Cunzhong Zhang

Effect of Ni2+ Content on Lithium/Nickel Disorder for Ni-Rich Cathode Materials

Li excess LiNi0.8Co0.1Mn0.1O2 was produced by sintering the Ni0.8Co0.1Mn0.1(OH)2 precursor with different amounts of a lithium source. X-ray photoelectron spectroscopy confirmed that a greater excess of Li(+) leads to an increase in the number of Ni(2+) ions. Interestingly, the level of Li(+)/Ni(2+) disordering decreases with an increase in Ni(2+) content determined by the I003/I104 ratio in the X-ray diffraction patterns. The electrochemical measurement shows that the cycling stability and rate capability improve with an increase in Ni(2+) content. After cycling, electrochemical impedance spectroscopy shows decreased charge transfer resistance, and the XRD patterns exhibit an increased I003/I104 ratio with an increase in Ni(2+) content, reflecting the decrease in the level of Li(+)/Ni(2+) disorder during cycling.

Engineered Biochar from Biofuel Residue: Characterization and Its Silver Removal Potential

A novel approach was used to prepare engineered biochar from biofuel residue (stillage from bagasse ethanol production) through slow pyrolysis. The obtained biochar was characterized for its physicochemical properties as well as silver sorption ability. Sorption experimental data showed that engineered biochar quickly and efficiently removed silver ion (Ag(+)) from aqueous solutions with a Langmuir maximum capacity of 90.06 mg/g. The high sorption of Ag(+) onto the biochar was attributed to both reduction and surface adsorption mechanisms. The reduction of Ag(+) by the biochar was confirmed with scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy analyses of the postsorption biochar, which clearly showed the presence of metallic silver nanoparticles on the surface of the carbon matrix. An antimicrobial ability test indicated that silver-laden biochar effectively inhibited the growth of Escherichia coli, while the original biochar without silver nanoparticles promoted growth. Thus, biochar, prepared from biofuel residue materials, could be potentially applied not only to remove Ag(+) from aqueous solutions but also to produce a new value-added nanocomposite with antibacterial ability.

Mg-Enriched Engineered Carbon from Lithium-Ion Battery Anode for Phosphate Removal

Three Mg-enriched engineered carbons (mesocarbon microbeads, MCMB) were produced from lithium-ion battery anode using concentrated nitric acid oxidization and magnesium nitrate pretreatment. The obtained 15%Mg-MCMB, 30%Mg-MCMB, and 40%Mg-MCMB have magnesium level of 10.19, 19.13, and 19.96%, respectively. FTIR spectrum shows the functional groups present on the oxidized MCMB including OH, C═O, C-H, and C-O. XRD, SEM-EDX, and XPS analyses show that nanoscale Mg(OH)2 and MgO particles were presented on the surface of the Mg-MCMB samples, which could serve as the main adsorption mechanism as to precipitate phosphate from aqueous solutions. The sorption experiments indicate that Mg modification dramatically promotes MCMBs phosphate removal ability and phosphate removal rates reach as high as 95%. Thus, modification of the spent LIBs anode could provide a novel direction of preparing wastewater adsorbent and develop an innovative way to achieve sustainable development.

Mesocarbon Microbead Carbon-Supported Magnesium Hydroxide Nanoparticles: Turning Spent Li-ion Battery Anode into a Highly Efficient Phosphate Adsorbent for Wastewater Treatment

Phosphorus in water eutrophication has become a serious problem threatening the environment. However, the development of efficient adsorbents for phosphate removal from water is lagging. In this work, we recovered the waste material, graphitized carbon, from spent lithium ion batteries and modified it with nanostructured Mg(OH)2 on the surface to treat excess phosphate. This phosphate adsorbent shows one of the highest phosphate adsorption capacities to date, 588.4 mg/g (1 order of magnitude higher than previously reported carbon-based adsorbents), and exhibits decent stability. A heterogeneous multilayer adsorption mechanism was proposed on the basis of multiple adsorption results. This highly efficient adsorbent from spent Li-ion batteries displays great potential to be utilized in industry, and the mechanism study paved a way for further design of the adsorbent for phosphate adsorption.

Effect of surface modification of metal hydride electrode on performance of MH/Ni batteries

Abstract A novel method was applied to the surface modification of the metal hydride(MH) electrode of MH/Ni batteries. Both sides of the electrode were plated with a thin silver film about 0.1μm thick using vacuum evaporation plating technology, and the effect of the electrode on the performance of MH/Ni batteries was examined. It is found that the surface modification can enhance the electrode conductivity and decrease the battery ohimic resistance. After surface modification, the discharge capacity at 5C (7.5A) is increased by 212 mA-h and the discharge voltage is increased by 0.11 V, the resistance of the batteries is also decreased by 32%. The batteries with modified electrode exhibit satisfactory durability. The remaining capacity of the modified batteries is 89% of the initial capacity even after 500 cycles. The inner pressure of the batteries during overcharging is lowered and the charging efficiency of the batteries is improved.

