Changsong Dai

A construction of novel iron-foam-based calcium phosphate/chitosan coating biodegradable scaffold material

Slow corrosion rate and poor bioactivity restrict iron-based implants in biomedical application. In this study, we design a new iron-foam-based calcium phosphate/chitosan coating biodegradable composites offering a priority mechanical and bioactive property for bone tissue engineering through electrophoretic deposition (EPD) followed by a conversion process into a phosphate buffer solution (PBS). Tensile test results showed that the mechanical property of iron foam could be regulated through altering the construction of polyurethane foam. The priority coatings were deposited from 40% nano hydroxyapatite (nHA)/ethanol suspension mixed with 60% nHA/chitosan-acetic acid aqueous solution. In vitro immersion test showed that oxidation-iron foam as the matrix decreased the amount of iron implanted and had not influence on the bioactivity of this implant, obviously. So, this method could also be a promising method for the preparation of a new calcium phosphate/chitosan coating on foam construction.

Effect of the addition CNTs on performance of CaP/chitosan/coating deposited on magnesium alloy by electrophoretic deposition.

CaP/chitosan/carbon nanotubes (CNTs) coating on AZ91D magnesium alloy was prepared via electrophoretic deposition (EPD) followed by conversion in a phosphate buffer solution (PBS). The bonding between the layer and the substrate was studied by an automatic scratch instrument. The phase compositions and microstructures of the composite coatings were determined by using X-ray diffraction (XRD), Fourier-transformed infrared spectroscopy (FTIR), Raman spectroscopy and scanning electron microscope (SEM). The element concentration and gentamicin concentration were respectively determined by inductively coupled plasma optical emission spectrometer (ICP-OES) test and ultraviolet spectrophotometer (UV). The cell counting kit (CCK) assay was used to evaluate the cytotoxicity of samples to SaOS-2 cells. The results showed that a few CNTs with their original tubular morphology could be found in the CaP/chitosan coating and they were beneficial for the crystal growth of phosphate and improvement of the coating bonding when the addition amount of CNTs in 500 ml of electrophoretic solution was from 0.05 g to 0.125 g. The loading amount of gentamicin increased and the releasing speed of gentamicin decreased after CNTs was added into the CaP/chitosan coating for immersion loading and EPD loading. The cell viability of Mg based CaP/chitosan/CNTs was higher than that of Mg based CaP/chitosan from 16 days to 90 days.

Optimized Li and Fe recovery from spent lithium-ion batteries via a solution-precipitation method

A new process is optimized and presented for the recovery and regeneration of LiFePO4 from spent lithium-ion batteries (LIBs). The recycling process reduces the cost and secondary pollution caused by complicated separation and purification processes in spent LIB recycling. Amorphous FePO4·2H2O was recovered by a dissolution-precipitation method from spent LiFePO4 batteries. The effects of different surfactants (i.e. CTAB, SDS and PEG), which were added to the solution on the recovered FePO4·2H2O, were investigated. Li2CO3 was precipitated by adding Na2CO3 to the filtrate. Then the LiFePO4/C material was synthesized by a carbon thermal reduction method using recycled FePO4·2H2O and Li2CO3 as the Fe, P, and Li sources. The as-prepared LiFePO4/C shows comparable electrochemical performance to that of commercial equivalents.

Electrochemical behavior of Mg-doped 7LiFePO4–Li3V2(PO4)3 composite cathode material for lithium-ion batteries

Mg-doping effects on the electrochemical property of LiFePO4–Li3V2(PO4)3 composite materials, a mutual-doping system, are investigated. X-ray diffraction study indicates that Mg doping decreases the cell volume of LiFePO4 in the composite. The cyclic voltammograms reveal that the reversibility of the electrode reaction and the diffusion of lithium ion is enhanced by Mg doping. Mg doping also improves the conductivity and rate capacity of 7LiFePO4–Li3V2(PO4)3 composite material and decreases the polarization of the electrode reaction. The discharge capacity of the Mg-doped composite was 93xa0mAhu2009g−1 at the current density of 1,500xa0mAu2009g−1, and Mg-doped composite has better discharge performance than the original 7LiFePO4–Li3V2(PO4)3 composite at low temperature, too. At −30xa0°C, the discharge capacity of Mg-doped LFVP is 89xa0mAhu2009g−1, higher than that of the original composite. Electrochemical impedance spectroscopy study shows that Mg2+ doping could enhance the electrochemical activity of 7LiFePO4–Li3V2(PO4)3 composite. Mg doping has a positive influence on the electrochemical performance of the LiFePO4–Li3V2(PO4)3 composite material.

