Electrostatic spray deposition of porous SnO₂/graphene anode films and their enhanced lithium-storage properties

Interphase stabilized electrospun SnO2 fibers as alloy anode via restricted cycling for Li-ion capacitors with high energy and wide temperature operation

The second-generation supercapacitor comprises the hybridized energy storage mechanism of Lithium-ion batteries and electrical double-layer capacitors, i.e, Lithium-ion capacitors (LICs). The electrospun SnO₂ nanofibers are synthesized by a simple electrospinning technique and are directly used as anode material for LICs with activated carbon (AC) as a cathode. However, before the assembly, the battery-type electrode SnO₂ is electrochemically pre-lithiated (Li_xSn + Li₂O), and AC loading is balanced with respect to its half-cell performance. First, the SnO₂ is tested in the half-cell assembly with a limited potential window of 0.005 to 1 V vs. Li to avoid the conversion reaction of Sn⁰ to SnO_x. Also, the limited potential window allows only the reversible alloy/de-alloying process. Finally, the assembled LIC, AC/(Li_xSn + Li₂O), displayed a maximum energy density of 185.88 Wh kg^-1 with ultra-long cyclic durability of over 20,000 cycles. Further, the LIC is also exposed to various temperature conditions (-10, 0, 25, & 50 °C) to study the feasibility of using them in different environmental conditions.

Boosting Reversibility and Stability of Li Storage in SnO2 -Mo Multilayers: Introduction of Interfacial Oxygen Redistribution

Among the promising high-capacity anode materials, SnO₂ represents a classic and important candidate that involves both conversion and alloying reactions toward Li storage. However, the inferior reversibility of conversion reactions usually results in low initial Coulombic efficiency (ICE, ≈60%), small reversible capacity, and poor cycling stability. Here, it is demonstrated that by carefully designing the interface structure of SnO₂ -Mo, a breakthrough comprehensive performance with ultrahigh average ICE of 92.6%, large capacity of 1067 mA h g^-1 , and 100% capacity retention after 700 cycles can be realized in a multilayer Mo/SnO₂ /Mo electrode. Furthermore, high capacity retentions are also achieved in pouch-type Mo/SnO₂ /Mo||Li half cells and Mo/SnO₂ /Mo||LiFePO₄ full cells. The amorphous SnO₂ /Mo interfaces, which are induced by redistribution of oxygen between SnO₂ and Mo, can precisely adjust the reversible capacity and cycling stability of the multilayers, while the stable capacities are parabolic with the interfacial density. Theoretical calculations and in/ex situ investigation reveal that oxygen redistribution in SnO₂ /Mo heterointerfaces boosts Li-ion transport kinetics by inducing a built-in electric field and improves the reaction reversibility of SnO₂ . This work provides a new understanding of interface-performance relationship of metal-oxide hybrid electrodes and pivotal guidance for creating high-performance Li-ion batteries.

Exfoliated Graphite Nanosheets Coating on Nano-grained SnO2/Li4Ti5O12 as a High-Performance Anode Material for Lithium-Ion Batteries

The SnO₂/Li₄Ti₅O₁₂/C compound was gained via hydrothermal, sintering, and ball milling methods. Nano-grained SnO₂/Li₄Ti₅O₁₂ are homogeneously wrapped in a sheet-like graphite. Li₄Ti₅O₁₂ possesses cyclic stability and superior rate capacity. Meanwhile, the SnO₂/Li₄Ti₅O₁₂ hybrid can supply abundant active sites for absorption of Li⁺, mitigate chemical stress in cycling, and prevent the ultrathin graphite nanosheets from stacking. Besides, the sheet-like graphite could reduce volume variation in cycling and reduce transmission distance for the electron or Li⁺. Therefore, an outstanding electrochemical property of the SnO₂/Li₄Ti₅O₁₂/C composite can be obtained.

