Shengming Xu

Synthesis and performance of Li[(Ni1/3Co1/3Mn1/3)1−xMgx]O2 prepared from spent lithium ion batteries

To reduce cost and secondary pollution of spent lithium ion battery (LIB) recycling caused by complicated separation and purification, a novel simplified recycling process is investigated in this paper. Removal of magnesium is a common issue in hydrometallurgy process. Considering magnesium as an important additive in LIB modification, tolerant level of magnesium in leachate is explored as well. Based on the novel recycling technology, Li[(Ni(1/3)Co(1/3)Mn(1/3))(1-x)Mg(x)]O(2) (0 ≤ x ≤ 0.05) cathode materials are achieved from spent LIB. Tests of XRD, SEM, TG-DTA and so on are carried out to evaluate material properties. Electrochemical test shows an initial charge and discharge capacity of the regenerated LiNi(1/3)Co(1/3)Mn(1/3)O(2) to be 175.4 mAh g(-1) and 152.7 mAh g(-1) (2.7-4.3 V, 0.2C), respectively. The capacity remains 94% of the original value after 50 cycles (2.7-4.3 V, 1C). Results indicate that presence of magnesium up to x=0.01 has no significant impact on overall performance of Li[(Ni(1/3)Co(1/3)Mn(1/3))(1-x)Mg(x)]O(2). As a result, magnesium level as high as 360 mg L(-1) in leachate remains tolerable. Compared with conventional limitation of magnesium content, the elimination level of magnesium exceeded general impurity-removal requirement.

Co9S8 nanoparticles encapsulated in nitrogen-doped mesoporous carbon networks with improved lithium storage properties

We report the designed synthesis of unique Co9S8 nanoparticles encapsulated in nitrogen-doped mesoporous carbon networks (Co9S8@NMCN nanocomposites). Uniform zeolitic imidazolate framework-67 was first synthesized and then transformed into Co9S8@NMCN nanocomposites by thermal annealing with sulfur powders in an Ar atmosphere. The structural and compositional analysis were conducted by employing X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS), which show that each Co9S8 nanoparticle is well encapsulated in nitrogen-doped carbon layers. When evaluated as an anode material for LIBs, the as-prepared composite electrodes delivered superior capacity, excellent cycling stability and rate capability, which are attributed to the advantageous structural features.

Lithium recycling and cathode material regeneration from acid leach liquor of spent lithium-ion battery via facile co-extraction and co-precipitation processes

A novel process for extracting transition metals, recovering lithium and regenerating cathode materials based on facile co-extraction and co-precipitation processes has been developed. 100% manganese, 99% cobalt and 85% nickel are co-extracted and separated from lithium by D2EHPA in kerosene. Then, Li is recovered from the raffinate as Li2CO3 with the purity of 99.2% by precipitation method. Finally, organic load phase is stripped with 0.5M H2SO4, and the cathode material LiNi1/3Co1/3Mn1/3O2 is directly regenerated from stripping liquor without separating metal individually by co-precipitation method. The regenerative cathode material LiNi1/3Co1/3Mn1/3O2 is miro spherical morphology without any impurities, which can meet with LiNi1/3Co1/3Mn1/3O2 production standard of China and exhibits good electrochemical performance. Moreover, a waste battery management model is introduced to guarantee the material supply for spent battery recycling.

Synthesis of porous MnCo2O4 microspheres with yolk–shell structure induced by concentration gradient and the effect on their performance in electrochemical energy storage

In this study, novel spherical yolk–shell MnCo2O4 powders with concentration gradient have been synthesized. The porous microspheres with yolk–shell structure (2.00–3.00 μm in average diameter, ∼200 nm in thickness of shell) are built up by irregular nanoparticles attached to each other. It is shown that the formation of yolk–shell structure may be induced by the core–shell concentration gradient. And the Co:Mn atomic ratios of core and shell are about 1.65:1 and 2.61:1, respectively. Interestingly, a similar uniform spherical MnCo2O4 without yolk–shell structure and concentration gradient prepared as a contrast, the superior electrochemical performance of the former by using in Li-ion batteries and supercapacitors has been proved including higher initial discharge capacity (1445.1 mA h g−1 at 0.2 A g−1) and initial specific capacitance (761.3 F g−1 at 2 A g−1), and more advanced capacity retention (∼860.0 mA h g−1 after 40 cycles at 0.2 A g−1, and ∼330.0 F g−1 after 3000 cycles at 12 A g−1).

QCM-D study of nanoparticle interactions.

Quartz crystal microbalance with dissipation monitoring (QCM-D) has been proven to be a powerful research tool to investigate in situ interactions between nanoparticles and different functionalized surfaces in liquids. QCM-D can also be used to quantitatively determine adsorption kinetics of polymers, DNA and proteins from solutions on various substrate surfaces while providing insights into conformations of adsorbed molecules. This review aims to provide a comprehensive overview on various important applications of QCM-D, focusing on deposition of nanoparticles and attachment-detachment of nanoparticles on model membranes in complex fluid systems. We will first describe the working principle of QCM-D and DLVO theory pertinent to understanding nanoparticle deposition phenomena. The interactions between different nanoparticles and functionalized surfaces for different application areas are then critically reviewed. Finally, the potential applications of QCM-D in other important fields are proposed and knowledge gaps are identified.

