Construction of dual crosslinked network binder via sequential ionic crosslinking for high-performance silicon anodes

Nowadays,silicon has become a promising anode active material for lithium-ion batteries due to its high specific capacity.However,traditional binder materials cannot effectively restrain the volume expansion of silicon during lithiation/delithiation.Inspired by the growth process of climbing plants,we sequentially crosslink sodium alginate with calcium ions and hyperbranched polyethyleneimine to construct a dual crosslinked network binder.During the sequentially crosslinking,sodium alginate preferentially crosslinks with Ca^(2+)to form the"trellis"network,which restricts the free movement of hyperbranched polyethyleneimine and guides it,like"vine",to gradually anchor on the surrounding"trellis"through hydrogen and ionic bonding.In this dual crosslinked network,the ionic ally crosslinked sodium alginate maintains the anode structural integrity;the anchored hyperbranched polyethyleneimine forms strong multidimensional hydrogen bonds with silicon nanoparticles through its amino-rich branch chains;and the network utilizes the bonding reversibility of hydrogen and ionic bonds to repeatedly eliminate the mechanical stress and self-heal the structure damages caused by the volume change of silicon.Benefited from the multifunction of the dual crosslinked network,the silicon anode has achieved an excellent electrochemical performance with a specific capacity of 2403 mAh·g^(-1)at the current density of500 mA·g^(-1)after 100 cycles.

Release of Anticancer Drug 5-Fluorouracil from Different Ionically Crosslinked Alginate Beads

In this research;the release of 5-Fluorouracil (5-FU) from different ionically crosslinked alginate (Alg) beads was investigated by using Fe3+, Al3+, Zn2+, and Ca2+, ions as crosslinking agent. The prepared beads were characterized by Fourier Transform Infrared Spectroscopy (FTIR) Differential Scanning Calorimetry (DSC) and Scanning Electron Micros-copy (SEM). The drug release studies were carried out at three pH values 1.2, 6.8 and 7.4 respectively each for two hours. The effects of the preparation conditions as crosslinker type, drug/polymer (w/w) ratio, crosslinker concentration and time of exposure to crosslinker on the release of 5-FU were investigated for 6 hours at 37℃. It was observed that 5-FU release from the beads followed the order of Fe > Zn > Al > Ca-Alg and increased with increasing drug/polymer ratio. At the end of 6 hours, the highest 5-FU release was found to be 90% (w/w) for Fe-Alg beads at the drug/polymer ratio of 1/8 (w/w), crosslinker concentration of 0.05 M, exposure time of 10 minutes respectively. The swelling measurements of the beads supported the release results. Release kinetics was described by Fickian and non-Fickian approaches.

Polymer light-emitting electrochemical cells:Recent developments to stabilize the p-i-n junction and explore novel device applications

Polymer light-emitting electrochemical cells (PLECs) employ a thin layer of a luminescent conjugated polymer admixed with an ionic source and an ionic conductor for the in-situ formation of p-i-n junction and subsequent efficient injections of both electrons and holes.The junction formation enables the use of air-stable conductors as the cathode and a relatively thick emissive polymer layer that is more compatible with low-cost solution-based processes.This paper overviews the operation mechanism of the PLECs,the properties and drawbacks of the devices.The employment of crosslinkable ionic conductors to stabilize the p-i-n junction is reviewed.The resulting static junction electroluminesces light at high brightness,high efficiency,and prolonged lifetime.Silver paste and carbon nanotubes can be used as the cathode,thus,PLECs were fabricated by lamination.Using single wall carbon nanotubes coated elastic substrate as both anode and cathode,the PLECs can be made highly stretchable.