Mesocarbon Microbeads Research Articles

Effect of Nano-Fillers on Capacity Retention and Rate Capability of Mesocarbon Microbeads Anode

Thin film mesocarbon microbeads (MCMB) composite electrodes consisting of hybrid nano-fillers of carbon black (CB) and carbon nanotubes (CNT) have been developed and characterized by evaluating their electrical and electrochemical properties. The composite electrodes have been fabricated with various weight fractions of CB and CNT. It is shown that by partial replacement of CB by CNT in electrodes, a synergistic improvement in electrical conductivity, initial capacity and stability in cycling behavior at low (0.25C) as well as at high rates (4C) is achievable. This is attributed to the combined effect of (i) hybrid of CB-CNT providing short- and long-range conducting pathways by effectively filling the gaps between MCMB-MCMB, CNT-CNT and MCMB-CNT clusters, and (ii) formation of a compact and stable solid-electrolyte film resulting in a compact three-dimensional conducting scaffold. The electrodes with CB-CNT hybrid additives exhibit best performance in terms of capacity retention (342.8 mAhg−1 after 50 cycles with almost 98% capacity retention at 0.25C and 280.0 mAhg−1 after 100 cycles at 4C) and rate capability. This kind of approach to create a hybrid of geometrically distinct shape, aspect ratio and dispersion characteristics conducting fillers manifests a promising strategy to develop improved performance composite anodes for future lithium-ion batteries.

CVD-Synthesis of MCMB/CNTs Hybrids with Low Specific Surface Area for Supercapacitors

Carbon nanotubes (CNTs) have been successfully grown on the surfaces of mesocarbon microbeads (MCMB) via a chemical vapor deposition (CVD) method by using iron particles as the catalyst. The morphologies of the hybrids were modulated by controlling the ratio (r) of H2 to C2H2. The obtained CNTs are uniform with an average diameter of 20 nm when r = 2 at 750°C. The specific surface area of such MCMB-CNTs-2 is 34.5 m2·g−1, and the specific capacitance is 319 F·g−1 at the current density of 1 A·g−1. More importantly, MCMB-CNTs-2 exhibits extraordinary cycling life stability (the retention is 88.4% after 5000 cycles), despite some CNTs may break off from MCMB surface after cycles. We attribute the improvement of electrochemical properties to the mesoporous structure and excellent electrical conductivity of the hybrids with low specific surface area. Our study indicates that the MCMB/CNTs hybrids are promising candidates for the electrode materials of supercapacitors.

Silicon Carbide-Derived Carbon Coated Graphitized Mesocarbon Microbead Composites for Anode of Lithium-Ion Battery

Unique silicon carbide-derived carbon (SiC-CDC) and graphitized mesocarbon microbead (GMCMB) composites (GMCMB@SiC-CDC) were prepared by solid reaction of GMCMB and silicon and following etching reaction with chlorine. The microstructure of SiC-CDC was characterized as mainly amorphous carbon combined with some short and curved sheets of graphite. N2 adsorption/desorption isotherms and pore size distributions proved the composites presented both an enormous amount micropores centered at around 0.5~0.6 nm and a few mesopores (2~50 nm). The GMCMB@SiC-CDC composites showed higher specific surface area and pore volume, especially the microporous surface area and volume. The composites as the anode materials manifested much higher charge specific capacities of 877.6 mAh·g-1 at the first cycle compared with pure GMCMB of 359.6 mAh·g-1, which was probable that Li ions could insert into not only carbon layers but also micropores. The GMCMB@SiC-CDC composites presented better discharge specific capacities at higher charge/discharge rates. The component and electrochemical performances of the composites can be optimized through changing the molar ratio of GMCMB/Si to control the corresponding proportion of SiC-CDC and GMCMB.

