Long-life Lithium-ion Batteries Research Articles

Hierarchical carambola-like Li4Ti5O12-TiO2 composites as advanced anode materials for lithium-ion batteries

Hierarchically structured Li4Ti5O12-TiO2 (LTO-TiO2) composites are synthesized using a facile hydrothermal approach upon reaction time control. With control over the time of hydrothermal reaction at 18h, a hierarchical dual-phase LTO-TiO2 composite with appropriate amount of anatase TiO2 can be obtained, and it possesses a uniform carambola-like framework assembled by numerous ultrathin nanosheets, which enable a relatively large specific surface area, along with abundant interlayer channels to favor electrolyte penetration. When used as anode materials for lithium-ion batteries, such carambola-like LTO-TiO2 composite exhibits remarkably improved capacity, high-rate capability, and cycling stability over other LTO-TiO2 samples, which are synthesized at different time of hydrothermal reaction. Specifically, it deliveries a discharge capacity as high as 115.1 and 91.2mAhg−1at a very high current rate of 20 and 40C, respectively, while a stable reversible capacity of 171.7mAhg−1 can be retained after 200 charge-discharge cycles at 1C, corresponding to 88.6% capacity retention. The excellent electrochemical performances benefit from the unique hierarchical carambola-like structure together with the mutually complementary intrinsic advantages between LTO and TiO2. The robust and porous nanosheets-assembled LTO-TiO2 framework not only offers a shorter transport pathway for electron and Li-ion migration within this composite material, but also is able to alleviate the structure distortion during the fast Li-ion insertion/extraction process. The work described here shows that the hierarchical carambola-like LTO-TiO2 composite is a promising anode material for high-power and long-life lithium-ion batteries.

Self-anchoring dendritic ternary vanadate compound on graphene nanoflake as high-performance conversion-type anode for lithium ion batteries

Development of three-dimensional ternary vanadate compounds with excellent structural stability on exfoliated graphene nanoflacks allows the first success of conversion-type sodium vanadate anode candidate for high-rate and long-life lithium-ion batteries(LIBs). Corresponding additive-free self-anchoring behavior of active sodium vanadates material on graphene surface is representatively investigated, architecturing unique dendritic structure, a first-of-this-kind configuration, with robust flexibility and sufficient capability of structure-preservation. The prepared nanocomposite provides a high reversible capacity over 800mAhg−1 and ultrafast charging/discharging capability with Li-ions via conversion-type reaction. More remarkably, the well-designed structure retains more than 96% of initial capacity with respect to their ultralong cycling stability, demonstrating the combined advantages of the facile hydrothermal protocol, high active material loading and architecture configuration for high-performance Li-ions storage. As a consequence, this research reveals the importance and effectiveness of self-assembling sodium vanadates on graphene nanoflakes with 3D hierarchial structure and indicates the significant potential of developing ternary vanadate compounds as promising anode candidate for LIBs.

Self-doped V4+–V2O5 nanoflake for 2 Li-ion intercalation with enhanced rate and cycling performance

Orthorhombic V2O5 has been considered as one of the most promising cathode materials for new lithium ion batteries (LIBs) due to its high specific capacity, easy synthesis and good safety. However, the poor rate and cycling performance of V2O5 electrodes significantly impede their applications in high-power and long-life LIBs. The present work reports facile synthesis of self-doped V4+–V2O5 nanoflakes through combusting the NH4V4O10 and VO2 (B) mixture in the presence of 2-ethylimidazole. The resulting V4+–V2O5 exhibited superior rate capability (a reversible capacity of 293, 268, 234, 214, 196 and 139mAhg−1 at 100, 300, 600, 1000, 2000 and 4000mAg−1, respectively) and remarkable cycling performance (95% capacity retention after 100 discharge/charge cycles at 2000mAg−1). The outstanding performance is derived from the uniform nanoflake structure, which offers more surface area and reaction sites for lithium ion intercalation, and the presence of tetravalent vanadium ions accompanied with oxygen vacancies, which might promote and catalyze the electrochemical reactions at the surface, in addition to improve the intrinsic electrical conductivity and Li ion diffusion coefficient, as reflected by the smaller polarization and more reversible and easier phase transitions than those of V2O5 without detectable V4+ and oxygen vacancies.