Effects of carbon contents on morphology and electrical properties of Li2MnSiO4/C prepared by a vacuum solid-state method

To improve the electrochemical performance of Li2MnSiO4 with low electric conductivity, the Li2MnSiO4/C composite are synthesized by a vacuum solid-state reaction of a mixture of SiO2, LiCH3COO, Mn(CH3COO)2 and designed mass of C6H12O6 · H2O as carbon sources. The crystalline structure and morphology of products are analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and laser scattering technology (LS) respectively. The tested results show that carbon doping decrease the crystallite sizes of products, but keep the aggregation of the particles and made the impurity increased instead. The results of constant current charge-discharge prove that the mixed carbon improve Li+ transmission performance and decrease inner polatization resistance of Li2MnSiO4 materials, but can not prevent the collapse of Li2MnSiO4 crystal structure. While the galvanostatic intermittent titration technique (GITT) results demonstrate that the primary reason for the improved electrochemical performance can be attributed to increased Li-ion diffusion coefficient

The impact of aluminum impurity on the regenerated lithium nickel cobalt manganese oxide cathode materials from spent LIBs

(D_{Li^ + } )

Enhanced cycle performance and lifetime estimation of lead-acid batteries

as a result from carbon doping.

Magnesium/chloride co-doping of lithium vanadium phosphate cathodes for enhanced stable lifetime in lithium-ion batteries

In this paper, an effective recycling process from spent LIBs has been developed. The aluminum residual commonly exists in hydrometallurgy, and also aluminum is considered as a resultant additive in LIB modification, therefore, the tolerability of aluminum was studied in this work. Li[(Ni1/3Co1/3Mn1/3)1−xAlx]O2 (0.01 ≤ x ≤ 0.05) cathode materials were regenerated from spent ternary LIBs. X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and electrochemical measurements were carried out to characterize the performances of all of the samples. XRD and XPS results indicate that Mn and Ni are possibly replaced by Al. When x ≤ 0.03, the initial discharge capacity is up to 170 mA h g−1 at 0.05C between 2.5 and 4.5 V, and more than 100 mA h g−1 at 2C. The results showed that the existence of aluminum of up to x = 0.03 has no significant impact on the cathode materials of Li[(Ni1/3Co1/3Mn1/3)1−xAlx]O2, and the content surpasses the conventional limitations.

Evaluation of long-term biocompatibility and osteogenic differentiation of graphene nanosheet doped calcium phosphate-chitosan AZ91D composites

Lead-acid batteries are preferred for energy storage applications because of their operational safety and low cost. However, the cycling performance of positive electrode is substantially compromised because of fast capacity decay caused by softening and shedding of the positive active material (PAM). The additives of PAM are considered as promising candidates to improve the cycling performance of a PbO2 electrode. In this study, SnSO4 and Sb2O3 are selected as additives to form positive plates. The incorporation of SnSO4 (0.1 wt%) and Sb2O3 (0.1 wt%) not only provides high porosity of PAM for ion and H2O transportation, but also offers larger reaction area during electrochemical processes. Therefore, excellent cycling performances are achieved at 40% and 60% depth of discharge (DoD). Meanwhile, the index of reaction depth (IRD), a parameter reflecting the state of a battery, is also obtained, and the IRD measurements can be used to predict the capabilities for cycling performances of lead-acid batteries.

Cycling stability of the Li3(V0.9Mg0.1)2(PO4)3/C cathode with an increase in the charge cut-off voltage

A Mg and Cl co-doped Li3V2(PO4)3/C (LVMPCl/C) material has been synthesized via a solid state method. The effects of Mg and Cl co-doping on the electrochemical properties, structure and morphology of Li3V2(PO4)3 are investigated. Detailed analysis of the XRD patterns suggests that Mg and Cl atoms partly occupy V and O sites in the crystal structure of Li3V2(PO4)3, respectively. The valence states of Mg and Cl elements are investigated using X-ray photoelectron spectroscopy (XPS). Combining XRD patterns with 31P NMR spectra, it is further demonstrated that doped Mg and Cl atoms affect the local electronic structure of P atoms in Li3V2(PO4)3. According to the results of electrochemical performance, LVMPCl/C exhibits excellent discharge capacity as high as 129.1 mA h g−1 at 0.1C. In addition, the capacity retention of LVMPCl/C is almost 100% after 100 cycles at 3.0–4.3 V. Impedance spectroscopy (EIS) and cyclic voltammetry (CV) curves illustrate the lower charge transfer resistance and much more decreased polarization of LVMPCl/C than the pristine one. The excellent electrochemical performance of LVMPCl/C can be attributed to its larger Li ion diffusion channels, which is ascribed to the increased unit-cell volumes, smaller particle sizes and higher electronic conductivity.