LiCr0.2Ni0.4Mn1.4O4 spinels exhibiting huge rate capability at 25 and 55 °C: Analysis of the effect of the particle size
Highlights
► Synthesized LiCr0.2Ni0.4Mn1.4O4 spinels exhibit the highest rate capability among LiNi0.5Mn1.5O4-based cathodes. ► The rate capability is enhanced at 25 and 55 °C on decreasing the particle size. ► LiCr0.2Ni0.4Mn1.4O4 heated at 900 °C delivers a high power of 31,000 W kg−1. ► LiCr0.2Ni0.4Mn1.4O4 at 900 °C is a really promising cathode for commercial Li-ion batteries.
Introduction
The electrification of the road transport, i.e. the wide use of electric vehicles (EVs), is one of the more straightforward ways to combat three of the most important challenges of the XXI century: (i) climatic change, (ii) increased pollution in large cities and (iii) strong dependence on fossil fuels. A key factor for EVs is the battery which must combine high energy and power with low pollution and cost [1]. Nowadays, lithium-ion batteries (LIBs) are the technology of choice to drive the EVs [1], [2], [3]. A major challenge in LIBs is to develop new electrode materials with power capabilities close to that of supercapacitors (∼10 kW kg−1) [4], [5], [6]. To reach this goal, several strategies are being developed. For instance (i) doping popular electrode materials such as LiCoO2 [7], [8] and LiMn2O4 [9], [10], (ii) coating the active materials such as carbon coated LiFePO4 [5], [11] or ZnO coated LiNi0.5Mn1.5O4 spinel [12] and (iii) tailoring the particle size of the electrode materials [2], [3], [13], [14], [15]. Probably, the latter strategy is the most followed because it has been widely demonstrated that the power output of LIBs can be notably increased by reducing the particle size, i.e. decreasing the Li+-diffusion pathways.
Among the cathode materials under study, LiMn2O4 type spinels (LMS) are one of the most promising candidates for the large-size LIBs needed for electrical vehicles. The main advantages are their low cost and environment friendliness [1], [9], [16], [17]. LMS-type oxydes have a cubic spinel structure, space group Fd-3 m [9], [17], [18]. It can be described as a close-cubic packed of O2− anions in which the Li+ cations are placed in the 8a tetrahedral positions and the manganese and dopant metal cations (M) are situated in the 16d octahedral sites. The [Mn,M]2O4 framework defines a three-dimensional network of channels through which the Li+ cations can be reversibly de-/inserted. Among the LMS-types cathodes, those derived of the spinel LiNi0.5Mn1.5O4 (LNMS) has been intensively studied since Zhong et al. [19] showed that LNMS was able to de-/inserted Li+ ions at very high potential (∼4.7 V vs. Li+/Li) [20], [21], [22], [23]. Moreover, LNMS-type cathodes show high reversible capacities (∼135 mAh g−1) at room temperature [21], [24], [25]. Unfortunately, the electrochemical performances of these cathodes notably worsen at elevated temperature (∼55 °C) [12], [22], [26], [27]. The development of new strategies to overcome this serious drawback is nowadays one of the most active research lines in the field of advanced cathodes for LIBs. We showed that it is possible to enhance the electrochemical performance of LNMS by doping with chromium. Among the LiCr2yNi0.5−yMn1.5−yO4 spinels synthesized, the sample with y = 0.1 (LiCr0.2Ni0.4Mn1.4O4) exhibited the best electrochemical performances [28]. Furthermore, we demonstrated that cycleability at 25 and at 55 °C of the LiCr0.2Ni0.4Mn1.4O4 spinel strongly depended on the particle size [27]. The samples synthesized at T ≥ 900 °C, with particle size >690 nm, shown a remarkable cycling performance even when cycling was performed at elevated temperature (55 °C). In this paper, we report the effect of particle size of the LiCr0.2Ni0.4Mn1.4O4 spinel annealed at T ≥ 900 °C on its rate capability and its specific power at 25 and 55 °C.