Microspherical ZnO synthesized from a metal-organic precursor for supercapacitors

In this paper, ZnO microspheres, which are composed of irregular nanoparticles, have been synthesized successfully from a metal-organic precursor. The average diameter is about 3.5xa0μm and the specific surface area is 7.53xa0m2xa0g−1. Measured by electrochemical tests as electrode materials for supercapacitors, the ZnO powders show high specific capacitances (1017.5xa0Fg−1 at 5xa0Ag−1 and 562.5xa0Fg−1 at 50xa0Ag−1, respectively) and excellent cycling stability (the specific capacitance was kept at 631.2xa0Fg−1 and 89.2xa0% retention after 3000xa0cycles at 18xa0Ag−1). These results show that the microspherical ZnO could be a potential electrode material for supercapacitors.

Oil removal of spent hydrotreating catalyst CoMo/Al2O3 via a facile method with enhanced metal recovery.

Deoiling process is a key issue for recovering metal values from spent hydrotreating catalysts. The oils can be removed with organic solvents, but the industrialized application of this method is greatly hampered by the high cost and complex processes. Despite the roasting method is simple and low-cost, it generates hardest-to-recycle impurities (CoMoO4 or NiMoO4) and enormous toxic gases. In this study, a novel and facile approach to remove oils from the spent hydrotreating catalysts is developed. Firstly, surface properties of spent catalysts are characterized to reveal the possibility of oil removal. And then, oils are removed with water solution under the conditions of 90°C, 0.1wt% SDS, 2.0wt% NaOH and 10ml/gL/S ratio for 4h. Finally, thermal treatment and leaching tests are carried out to further explore the advantages of oil removal. The results show that no hardest-to-recycle impurity CoMoO4 is found in XPS spectra of thermally treated samples after deoiling and molybdenum is leached completely with sodium carbonate solution. It means that the proposed deoiling method can not only remove oils simply and without enormous harmful gases generating, but also avoid the generation of detrimental impurity and promote recycling of valuable metals from spent hydrotreating catalysts.

Fabrication of coral like carbon black/MnO2 nano composites from commercial carbon black and their application in supercapacitors

A carbon black/MnO2 nano-composite (CB/MnO2) of coral-like architecture was synthesized from a commercially available conductive carbon black (CB) using an in situ method. The morphology and structural analysis of the synthesized CB/MnO2 revealed 10 nm thick MnO2 nano-sheets grown on the CB. The MnO2 nano-sheets of poorly crystalline δ-MnO2 birnessite structure assembled into a coral-like architecture. Energy dispersive X-ray (EDX) microanalysis showed high Mn content in the composite. Electrochemical tests using the synthesized CB/MnO2 showed a specific capacitance of 946 F g−1 at a current density of 0.3 A g−1, which was much higher than that of the composites reported in the literature. Under a current density of 30 A g−1, the CB/MnO2 electrode was shown to retain a high specific capacitance after 5000 charge/discharge cycles. The results from this study demonstrate that the CB/MnO2 nano composite materials of coral-like architecture fabricated with commercially available CB and MnO2 achieved a good electrochemical performance, exhibiting promising application prospects.

Si@void@C Nanofibers Fabricated Using a Self-Powered Electrospinning System for Lithium-Ion Batteries

In recent years, research in lithium-ion batteries (LIBs) has been focused on improving their performance in various ways, such as density, capacity, and lifetime, but little attention has been paid to the energy consumption cost in the manufacturing process. Herein, we report an energy-efficient preparation method of anode materials for LIBs based on a self-powered electrospinning system without an external power source, which consists of a rotatory triboelectric nanogenerator (r-TENG), a power management circuit, and an electrospinning unit. By harvesting kinetic energy from a handle rotation, the r-TENG is able to fully power the electrospinning system to fabricate nanofibers for LIBs. The as-obtained Si@void@C nanofibers present outstanding cyclic performance with a discharge capacity of 1045.2 mA h g-1 after 100 cycles and 88% capacity retention, along with an excellent high rate capacity of 400 mA h g-1 at a current density of 5 A g-1, which are completely comparable with those made by commercial electrospinning equipment. Our study demonstrates an innovative and distinct approach toward an extremely low-cost preparation procedure of electrode materials, leading to a great breakthrough for the LIB production industry.

Silica-Silver Nanocomposites as Regenerable Sorbents for Hg0 Removal from Flue Gases

Silica-silver nanocomposites (Ag-SBA-15) are a novel class of multifunctional materials with potential applications as sorbents, catalysts, sensors, and disinfectants. In this work, an innovative yet simple and robust method of depositing silver nanoparticles on a mesoporous silica (SBA-15) was developed. The synthesized Ag-SBA-15 was found to achieve a complete capture of Hg0 at temperatures up to 200 °C. Silver nanoparticles on the SBA-15 were shown to be the critical active sites for the capture of Hg0 by the Ag-Hg0 amalgamation mechanism. An Hg0 capture capacity as high as 13.2 mg·g-1 was achieved by Ag(10)-SBA-15, which is much higher than that achievable by existing Ag-based sorbents and comparable with that achieved by commercial activated carbon. Even after exposure to more complex simulated flue gas flow for 1 h, the Ag(10)-SBA-15 could still achieve an Hg0 removal efficiency as high as 91.6% with a Hg0 capture capacity of 457.3 μg·g-1. More importantly, the spent sorbent could be effectively regenerated and reused without noticeable performance degradation over five cycles. The excellent Hg0 removal efficiency combined with a simple synthesis procedure, strong tolerance to complex flue gas environment, great thermal stability, and outstanding regeneration capability make the Ag-SBA-15 a promising sorbent for practical applications to Hg0 capture from coal-fired flue gases.