A Novel Hydrated Iron Vanadate Cathode Material for Advanced Aqueous Nickel-Ion Batteries.

Aqueous nickel-ion batteries (ANIBs) as an emerging energy storage device attracted much attention owing to their multielectron redox reaction and dendrite-free Ni anode, yet their development is hindered by the divalent properties of Ni2+ and the lack of suitable cathode materials. Herein, a hydrated iron vanadate (Fe2V3O10.5∙1.5H2O, FOH) with a preferred orientation along the (200) plane is innovatively proposed and used as cathode material for ANIBs. The FOH cathode exhibits a remarkable capacity of 129.3 mAh g-1 at 50 mA g-1 and a super-high capacity retention of 95% at 500 mA g-1 after 700 cycles. The desirable Ni2+ storage capacity of FOH can be attributed to the preferentially oriented and tunnel structures, which offer abundant reaction active planes and a broad Ni2+ diffusion path, the abundant vacancies and high specific surface area further increase ion storage sites and accelerate ion diffusion in the FOH lattice. Furthermore, the Ni2+ storage mechanism and structural evolution in the FOH cathode are explored through ex situ XRD, ex situ Raman, ex situ XPS and other ex situ characteristics. This work opens a new way for designing novel cathode materials to promote the development of ANIBs.

Synthesis of the Carbon-Coated Nanoparticle Co9S8 and Its Electrochemical Performance as an Anode Material for Sodium-Ion Batteries.

A Co9S8/C nanocomposite is prepared using a solid-state reaction followed by a facile mechanical ball-milling treatment, with sucrose as the carbon source. The phases, morphologies, and detailed structures of the Co9S8/C nanocomposite are well-characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy. When evaluated as an anode material for sodium-ion batteries, the Co9S8/C nanocomposite electrode displays a reversible capacity of ∼567 mA h g-1 in the initial cycle and maintains a reversible capacity of ∼320 mA h g-1 after 30 cycles, indicating a larger capacity and a stable cycling performance. For comparison, the electrochemical performances of Co9S8 and Co9S8/C samples synthesized using the solid-state reaction are also displayed. The ex situ XRD and transmission electron microscopy tests demonstrate that Co9S8 undergoes a conversion-type sodium storage mechanism.

Superstructure ZrV2O7 nanofibres: thermal expansion, electronic and lithium storage properties.

ZrV2O7 has attracted much attention as a negative thermal expansion (NTE) material due to its isotropic negative structure. However, rarely has investigation of the lithium storage behaviors been carried out except our first report on it. Meanwhile, the electrochemical behaviors and energy storage characteristics have not been studied in depth and will be explored in this article. Herein, we report on the synthesis, characterization and lithium intercalation mechanism of superstructure ZrV2O7 nanofibres that were prepared through a facile solution-based method with a subsequent annealing process. The thermal in situ XRD technique combined with the Rietveld refinement method is adopted to analyze the change in the temperature-dependent crystal structure. Benefiting from the nanostructured morphology and relatively high electronic conductivity, it presents acceptable cyclic stability and rate capability. According to the operando evolution of the XRD patterns obtained from electrochemical in situ measurements, the Li intercalation mechanism of the solid solution process with a subsequent conversion reaction can be concluded. Finally, the amorphous state of the electrodes after the initial fully discharged state can effectively enhance the electrochemical performances.

Integrating molybdenum into zinc vanadate enables Zn3V2MoO8 as a high-capacity Zn-supplied cathode for Zn-metal free aqueous batteries.

The commercialization of aqueous zinc-ion batteries (AZIBs) has been hindered by the obsession with Zn-metal anode, just like the early days of lithium-ion batteries. Developing Zn-metal free aqueous batteries (ZFABs) with superior Zn-supplied cathodes is a promising way to escape this predicament. Herein, a novel mixed transition-metal spinel, Zn3V2MoO8, has been synthesized via a sol-gel technique and proposed as a Zn-supplied cathode material. Utilizing the synergistic effect of vanadium and molybdenum, Zn3V2MoO8 can provide a high capacity of 360.3 mA h g-1 at 100 mA g-1, which is the state-of-the-art in existing Zn-supplied cathodes, and the capacity retention is 82% over 700-4500 cycles at 10 A g-1. The mechanism is that Zn3V2MoO8 undergoes a phase transition to Zny(V,Mo)2O5-x·nH2O in the initial charge, and then protons and zinc ions intercalate/deintercalate concurrently into/from the new host. To construct ZFABs with a Zn3V2MoO8 cathode, two non-zinc materials (brass and 9,10-anthraquinone) are used as anodes. Thereby, the Zn3V2MoO8||9,10AQ battery reveals a more satisfactory electrochemical performance, with a stable capacity of 100.4 mA h g-1 lasting for 200 cycles, which provides a feasible scheme for the practical application of AZIBs.

