High-capacity Lithium Storage Materials Research Articles

Endothermic Dehydrogenation-Driven Preventive Magnesiation of Sio by Magnesium Hydride for High-Performance Sio-Based Lithium Storage Materials

Silicon monoxide (SiO)-based materials have gained much attention as high-capacity lithium storage materials because of their superior cycle performance. However, low initial Coulombic efficiency (ICE) of SiO derived from the irreversible electrochemical reaction of the amorphous SiO2 phase in SiO makes wide use of the SiO-based anode materials in lithium-ion batteries challenging. Magnesiation of SiO is one of the promising solutions to improve ICE of SiO-based anode materials. Here, we propose an endothermic dehydrogenation-driven magnesiation of SiO by employing MgH2 to improve both ICE and cycle performance. The resulting Si/Mg2SiO4 nanocomposite material showed much-improved ICE of 89.5% and long-term cycle performance for over 300 cycles compared to the homologue prepared by the magnesiation of SiO using Mg and pristine SiO. High-resolution transmission electron microscopy with thermogravimetry−differential scanning calorimetry revealed that the endothermic dehydrogenation of MgH2 mitigates the rapid temperature rise during magnesiation of SiO, thereby inhibiting the increase of Si domain size in the resulting Si/Mg2SiO4 nanocomposite. Detailed material characterization and electrochemical analysis of Si/Mg2SiO4 nanocomposite materials will be discussed in this presentation.

Endothermic Dehydrogenation-Driven Preventive Magnesiation of SiO for High-Performance Lithium Storage Materials.

Silicon monoxide (SiO)-based materials have gained much attention as high-capacity lithium storage materials based on their high capacity and stable capacity retention. However, low initial Coulombic efficiency associated with the irreversible electrochemical reaction of the amorphous SiO2 phase in SiO inhibits the wide usage of SiO-based anode materials for lithium-ion batteries. Magnesiation of SiO is one of the most promising solutions to improve the initial efficiency of SiO-based anode materials. Herein, we demonstrate that endothermic dehydrogenation-driven magnesiation of SiO employing MgH2 enhanced the initial Coulombic efficiency of 89.5% with much improved long-term cycle performance over 300 cycles compared to the homologue prepared by magnesiation of SiO with Mg and pristine SiO. High-resolution transmission electron microscopy with thermogravimetry-differential scanning calorimetry revealed that the endothermic dehydrogenation of MgH2 suppressed the sudden temperature rise during magnesiation of SiO, thereby inhibiting the coarsening of the active Si phase in the resulting Si/Mg2SiO4 nanocomposite.

Nano SnO2 and Sb2O3 combined with CNTs as a high-capacity lithium storage material

The combination of Sb2O3 or SnO2 with graphene has become a research hotpot in recent years. However, several problems, namely the loading of the active materials, space utilization in composites, and the intrinsic volume expansion of Sb2O3 and SnO2, have yet to be fully resolved. To overcome these disadvantages, in this work Sb2O3/carbon nanotubes (CNTs)/SnO2 composite have been synthesized, in which the CNTs act as a network to ensure the electronic conductivity and buffer of the volume expansion. The SnO2 nanoparticles are aligned by the CNTs and Sb2O3 is dispersed in the voids between them. Space utilization and the loading of the oxides are thereby maximized. Moreover, the resultant composite retains small amount of water or alcohol, which does not affect the cyclic stability, but may have increased the ionic and electronic conductivity, improving the electrochemical performance. A discharge capacity of 910 mAh g−1 after 250 cycles at 100 mA g−1 is realized for Sb2O3/CNT/SnO2. Moreover, the contribution of the pseudocapacitance to the rate discharge capability is obvious, which arises from the different heterointerfaces between Sb2O3/CNTs, CNTs/SnO2 or Sb2O3/SnO2. The homogenous distribution of Sn and Sb in CNTs after cycling leads to a lower discharge voltage, improving the application prospects. Although some collapse and cracks are detected, the CNTs network connects the oxides, ensuring the structural stability and the cyclic stability of Sb2O3/CNT/SnO2. This strategy represents a new concept for the design of multi-component materials for lithium storage.