Porous SnO2 nanostructure with a high specific surface area for improved electrochemical performance

Tin oxide (SnO₂) has been attractive as an alternative to carbon-based anode materials because of its fairly high theoretical capacity during cycling. However, SnO₂ has critical drawbacks, such as poor cycle stability caused by a large volumetric variation during the alloying/de-alloying reaction and low capacity at a high current density due to its low electrical conductivity. In this study, we synthesized a porous SnO₂ nanostructure (n-SnO₂) that has a high specific surface area as an anode active material using the Adams fusion method. From the Brunauer–Emmett–Teller analysis and transmission electron microscopy, the as-prepared SnO₂ sample was found to have a mesoporous structure with a fairly high surface area of 122 m² g⁻¹ consisting of highly-crystalline nanoparticles with an average particle size of 5.5 nm. Compared to a commercial SnO₂, n-SnO₂ showed significantly improved electrochemical performance because of its increased specific surface area and short Li⁺ ion pathway. Furthermore, during 50 cycles at a high current density of 800 mA g⁻¹, n-SnO₂ exhibited a high initial capacity of 1024 mA h g⁻¹ and enhanced retention of 53.6% compared to c-SnO₂ (496 mA h g⁻¹ and 23.5%).

A porous SnO₂ nanostructure as an anode active material showed significantly improved electrochemical performance.

Facile one-pot synthesis of Ge/TiO2 nanocomposite structures with improved electrochemical performance

Germanium (Ge) as an alternative to graphite exhibits a fairly high theoretical energy density and improved Li⁺ ion diffusivity. However, the seriously deteriorated electrochemical performance of Ge during cycling and the difficulty in the preparation of Ge-based nanostructures can hinder the utilization of Ge as an anode. Thus, in this study, a nanocomposite structure with Ge and TiO₂ (Ge/TiO₂) was synthesized using a facile one-pot method with different ratios of a Ge source with a dominant GeO₂ phase and titanium isopropoxide. From X-ray diffraction, electron microscopy, and X-ray photoelectron spectroscopy, the Ge/TiO₂ nanocomposites were found to be spherical structures homogeneously consisting of the reduced Ge as an active material and amorphous TiO₂ as a matrix. In particular, the Ge/TiO₂ nanocomposite with an appropriate amount of TiO₂ exhibited improved electrochemical properties, i.e., a coulombic efficiency of 97% and a retention of 61% for 100 cycles, compared to commercial Ge (a coulombic efficiency of 82% and a retention of 16%). This demonstrates that the amorphous TiO₂ matrix could relieve a volumetric expansion of the Ge active material in the nanocomposite electrode generated during the cycling process.

Designed Nanoarchitectures by Electrostatic Spray Deposition for Energy Storage

The development of advanced electrode materials for various energy-storage systems, especially the fabrication of designed structures and morphologies of electrode materials, has attracted intense interest in both the academic and industrial fields. Among the various synthesis methods, electrostatic spray deposition (ESD) is a simple but versatile approach, by which materials can be fabricated with various morphologies, such as granular, dense, and porous, in an easily controllable manner. Herein, motivated by the rapid advancements of the given technology, a comprehensive introduction of ESD is provided, with emphasis on the kinds of materials and the types of morphology that can be obtained, along with the important control parameters. The progress on electrode materials, which are applied in a great variety of energy-storage systems, such as Li-ion batteries, Na-ion batteries, supercapacitors, Li-S batteries, and Li-O₂ batteries, prepared by ESD is also summarized. How the specific morphologies designed by ESD improve the electrochemical performance for different types of electrode materials is also discussed. The aim is to promote the collaborative efforts among different communities to optimize and develop the ESD technique and to explore advanced electrode materials for energy storage.

Sandwiched spherical tin dioxide/graphene with a three-dimensional interconnected closed pore structure for lithium storage

Low reversion of lithium oxide (Li2O) and the tin (Sn) coarsening causing irreversible capacity loss is the main reason for the poor cycle performance in tin dioxide (SnO2) based composites. In this research, a novel sandwiched spherical tin dioxide/graphene with a three-dimensional interconnected closed pore structure is synthesized. The microstructural characterization shows that the spherical graphene with submicron sized diameters interconnects with each other forming an interconnected flexible conductive network, whereas a large number of SnO2 nanoparticles (approximately 5 nm) are limited homogeneously in between the interlayers of the sphere-like graphene shell. The sandwich structure of the SnO2/graphene and the closed graphene sphere can provide double protection for the SnO2. When it is used as an anode material for energy storage, the generated Li2O can remain in close contact with Sn to make the conversion reaction (SnO2 + 4Li+ + 2e- ↔ Sn + Li2O) highly reversible in situ and the reversibility even does not diminish markedly after 100 cycles. A high reversible specific capacity of 914.8 mA h g-1 is expressed in the sandwiched spherical SnO2/graphene composite at 100 mA g-1 after 100 cycles, which is significantly higher than that of a SnO2/graphene aerogel with an open pore structure.