High-performance CuO/Cu composite current collectors with array-pattern porous structures for lithium-ion batteries

The surface structure and material composition of current collectors significantly affect the electrochemical performances of lithium-ion batteries. This study forms array-pattern blind holes and creates a layer of copper oxide (CuO) on the surface of thin copper plates using the chemical etching method. This copper plate is made into a CuO/Cu composite current collector with array-pattern porous structures for lithium-ion batteries. Using mesocarbon microbead graphite powders as the anode material, this new composite current collector is assembled into CR2032 coin half-cells for electrochemical tests. Batteries with this porous current collector exhibit high reversible discharge capacities of 383.9mAhg−1 at 0.5mA and 374mAhg−1 even after 0.2C and 0.5C rate cycles, whereas batteries with a complanate current collector deliver only 309.6mAhg−1 and 296.7mAhg−1. It is believed that the array-pattern blind holes coupled with the morphological effects of the oatmeal-like CuO significantly enhance the electrochemical performances of batteries in terms of reversible capacity, cycling stability, electrical conductivity and coulombic efficiency.

Surface Modified Pinecone Shaped Hierarchical Structure Fluorinated Mesocarbon Microbeads for Ultrafast Discharge and Improved Electrochemical Performances

Among all primary lithium batteries, Li/CFx primary battery possesses the highest energy density of 2180 Wh kg−1. However, a key limitation is its poor rate capability because the cathode material CFx is intrinsically a poor electronic conductor. Here, we developed a so-called “doing subtraction” method to modify the pinecone shaped fluorinated mesocarbon microbead (F-MCMB). The modified fluorinated mesocarbon microbead (MF-MCMB), manifests the advantage of open-framed structure, possesses good electronic conductivity and removes transport barrier for lithium ions. Thus, high capacity performance and excellent rate capability without compromising capacity can be obtained. A capacity of 343 mAhg−1 and a maximum power density of 54600 W kg−1 are realized at an ultrafast rate of 40 C (28A g−1). In addition, the MF-MCMB cathode does not show any voltage delay even at 5C during the discharge, which is a remarkable improvement over the state-of-the-art CFx materials.

Energy Storage: A Dual‐Ion Battery Constructed with Aluminum Foil Anode and Mesocarbon Microbead Cathode via an Alloying/Intercalation Process in an Ionic Liquid Electrolyte (Adv. Mater. Interfaces 23/2016)

Energy Storage: A Dual‐Ion Battery Constructed with Aluminum Foil Anode and Mesocarbon Microbead Cathode via an Alloying/Intercalation Process in an Ionic Liquid Electrolyte (Adv. Mater. Interfaces 23/2016)

Design and synthesis of a novel 3D hierarchical mesocarbon microbead as anodes for lithium ion batteries and sodium ion batteries

This work presents a feasible route for the facile synthesis of three-dimensional (3D) hierarchical mesocarbon microbead (MCMB) as anodes for lithium ion batteries (LIBs) and sodium ion batteries (SIBs). The MCMB is oxidized by modified hummers method, and then the precursor is treated by hydrogen reduction to form the HMCMB. The HMCMB with graphene-like architecture has high specific surface, sufficient pore volume, and increased interlayer spacing, which can provide more active insertion/extraction sites and reduce the Li+/Na+ diffusion resistance. When employed as anode materials for LIBs and SIBs, HMCMB anodes exhibit improved lithium and sodium storage capability. The HMCMB delivers a higher reversible capacity (471.1 and 177.5 mAh g−1 at 100 mA g−1 after 100 cycles) and a good rate performance (250 and 121 mAh g−1 even at 1000 mA g−1) for LIBs and SIBs, respectively.

Carbon Composites for a High‐Energy Lithium–Sulfur Battey with a Glyme‐Based Electrolyte

AbstractA comparative study of sulfur composites using carbon of various natures, namely, graphite, mesocarbon microbeads, and multi‐walled carbon nanotubes, is performed in lithium battery design and evaluation. Morphological and structural analyses, by means of SEM and XRD, cyclic voltammetry and galvanostatic cycling in lithium cells are employed for characterization of the materials. Tetraethylene glycol dimethyl ether containing lithium trifluoromethansulfonate is considered the preferred electrolyte for performing the electrochemical tests. Prior to use in cells, the electrolyte characteristics in terms of 1H, 7Li, and 19F nuclei self‐diffusion coefficients, ionic conductivity, and ionic association degree are studied by combining NMR and impedance spectroscopy. The best lithium–sulfur composite reported herein achieves a capacity higher than 500 mAh g−1 over 140 cycles with no sign of dendrite formation or failure. This performance is considered sufficiently suitable for the development of high‐energy lithium batteries, in particular, considering the expected safety of the cells by employing a nonflammable glyme electrolyte instead of a conventional carbonate‐based one.