Section snippets
Experimental/materials and methods
The “as-prepared” LiCr0.2Ni0.4Mn1.4O4 spinel was synthesized by the sucrose aided combustion method previously described [28]. Three LiCr0.2Ni0.4Mn1.4O4 samples have been prepared by annealing for 1 h the “as-prepared” spinel at 900, 950 and 1000 °C being the heating/cooling rate of 2 °C min−1. The samples are labeled as “SACNumber” where SAC and Number stand for Sucrose Aided Combustion and for the annealing temperature, respectively.
The analysis of the phase purity and the structural
Result and discussion
The structural characterization of the SAC-samples was carried out by X-ray diffraction. The corresponding patterns, given in Fig. 1, indicate that single phase spinels were obtained for the three annealing temperatures. The absence of the (2 2 0) diffraction peak around 2θ = 30° indicates that there is no transition metal ions in the 8a tetrahedral positions. The cubic unit cell parameter (ac) for the SAC-spinels is summarized in Table 1. The likeness of the ac-values indicates that the cubic
Conclusion
LiCr0.2Ni0.4Mn1.4O4 cathode materials have been prepared by the sucrose aided combustion method followed by thermal treatments at 900, 950 and 1000 °C. The structural study shows that SAC-samples are single-phase cubic spinel. They have similar unit cell parameter (ac ∼ 8.189 Å) indicating that there is no structural modification on heating. The morphological characterization by TEM evidences that the main effect of the thermal treatment is the remarkable growth of the particle size from 695 nm at
Acknowledgments
Financial support through the projects MAT2008-03182 (MICINN), MATERYENER P2009/PPQ-1626 (CAM) and 2009MA0007 (CSIC/CNRST) are gratefully recognized. M. Aklalouch thanks the AECI for the MAEC-AECI fellowship.
References (35)
- et al.
Solid State Ion.
(1992) - et al.
J. Power Sources
(2009) - et al.
Electrochim. Acta
(2010) - et al.
Electrochim. Acta
(2006) - et al.
J. Power Sources
(2007) - et al.
J. Power Sources
(2011) - et al.
J. Power Sources
(2006) - et al.
Electrochim. Acta
(2010) - et al.
J. Power Sources
(2011) - et al.
J. Electroanal. Chem.
(2004)
Electrochim. Acta
J. Power Sources
Electrochem. Commun.
J. Solid State Chem.
Nature
Angew. Chem.
Cited by (41)
High-voltage cathode materials by combustion-based preparative approaches for Li-ion batteries application
2020, Journal of Power SourcesGeminal pyrrolidinium and piperidinium dicationic ionic liquid electrolytes. Synthesis, characterization and cell performance in LiMn<inf>2</inf>O<inf>4</inf> rechargeable lithium cells
2019, Journal of Power SourcesCitation Excerpt :It also has to be remarkable that the rate capability delivered by the cell based on the synthesized IL-1 dicationic ionic liquid electrolyte is higher than that calculated for the cell based on Pyr14 pyrrolidinium ionic liquid electrolyte [76,77], one of the most extensively studied IL. As the main drawback of the LiMn2O4-based cathodes in conventional electrolytes is the significant capacity loss during cycling at elevated temperatures (above 50 °C) [61,69,78] and taking into account the better thermal stability of the ionic liquid-based electrolytes [79,80] we considered relevant to investigate the cycling performance of the LMO-cells assembled with the synthesized IL-based electrolytes. Cycling tests were performed at 60 °C in the voltage range 3.5V–4.5 V at 0.2C charge/discharge rate.
Structural, electrical and electrochemical studies on doubly doped LiMn<inf>2−x</inf>(GdNi)<inf>x</inf>O<inf>4</inf> cathode materials for Li-ion batteries
2018, Materials LettersCitation Excerpt :It has been reported that multiple cation substitution has synergistic effect on improving the properties of LMO [5]. It is found that Ni substitution in LMO improves the performance of Li-ion battery [6–8]. The functions of LMO have been improved with substitution of rare earth elements [9,10] and co-substitution with transition elements [11,12].