Cross-Linked Sodium Alginate-Sodium Borate Hybrid Binders for High-Capacity Silicon Anodes in Lithium-Ion Batteries

Silicon is considered one of the most promising next-generation anode materials for lithium-ion batteries. It has the advantages of high theoretical specific capacity (4200 mAh·g^-1), which is 10 times larger than that of a commercial graphite anode (372 mAh·g^-1). However, there are some problems such as the pulverization of the electrode and an unstable solid electrolyte interphase (SEI) layer aroused by the huge bulk effect (>300%) of Si during the repeated lithiation/delithiation process. A binder plays a vital role in the conventional lithium-ion batteries that can effectively relieve the bulk expansion stress of a silicon anode. In this work, the inorganic cross-linker sodium borate (SB) and the commonly used binder sodium alginate (SA) were condensed through an esterification reaction and the reaction product was marked as SA-SB. It is found that the mechanical robustness and the peel strength of SA-SB are improved after cross-linking, which is conducive to maintaining the structural stability of the silicon anode in long cycle life. In consequence, the capacity retention of the silicon anode using the SA-SB binder (64.1%) is higher than that of SA (50.6%) after 100 cycles at 0.2 A·g^-1.

Fabrication of SiOx-G/PAA-PANi/Graphene Composite With Special Cross-Doped Conductive Hydrogels as Anode Materials for Lithium Ion Batteries

Silicon oxides (SiO_x) have been considered to be the likeliest material to substitute graphite anode for lithium-ion batteries (LIBs) due to its high theoretical capacity, appropriate working potential plus rich abundance. Nevertheless, the two inherent disadvantages of volume expansion and low electrical conductivity of SiO_x have been a main obstacle to its application. Here, SiO_x-G/PAA-PANi/graphene composite has been successfully synthesized by in-situ polymerization, in which SiO_x-G particles linked together by a graphene-doped polyacrylic acid-polyaniline conductive flexible hydrogel and SiO_x-G is encapsulated inside the conductive hydrogel. We demonstrate that SiO_x-G/PAA-PANi/graphene composite possesses a discharge-specific capacity of 842.3 mA h g⁻¹ at a current density of 500 mA g⁻¹ after a cycle life of 100 cycles, and a good initial coulombic efficiency (ICE) of 74.77%. The superior performance probably due to the lithium ion transmission rate and the electric conductivity enhanced by the three-dimensional (3D) structured conductive polymer hydrogel.

Modified Polyacrylic Acid-Zinc Composites: Synthesis, Characterization and Biological Activity

Polyacrylic acid (PAA) is an important industrial chemical, which has been extensively applied in various fields, including for several biomedical purposes. In this study, we report the synthesis and modification of this polymer with various phenol imides, such as succinimide, phthalimide and 1,8-naphthalimide. The as-synthesized derivatives were used to prepare polymer metal composites by the reaction with Zn⁺². These composites were characterized by using various techniques, including NMR, FT-IR, TGA, SEM and DSC. The as-prepared PAA-based composites were further evaluated for their anti-microbial properties against various pathogens, which include both Gram-positive and Gram-negative bacteria and different fungal strains. The synthesized composites have displayed considerable biocidal properties, ranging from mild to moderate activities against different strains tested.