MgMoO4 as an anode material for lithium ion batteries and its multi-electron reaction mechanism.

Single-phase magnesium molybdate, MgMoO4, is successfully synthesized by a facile sol-gel method. Attributed to the multielectron reaction and the synergistic effect of the elements molybdenum (Mo) and magnesium (Mg), the MgMoO4 electrode exhibits excellent electrochemical properties. After activation, benefiting from the decrease in particle size and the uniform nanosphere morphology, the MgMoO4 electrodes can deliver a stable high specific capacity of about 1060 mA h g-1 at a current density of 100 mA g-1 after 600 cycles. Based on the important role of the activation process, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and scan rate cyclic voltammetry (CV) measurement methods were employed to reveal the effect of the activation process on the electrochemical behavior of the electrode material. Furthermore, by combining the in situ X-ray diffraction (XRD) and ex situ X-ray photoelectron spectroscopy (XPS) results, we illustrate the lithium storage mechanism of the MgMoO4 electrode in detail.

A novel strategy via electrode catalysis induced nano transformation for lithiated-bimetallic-oxides to avoid the long activation process of advanced lithium-ion batteries.

Improving the anode materials for lithium-ion batteries with a long activation process, poor cycle stability, and low Coulomb efficiency is of great significance for developing novel high-performance anode materials. Orthorhombic LiVMoO5 with high specific capacity was applied to the anode field of lithium-ion battery for the first time. However, the activation process led to its poor cyclic performance. By adopting a novel nano-transformation treatment process in a water and oxygen environment, we effectively avoided the long-term activation process. The specially treated LiVMoO5 electrode (STLVME) exhibited excellent reversible specific capacity (∼1100 mA h g-1) and rate cycle stability (capacity retention rate ∼100%). Furthermore, GITT and EIS also showed that compared with the primitive LiVMoO5 electrode (LVME), smaller internal resistance and a higher Li+ diffusion coefficient were caused using the novel treatment process, significantly improving the rate cycle stability. Using in situ XRD and ex situ characterization, we illustrated the lithium storage mechanism of LVME and STLVME. In addition, the practical application potential of LVME and STLVME was also explored by assembling the full cells. Because the long-term activation process was effectively avoided, the full-cell exhibited amazing cycle stability, indicating that STLVME can be considered a promising potential anode for practical applications in energy storage devices.

Insights into the enhanced electrochemical performance of MnV2O6 nanoflakes as an anode material for advanced lithium storage.

Binary transition metal oxides (BTMOs) are regarded as potential anode materials for lithium-ion batteries (LIBs) owing to their low cost, high specific capacities, and environmental friendliness. In this work, MnV2O6 nanoflakes are successfully synthesized by a facile hydrothermal method. When evaluated as an anode material for LIBs, benefiting from the activation process, the as-prepared MnV2O6 nanoflake electrode delivers a high reversible specific capacity of 1439 mA h g-1 after 300 cycles at a current density of 200 mA g-1, and especially presents a specific capacity of 1010 mA h g-1 after 700 cycles at a higher current density of 1 A g-1. Furthermore, MnV2O6 shows a pleasurable rate capability; a reversible specific capacity of 867 mA h g-1 can be obtained at a current density of 2000 mA g-1, and when the current density is returned to 200 mA g-1 and continues for another 80 cycles, the specific capacity can still reach 1499 mA h g-1. Meanwhile, the morphology variation and electrochemical kinetic behavior of the MnV2O6 electrode during cycling are scrutinized in detail. After that, the electrochemical reaction mechanism of MnV2O6 during the discharge/charge process is corroborated by in situ X-ray diffraction (XRD), which involves the coexistence of a conversion reaction and solid solution behavior. The practical application of MnV2O6 nanoflakes as an anode material is examined as well. Sure enough, the NCM811//MnV2O6 full-cell exhibits excellent lithium-storage performance.