Ultradispersed Nanoarchitecture of LiV3O8 Nanoparticle/Reduced Graphene Oxide with High-Capacity and Long-Life Lithium-Ion Battery Cathodes.

Lack of high-performance cathode materials has become the major barriers to lithium-ion battery applications in advanced communication equipment and electric vehicles. In this paper, we report a versatile interfacial reaction strategy, which is based on the idea of space confinement, for the synthesis of ultradispersed LiV3O8 nanoparticles (~10 nm) on graphene (denoted as LVO NPs-GNs) with an unprecedented degree of control on the separation and manipulation of the nucleation, growth, anchoring, and crystallization of nanoparticles in a water-in-oil emulsion system over free growth in solution. The prepared LVO NPs-GNs composites displayed high performance as an cathode material for lithium-ion battery, including high reversible lithium storage capacity (237 mA h g−1 after 200 cycles), high Coulombic efficiency (about 98%), excellent cycling stability and high rate capability (as high as 176 mA h g−1 at 0.9 A g−1, 128 mA h g−1 at 1.5 A g−1, 91 mA h g−1 at 3 A g−1 and 59 mA h g−1 at 6 A g−1, respectively). Very significantly, the preparation method employed can be easily adapted and may opens the door to complex hybrid materials design and engineering with graphene for advanced energy storage.

Controlled synthesis of mesoporous nanostructured anatase TiO2on a genetically modified Escherichia coli surface for high reversible capacity and long-life lithium-ion batteries

Deposition and mineralization of TiO2on genetically modifiedEscherichia colisurface has been achieved, leading to formation of a nanostructured anatase TiO2with enhanced electrochemical performance as anode electrodes of lithium-ion batteries.

Tuning structural stability and lithium-storage properties by d-orbital hybridization substitution in full tetrahedron Li2FeSiO4 nanocrystal

Full tetrahedron connected structures possess considerable potential as cathodes for lithium-ion batteries (LIBs) due to more lithium storage sites to obtain high specific capacity. However, different from the full octahedron and octahedron/tetrahedron hybrid structures with coplanar or collinear, the tetrahedron network is connected by common vertex, which provokes structural instability and poor electrochemistry performance. Here, using first principles calculations combined with experiments, we found that a heavy distortion and big volume expansion during delithiation for full tetrahedron (LiO4, FeO4 and SiO4 tetrahedra) Li2FeSiO4 nanocrystal lead to phase change or even structure fracture, and the optimized Ti(IV) doped in Fe sites can enhance the coupling effect among the tetrahedra by the strong d-orbital hybridization and like “spring” to hold these tetrahedra and prohibit structure fracture. Meanwhile, the Ti(IV) doping can also shorten the distance of two adjacent Li sites to decrease the activation barrier for Li-ion diffusion. Furthermore, the n-type doping effect increases the electronic conductivity. This discovery can be extended to other tetrahedron structures as well, providing a general approach to develop promising next-generation cathode materials for high-energy and long-life lithium-ion batteries.

Copper Silicate Hydrate Hollow Spheres Constructed by Nanotubes Encapsulated in Reduced Graphene Oxide as Long-Life Lithium-Ion Battery Anode.

