Structural Change Induced by Electrochemical Lithium Insertion in Cobalt Vanadium Oxide

Abstract

We investigated the open-circuit potentials (OCPs) and structure of CoV3normalO8 in the first discharge and charge processes. The OCPs in the discharge and charge processes traced different routes. In the discharge process, the OCPs declined slowly at ∼2.4V and reduced more slowly at ∼2.2V . From the change in the cell parameters, lithium was found to be intercalated in the tunnel space of CoV3normalO8 at low lithium contents. Further lithium insertion induced an amorphous material and a crystalline one. The generation reaction of these substances containing lithium ions resulted in an irreversible capacity in the first cycle. Considering that the observed OCPs were distributed over a wide range of potentials in the charge process, it was probable that lithium was extracted dominantly from the newly generated amorphous substance. We concluded that the amorphous substance exhibited a reversible discharge-charge cycle performance after the second cycle.

Ordered magnetism in the intrinsically decorated jeff=12α−CoV3O8

“…The corresponding unit cell was found to consist of three metal sites with octahedral (16k), tetrahedral (8j) and trigonal bipyramidal (8j) coordination, with Co 2+ and V 4+ with half occupancies independently distributed over the 16k site and V 5+ with full occupancies in the latter two 8j sites. Structural refinements utilizing 910 out of a total of 985 measured reflections confirmed two important conclusions from previous studies 52,61 . Firstly, Co 2+ and V 4+ are both randomly and equally distributed over the 16k site with refined occupancies of 0.506(6) and 0.494(4), respectively.…”

“…A mixture of the α-CoV 2 O 6 polycrystalline precursor and V 2 O 5 in a 3:2 ratio in the presence of approximately 0.01% (w/w) of B 2 O 3 (Alfa Aesar, 98.5%) was heated in a vacuum sealed quartz tube at 780 • C for 24 h and subsequently cooled to 700 • C at a rate of 1 • C hr −1 . After 24 h of heating at 700 • C, the sample was cooled to 600 • C at a rate of 1 C under static vacuum in a sealed quartz tube with intermittent grindings until laboratory powder x-ray diffraction confirmed no discernable impurities 53,61 . All stoichiometric mixtures of polycrystalline precursors were first mixed thoroughly together and finely ground to homogeneity with acetone using an agate mortar and pestle.…”

Higher, Stronger, Better…︁ A Review of 5 Volt Cathode Materials for Advanced Lithium‐Ion Batteries

“…), y ≤ 0.1, enhances the cycling capability of LiMn y Co 1‐ y PO 4 ;211 LiCoPO 4 F has a voltage plateau even closer to 5 V then LiCoPO 4 212 and the theoretical estimation indicates the intercalation voltage of ∼4.9 V for cathode with ‐SO 4 F anion 161, 213. At the same time, Co‐based cathodes with ‐SiO 4 ,188, 189, 214 ‐BO 3 ,194 and ‐V 3 O 8 215 anions were found to have distinctly lower voltages (all these results agree well with ab‐initio calculations) 191, 216…”

Transition metal vanadium oxides and vanadate materials for lithium batteries

“…Note that irreversible discharge-charge properties are observed in the first cycle, which originate from the generation of an amorphous material and a crystalline one induced by lithium insertion. 57 CoV 2 O 5 powder with amorphous character, which has been prepared from the mild combustion of V 2 O 5 , Co(NO 3 ) 2 and glycine, delivers an initial capacity of $275 mA h g À1 between 2 and 4 V with no capacity fading after several cycles, and thus is a potential candidate for positive electrode material. 58 In another example, the spinel-type cobalt vanadate, LiCoVO 4 , is found to show large reversible capacity and highrate performance as the anode materials, due to the formation of nanometre scale cobalt particles.…”