Layered Potassium Titanium Niobate/Reduced Graphene Oxide Nanocomposite as a Potassium-Ion Battery Anode.

With graphite currently leading as the most viable anode for potassium-ion batteries (KIBs), other materials have been left relatively under-examined. Transition metal oxides are among these, with many positive attributes such as synthetic maturity, long-term cycling stability and fast redox kinetics. Therefore, to address this research deficiency we report herein a layered potassium titanium niobate KTiNbO5 (KTNO) and its rGO nanocomposite (KTNO/rGO) synthesised via solvothermal methods as a high-performance anode for KIBs. Through effective distribution across the electrically conductive rGO, the electrochemical performance of the KTNO nanoparticles was enhanced. The potassium storage performance of the KTNO/rGO was demonstrated by its first charge capacity of 128.1 mAh g-1 and reversible capacity of 97.5 mAh g-1 after 500 cycles at 20 mA g-1, retaining 76.1% of the initial capacity, with an exceptional rate performance of 54.2 mAh g-1 at 1 A g-1. Furthermore, to investigate the attributes of KTNO in-situ XRD was performed, indicating a low-strain material. Ex-situ X-ray photoelectron spectra further investigated the mechanism of charge storage, with the titanium showing greater redox reversibility than the niobium. This work suggests this low-strain nature is a highly advantageous property and well worth regarding KTNO as a promising anode for future high-performance KIBs.

Organosulfur Compounds Enable Uniform Lithium Plating and Long-Term Battery Cycling Stability.

Lithium metal represents an ultimate anode material of lithium batteries for its high energy density. However, its large negative redox potential and reactive nature can trigger electrolyte decomposition and dendrite formation, causing unstable cycling and short circuit of batteries. Herein, we engineer a resilient solid electrolyte interphase on the Li anode by compositing the battery separator with organosulfur compounds and inorganic salts from garlic. These compounds take part in battery reactions to suppress dendrite growth through reversible electrochemistry and attenuate ionic concentration gradient. When the Li anode and the separator are paired with the LiFePO4 cathode, one obtains a battery delivering long-term cycling stability of 3000 cycles, a rate capacity of 100 mAh g-1 at 10 C (2.5 mA cm-2), a Coulombic efficiency of 99.9%, and a low battery polarization. Additionally, with high-loading 20 mg cm-2 LiFePO4 cathodes, an areal capacity of 3.4 mAh cm-2 is achieved at 0.3 C (1 mA cm-2).

Suppression of Polysulfide Dissolution and Shuttling with Glutamate Electrolyte for Lithium Sulfur Batteries.

The lithium sulfur battery is regarded as a potential next-generation high-energy battery system. However, polysulfides dissolve and shuttle through the electrolytes, causing rapid capacity decay, serious self-discharge, and poor high-temperature performances. Here, we demonstrate that by directly introducing glutamate into commercial electrolytes, these issues can be tackled simultaneously. With abundant negatively charged hydroxyl groups, the glutamate additive electrolyte effectively suppresses the shuttling of negatively charged polysulfide ions through strong repulsive interaction up to 1.54 eV. With glutamate additive electrolyte, the lithium sulfur battery has a capacity retention of 60% after 1000 cycles at 5.95 mA/cm2, a self-discharge rate on the order of one-third that of commercial electrolytes, and stable operation at 60 °C.

A Highly Stable Separator from an Instantly Reformed Gel with Direct Post-Solidation for Long-Cycle High-Rate Lithium-Ion Batteries.

An efficient, scalable, and cost-effective approach was developed to synthesize a hierarchically constructed polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) separator from an instantly reformed solution. With partially dissolved PVDF-HFP as separator skeleton, the incorporation of warm PVDF-HFP solution in acetone led to a cross-linked structure before N-methyl-2-pyrrolidone (NMP) was added to solidify the hierarchical inner-bound structure of fresh PVDF-HFP. Owing to its hierarchical microporous structure, the separator exhibited remarkable wettability with a small contact angle of 18° and an electrolyte uptake of 114.81 %, leading to a high room-temperature ionic conductivity of 3.27×10-3  S cm-1 . The hierarchical structure provided short pathways for efficient ion transfer with more electrolyte trapped inside and small intervals between adjacent nanopores. The separator outperformed commercial separators, showing high rate capacities of 104.8 mAh g-1 at 5 C and 95 mAh g-1 at 10 C as well as unparalleled perfect capacity retention at 10 C after 1000 cycles.

Coordination-dependent surface strain and rational construction of robust structures.

A surface relaxation model is established to study the elastic properties of nanoscale structures. This model predicts coordination-dependent strain at the surface and thickness-dependent stiffness of a material. Several atomic layers at the surface endure a significant strain gradient, which is dominated by the intrinsic properties of the material. The stiffness of low-dimensional materials is enhanced by surface relaxation effect. Surface effects on strong structures, including honeycomb structure and octet-truss structure with a high stiffness-to-weight ratio, are discussed. For these structures assembled with nanobeams, the Young's modulus decreases with decreasing size of the struts. The coupling between Young's modulus and relative density can be scaled down by engineering tensile strain on the struts.

Protocatechualdehyde prevents methylglyoxal-induced mitochondrial dysfunction and AGEs-RAGE axis activation in human lens epithelial cells.

Methylglyoxal (MGO), a glucose derived dicarbonyl intermediate, is a major precursor of advanced glycation end products (AGEs) which have been linked to the development of diabetic cataract. Protocatechualdehyde (PCA), a phenolic acid compound, is found in the roots of Salvia miltiorrhiza. This study was to investigate the effect of PCA against MGO-induced cytotoxicity in human lens epithelial cells (SRA01/04 cells) and the possible involved molecular mechanism. The results showed that PCA alleviated MGO-induced mitochondrial dysfunction and apoptosis in SRA01/04 cells. Furthermore, PCA was capable of inhibiting MGO-mediated AGEs formation and blocking receptor of AGEs expression in SRA01/04 cells. It is concluded that PCA could be useful in attenuation of MGO-induced cell damage and the possible mechanism is involved in modulating AGEs-receptor of AGEs axis in human lens epithelial cells, which suggests that PCA has a potential protective effect on diabetic cataract.