Self-Relaxant Superelastic Matrix Derived from C60 Incorporated Sn Nanoparticles for Ultra-High-Performance Li-Ion Batteries

Homogeneously dispersed Sn nanoparticles approximately ⩽10 nm in a polymerized C₆₀ (PC₆₀) matrix, employed as the anode of a Li-ion battery, are prepared using plasma-assisted thermal evaporation coupled by chemical vapor deposition. The self-relaxant superelastic characteristics of the PC₆₀ possess the ability to absorb the stress-strain generated by the Sn nanoparticles and can thus alleviate the problem of their extreme volume changes. Meanwhile, well-dispersed dot-like Sn nanoparticles, which are surrounded by a thin SnO₂ layer, have suitable interparticle spacing and multilayer structures for alleviating the aggregation of Sn nanoparticles during repeated cycles. The Ohmic characteristic and the built-in electric field formed in the interparticle junction play important roles in enhancing the diffusion and transport rate of Li ions. SPC-50, a Sn-PC₆₀ anode consisting of 50 wt % Sn and 50 wt % PC₆₀, as confirmed by energy-dispersive X-ray spectroscopy analysis, exhibited the highest electrochemical performance. The resulting SPC-50 anode, in a half-cell configuration, exhibited an excellent capacity retention of 97.18%, even after 5000 cycles at a current density of 1000 mA g^-1 with a discharge capacity of 834.25 mAh g^-1. In addition, the rate-capability performance of this SPC-50 half-cell exhibited a discharge capacity of 544.33 mAh g^-1 at a high current density of 10 000 mA g^-1, even after the current density was increased 100-fold. Moreover, a very high discharge capacity of 1040.09 mAh g^-1 was achieved with a capacity retention of 98.67% after 50 cycles at a current density of 100 mA g^-1. Futhermore, a SPC-50 full-cell containing the LiCoO₂ cathode exhibited a discharge capacity of 801.04 mAh g^-1 and an areal capacity of 1.57 mAh cm^-2 with a capacity retention of 95.27% after 350 cycles at a current density of 1000 mA g^-1.

Aqueous Binder Enhanced High-Performance GeP5 Anode for Lithium-Ion Batteries

GeP5 is a recently reported new anode material for lithium ion batteries (LIBs), it holds a large theoretical capacity about 2300 mAh g-1, and a high rate capability due to its bi-active components and superior conductivity. However, it undergoes a large volume change during its electrochemical alloying and de-alloying with Li, a suitable binder is necessary to stable the electrode integrity for improving cycle performance. In this work, we tried to apply aqueous binders LiPAA and NaCMC to GeP5 anode, and compared the difference in electrochemical performance between them and traditional binder PVDF. As can be seen from the test result, GeP5 can keep stable in both common organic solvents and proton solvents such as water and alcohol solvents, it meets the application requirements of aqueous binders. The electrochemistry results show that the use of LiPAA binder can significantly improve the initial Coulombic efficiency, reversible capacity, and cyclability of GeP5 anode as compared to the electrodes based on NaCMC and PVDF binders. The enhanced electrochemical performance of GeP5 electrode with LiPAA binder can be ascribed to the unique high strength long chain polymer structure of LiPAA, which also provide numerous uniform distributed carboxyl groups to form strong ester groups with active materials and copper current collector. Benefit from that, the GeP5 electrode with LiPAA can also exhibit excellent rate capability, and even at low temperature, it still shows attractive electrochemical performance.

Composites of Layered M(HPO4)2 (M = Zr, Sn, and Ti) with Reduced Graphene Oxide as Anode Materials for Lithium Ion Batteries