Impact of hydrogen on lithium storage on graphene edges

Hard carbons are extensively studied as high-capacity lithium storage materials. These excess capacities are closely related to the lithium adsorption on the active sites of the carbons. As a common residual element of the hard carbons, the presence of the hydrogen (H) strongly affects the lithium storage and its capacity. Herein, models of graphene nanoribbons with bare zigzag edges (GC) and with pyridinic nitrogen edges (GN) are constructed, respectively, to study the influence of hydrogen by the density functional theory (DFT) calculations. Our calculations show that there is a strong interaction between Li and the H-free GC or GN. However, the presence of H on the edges lowers the average potential, and the interaction becomes significantly weak. The Li atoms can replace the H atoms and form LiN bonds on the H-terminated GN edges, but this hardly takes place on the H-terminated GC. This study fills in the gaps about the H influence on the lithium adsorption in the carbonaceous materials and helps to optimize the structure of the carbon for lithium adsorption.

A green ligand-based copper–organic framework: a high-capacity lithium storage material and insight into its abnormal capacity-increase behavior

The abnormal capacity-increase behavior of high-Li-storage-performance Cu-CIT MOF is investigated by EPR and XAFS, which is found to be induced by gradual redox participation of metal centers during cycles.

Chemically anchored two-dimensional-SiO x /zero-dimensional-MoO2 nanocomposites for high-capacity lithium storage materials.

Silicon oxides are promising alternatives for graphite anodes in lithium-ion batteries. SiOx nanosheets exhibit favorable anodic performances, including outstanding capacity retention and dimensional stability, due to their unique two-dimensional (2D) microstructures, but suffer from low specific capacity and poor initial coulombic efficiency. Here we demonstrate that chemically anchoring of molybdenum dioxide (MoO2) nanoparticles on the surface of 2D-SiOx nanosheets via a Mo–O–Si bond boosts both the reversible capacity and initial coloumbic efficiency without sacrificing the useful properties of 2D-SiOx nanosheets. The enhancements can be attributed to the introduction of a zero-dimensional MoO2 nano-object, which offers abnormal storage sites for lithium. The proposed nano-architecturing shows how we can maximize the advantages of 2D nanomaterials for energy storage applications.

A fast π-π stacking self-assembly of cobalt terephthalate dihydrate and the twelve-electron lithiation-delithiation of anhydrous cobalt terephthalate

Crystalline metal-organic frameworks of divalent transition metal terephthalate belong to a new kind of high-capacity lithium storage materials. In this paper, CoCl2 aqueous solution and CoCl2·6H2O particles are comparatively used as starting materials to react with aqueous lithium terephthalate (Li2TP), resulting in the hierarchical architectures of dihydrate cobalt terephthalate (CoTP·2H2O No.1, No.2) by a solution-based π-π stacking self-assembly, respectively. Each of the two hydrated samples, as well as its well-crystallized anhydrous counterpart (CoTP No.1 or No.2), acquire a specific surface area no bigger than 4.5 m2 g−1 but deliver a reversible capacity no less than 815.0 mAh g−1 at 200 mA g−1 in the 100th cycle. The decreasing order of lithium-storage capability (CoTP·2H2O No.1 < CoTP·2H2O No.2 < CoTP No.1 < CoTP No.2) and its reverse trend of charge-transfer resistance indicate an adverse effect of crystal water, conflicting with the previously demonstrated enhancement of crystal water in inorganic cupric oxalate hydrates. Especially, combining voltage profile with its differential curve clearly reveals a 12-electron transfer lithiation-delithiation mechanism, which explains the ultrahigh reversible capacity (1234.2 mAh g−1, the 350th cycle) of CoTP No.2 structure and indicates a successful approach to the facile preparation of the organic anode material for high-performance lithium-ion batteries.

