Cyclic Voltammetry of Pulsed Laser Deposited Li x Mn2 O 4 Thin Films

Abstract

Electrochemical properties of thin films of LiMn2O4 spinel prepared by pulsed laser deposition were studied using constant current cycling and cyclic voltammetry. Films have been cycled more than 220 times with no significant capacity fading. The shape of the cyclic voltammogram is very sensitive to the composition and morphology of the film. The diffusion process for the LirMn2O4 thin films with an excess of lithium (x> 1) appears to be slower than for lithium-deficient films. Films were subjected to overcharge (5 V vs. Li/Lit) and overdischarge (2 V vs. Li/Lit). Overcharge does not significantly affect the structure of the film. Overdischarge leads to changes in the shape of the cyclic voltammogram: (i) loss of resolution of the two oxidation peaks at 4.1 and 4.2 V which are the signatures of the spinel structure, and (ii) loss of capacity. These changes in the electrochemical behavior may be correlated to the structural disorder associated with the phase transition when more than one lithium is intercalated in LiMn2O4. It is a reversible phenomenon.

Electrochemical features of ball-milled lithium manganate spinel for rapid-charge cathodes of lithium ion batteries

“…The two current peaks, marked as P 1a and P 2a in the anodic cycle of Fig. 3a show the expected two-step process of Li + extraction from LMO [17,19]. The cathodic counterparts of these current features are labeled as P 1c and P 2c , respectively.…”

“…The present study explores the electrochemical considerations of material utilization for supporting fast charge/discharge of LMO cathodes prepared in this approach. To do this, a phenomenological framework, adapted from earlier treatments of the problem [19,24], is extended here to combine the results of EIS and galvanostatic measurements. The relative timescales for diffusion and charge transfer by Li + in the LMO lattice are determined, and the effects of mechanical milling on these time parameters are examined.…”

Structural and electrical properties of lithium manganese oxide thin films grown by pulsed laser deposition

“…Among them, lithium manganese oxide (LiMn 2 O 4 ) has been considered to be one of the most promising cathode materials for Li-ion batteries because it's low cost, nontoxic, and available from abundant material sources [5,6]. LiMn 2 O 4 belongs to Fd3m space group with spinel cubic structure, in which Li ions occupy the 8a tetrahedral interstices and manganese cations occupy 16d octahedral interstices of a cubic-close packed array constituted by oxygen atoms located in the 32e position [7]. Li [Mn 2 ]O 4 system is of particular interest as only Li + resides in the interstitial space defined by the [Mn 2 ]O 4 framework.…”

LiMn2O4 films grown by pulsed-laser deposition

“…In the fabrication of LiMn204 thin films, formation of the spinel structure is known to be crucial for obtaining a good rechargeability of the cells. Various aspects of LiMn204 thin films prepared by RF sputtering [11], electron beam deposition [8][9], pyrolitic preparation [12], and pulsed-laser deposition [16][17][18] have been reported. Thin films of amorphous LiMn204 have been prepared onto substrates maintained at low-temperature (< 150 ~ by Shokoohi et al [8] and Bates et al [9] with reactive electron beam evaporation and Hwang et al [11] at 500 ~ In the present work, we report on the growth of thin LiMn204 films onto silicon substrates maintained at a temperature of 300 ~ using the pulsed-laser deposition technique.…”