Cubic MnV2O4 fabricated through a facile sol-gel process as an anode material for lithium-ion batteries: morphology and performance evolution.

Metal vanadates have been popularly advocated as promising anode materials for lithium-ion batteries (LIBs) benefiting from their high theoretical specific capacity and abundant resources. Given that manganese and vanadium are reasonably economical elements and enjoy assorted redox reactions, they have extensive application prospects in energy storage systems. Here, we synthesized cubic MnV2O4 as an anode for LIBs by an efficient sol-gel process. As a result, the MnV2O4 electrode delivers distinguished electrochemical performance, including an appealing reversible specific capacity of nearly 1325 mA h g-1 for 500 cycles at 200 mA g-1, excellent cycling stability with a capacity of 399 mA h g-1 up to 500 cycles at 2000 mA g-1 and a favorable rate capability of 516/410 mA h g-1 at 1000/2000 mA g-1 (when the current density recuperates to 200 mA g-1, the specific capacity still boosts as the number of cycles increases). What's more, electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) under various scan rates and scanning electron microscopy (SEM) are executed to ascertain with a greater depth the electrochemical kinetic characteristics and morphology of the MnV2O4 electrode in different states. These results make known that MnV2O4 is a credible anode material for LIBs, and such a facile and economical synthetic route can be extended to the preparation of other metal vanadate materials.

Unusual Dual-Site Substitution Adjusts the Degree of Stacking Disorder in Honeycomb Na3Ni2SbO6 Cathode for Sodium-Ion Batteries.

O'3-Na3Ni2SbO6 with a honeycomb cation order, as a potential cathode, presents simplified phase-transition steps and a high average voltage. To mitigate the intrinsic phase irreversibility, Mg, Zn, and Co have been introduced to displace part of the Ni, which inevitably reduces the theoretical capacity related to the Ni2+/Ni3+ redox reaction. In this work, an unusual dual-site substitution is carried out to increase the P'3-O'3 structure reversibility without sacrificing the practical capacity. In addition, it is found that special stacking faults along the c-axis direction can be induced by doping to result in incomplete Sb/Ni disorder, though the honeycomb order remains in every TM (transition-metal) layer. The codoped Na2.85Cs0.15Ni1.9Mg0.1SbO6 has a high degree of disorder, which breaks the ideal monoclinic symmetry (C2/m) and partly upgrades its structure to higher-symmetry models. Profiting from the influence of stacking disorder and doping ions on the coordination environment around Na, more gradual and smaller variations of the lattice parameters appear upon Na-ion extraction/insertion. Consequently, this cathode displays a high initial discharge capacity (120 mAh g-1), long-term cycling stability, and excellent rate performance (66 mAh g-1 under 10 C). These findings reveal that not only a full TM-disordered arrangement but also this incomplete stacking disorder can effectively improve the performance of a layered cathode.

Preparation and electrochemical performance of nanowire-shaped Na3Mn2-xFex(P2O7)(PO4) for sodium-ion and lithium-ion batteries.

A series of Fe-doped Na3Mn2-xFex(P2O7)(PO4) (x = 0, 0.2, 0.4) (abbreviated as NMFP-0/NMFP-0.2/NMFP-0.4) compounds have been successfully prepared using the sol-gel method. The Rietveld refinement results indicate that single-phase Na3Mn2-xFex(P2O7)(PO4) with an orthorhombic structure can be obtained. Our results reveal that by controlling the raw materials, the molar ratio of the reactants, the stirring rate of the precursor, the annealing temperature rate, and the reaction time, the proportion of nanowires in the morphology increases as the Fe component rises, and the NMFP-0.4 nanowire-shaped compounds show the best electrochemical activity when used as a cathode material for SIBs. Additionally, its specific capacity is enhanced to ∼126 mA h g-1 in the first cycle when operated at 0.1 C and a working potential window of 1.8-4.3 V (vs. Na/Na+). The material can also be applied in lithium-ion batteries as an anode and achieves ∼600 mA h g-1 specific capacity at a current density of 0.1 C (1 C = 1000 mA g-1) in a working potential window of 0.01-3 V (vs. Li/Li+).

