nanowire arrays (n-SNWAs) with a coral-like surface on Cu foam via a one-step CVD method, in which the Cu foam can simultaneously act as a catalyst and current collector. The unique coral-like surface endows n-SNWAs with a high structural integrity, which is beneficial for enhancing their electrochemical performance. In addition, the as-prepared n-SNWAs on Cu foam can be directly applied as the anode for lithium-ion batteries (LIBs), exhibiting a very high reversible discharge capacity (2745 mA h g(-1) at 200 mA g(-1)) and a fast charge and discharge capability (884 mA h g(-1) at 3200 mA g(-1)), which is much higher than the conventional SNWAs (c-SNWAs, only 127 mA h g(-1) at 3200 mA g(-1)). Meanwhile, they deliver an improved cycling stability (2178 mA h g(-1) at 400 mA g(-1) after 50 cycles). More significantly, the as-synthesized n-SNWAs on Cu foam also possess a superior specific areal capacity of 4.1 mA h cm(-2) at 0.6 mA cm(-2). Such excellent electrochemical performance is superior, or at least comparable, to the best report for Si anode materials. Combining the cost-effective and facile preparation method, the present n-SNWAs on Cu foam can serve as a promising anode for LIBs.

Highly conductive and flexible polymer composites with improved mechanical and electromagnetic interference shielding performances.

New flexible and conductive materials (FCMs) comprising a quartz fiber cloth (QFC) reinforced multi-walled carbon nanotubes (MWCNTs)-carbon aerogel (QMCA) and poly(dimethylsiloxane) (PDMS) have been successfully prepared. The QMCA-PDMS composite with a very low loading of MWCNTs (∼1.6 wt%) demonstrates enhanced performance in tensile strength (129.6 MPa), modulus (3.41 GPa) and electromagnetic interference (EMI) shielding efficiency (SE) (∼16 dB in X-band (8.2-12.4 GHz) region). Compared to the QC (where MWCNTs were simply deposited on the QFCs without forming aerogel networks) based PDMS composite, a ∼120%, 330% and 178% increase of tensile strength, modulus, and EMI SE was obtained, respectively. Moreover, the EMI SE of the QMCA-PDMS composite can further reach 20 dB (a SE level needed for commercial applications) with only 2 wt% MWCNTs. Furthermore, the conductivity of the QMCA-PDMS laminate can reach 1.67 S cm(-1) even with very low MWCNTs (1.6 wt%), which still remains constant even after 5000 times bending and exhibits an increase of ∼170% than that of MWCNT-carbon aerogel (MCA)-PDMS at 20% strain. Such intriguing performances are mainly attributed to their unique networks in QMCA-PDMS composites. In addition, these features can also protect electronics against harm from external forces and EMI, giving the brand-new FCMs huge potential in next-generation devices, like E-skin, robot joints and so on.