OXTR brain tissue expression quantitative locus rs237895 moderates the association between maternal childhood maltreatment and non-optimal maternal behavior with implications for offspring socio-emotional development and attachment security

Crystalline metal-organic frameworks of divalent transition metal terephthalate belong to a new kind of high-capacity lithium storage materials. In this paper, CoCl2 aqueous solution and CoCl2·6H2O particles are comparatively used as starting materials to react with aqueous lithium terephthalate (Li2TP), resulting in the hierarchical architectures of dihydrate cobalt terephthalate (CoTP·2H2O No.1, No.2) by a solution-based π-π stacking self-assembly, respectively. Each of the two hydrated samples, as well as its well-crystallized anhydrous counterpart (CoTP No.1 or No.2), acquire a specific surface area no bigger than 4.5 m2 g−1 but deliver a reversible capacity no less than 815.0 mAh g−1 at 200 mA g−1 in the 100th cycle. The decreasing order of lithium-storage capability (CoTP·2H2O No.1 < CoTP·2H2O No.2 < CoTP No.1 < CoTP No.2) and its reverse trend of charge-transfer resistance indicate an adverse effect of crystal water, conflicting with the previously demonstrated enhancement of crystal water in inorganic cupric oxalate hydrates. Especially, combining voltage profile with its differential curve clearly reveals a 12-electron transfer lithiation-delithiation mechanism, which explains the ultrahigh reversible capacity (1234.2 mAh g−1, the 350th cycle) of CoTP No.2 structure and indicates a successful approach to the facile preparation of the organic anode material for high-performance lithium-ion batteries.

Bulky carbon layer inlaid with nanoscale Fe2O3 as an excellent lithium-storage anode material

Bulky carbon layer uniformly distributed with nanoscale Fe2O3 was prepared via a direct carbonation of Fe3+–polyacrylonitrile complexes at 700°C under N2 flow. The iron oxide carbon composites exhibited an excellent cycling performance for lithium storage with a reversible capacity of ∼810mAhg−1 after 250 cycles at a current rate of 100mAg−1. The enhancement was mainly attributed to dual functions of bulky carbon layer which facilitated the lithium-ion diffusion and accommodated the volume changes of active Fe2O3 during charge/discharge process. Our novel chemical strategy is quite effective for scalable fabrication of high capacity lithium-storage materials.

Microstructure Controlled Porous Silicon Particles as a High Capacity Lithium Storage Material via Dual Step Pore Engineering

AbstractTo overcome the lithium storage barriers of current lithium‐ion batteries, it is imperative that conventional low capacity graphite anodes be replaced with other higher capacity anode materials. Silicon is a promising alternative anode material due to its huge energy densities; however, its lithium‐concentration‐dependent volumetric changes can induce severely adverse effects that lead to drastic degradations in capacity during cycling. The dealloying of Si–metal alloys is recently suggested as a scalable approach to fabricate high‐performance porous Si anode materials. Herein, a microstructure controlled porous Si is developed by the dealloying in conjunction with wet alkaline chemical etching. The resulting 3D networked structure enables enhancement in lithium storage properties when the Si‐based material is applied not only as a single active material but also in a graphite‐blended electrode.

A Porous Silicon Anode Material Prepared By Chemical Etching for High-Performance Lithium-Ion Batteries

Lithium-ion batteries (LIBs) have played a critical role in the development of portable electronics and have gained a great deal of attention as power sources for emerging applications such as wearable devices, electric vehicles and robots. However, current LIBs reached technological limits for increasing their energy densities. In order to solve this, much research effort has been devoted to finding high capacity electrode materials to replace currently used materials such as graphite anode in LIBs. Although silicon-based materials are regarded as one of the most promising candidates for anodes because of their huge capacities, the huge volume expansion/contraction of Si during cycling lead to drastic capacity degradation. Recently, porous silicon materials have been revealed to accommodate the large volume change of Si, thus showing outstanding electrochemical performances. However, their use in LIBs suffers from the complicated and limited routes for their synthesis. In this presentation, we represent a porous Si material prepared by scalable and nontoxic chemical etching process as a high capacity lithium storage material for LIBs. This material synthesis concept presented herein represents a means of improving the electrochemical properties of porous Si anode materials for use in commercial LIBs.