Synthesis of a full range Fe-doped ZnFexCo2-xO4 and its application as anode material for lithium-ion battery.

Fe-Doped ZnFexCo2-xO4 (x = 0.00, 0.17, 0.33, 0.47, 0.67, 0.87, 1.17, 1.37, 1.67, 1.87, 2.00) compounds were prepared by a sol-gel method. X-ray diffraction measurements show that Fe-doping does not change the crystal structure of ZnCo2O4 and dopant Fe successfully occupies the 16c Co site. Because of the bigger radius of the doping ion, the cell parameters and cell volumes of ZnFexCo2-xO4 compounds present an obvious linear increase with increasing Fe content. In addition, attributed to the similar crystal structures for ZnFe2O4 and ZnCo2O4, a full range (0 ≤ x ≤ 2) of ZnFexCo2-xO4 solid solution phases was obtained. V/I measurement results show that a small Fe doping content obviously improved the electronic conductivity of the sample. In addition, due to the smaller particles size and uniform particle distribution caused by Fe doping, the lithium ion diffusion coefficient of the sample was increased by 2 orders of magnitude. Based on the improved electronic conductivity combined with the significantly increased lithium-ion diffusion coefficient, a sample with Fe doping content of x = 0.33, ZnFe0.33Co1.67O4, presents a high reversible specific capacity and excellent rate cycle stability. At a rate of 100 mA g-1, a relatively high discharge capacity of 850 mA h g-1 can still be obtained after 100 cycles, which is obviously higher than that of pure ZnCo2O4 (only 295 mA h g-1). Even at a higher discharge rate of 500 mA g-1, a discharge capacity of 450 mA h g-1 with a capacity retention of nearly 100% was obtained. Based on its excellent electrochemical properties, ZnFe0.33Co1.67O4 will be a promising anode material for rechargeable lithium-ion batteries.

Facile synthesis of one-dimensional vanadyl acetate nanobelts toward a novel anode for lithium storage.

Transition metal oxides (TMOs) are prospective anode materials for lithium-ion batteries (LIBs), owing to their high theoretical specific capacity. However, the inherently low conductivity of TMOs restricts their application. The coupling of lithium-ion conducting polymer ligands with TMO structures is favorable for the dynamics of electrochemical processes. Herein, vanadyl acetate (VA) nanobelts, an organic-inorganic hybrid material, are synthesized for the first time as an anode material for LIBs. As a result, the VA nanobelt electrode displays an outstanding electrochemical performance, including a highly stable reversible specific capacity (around 1065 mA h g-1 at 200 mA g-1), superior long-term cyclability (with a capacity of approximately 477 mA h g-1 at 2 A g-1 over 500 cycles) and attractive rate capability (1012 mA h g-1 when the current density recovers to 200 mA g-1). In addition, scanning electron microscopy (SEM), cyclic voltammetry (CV) curves at different scanning rates and electrochemical impedance spectroscopy (EIS) are used to investigate the variation of the specific capacity and the electrochemical kinetic characteristics of the VA electrode during cycling in detail, respectively. Also, the structural variations of the VA electrode in the initial two cycles are also investigated by in situ XRD testing. The periodic evolution of the in situ XRD patterns demonstrates that the VA nanobelt electrode shows excellent reversibility for Li+ ion insertion/extraction. This work offers an enlightening insight into the future research into organo-vanadyl hybrids as advanced anode materials.

The facile synthesis and electrochemical performance of Ni2V2O7 as a novel anode material for lithium-ion batteries.

The single-phase binary nickel vanadate Ni2V2O7 was successfully synthesized by a simple solid-state method to explore novel anode materials for lithium-ion batteries. After an activation process, the Ni2V2O7 electrode exhibited excellent electrochemical performance with a stable, high specific capacity of about 960 mA h g-1 at a current density of 100 mA g-1, which is attributed to the multiple valence states and the synergistic effect of the transition elements V and Ni. Even at a high current density of 2000 mA g-1, a stable specific capacity of about 400 mA h g-1 was still obtained. Considering the influence of the activation process on the electrochemical performance of the Ni2V2O7 electrode, we studied the origin of the excellent electrochemical performance, where the improved lithium diffusion coefficient and increased pseudocapacitive contribution caused by the activation process led to a significant improvement in the electrochemical performance, including rate capacity and cycle stability. By combining in situ X-ray diffraction (XRD) and ex situ X-ray photoelectron spectroscopy (XPS) methods, for the first time, we illustrate the detailed lithium storage mechanism of the Ni2V2O7 electrode during the lithium insertion/extraction process.