Hierarchical copper silicate hydrate hollow spheres-reduced graphene oxide (RGO) composite is successfully fabricated by a facile hydrothermal method using silica as in situ sacrificing template. The electrochemical performance of the composite as lithium-ion battery anode was studied for the first time. Benefiting from the synergistic effect of the hierarchical hollow structure and conductive RGO matrix, the composite exhibits excellent long-life performance and rate capability. A capacity of 890 mAh/g is achieved after 200 cycles at 200 mA/g and a capacity of 429 mAh/g is retained after 800 cycles at 1000 mA/g. The results indicate that the strategy of combining hierarchical hollow structures with conductive RGO holds the potential in addressing the volume expansion issue of high capacity anode materials.

Carbon-wrapped TiO2 nanocubes exposed with (001) active facets for high-rate and long-life lithium-ion batteries

A novel method is developed to synthesis TiO2/carbon nanostructured composites (T/CNC) as high-performance anode materials for Li-ion batteries using resorcinol/formaldehyde (RF) as the carbon source. With assistance of hydrofluoric acid (HF) as a shape-controlling agent, TiO2 nanocubes exposed with (001) active facets can be obtained. The T/CNC sample shows higher BET surface area (358 m2 g−1) than the previous materials reported before. When evaluated for lithium storage properties, the T/CNC is able to deliver a capacity of 340.4 mA h g−1 after 90 cycles at 0.59 C, which is superior to those reported in previous work. At a high rate of 15 C, a high reversible discharge capacity of 126.7 mA h g−1 is obtained up to 500 cycles and demonstrates excellent rate performance and long-term cycling stability.

Evidence of covalent synergy in silicon-sulfur-graphene yielding highly efficient and long-life lithium-ion batteries.

Silicon has the potential to revolutionize the energy storage capacities of lithium-ion batteries to meet the ever increasing power demands of next generation technologies. To avoid the operational stability problems of silicon-based anodes, we propose synergistic physicochemical alteration of electrode structures during their design. This capitalizes on covalent interaction of Si nanoparticles with sulfur-doped graphene and with cyclized polyacrylonitrile to provide a robust nanoarchitecture. This hierarchical structure stabilized the solid electrolyte interphase leading to superior reversible capacity of over 1,000 mAh g−1 for 2,275 cycles at 2 A g−1. Furthermore, the nanoarchitectured design lowered the contact of the electrolyte to the electrode leading to not only high coulombic efficiency of 99.9% but also maintaining high stability even with high electrode loading associated with 3.4 mAh cm−2. The excellent performance combined with the simplistic, scalable and non-hazardous approach render the process as a very promising candidate for Li-ion battery technology.

Amorphous GeOx-Coated Reduced Graphene Oxide Balls with Sandwich Structure for Long-Life Lithium-Ion Batteries

Amorphous GeOx-coated reduced graphene oxide (rGO) balls with sandwich structure are prepared via a spray-pyrolysis process using polystyrene (PS) nanobeads as sacrificial templates. This sandwich structure is formed by uniformly coating the exterior and interior of few-layer rGO with amorphous GeOx layers. X-ray photoelectron spectroscopy analysis reveals a Ge:O stoichiometry ratio of 1:1.7. The amorphous GeOx-coated rGO balls with sandwich structure have low charge-transfer resistance and fast Li(+)-ion diffusion rate. For example, at a current density of 2 A g(-1), the GeOx-coated rGO balls with sandwich and filled structures and the commercial GeO2 powders exhibit initial charge capacities of 795, 651, and 634 mA h g(-1), respectively; the corresponding 700th-cycle charge capacities are 758, 579, and 361 mA h g(-1). In addition, at a current density of 5 A g(-1), the rGO balls with sandwich structure have a 1600th-cycle reversible charge capacity of 629 mA h g(-1) and a corresponding capacity retention of 90.7%, as measured from the maximum reversible capacity at the 100th cycle.

Carbon-Anchored MnO Nanosheets as an Anode for High-Rate and Long-Life Lithium-Ion Batteries.