Nickel cobaltite nanoflakes grown around nickel foam-supported expanded mesocarbon microbeads for battery-like electrochemical capacitors

The eMCMBs (expanded mesocarbon microbeads) composed of fluffy graphene oxide nanosheets were obtained by chemical oxidation of MCMB graphite powder. The eMCMBs were attached to the skeleton of nickel foam through electrophoretic deposition. After heat treatment in reducing atmosphere, the eMCMBs were converted into reduced eMCMBs (reMCMBs) composed of sponge-like graphene nanosheets. Nickel foam with attached reMCMBs was used as a highly conductive scaffold to support nickel cobaltite nanoflakes. The sponge-like reMCMBs accommodated electrolyte solution, afforded current collector, and functioned as a stress buffer to alleviate electrode damage. Macroporous nickel cobaltite film with mesoporous thin nanoflakes could provide large amounts of pores for easy penetration of electrolyte solution, huge interfacial area for facile redox reactions, and short transport distance for ions and electrons. Nickel cobaltite grown around nickel foam with attached reMCMBs could deliver a high specific capacitance of 1025 F g−1 at 5 A g−1, greater than that grown around nickel foam (688 F g−1). Nickel cobaltite nanoflakes grown on reMCMBs turned out to decrease the kinetic resistance, diffusive impedance, and volumetric strain, resulting in better capacitance, rate capability, and electrochemical stability.

Ion-Catalyzed Synthesis of Microporous Hard Carbon Embedded with Expanded Nanographite for Enhanced Lithium/Sodium Storage.

Hard carbons attract myriad interest as anode materials for high-energy rechargeable batteries due to their low costs and high theoretical capacities; practically, they deliver unsatisfactory performance due to their intrinsically disordered microarchitecture. Here we report a facile ion-catalyzed synthesis of a phenol-formaldehyde resin-based hard-carbon aerogel that takes advantage of the chelation effect of phenol and Fe3+, which consists of a three-dimensionally interconnected carbon network embedded with hydrogen-rich, ordered microstructures of expanded nanographites and carbon micropores. The chelation effect ensures the homodispersion of Fe in the polymer segments of the precursor, so that an effective catalytic conversion from sp3 to sp2 carbon occurs, enabling free rearrangement of graphene sheets into expanded nanographite and carbon micropores. The structural merits of the carbon offer chances to achieve lithium/sodium storage performance far beyond that possible with the conventional carbon anode materials, including graphite and mesocarbon microbeads, along with fast kinetics and long cycle life. In this way, our hard carbon proves its feasibility to serve as an advanced anode material for high-energy rechargeable Li/Na batteries.

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.

Meso Carbon Micro Bead (MCMB) Based Graphitized Carbon for Negative Electrode in Lithium Ion Battery

Lithium ion battery performance of graphitized Meso Carbon Micro Beads (MCMB) as an anode material was investigated in full cell battery system containing LiCoO<sub>2</sub> cathode, PE separator and LiPF<sub>6</sub> electrolyte. The commercial MCMB, which was fabricated by Linyi<sup>TM</sup>, was sintered at 500⁰C for five hour to make graphitized MCMB. The microstructure of graphitized MCMB was characterized using XRD and SEM to show the crystalinity, crystal phase and morphology of the MCMB particle. The result indicated that the crystal phase of the sample was changed into graphitized carbon .The electrode was made using coating method. We used copper foil as the substrate for anode. The anode materials consist of graphitized MCMB (active material), Polyvinylidene fluoride/PVDF (binder) and acetylene black (additive material). Full cell battery was tested using charge-discharge and cyclic voltammetry (CV) methods. From the CV characterization, cyclic voltammograms of the cell show characteristic lithium intercalation through reduction-oxidation peak. Charge-discharge test showed the discharge and charge capacity of the cells. According charge discharge test, commercial MCMB was better that graphitized MCMB.