Tetravalent metal phosphates (M(HPO₄)₂, M = Zr, Sn, and Ti) have robust layered structures with interlayer d spacings over 7.5 Å, but show poor electrical conductivity. On the other hand, single-atomic-layered reduced graphene oxide (rGO) sheets exhibit a high electrical conductivity. In this work, the combination of rGO and M(HPO₄)₂ is explored for their potential as anode materials for lithium ion batteries (LIBs). Specifically, rGO/M(HPO₄)₂ composites are prepared, and their electrochemical performances are investigated systematically. In comparison with bare M(HPO₄)₂, the rGO/M(HPO₄)₂ composites exhibit larger specific capacity, higher rate capability, better cyclic stability, lower voltage for lithium ion insertion and extraction, and improved first Coulombic efficiency. We propose that the superior electrochemical performances of the composites are primarily contributed to the large interlayer space of M(HPO₄)₂ and the rGO sheets cladded on the surfaces of the layered M(HPO₄)₂. The attached rGO sheets bridge the layers together forming a network that is beneficial for the electron and ion diffusion within the composites, thus enhancing the discharge/charge rate capability of the composites. In addition, the attached rGO sheets provide extra anchoring sites for Li⁺; the specific capacity of the composites as anode materials is thus enhanced.

Ultrafast, Highly Reversible, and Cycle-Stable Lithium Storage Boosted by Pseudocapacitance in Sn-Based Alloying Anodes

Boosting power density is one of the primary challenges that current lithium ion batteries face. Alloying anodes that possess suitable potential windows stand at the forefront in pursuing ultrafast and highly reversible lithium storage to achieve high power/energy lithium ion batteries. Herein, ultrafast lithium storage in Sn-based nanocomposite anodes is demonstrated, which is boosted by pseudocapacitance benefitting from a high fraction of highly interconnected interfaces of Fe/Sn/Li₂ O. By tailoring the voltage window in the range of 0.005-1.2 V for the alloying/dealloying reactions, such Sn-based nanocomposite anodes achieve simultaneous ultrahigh rate capability, superlong cycling performance, and close-to-100% Coulombic efficiency. The nanocomposite anode delivers a high reversible capacity (≈420 mAh g^-1 ) at 1 A g^-1 for more than 1200 cycles, corresponding to only 0.016% per cycle of capacity decay. A reversible capacity of 350 mAh g^-1 can be maintained at an ultrahigh current density of 80 A g^-1 , with 67.3% capacity retention relative to the capacity at 1 A g^-1 . This combination of pseudocapacitive lithium storage and spatially confined electrochemical reactions in Sn-based nanocomposite anode materials may pave the way for the development of high power/energy and long life lithium ion batteries.

In Situ Synthesis of Tungsten-Doped SnO2 and Graphene Nanocomposites for High-Performance Anode Materials of Lithium-Ion Batteries

The composite of tungsten-doped SnO₂ and reduced graphene oxide was synthesized through a simple one-pot hydrothermal method. According to the structural characterization of the composite, tungsten ions were doped in the unit cells of tin dioxide rather than simply attaching to the surface. Tungsten-doped SnO₂ was in situ grown on the surface of graphene sheet to form a three-dimensional conductive network that enhanced the electron transportation and lithium-ion diffusion effectively. The issues of SnO₂ agglomeration and volume expansion could be also avoided because the tungsten-doped SnO₂ nanoparticles were homogeneously distributed on a graphene sheet. As a result, the nanocomposite electrodes of tungsten-doped SnO₂ and reduced graphene oxide exhibited an excellent long-term cycling performance. The residual capacity was still as high as 1100 mA h g^-1 at 0.1 A g^-1 after 100 cycles. It still remained at 776 mA h g^-1 after 2000 cycles at the current density of 1A g^-1.

Three-Dimensional Graphene/Single-Walled Carbon Nanotube Aerogel Anchored with SnO2 Nanoparticles for High Performance Lithium Storage

A unique 3D graphene-single walled carbon nanotube (G-SWNT) aerogel anchored with SnO₂ nanoparticles (SnO₂@G-SWCNT) is fabricated by the hydrothermal self-assembly process. The influences of mass ratio of SWCNT to graphene on structure and electrochemical properties of SnO₂@G-SWCNT are investigated systematically. The SnO₂@G-SWCNT composites show excellent electrochemical performance in Li-ion batteries; for instance, at a current density of 100 mA g^-1, a specific capacity of 758 mAh g^-1 was obtained for the SnO₂@G-SWCNT with 50% SWCNT in G-SWCNT and the Coulombic efficiency is close to 100% after 200 cycles; even at current density of 1 A g^-1, it can still maintain a stable specific capacity of 537 mAh g^-1 after 300 cycles. It is believed that the 3D G-SWNT architecture provides a flexible conductive matrix for loading the SnO₂, facilitating the electronic and ionic transportation and mitigating the volume variation of the SnO₂ during lithiation/delithiation. This work also provides a facile and reasonable strategy to solve the pulverization and agglomeration problem of other transition metal oxides as electrode materials.