In situ hydrothermal synthesis of double-carbon enhanced novel cobalt germanium hydroxide composites as promising anode material for sodium ion batteries.

Germanium (Ge)-based materials are considered to be one of the most promising anode materials for sodium-ion batteries (SIBs). Nevertheless, the practical electrochemical performance is severely hampered by poor cyclability due to volumetric expansion of Ge upon cycling. Herein, double-carbon confined cobalt germanium hydroxide (CGH@C/rGO) composites has been facilely synthesized with the supportion of l-ascorbic acid and graphene oxide (GO) as anode materials for sodium-ion storage. As a result, the CGH@C/rGO anode delivers a high cyclic stability with a reversible capacity of 416 mA h g-1 after 100 cycles at 100 mA g-1 and an excellent rate capability of 206 mA h g-1 at 2000 mA g-1 compared with CGH, CGH@C and CGH/rGO composites. Besides, the reversible capacity of 266 mA h g-1 still remained even after 500 cycles at current density of 1 A g-1. Such outstanding electrochemical performance could be accredited to a strong interaction between CGH, carbon, and graphene, which increases the electronic conductivity, relieves the volume expansion aroused by sodiation/desodiation, shortens the pathway of electron/ion transportation that further improving the reaction kinetics and endowing the material with remarkable cycling capability. Obviously, this in situ hydrothermal synthesis of double carbon coating strategy can be extended to designing other candidates of anode materials for SIBs.

Electrochemically Induced Structural and Morphological Evolutions in Nickel Vanadium Oxide Hydrate Nanobelts Enabling Fast Transport Kinetics for High-Performance Zinc Storage.

Suitable intercalation cathodes and fundamental insights into the Zn-ion storage mechanism are the crucial factors for the booming development of aqueous zinc-ion batteries. Herein, a novel nickel vanadium oxide hydrate (Ni0.25V2O5·0.88H2O) is synthesized and investigated as a high-performance electrode material, which delivers a reversible capacity of 418 mA h g-1 with 155 mA h g-1 retained at 20 A g-1 and a high capacity of 293 mA h g-1 in long-term cycling at 10 A g-1 with 77% retention after 10,000 cycles. More importantly, multistep phase transition and chemical-state change during intercalation/deintercalation of hydrated Zn2+ are illustrated in detail via in situ/ex situ analytical techniques to unveil the Zn2+ storage mechanism of the hydrated and layered vanadium oxide bronze. Furthermore, morphological development from nanobelts to hierarchical structures during rapid ion insertion and extraction is demonstrated and a self-hierarchical process is correspondingly proposed. The unique evolutions of structure and morphology, together with consequent fast Zn2+ transport kinetics, are of significance to the outstanding zinc storage capacity, which would enlighten the mechanism exploration of the aqueous rechargeable batteries and push development of vanadium-based cathode materials.

A 3D interconnected NH4Fe0.6V2.4O7.4@C nanocomposite with superior sodium storage properties.

A novel 3D interconnected NH4Fe0.6V2.4O7.4@C nanocomposite was in situ synthesized through a facile hydrothermal reaction at low temperature (98 °C), and its electrochemical performance as a cathode for sodium-ion batteries (SIBs) was investigated for the first time. Under the intercalation of Fe3+ and carbon-coating, as-prepared samples turned to 3D interconnected structures, which were composed of NH4Fe0.6V2.4O7.4 nanoparticles and carbon chains. The 3D interconnected NH4Fe0.6V2.4O7.4@0.5 wt%C nanocomposite exhibits a high discharge specific capacity of 306 mA h g-1 at a current density of 20 mA g-1 and a high-rate capacity of 130 mA h g-1 at 0.4 A g-1. The results of EIS and ex situ SEM indicated that the 3D interconnected NH4Fe0.6V2.4O7.4@0.5 wt%C nanocomposite possesses good electrical conductivity and structural stability. The ex situ XRD results suggest that NH4Fe0.6V2.4O7.4@0.5 wt%C undergoes a reversible insertion/de-insertion mechanism during a charge/discharge process. Our work demonstrates that the 3D interconnected NH4Fe0.6V2.4O7.4@C nanocomposite material could be considered as a potential cathode for sodium ion batteries.