Si/SiOx -Conductive Polymer Core-Shell Nanospheres with an Improved Conducting Path Preservation for Lithium-Ion Battery.

Non-stoichiometric SiOx based materials have gained much attention as high capacity lithium storage materials. However, their anode performance of these materials should be further improved for their commercial success. A conductive polymer, poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS), is employed as a flexible electrical interconnector to improve the electrochemical performance of Si/SiOx nanosphere anode materials for lithium ion batteries (LIBs). The resulting Si/SiOx -PEDOT:PSS core-shell structured material with the small amount (1 wt %) of PEDOT:PSS shows the improved initial reversible capacity of 968.2 mA h g-1 with excellent long-term cycle performance over 200 cycles. These promising properties can be attributed to the use of the electroconductive and flexible PEDOT:PSS shell layer, which protects the electrical conduction pathways in the electrode from the large volume changes of silicon during cycling.

Carbon Nanofiber/3D Nanoporous Silicon Hybrids as High Capacity Lithium Storage Materials.

Carbon nanofiber (CNF)/3D nanoporous (3DNP) Si hybrid materials were prepared by chemical etching of melt-spun Si/Al-Cu-Fe alloy nanocomposites, followed by carbonization using a pitch. CNFs were successfully grown on the surface of 3DNP Si particles using residual Fe impurities after acidic etching, which acted as a catalyst for the growth of CNFs. The resulting CNF/3DNP Si hybrid materials showed an enhanced cycle performance up to 100 cycles compared to that of the pristine Si/Al-Cu-Fe alloy nanocomposite as well as that of bare 3DNP Si particles. These results indicate that CNFs and the carbon coating layer have a beneficial effect on the capacity retention characteristics of 3DNP Si particles by providing continuous electron-conduction pathways in the electrode during cycling. The approach presented here provides another way to improve the electrochemical performances of porous Si-based high capacity anode materials for lithium-ion batteries.

Hydrogen silsequioxane-derived Si/SiO(x) nanospheres for high-capacity lithium storage materials.

Si/SiOx composite materials have been explored for their commercial possibility as high-performance anode materials for lithium ion batteries, but suffer from the complexity of and limited synthetic routes for their preparation. In this study, Si/SiOx nanospheres were developed using a nontoxic and precious-metal-free preparation method based on hydrogen silsesquioxane obtained from sol-gel reaction of triethoxysilane. The resulting Si/SiOx nanospheres with a uniform carbon coating layer show excellent cycle performance and rate capability with high-dimensional stability. This approach based on a scalable sol-gel reaction enables not only the development of Si/SiOx with various nanostructured forms, but also reduced production cost for mass production of nanostructured Si/SiOx.

Sn nanocrystal/carbon composites as high-capacity anode materials for lithium rechargeable batteries

High-capacity lithium-storage materials in metal composite form are being extensively researched, which can replace the carbon-based lithium intercalation materials currently commercialized as the negative electrode of lithium rechargeable batteries. Herein, Sn nanocrystals and Sn nanocrystal/carbon composites with various particle sizes are prepared by the chemical reduction method where surfactant can control the resultant particle size because the particle size of metal-based materials is the main underlying factor for their electrochemical enhancement. The chemical reduction approach using surfactants is very effective for varying the particle size of Sn nanocrystals. Sn nanocrystals with the optimized particle size in terms of anodic properties are made into a composite with carbon acting as an agglomeration preventer as well as an electronic conductor. The controlled size of the Sn nanocrystal in the carbon is associated with their drastically improved electrochemical performance retaining above 65% of the initial capacity after 30 cycles.

