Lithium metal is the most attractive anode material for batteries because of its high specific capacity (3861 mAh g−1) and low negative potential (−3.04 V vs. NHE). However, lithium dendrite growth during lithium deposition leads to serious safety problems and poor cycling performance. The conventional liquid electrolyte used in lithium-ion batteries results in significant lithium dendrite formation at room temperature and a high current density. Thus, there has been much research effort to achieve the suppression of lithium dendrite formation. Recently, a new class of non-aqueous liquid electrolyte with a high concentration of lithium salts, such as solvated ionic liquid and solvent-in-salt electrolytes, has been reported to suppress lithium dendrite formation. Solid polymer electrolytes have been known to suppress lithium dendrite formation; however, the low lithium ion conductivity and high interface resistance between lithium and the polymer electrolyte at room temperature limits their use for conventional batteries. The interface resistance was significantly decreased by the addition of an ionic liquid into a polymer electrolyte and lithium dendrite formation was suppressed. A theoretical analysis predicted that if a homogenous solid electrolyte with a shear modulus of 6 GPa was obtained, then the lithium dendrite problem would be solved. However, some lithium conducting solid electrolytes such as Li7La3Zr2O12 still exhibit lithium dendrite formation. In this review, we introduce the recent status of lithium dendrite formation on lithium metal in contact with liquid, solid polymer, and solid electrolytes.
NiO nanopowders and NiO/nickel foam (NF) hybrid were synthesized by microwave hydrothermal method and the following heating process. NiO nanopowders show the morphology of microspheres (diameter is about 3 µm), which are composed of porous nanoflakes. NiO/NF hybrid shows a porous nanoflakes array structure, the thickness of nanoflakes is 10 nm. Electrochemical measurements indicate that the maximum specific capacitance of NiO nanopowders is about 85.4 F/g at a scan rate of 5 mV/s, while this value is up to 234.8 F/g for NiO/NF hybrid. Electrochemical impedance spectrum (EIS) data show that the Rs and Rct values of NiO/NF hybrid (1.9 Ω and 0.25 Ω) are smaller than that of the NiO nanopowders which are coated on nickel foam (3.6 Ω and 0.3 Ω). In conclusion, the ultrathin porous NiO/NF is directly used as a binderfree supercapacitor electrode, which exhibited significantly improved supercapacitor performance compared to NiO nanopowders.
In this work, thiol aromatic aldehyde was used as a substrate material to be assembled on the electrode surface through Au-S chemical bond, resulting in an aldehyde-containing self-assembled monolayer. The aldehyde groups of this self-assembled monolayer can immobilize antibodies directly through the covalent bonding with amino groups of antibody, in which no additional chemical cross-linker is required. We fabricated an electrochemical impedance immunosensor based on aldehyde-containing self-assembled monolayers for the detection of hepatitis B surface antigen within the range from 0.1 to 70 ng mL−1 with a detection limit of 0.06 ng mL−1 obtained by 3σ. The proposed immunosensor is simple and has a good specificity and reproducibility.
A novel and sensitive method is described for voltammetric study and determination of dinitramine, commonly used pesticide, based on its electrochemical reduction at a multi-walled carbon nanotube (MWCNT) modified glassy carbon electrode. Cyclic voltammetry (CV) was used to investigate the redox properties of this modified electrode at various solutions pH values and various scan rates. CV studies indicated that the reduction process has an irreversible and diffusion-like behavior in a reduction mechanism with equal number of electrons and protons. The square-wave voltammetry (SWV) was applied as a very sensitive voltammetric detection method for the determination of dinitramine. Under optimal conditions, the proposed method exhibited acceptable analytical performances in terms of linearity (over the concentration range from 4.0 × 10−8 to 1.4 × 10−6 and 1.4 × 10−6 to 2 × 10−5 mol L−1, R2 = 0.999), detection limit (0.8 × 10−8 mol L−1) and repeatability (RSD = 2.36%, n = 10, for 5.0 × 10−6 mol L−1 dinitramine). To further validate its possible application, the method was used for the quantification of dinitramine in water samples.
Sodium-ion batteries potentially provide the opportunities to realize the energy storage system beyond the state-of-the-art lithium-ion batteries, though at present their performance is limited partly due to lack of suitable positive electrode materials. NASICON-type Na3V2(PO4)3 is a promising candidate for the positive electrode materials because of its high capacity and high operating potential, however, the electrode reaction of Na1+2xV2(PO4)3 (0 ≤ x ≤ 1) including a biphasic region is not yet fully understood. Here, in order to clarify the microscopic mechanism of the biphasic reaction, the reaction entropy of the electrochemical cell including the Na1+2xV2(PO4)3 positive electrode was measured using the potentiometric method. The temperature-dependent open-circuit-voltage reveals that the reaction entropy is almost constant for 0.1 ≤ x ≤ 0.9. The constant reaction entropy of the electrochemical cell suggests that the electrode reaction proceeds through the boundary migration between the Na-rich and -poor phases without substantial change in the configurational entropy.
Effect of hydrogen on the surface reactivity of X80 pipeline steel was studied by scanning electrochemical microscopy (SECM), electrochemical impedance spectroscopy (EIS) and secondary ion mass spectroscopy (SIMS). Hydrogen can enhance the reactivity of passive film formed on X80 pipeline steel, reduce the corrosion resistance and thickness of this passive layer, which is due to an increase in hydroxide in the passive layer.
Lithium-ion batteries with higher energy and power density are required as power sources. Silicon is very attractive as an anode material for lithium-ion batteries because of its high capacity. Silicon anode has problems, which include the expansion and cracking of silicon particles by electrochemical lithiation. In order to overcome this problem, silicon nanoparticle as an anode material is proposed. Since the silicon nanoparticle can be easily oxidized the influence of oxygen content of silicon particle was investigated. The initial coulombic efficiency of lithium extraction/insertion decreased when the oxygen content increased. It was found that adding of metal elements such as Al, Zr, La, Ca during preparing silicon nanoparticles by a thermal plasma method is effective to decrease the formation of silicon oxide. In particular, a cell with an anode formed from Al adding silicon particles exhibited high power density of 2835 W kg−1 like a capacitor. Conductive agent content gives influence to the performance of the electrode. The choice of a binder is very important to solve the problem of the large capacity fade observed along cycling. Thus, the influences of conductive additive contents and polymer binders of silicon electrodes on the electrochemical performance were investigated.