Mo6+ Doping in Li3VO4 Anode for Li-Ion Batteries: Significantly Improve the Reversible Capacity and Rate Performance.

Consider the almost insulator for pure Li3VO4 with a band gap of 3.77 eV, to significantly improve the electrical conductivity, the novel Li3V1-xMoxO4 (x = 0.00, 0.01, 0.02, 0.05, and 0.10) anode materials were prepared successfully by simple sol-gel method. Our calculations show that, by substitute Mo6+ for V5+, the extra electron occupied the V 3p empty orbital and caused the Fermi level shift up into the conduction band, where the Mo-doped Li3VO4 presents electrical conductor. The V/I curve measurements show that, by Mo doping in V site, the electronic conductivity of the Li3VO4 was increased by 5 orders of magnitude. And thence the polarization was obviously reduced. EIS measurement results indicated that by Mo-doping a higher lithium diffusion coefficient can be obtained. The significantly increased electronic conductivity combined the higher lithium diffusion coefficient leads to an obvious improvement in reversible capacity and rate performance for the Mo-doped Li3VO4. The resulting Li3V1-xMoxO4 (x = 0.01) material exhibited the excellent rate capability. At a high rate 5 C, a big discharge capacity of the initial discharge capacity 439 mAh/g can be obtained, which is higher than that of pure Li3VO4 (only 166 mAh/g), and after 100 cycles the mean capacity fade is only 0.06% per cycle.

Synthesis and structural data of a Fe-base sodium metaphosphate compound, NaFe(PO3)3.

This data article contains the synthesis and structure information of a new Fe-base sodium metaphosphate compound, which is related to the research article entitled 'Synthesis, structural, magnetic and sodium deinsertion/insertion properties of a sodium ferrous metaphosphate, NaFe(PO3)3' by Lin et al. [1]. The research article has reported a new Fe-base metaphosphate compound NaFe(PO3)3, which is discovered during the exploration of the new potential electrode materials for sodium-ion batteries. In this data article, the synthesized process of this metaphosphate compound and the morphology of the obtained sample will be provided. The high-power XRD Rietveld refinement is applied to determine the crystal structure of this metaphosphate compound and the refinement result including the main refinement parameters, atomic coordinate and some important lattace parameters are stored in the cif file. Also, the refined structure has be evaluated by checkcif report and the result is also provided as the supplementary materials.

Nanotube Li2MoO4: a novel and high-capacity material as a lithium-ion battery anode.

Carbon-coated Li2MoO4 hexagonal hollow nanotubes were fabricated via a facile sol-gel method involving the solution synthesis of Li2MoO4 with subsequent annealing under an inert atmosphere to decompose the organic carbon source. To the best of our knowledge, this is the first report on the synthesis of Li2MoO4 nanotubes. More significantly, we have found that Li2MoO4 can be used as an anode material for lithium-ion batteries (LIBs). When evaluated as an anode material, the carbon-coated Li2MoO4 hollow nanotubes show an excellent electrochemical performance with a high reversible capacity (∼550 mA h g(-1)) after 23 cycles, good rate capability and cycling stability. Meanwhile, carbon-free Li2MoO4 sample, fabricated via a solid state reaction, was also prepared for comparison. The Li storage mechanism has been investigated in-detail by advanced XPS, in situ XRD and HRTEM.

Hydrothermal synthesis and electrochemical properties of Li3V2(PO4)3/C-based composites for lithium-ion batteries.

To improve performance at higher rates, we developed a hydrothermal method to prepare carbon-coated monoclinic lithium vanadium phosphate (Li(3)V(2)(PO(4))(3)) powder to be used as a cathode material for Li-ion batteries. The structural, morphological and electrochemical properties were characterized by X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM), and galvanostatic charge-discharge cycling. A superior cycle and rate behavior are demonstrated for Li(3)V(1.85)Sc(0.15)(PO(4))(3)/C and Li(2.96)Ca(0.02)V(2)(PO(4))(3)/C electrodes at charge-discharge current rates above 5C.