Synergistic effects of transition metal substitution in conversion electrodes for lithium-ion batteries

Different solid solutions in the FexCo1−xC2O4·2H2O system have been prepared in the form of nanoribbons by a reverse micelles method. The orthorhombic crystallographic structure differs from the monoclinic massive products FeC2O4·2H2O and CoC2O4·2H2O. The dehydration process is studied by thermal analysis to prepare the anhydrous solid solution oxysalts, in which the nanoribbon-shaped particles are preserved and a porous system is developed. Anhydrous mixed oxalates are used for the first time as high-capacity lithium storage materials with improved rate performance, and display synergistic effects as compared with the end members. Fe0.75Co0.25C2O4 displays a reversible capacity ca. 600 mA h g−1 at 5C rate with a very good capacity retention after 75 cycles by a hybrid mechanism. The solids display faradaic capacities due to a novel conversion reaction that produces nanodispersed transition metals, which is responsible for the high energy density, and a capacitive response that leads to high power densities in Li-ion batteries. The low temperature synthesis of these materials makes them an inexpensive option for this purpose.

Cobalt Oxalate Nanoribbons as Negative-Electrode Material for Lithium-Ion Batteries

Orthorhombic cobalt oxalate dihydrate has been prepared in the form of nanoribbons by a reverse micelles method. The crystallographic structure of the resulting solid differs from the monoclinic massive product. A careful dehydration of the nanocrystals leads to anhydrous cobalt oxalate in which the nanoribbon-shaped particles are preserved and Co2+ ions are located in a centrosymmetric environment. CoC2O4 is used for the first time as high-capacity lithium storage materials with improved rate performance. The anhydrous solids react with lithium, leading to metallic cobalt and lithium oxalate, as shown by XAS and FTIR measurements. The new electrode material displays reversible capacities close to 900 mA·h·g−1 between 0 and 2 V versus lithium by a novel reaction mechanism which involves cobalt reduction−reoxidation.

Synthesis and Electrochemical Reaction with Lithium of Mesoporous Iron Oxalate Nanoribbons

Mesoporous FeC 2O 4 was prepared by dehydration of bulk monoclinic- and micellar orthorhombic FeC 2O 4.2H 2O precursors at 200 degrees C. The micellar material shows nanoribbon shaped particles, which are preserved after dehydration. These solids are used as high-capacity lithium storage materials with improved rate performance. The mesoporous nanoribbons exhibit higher capacities close to 700 mA h/g after 50 cycles at 2C (C = 1 Li h (-1) mol (-1)) rate between 0 and 2 V.

The Role of Oxygen in Low-potential Li Insertion in Metal Oxide Anode Materials

ABSTRACTTransition metal oxides are high-capacity lithium storage materials of interest as possible anode materials in the next generation of Li ion batteries. By using X-ray absorption spectroscopy we have obtained an understanding of the process of Li uptake and removal within Na0.25MoO3. Our results show the Li2O matrix on reduction is not inert; Mo-O bonds are reversibly consumed on discharge and are regenerated on charge, with the Li2O matrix acting as the oxygen reservoir. The migration of oxygen atoms from the matrix to the active centers occurs at a voltage below that expected for the Li2O free energy of formation. Polarization on charge is not due only to oxygen migration but also to metal rearrangement within the electrode material. The reversibility of the Mo-O bond formation on repeated cycles is a function of the depth of discharge, with 200 mV being the lower limit.

Tin-Based Amorphous Oxide: A High-Capacity Lithium-Ion-Storage Material

A high-capacity lithium-storage material in metal-oxide form has been synthesized that can replace the carbon-based lithium intercalation materials currently in extensive use as the negative electrode (anode) of lithium-ion rechargeable batteries. This tin-based amorphous composite oxide (TCO) contains Sn(II)-O as the active center for lithium insertion and other glass-forming elements, which make up an oxide network. The TCO anode yields a specific capacity for reversible lithium adsorption more than 50 percent higher than those of the carbon families that persists after charge-discharge cycling when coupled with a lithium cobalt oxide cathode. Lithium-7 nuclear magnetic resonance measurements evidenced the high ionic state of lithium retained in the charged state, in which TCO accepted 8 moles of lithium ions per unit mole.