Meso Carbon Micro Bead (MCMB) Based Graphitized Carbon for Negative Electrode in Lithium Ion Battery

Lithium ion battery performance of graphitized Meso Carbon Micro Beads (MCMB) as an anode material was investigated in full cell battery system containing LiCoO<sub>2</sub> cathode, PE separator and LiPF<sub>6</sub> electrolyte. The commercial MCMB, which was fabricated by Linyi<sup>TM</sup>, was sintered at 500⁰C for five hour to make graphitized MCMB. The microstructure of graphitized MCMB was characterized using XRD and SEM to show the crystalinity, crystal phase and morphology of the MCMB particle. The result indicated that the crystal phase of the sample was changed into graphitized carbon .The electrode was made using coating method. We used copper foil as the substrate for anode. The anode materials consist of graphitized MCMB (active material), Polyvinylidene fluoride/PVDF (binder) and acetylene black (additive material). Full cell battery was tested using charge-discharge and cyclic voltammetry (CV) methods. From the CV characterization, cyclic voltammograms of the cell show characteristic lithium intercalation through reduction-oxidation peak. Charge-discharge test showed the discharge and charge capacity of the cells. According charge discharge test, commercial MCMB was better that graphitized MCMB.

Improved Electrochemical Performance of Modified Mesocarbon Microbeads for Lithium‐Ion Batteries Studied using Solid‐State Nuclear Magnetic Resonance Spectroscopy

AbstractLithium‐intercalating materials such as graphite are of great interest, especially for application in lithium‐ion batteries. In this work we present an investigation of the electrochemical performance of mesocarbon microbeads (MCMB) modified with copper to reveal the basic electrochemical mechanisms. Copper‐modified graphite is known to have better long‐term cycling behavior as well as higher capacity compared to the pristine material. Several reasons for these effects were postulated but not proven. Solid‐state nuclear magnetic resonance (NMR) spectroscopy provides structural and dynamic information on lithium in ionic conductors. To elucidate the changes in structure and dynamics for the pristine and the modified material, we have employed multi‐nuclear solid‐state NMR spectroscopy as well as 7Li spin‐lattice relaxation measurements and were able to clarify some reasons for the improved characteristics of copper‐modified graphite compared to the pristine material, which include increased solid–electrolyte interface (SEI) formation, a facilitated diffusion of lithium ions through the SEI, and reduced moisture.

Evaluation of di(2,2,2-trifluoroethyl) sulfite as a film-forming additive on the MCMB anode of lithium-ion batteries

Abstract This study demonstrates a sulfur-based compound, di(2,2,2-trifluoroethyl) sulfite (DTFES), as a new solid electrolyte interphase (SEI) forming additive on mesocarbon microbeads (MCMB). When placed in the electrolyte, it can dramatically enhance the performance of lithium-ion batteries (LIBs). The capacity loss was significantly decreased from 17.4% to 6.3% after 100 charge-discharge cycles due to the addition of DTFES. Differential capacity (dQ/dV) versus voltage (V) analysis showed that DTFES was decomposed in advance versus to electrolyte solvents. The effects of DTFES were characterized by charge-discharge testing, electrochemical impedance spectroscopy (EIS), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). These results indicate that the SEI film formed on MCMB by DTFES plays an important role in LIBs performance. Their subsequent reaction pathways are proposed in the paper.

Title: Mechanical Behaviour of Lithium Ion Pouch Cells Under the Influences of Electrochemical Aging or Mechanical Injury

