Nanocrystalline ZnFe[sub 2]O[sub 4] and Ag-Doped ZnFe[sub 2]O[sub 4] Films Used as New Anode Materials for Li-Ion Batteries

Abstract

Nanocrystalline ZnFe 2 O 4 and Ag x ZnFe 2 O 4 (x ϭ 0.16, 0.37, 0.50) thin films have been prepared by reactive pulsed laser deposition, and used as anode materials for Li-ion batteries for the first time. X-ray diffraction ͑XRD͒ and scanning electron microscopy measurements showed that the prepared films were composed of a nanocrystalline structure with the average particle size less than 100 nm. The initial reversible capacity of ZnFe 2 O 4 and Ag 0.37 ZnFe 2 O 4 film electrodes reached 556 and 700 mAh/g, respectively, at a current density of 10 A cm Ϫ2 between 0.01 and 3.0 V. The Ag 0.37 ZnFe 2 O 4 film electrode exhibited better cyclability than ZnFe 2 O 4 film electrode, and retained 91% of the reversible capacity up to 100 cycles. According to our results on cyclic voltammetry of Li/ZnFe 2 O 4 cell coupled with ex situ photoelectron spectroscopy and XRD measurements of as-deposited and lithiated film electrodes, we suggest that the mechanism of ZnFe 2 O 4 film reacted with lithium involves reduction of Zn 2ϩ and Fe 3ϩ to metallic Zn and Fe 2ϩ , accompanying the formation of Li-Zn alloy. The dramatically improved electrochemical performance of Ag 0.37 ZnFe 2 O 4 film electrode might be related to the change of the reaction process after silver doping.

Nanostructured ZnFe2O4 as Anode Material for Lithium-Ion Batteries: Ionic Liquid-Assisted Synthesis and Performance Evaluation with Special Emphasis on Comparative Metal Dissolution

“…The first irreversible capacity can be attributed to the decomposition of electrolyte to form the solid electrolyte interphase (SEI) on the electrode surface. 34,40,60 As for many other conversion materials, the discharge curve spans over a wide potential range, in this case 3V, with a medium de-lithiation potential of 1.7 V vs. Li/Li + (at 1C), affecting the available energy content in a full cell. In addition, there is a large hysteresis, which will affect the energy efficiency.…”

“…This material demonstrated a rather poor cycling performance since only a capacity retention of 78% was obtained after 100 cycles. 34 Deng et al • Simple synthesis route (easy to operate) conc. HNO 3 ;…”

Synthesis of Nanocrystalline Copper Ferrites by Electrochemical Techniques for Toxic Gas Sensing, Li Ion Battery and Medical Applications

“…Pulsed laser deposition techniques [7][8][9], dip coating [10], sputtering [11], laser ablation [12], vacuum arc evaporation [13] and the sol-gel method [14] have been used to synthesis mixed iron-oxide thin films. To obtain crystallization, these techniques require heating the substrate for several hundred degrees Celsius.…”

A 57Fe Mössbauer spectroscopy study of iron nanoparticles obtained in situ in conversion ferrite electrodes

“…Thus, it was found that NiCo 2 O 4 can be cycled vs. both Li and Na [2], while XAS studies revealed the full reduction to the metallic state and an incomplete oxidation during charge [3]. Other examples of spinel materials studied so far contain iron in their stoichiometry, such as NiFe 2 O 4 [4] ZnFe 2 O 4 [5], and CoFe 2 O 4 [6] and CuFe 2 O 4 [7].…”

“…Powerful spectroscopic techniques have been used to gain for information about the reactions taking place. Thus Mössbauer spectroscopy (MS) [4], XPS [5,8] and XAS [3] were used for these purposes. In this communication, we show that 57 Fe MS provides valuable information about the changes in oxidation state, local environment and magnetic ordering of CoFe 2 O 4 in electrodes cycled vs. lithium.…”