Developing electrode materials with high rate as well as prolonged cycle is particularly necessary for the ever-growing market penetration of electric vehicles and hybrid electric vehicle. Herein, we demonstrate a facile and efficient strategy to synthesize MnO/C hybrid via freeze-drying followed by thermal treatment in N2 atmosphere. The MnO nanosheets are firmly anchored onto carbon layers to form MnO/C hybrid. When used as an anode in lithium-ion batteries, the typical MnO/C hybrid displays a high initial Coulombic efficiency of 83.1% and delivers a high capacity of 1449.8 mAh g(-1) after 100 cycles at 0.3 A g(-1). Furthermore, the typical MnO/C hybrid can still maintain significantly high capacity of 1467.0 mAh g(-1) after 2000 cycles at 5 A g(-1), which may be the best performance reported so far for MnO-based materials. The superior electrochemical performance of the MnO/C hybrid may be attributed to its unique microstructure features such as effective conductive pathway of carbon sheets, firm connection between MnO and carbon sheets, and small-sized MnO.

Nanosheets of Earth-Abundant Jarosite as Novel Anodes for High-Rate and Long-Life Lithium-Ion Batteries

Nanosheets of earth-abundant jarosite were fabricated via a facile template-engaged redox coprecipitation strategy at room temperature and employed as novel anode materials for lithium-ion batteries (LIBs) for the first time. These 2D materials exhibit high capacities, excellent rate capability, and prolonged cycling performance. As for KFe3(SO4)2(OH)6 jarosite nanosheets (KNSs), the reversible capacities of above 1300 mAh g(-1) at 100 mA g(-1) and 620 mAh g(-1) after 4000 cycles at a very high current density of 10 A g(-1) were achieved, respectively. Moreover, the resulting 2D nanomaterials retain good structural integrity upon cycling. These results reveal great potential of jarosite nanosheets as low-cost and high-performance anode materials for next-generation LIBs.

Anchoring ultra-fine TiO2–SnO2solid solution particles onto graphene by one-pot ball-milling for long-life lithium-ion batteries

A low cost, up-scalable and one-pot wet-mechanochemical approach is designed for fabricating TiO2–SnO2@graphene nanocomposites where TiO2and SnO2solid solution nanoparticles are evenly anchored on graphene sheets.

Facile synthesis of reduced graphene oxide wrapped nickel silicate hierarchical hollow spheres for long-life lithium-ion batteries

A NiSiO/RGO composite facilitates electron transportation and accommodates the large volume variation during lithium ion insertion and extraction.

CoMoO4 nanoparticles anchored on reduced graphene oxide nanocomposites as anodes for long-life lithium-ion batteries.

A self-assembled CoMoO4 nanoparticles/reduced graphene oxide (CoMoO4NP/rGO), was prepared by a hydrothermal method to grow 3-5 nm sized CoMoO4 particles on reduced graphene oxide sheets and used as an anode material for lithium-ion batteries. The specific capacity of CoMoO4NP/rGO anode can reach up to 920 mAh g(-1) at a current rate of 74 mA g(-1) in the voltage range between 3.0 and 0.001 V, which is close to the theoretical capacity of CoMoO4 (980 mAh g(-1)). The fabricated half cells also show good rate capability and impressive cycling stability with 8.7% capacity loss after 600 cycles under a high current density of 740 mA g(-1). The superior electrochemical performance of the synthesized CoMoO4NP/rGO is attributed to the synergetic chemical coupling effects between the conductive graphene networks and the high lithium-ion storage capability of CoMoO4 nanoparticles.