As a major obstacle preventing the industrial application of the lithium ion batteries on a larger scale, such as in the automobile industry, the capacity retention which represents the characteristic of the E-Mobile remains still a challenge for further investigation. Among the causes leading to the capacity degradation mechanical stress is a most important inducement. Thus, it is necessary to take a look at the mechanical behaviour of a cell with serious capacity deterioration. The mechanical stress can either be generated by the lithium insertion inside the cell during the running electrochemical process or be imposed by an external force before the cycling during the manufacture. Accordingly, the mechanical behaviour of the electrode must be observed considering electrochemical aging and mechanical injury respectively. In our work the mechanical behaviour is investigated by monitoring the surface displacement by digital image correlation technique (DIC) parallel to the cycling according to a constant current scheme (CC) in a Voltage range between 3.0V and 4.2V. Two lithium ion pouch cells which are situated in different conditions – at the end of its cycle life and under influence of mechanical injury were selected for this research. Each samples consists of single anode (65x45mm) and cathode (70x50mm) using NMC (nickel manganese cobalt oxide) and MCMB (Meso Carbon Micro Beads) as electrode materials for cathode and anode respectively. While 12 tests according to the same procedure one cell was charged and discharged with 5 currents (6mA, 8.5mA, 11mA, 13mA, 20mA) for 3 cycles at each charging current, and 3 different charging currents (3mA, 5mA and 6mA) were applied on the other sample after it was damaged mechanically. Normally, the lifespan of a lithium ion cell can be divided into three phases: the first two or three cycles with a considerable decrease of the capacity due to the formation of the surface film and a fierce volume expansion; the following cycling with a stable capacity retention at a steady level; the last phase exhibiting an irreversible capacity decrease to such a low level that the cell is no more useful. According to our results, however, the decrease of the capacity is not gradually, even in the last phase of the cell’s lifespan, but abruptly at a certain cycle, which is represented not only by the sudden fall of the capacity but also on the progress of the displacement. In comparison with the displacement behaviour on a cell at normal working condition, anomalous irreversible progress develops and can be recognized as increasing displacement resulting from the irreversible processes inside the cell. When the limitation of the mechanical durance of the system is exceeded, a permanent deformation is formed and then the displacement maintains a fluctuation at a low level indicating the low intensity of the remaining electrochemical reaction. Besides, the irregular behaviour is no longer located merely in the edge areas of the cell but can be observed all over the cell surface as displacement pattern with low intensity which describes the local difference of the surface displacement. By post mortem analysis of the cell it can be concluded that the weakened adhesion and the exfoliation of the electrode material on the current collector may be the major cause for this behaviour. In comparison, the mechanical injury causes more serious damage of the electrode structure than normal cycling, resulting in capacity deterioration in only a few cycles. This is accompanied with severe permanent displacement evolution over the entire displacement pattern on the anode surface. While the displacement in the area without the imposition of the injury exhibits continuous progression on the displacement plot which illustrates the temporal evolution of the displacement, a sudden drop on the displacement plots appears in the injured area correlating to the exfoliation due to imposed mechanical damage. To summarize our results, we can drew the conclusion that the electrochemical state of the cell can be associated with the displacement behaviour on the surface of the cell. The deterioration of material adhesion and exfoliation lead to loss of electrical connectivity which is the determined steps for severe capacity degradation. Mechanical injury brings fierce structure damage which can accelerate the degradation progress. Furthermore, we can assume that the aging of the anode caused by electrochemical cycling develops finally into structure damage, comparable as if the anode was injured by mechanical forces. The improvement of the electrode integrity is the most important measure to upgrade the capacity retention of the lithium-ion battery. Figure 1

Near Zero Volt Tolerant Lithium Ion Cells: Benefits for Safe Storage, Shipping, and Medical Implants

