A Vanadium-Based Cathode for Lithium-Ion Batteries

Abstract

Over the past decade, a tremendous amount of research has been conducted on cathode materials for use in lithium 1 and lithium-ion batteries. 2,3 Many different metal oxides and chalcogenides have been explored. In the case of lithium-ion batteries, for which the cathode must supply the lithium to a nonlithiated anode, cathodes based on manganese (LiMn 2 O 4 ), 4 cobalt (LiCoO 2 ), 5 and nickel (LiNiO 2 ), 6 and combinations thereof (LiM 1x M 2 1Ϫx O 2 ), (where M 1 and M 2 are Co, Ni, and/or Mn) 7 are the most common. Vanadiumbased materials are absent due to the difficulty in preparing an environmentally stable lithiated oxide in a one-step process.Vanadium oxides have been the focus of much research for lithium metal batteries. Chemistries based on V 2 O 5 , 8-10 V 6 O 13 , 11-14 and LiV 3 O 8 15,16 have proven to yield viable materials in metallic systems. However, for use in a lithium-ion battery, where the cathode is the source of lithium, these materials are not suitable. If they were lithiated, they would be attractive materials for lithium-ion batteries due to their high-energy storage capabilities. The amount of energy that can be stored in vanadium systems is higher 17 than that of current materials, LiMn 2 O 4 , LiCoO 2 , and LiM 1 1Ϫx M x 2 O 2 , where M 1 and M 2 ϭ Co, Ni, and/or Mn.Lithiation of metal oxides for producing viable cathodes has proven difficult. The most obvious lithiating reagent is butyllithium. Due to its strong reducing ability, butyllithium can easily over reduce the metal oxide, thus destroying the desired lithiated structure. A milder reducing/lithiating reagent, lithium iodide, has been used successfully to lithiate LiMn 2 O 4 to Li 2 Mn 2 O 4 . 18 Li 2 Mn 2 O 4 , a 3 V cathode, decomposes rapidly in moist air; dry conditions are required so the lithiated metal oxide will not decompose. Pistoia et al., reported 16 that Li 1ϩx V 3 O 8 systems are moisture insensitive for very low values of x.Using inherent features of vanadium oxides, we have prepared a lithiated vanadium oxide. When lithiated, it can be used as the cathode material in a lithium-ion battery. In this manuscript, we present a synthetic method for lithiation of a vanadium oxide. Characterization of the parent compound, LiV 3 O 7.9 , and the lithiated vanadium oxide, Li 4 V 3 O 7.9 , are discussed as well as their respective capacities, rate capabilities, energy storage, and long-term cycle abilities. ExperimentalSynthesis.-All materials were used as received. LiV 3 O 7.9 was prepared by first grinding together V 2 O 5 (battery grade, Kerr-McGee Chemical LLC), LiOHиH 2 O (reagent grade, Aldrich Chemical Corporation), and NH 4 CO 2 CH 3 (reagent grade, Aldrich Chemical Corporation) in a 4:3:1 molar ratio, respectively. Then, the mixture was placed in an alumina crucible (Coors Corporation) and heated at 585ЊC in air for 16 h. After cooling, the material was ground and reheated at 585ЊC in air for an additional 16 h. The resulting product was black in color.Reduction (lithiation) of the LiV 3 O 7.9 by Li 2 S (Alfa-Ae...

A Feasibility Study on the Use of Li4V3O8 as a High Capacity Cathode Material for Lithium‐Ion Batteries

“…Material synthesis: The Li 1.1 V 3 O 8 precursor material was synthesised through a spray-drying process in air using a Mobile Minor 2000 type device, followed by heat treatment in air at 320 8C for 1 h. [17] Li 4 V 3 O 8 was prepared through reduction of this Li 1.1 V 3 O 8 precursor material by Li 2 S (Alfa-Aesar) under a dry nitrogen gas atmosphere. The reactants, with molar ratio of Li/V (1.45/1), were heated under reflux in anhydrous acetonitrile (99.99 %, Merck, Germany) at 80 8C for 24 h. [18] It is important to note that there should be no reaction between the Li 1.1 V 3 O 8 and the anhydrous acetonitrile solvent. Therefore, any possible V dissolution during this step would be negligible and should have no bearing on the electrochemical properties of the final product, because the amount of lithiation was calculated using ICP-OES based on the final dried product.…”

“…The vanadium content was determined by a potentiometric titration technique. [18] The materials were analyzed by X-ray diffraction (XRD) using a Bruker "D4-Endeavor" equipped with a diffracted-beam monochromator (Cu-Ka radiation) in the 5-708 (2q Cu ) range using a 0.028 (2q Cu ) step of 3.6 s duration. The unit cell structural parameters were refined by the Rietveld method using the Fullprof/Winplotr software package.…”

“…[14][15][16] Herein, we report on an inexpensive and industrially scalable method for producing Li 4 V 3 O 8 using a spray-drying method to produce the Li 1.1 V 3 O 8 precursor materials in the first instance, [17] followed by chemical lithiation of the precursor materials with Li 2 S in acetonitrile. [18] Systematic characterisations of the lithiated vanadates in terms of their physical properties (XRD and SEM) as well as their electrochemical performance are discussed in detail. In addition, a comprehensive feasibility study of these over-lithiated vanadates when applied as cathodes in the Li-ion battery full-cell configuration is presented.…”

“…One possible solution would be to synthesize a Li 1+ x V 3 O 8 (2< x <4) compound for which a theoretical reversible specific capacity above 200 mAh g −1 is achievable 14–16. Herein, we report on an inexpensive and industrially scalable method for producing Li 4 V 3 O 8 using a spray‐drying method to produce the Li 1.1 V 3 O 8 precursor materials in the first instance,17 followed by chemical lithiation of the precursor materials with Li 2 S in acetonitrile 18. Systematic characterisations of the lithiated vanadates in terms of their physical properties (XRD and SEM) as well as their electrochemical performance are discussed in detail.…”

Hydrothermal Synthesis of V[sub 2]O[sub 5]⋅1.9H[sub 2]O Single Crystals with Novel Electrochemical Characteristics

“…7 These vanadium-based oxides showing distinctive physicochemical properties are widely studied for several applications, e.g., catalysts of chemical reactions 8,9 and Li-ion batteries. 6,[10][11][12][13][14] The V 2 O 5 -like materials with a layered structure show the typical redox intercalation ability for various intercalating species, 13,14 and have been considered as an important electrode material in the development of high-energy density Li-ion batteries. 14 Accordingly, the relationship between textural characteristics and physicochemical properties of V 2 O 5 -like materials appears to be an interesting research field in both materials science and chemistry.…”