Micro-size spherical TiO2(B) secondary particles as anode materials for high-power and long-life lithium-ion batteries

Electrochemical properties of micro-size spherical TiO2(B) secondary particles have been investigated in order to develop TiO2(B) anodes for lithium-ion batteries with high-power and long-life performance. The spherical TiO2(B) electrodes with a small amount of a carbon conductor additive had a high electrode density of 2.2 g cm−3 and a volumetric reversible capacity of 475 mAh cm−3 comparable to that of graphite electrodes. Compared with nano-size needle-like TiO2(B) electrodes, the spherical TiO2(B) electrodes exhibited higher-rate discharge capability and longer-cycle life performance. The impedance of the TiO2(B)/electrolyte interface model indicated that the charge transfer resistance Rc and the passivating film resistance Rf of the spherical TiO2(B) were much smaller than those of the needle-like one. The high-rate discharge and the long-cycle performance of the spherical TiO2(B) electrode are attributed to the superior electronic connective property and Rc and Rf values smaller than those of the needle-like one. Lithium-ion cells using the spherical TiO2(B) anodes and LiNi0.8Co0.1Mn0.1O2 cathode with a capacity of 2.8 Ah exhibited a high energy density of 100 Wh kg−1, a high output power density of 1800 W kg−1 for 10 s pulse, and a long cycle life of more than 3000 cycles.

Mesoporous single-crystalline V2O5 nanorods assembled into hollow microspheres as cathode materials for high-rate and long-life lithium-ion batteries.

Mesoporous single-crystalline V2O5 nanorods assembled into novel hollow microspheres have been synthesized as cathode materials for lithium-ion batteries by a simple solvothermal treatment of NH4VO3 and ethylene glycol with subsequent annealing in air at 400 °C, which delivered a very high reversible capacity of 145.8 mA h g(-1) at 2.5-4.0 V (vs. theoretical value: 147 mA h g(-1)) with much improved capacity retention and long cycle life at various rates.

Unravelling the correlation between the aspect ratio of nanotubular structures and their electrochemical performance to achieve high-rate and long-life lithium-ion batteries.

The fundamental understanding of the relationship between the nanostructure of an electrode and its electrochemical performance is crucial for achieving high-performance lithium-ion batteries (LIBs). In this work, the relationship between the nanotubular aspect ratio and electrochemical performance of LIBs is elucidated for the first time. The stirring hydrothermal method was used to control the aspect ratio of viscous titanate nanotubes, which were used to fabricate additive-free TiO2 -based electrode materials. We found that the battery performance at high charging/discharging rates is dramatically boosted when the aspect ratio is increased, due to the optimization of electronic/ionic transport properties within the electrode materials. The proof-of-concept LIBs comprising nanotubes with an aspect ratio of 265 can retain more than 86 % of their initial capacity over 6000 cycles at a high rate of 30 C. Such devices with supercapacitor-like rate performance and battery-like capacity herald a new paradigm for energy storage systems.

Designed synthesis of NiO@polypyrrole hollow spheres for long-life lithium storage

A novel type of NiO-based anodes, i.e., NiO@polypyrrole hollow spheres (NiO@PPy HSs), has been constructed by using SiO2 spheres as templates. The PPy component serves as an ideal supporting matrix for NiO anodes owing to its high structural stability and electrical conductivity. Thus, the NiO@PPy HSs demonstrate markedly enhanced lithium storage capabilities in terms of cycling stability compared with bare NiO spheres. For example, a high reversible capacity of 520.0 mA h g−1 can be delivered after 200 cycles in NiO@PPy anode at a current density of 100 mA g−1. The superior cycling stability of NiO@PPy HSs makes it an ideal anodic candidate for long-life lithium-ion batteries.

A Co-free layered LiNi0.7Mn0.3O2 cathode material for high-energy and long-life lithium-ion batteries

A Co-free layered cathode material, LiNi0.7Mn0.3O2, was synthesized using the co-precipitation method. The optimum conditions for the cathode were determined on the basis of particle size. The relationship between the cathode material’s particle size and its lithium-ion battery performance was studied on the basis of the capacity and cyclability. The LiNi0.7Mn0.3O2 material exhibited a high reversible capacity of 176mAhg−1 and a high cyclability, with 98% capacity retention after 40 cycles under the optimum conditions with a specific reaction time. A mechanism based on the structures and morphologies of the synthesized cathode materials is proposed.