There are inherent safety risks associated with lithium ion batteries leading to greater restrictions and regulations on shipping and inactive storage. Maintaining the cell(s) of a lithium ion battery at a near zero voltage with an applied fixed load is one promising approach which can lessen (and potentially eliminate) the risk of entering thermal runaway when in an inactive state. However, a near zero lithium ion cell voltage can be damaging if the anode potential increases to above ~3.1 V vs. Li/Li+ where dissolution of the anode copper current collector and other side reactions occur. Approaches using alternative anode current collectors (e.g. titanium) which are stable at higher electrochemical potentials vs. Li/Li+ have had success in mitigating anode substrate dissolution during storage of cells at near zero voltage. However, several anticipated tradeoffs exist with titanium current collectors including increased foil thickness, increased cost, and lower bulk conductivity compared to standard copper foils. An alternative approach to prevent copper current collector dissolution during near zero volt storage is to ensure that the anode electrochemical potential remains less than the copper dissolution potential during near zero volt storage. Past approaches to achieve this have included secondary electrode active materials with intermediate discharge potentials and high first cycle loss cathode additives. However, addition of secondary active materials or additives to the electrodes that may not contribute to the discharge energy of the cell during normal cycling will reduce cell energy density. Additionally, secondary materials may have other operational concerns such as gassing or instability in the operational potential range of the electrode they are added to. In the present work, the anode potential of a lithium ion cell is maintained less than the copper dissolution potential during near zero volt storage using anode pre-lithiation prior to cell assembly. Specifically, pouch cells were fabricated with a LiCoO2 cathode and a mesocarbon microbead (MCMB) anode that was cycled and partially pre-lithiated with active lithium. Three electrode tests with a lithium metal reference and 1.2 M LiPF6 3:7 EC:EMC electrolyte showed that the electrochemical potential of the anode is less than the copper dissolution potential throughout a multiple day near zero volt storage period. Specifically, during the transient period of cell discharge to near zero volts under fixed load over the course of several hours, the anode potential is <1.9 V vs. Li/Li+. After the cell reaches near zero volts and a quasi-equilibrium state, the electrochemical potential that the electrodes asymptote to, the electrode asymptotic potential (EAP), is ~1.9 V vs. Li/Li+ which is less than the copper dissolution potential. The LiCoO2:MCMB pouch cell maintained 99% of its original capacity and average discharge voltage after three, 3-day storage periods at near zero volts cell voltage under fixed load at room temperature. In a second demonstration, a LiCoO2/MCMB cell with a pre-lithiated anode was stored for 7-day periods under a fixed load at near zero volts. The cell maintained 99% of its original capacity and average discharge voltage after three, 7-day storage periods at near zero volts cell voltage at room temperature. A third LiCoO2/MCMB cell with a pre-lithiated anode maintained >99% of its discharge capacity after a 3-day near zero volt storage period under fixed load at 45 °C. High temperature tolerance could impact the reliability of cells in medical implants, which can be inadvertently overdischarged due to patient non-compliance. Lowering the transient period anode potential and EAP of a cell with anode pre-lithiation is an emerging concept to achieve lithium ion cells with high tolerance to storage at near zero voltage at room temperature and elevated temperatures. The demonstrated cell modifications to achieve this performance utilized conventional materials and required no change of typical cell construction parameters. Thus, anode pre-lithiation is an attractive design for near zero volt storage-tolerant lithium ion cells.

A Dual‐Ion Battery Constructed with Aluminum Foil Anode and Mesocarbon Microbead Cathode via an Alloying/Intercalation Process in an Ionic Liquid Electrolyte

A novel dual‐ion battery constructed with aluminum foil anode and mesocarbon microbead (MCMB) cathode based on a lithium‐salt containing ionic liquid electrolyte is prepared. The working mechanism of this Al‐MCMB dual‐ion battery is demonstrated to be intercalation/deintercalation of anions into/from the MCMB cathode and AlLi alloying/dealloying at the Al anode. Owing to the good stability of ionic liquid at high working voltage and the protection of fluoroethylene carbonate additive in the electrolyte by forming stable solid electrolyte interphase film on the Al foil, the battery presents superior cycling stability at high cut‐off voltage of 4.8 V with a reversible capacity of 98 mAh g−1 after 300 cycles at 0.5 C with negligible decay. Moreover, as the Al foil is directly utilized as both anode material and current collector, the energy density of the packaged Al‐MCMB cell can be further increased, which is estimated to be 221 W h kg−1 at the power density of 109 W kg−1 and remains 185 W h kg−1 at 1141 W kg−1, much better than most commercial lithium‐ion batteries.

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.

Formation of graphene flowers during high temperature activation of mesocarbon microbeads with KOH

Graphene flowers on porous activated carbon was successfully obtained by activation of mesocarbon microbeads (MCMB) with KOH at high temperature. By investigation of structure evolution with temperature from 800 to 1100 °C, it was found the coarse surface of activated carbon with cracks and small particles became to be graphene flowers when the activation temperature reached 1000 °C. The activated carbon with graphene flowers had high specific surface area value (1855 m2/g) and pore volume (1.18 cm3/g), which was ascribed to the chemical reactions, K intercalation and existence of graphene flowers. From the microstructural analysis, it was deduced that graphene flowers on the activated carbon was obtained from the high ordered layers in the small building units of MCMB, which processed the removal of disordered carbon, remaining the high ordered layers left under high temperature activation.