Tin-based materials supported on nitrogen-doped reduced graphene oxide towards their application in lithium-ion batteries

Recently, nitrogen-doped graphene has attracted significant attention for application as an anode in lithium-ion batteries due to effective modulation of the electronic properties of graphene.

Interaction Induced High Catalytic Activities of CoO Nanoparticles Grown on Nitrogen-Doped Hollow Graphene Microspheres for Oxygen Reduction and Evolution Reactions

Nitrogen doped graphene hollow microspheres (NGHSs) have been used as the supports for the growth of the CoO nanoparticles. The nitrogen doped structure favors the nucleation and growth of the CoO nanoparticles and the CoO nanoparticles are mostly anchored on the quaternary nitrogen doped sites of the NGHSs with good monodispersity since the higher electron density of the quaternary nitrogen favors the nucleation and growth of the CoO nanoparticles through its coordination and electrostatic interactions with the Co(2+) ions. The resulting NGHSs supported CoO nanoparticles (CoO/NGHSs) are highly active for the oxygen reduction reaction (ORR) with activity and stability higher than the Pt/C and for the oxygen evolution reaction (OER) with activity and stability comparable to the most efficient catalysts reported to date. This indicates that the CoO/NGHSs could be used as efficient bi-functional catalysts for ORR and OER. Systematic analysis shows that the superior catalytic activities of the CoO/NGHSs for ORR and OER mainly originate from the nitrogen doped structure of the NGHSs, the small size of the CoO nanoparticles, the higher specific and electroactive surface area of the CoO/NGHSs, the good electric conductivity of the CoO/NGHSs, the strong interaction between the CoO nanoparticles and the NGHSs, etc.

A facile post-process method to enhance crystallinity and electrochemical properties of SnO2/rGO composites with three-dimensional hierarchically porous structure

In this work, three SnO₂/reduced graphene oxide (SnO₂/rGO) composites with a three-dimensional hierarchically porous structure were synthesized via freeze drying and different annealing temperatures in an air atmosphere.

Ti–Sn–O composite oxides coated with N-doped carbon exhibiting enhanced lithium storage performance

The long-term cycling performance of S1-400C1 and TiO₂-400C1 at different rates.

Fluorine-Doped Tin Oxide Nanocrystal/Reduced Graphene Oxide Composites as Lithium Ion Battery Anode Material with High Capacity and Cycling Stability

Tin oxide (SnO2) is a kind of anode material with high theoretical capacity. However, the volume expansion and fast capability fading during cycling have prevented its practical application in lithium ion batteries. Herein, we report that the nanocomposite of fluorine-doped tin oxide (FTO) and reduced graphene oxide (RGO) is an ideal anode material with high capacity, high rate capability, and high stability. The FTO conductive nanocrystals were successfully anchored on RGO nanosheets from an FTO nanocrystals colloid and RGO suspension by hydrothermal treatment. As the anode material, the FTO/RGO composite showed high structural stability during the lithiation and delithiation processes. The conductive FTO nanocrystals favor the formation of stable and thin solid electrolyte interface films. Significantly, the FTO/RGO composite retains a discharge capacity as high as 1439 mAhg(-1) after 200 cycles at a current density of 100 mAg(-1). Moreover, its rate capacity displays 1148 mAhg(-1) at a current density of 1000 mAg(-1).

Enhanced Reaction Kinetics and Structure Integrity of Ni/SnO2 Nanocluster toward High-Performance Lithium Storage

SnO2 is regarded as one of the most promising anodes via conversion-alloying mechanism for advanced lithium ion batteries. However, the sluggish conversion reaction severely degrades the reversible capacity, Coulombic efficiency and rate capability. In this paper, through constructing porous Ni/SnO2 composite electrode composed of homogeneously distributed SnO2 and Ni nanoparticles, the reaction kinetics of SnO2 is greatly enhanced, leading to full conversion reaction, superior cycling stability and improved rate capability. The uniformly distributed Ni nanoparticles provide a fast charge transport pathway for electrochemical reactions, and restrict the direct contact and aggregation of SnO2 nanoparticles during cycling. In the meantime, the void space among the nanoclusters increases the contact area between the electrolyte and active materials, and accommodates the huge volume change during cycling as well. The Ni/SnO2 composite electrode possesses a high reversible capacity of 820.5 mAh g(-1) at 1 A g(-1) up to 100 cycles. More impressively, large capacity of 841.9, 806.6, and 770.7 mAh g(-1) can still be maintained at high current densities of 2, 5, and 10 A g(-1) respectively. The results demonstrate that Ni/SnO2 is a high-performance anode for advanced lithium-ion batteries with high specific capacity, excellent rate capability, and cycling stability.