Kinetics Tuning the Electrochemistry of Lithium Dendrites Formation in Lithium Batteries through Electrolytes

Lithium batteries are one of the most advance energy storage devices in the world and have attracted extensive research interests. However, lithium dendrite growth was a safety issue which handicapped the application of pure lithium metal in the negative electrode. In this investigation, two solvents, propylene carbonate (PC) and 2-methyl-tetrahydrofuran (2MeTHF), and four Li+ salts, LiPF6, LiAsF6, LiBF4 and LiClO4 were investigated in terms of their effects on the kinetics of lithium dendrite formation in eight electrolyte solutions. The kinetic parameters of charge transfer step (exchange current density, j0, transfer coefficient, α) of Li+/Li redox system, the mass transfer parameters of Li+ (transfer number of Li+, tLi+, diffusion coefficient of Li+, DLi+), and the conductivity (κ) of each electrolyte were studied separately. The results demonstrate that the solvents play a critical role in the measured j0, tLi+, DLi+, and κ of the electrolyte, while the choice of Li+ salts only slightly affect the measured parameters. The understanding of the kinetics will gain insight into the mechanism of lithium dendrite formation and provide guidelines to the future application of lithium metal.

Synthesis of Mg-Decorated Carbon Nanocomposites from MesoCarbon MicroBeads (MCMB) Graphite: Application for Wastewater Treatment

The potential application of a carbon nanocomposite from battery anode materials modified with magnesium (Mg) was explored to remove phosphate from aqueous solutions. Thermogravimetric analysis (TGA) shows that the Mg content of the prepared Mg/C composite is around 23.5%. Laboratory batch adsorption kinetics and equilibrium isotherm experiments demonstrate that the composite has an extremely high phosphate adsorption capacity of 406.3 mg PO4/g, which is among the highest phosphate removal abilities reported so far. Results from XRD, SEM-EDX, and XPS analyses of the postsorption Mg/C composite indicate that phosphate adsorption is mainly controlled by the precipitation of P to form Mg3(PO4)2·8H2O and MgHPO4·1.2H2O nanocrystals on the surface of the adsorbent. The approach of synthesizing Mg-enriched carbon-based adsorbent described in this work provides new opportunities for disposing spent batteries and developing a low-cost and high-efficiency adsorbent to mitigate eutrophication.

Ultralong Cycle Life Achieved by a Natural Plant: Miscanthus × giganteus for Lithium Oxygen Batteries

Large energy-storage systems and electric vehicles require energy devices with high power and high energy density. Lithium oxygen (Li-O2) batteries could achieve high energy density, but they are still facing problems such as low practical capacity and poor cyclability. Here, we prepare activated carbons (MGACs) based on the natural plant Miscanthus × giganteus (MG) through slow pyrolysis. It possesses a large surface area, plenty of active sites, and high porosity, which are beneficial to the utilization of oxygen electrode in Li-O2 batteries. The MGACs-based oxygen electrode delivers a high specific capacity of 9400 mAh/g at 0.02 mA/cm2, and long cycle life of 601 cycles (with a cutoff capacity of 500 mAh/g) and 295 cycles (with a cutoff capacity of 1000 mAh/g) at 0.2 mA/cm2, respectively. Additionally, the material exhibits high rate capability and high reversibility, which is a promising candidate for the application in Li-O2 batteries.

Facile low-temperature one-step synthesis of pomelo peel biochar under air atmosphere and its adsorption behaviors for Ag(I) and Pb(II)

This study prepared a novel low-cost surface functionalized carbon adsorbent (PPC) from biomass waste (pomelo peel) through a facile low-temperature (250 °C) one-step method under regular air atmosphere. The adsorption performance and mechanism of the carbon material for Ag(I) and Pb(II) were investigated by a range of sorption experiments and characterizations including SEM, EDX, XRD and FTIR. Sorption experimental results suggested that PPC had high adsorption capacities of 137.4 and 88.7 mg/g for Ag(I) and Pb(II), respectively, with adsorbent dosage of 2 g/L at unadjusted solution pH and room temperature (23 ± 1 °C). The characterization results indicated high-efficiency removal of the heavy metals by PPC was attributed to the strong chemical adsorption involving that Ag(I) ions were reduced as metallic Ag particles by oxygenic functional groups and Pb(II) ions were precipitated as Pb5(PO4)3OH crystals by phosphorous functional groups on the carbon surfaces. This study provides the possibility of synthesis high-efficient adsorbent using economic and environmental-friendly approach with low energy consumption.

New Application of Waste Citrus Maxima Peel Derived Carbon as an Oxygen Electrode Material for Lithium Oxygen Batteries

Recently, lithium oxygen battery has become a promising candidate to satisfy the current large-energy-storage devices demand because of its amazing theoretical energy density. However, it still faces problems such as poor reversibility and short cycle life. Here, citrus maxima peel (CMP) was used as a precursor to prepare activated and Fe-loading carbon (CMPACs and CMPACs-Fe, respectively) via pyrolysis in nitrogen atmosphere at 900 °C, in which KOH was added as an activator. Electrochemical measurements show that CMPAC-based Li-O2 battery possesses high specific capacity of 7800 mA h/g, steady cycling performance of 466 cycles with a corresponding Coulombic efficiency of 92.5%, good rate capability, and reversibility. Besides, CMPACs-Fe-based O2 electrode delivers even lower overpotential in both charge and discharge processes. We conclude that these excellent electrochemical performances of CMPACs and CMPACs-Fe-based O2 electrode benefit from their cellular porous structure, plenty of active sites, and large specific surface area (900 and 768 m2/g), which suggest that these biomass-derived porous carbons might become promising candidates to achieve efficient lithium oxygen battery.