Three dimensional metal oxides–graphene composites and their applications in lithium ion batteries

The review focuses on the effects of morphology, composition and interaction of 3d metal oxide–graphene composites on the performances of libs.

Incorporation of PEDOT:PSS into SnO2/reduced graphene oxide nanocomposite anodes for lithium-ion batteries to achieve ultra-high capacity and cyclic stability

A conducting polymer matrix of PEDOT:PSS is incorporated into SnO₂/reduced graphene oxide composite for increasing the stability of lithium-ion battery anodes.

Facile synthesis of Fe2O3/MWCNT composites with improved cycling stability

Fe₂O₃ nanoparticles were fabricated via a facile method and loaded into the void space in the intertwined MWCNT matrix or on the MWCNTs homogeneously. The as-prepared Fe₂O₃/MWCNTs composites deliver a discharge capacity of 1026 mA h g⁻¹ at a current rate of 0.2 C after 50 cycles, which has a 81.2% capacity retention.

Solvothermal-induced 3D macroscopic SnO2/nitrogen-doped graphene aerogels for high capacity and long-life lithium storage

3D macroscopic tin oxide/nitrogen-doped graphene frameworks (SnO2/GN) were constructed by a novel solvothermal-induced self-assembly process, using SnO2 colloid as precursor (crystal size of 3-7 nm). Solvothermal treatment played a key role as N,N-dimethylmethanamide (DMF) acted both as reducing reagent and nitrogen source, requiring no additional nitrogen-containing precursors or post-treatment. The SnO2/GN exhibited a 3D hierarchical porous architecture with a large surface area (336 m(2)g(-1)), which not only effectively prevented the agglomeration of SnO2 but also facilitated fast ion and electron transport through 3D pathways. As a result, the optimized electrode with GN content of 44.23% exhibited superior rate capability (1126, 855, and 614 mAh g(-1) at 1000, 3000, and 6000 mA g(-1), respectively) and extraordinary prolonged cycling stability at high current densities (905 mAh g(-1) after 1000 cycles at 2000 mA g(-1)). Electrochemical impedance spectroscopy (EIS) and morphological study demonstrated the enhanced electrochemical reactivity and good structural stability of the electrode.

Graphene/Fe2O3/SnO2 ternary nanocomposites as a high-performance anode for lithium ion batteries

We report an rGO/Fe2O3/SnO2 ternary nanocomposite synthesized via homogeneous precipitation of Fe2O3 nanoparticles onto graphene oxide (GO) followed by reduction of GO with SnCl2. The reduction mechanism of GO with SnCl2 and the effects of reduction temperature and time were examined. Accompanying the reduction of GO, particles of SnO2 were deposited on the GO surface. In the graphene nanocomposite, Fe2O3 nanoparticles with a size of ∼20 nm were uniformly dispersed surrounded by SnO2 nanoparticles, as demonstrated by transmission electron microscopy analysis. Due to the different lithium insertion/extraction potentials, the major role of SnO2 nanoparticles is to prevent aggregation of Fe2O3 during the cycling. Graphene can serve as a matrix for Li+ and electron transport and is capable of relieving the stress that would otherwise accumulate in the Fe2O3 nanoparticles during Li uptake/release. In turn, the dispersion of nanoparticles on graphene can mitigate the restacking of graphene sheets. As a result, the electrochemical performance of rGO/Fe2O3/SnO2 ternary nanocomposite as an anode in Li ion batteries is significantly improved, showing high initial discharge and charge capacities of 1179 and 746 mAhg(-1), respectively. Importantly, nearly 100% discharge-charge efficiency is maintained during the subsequent 100 cycles with a specific capacity above 700 mAhg(-1).