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Facile preparation of core@shell and concentration-gradient spinel particles for Li-ion battery cathode materials

View Article: PubMed Central - PubMed

ABSTRACT

Core@shell and concentration-gradient particles have attracted much attention as improved cathodes for Li-ion batteries (LIBs). However, most of their preparation routes have employed a precisely-controlled co-precipitation method. Here, we report a facile preparation route of core@shell and concentration-gradient spinel particles by dry powder processing. The core@shell particles composed of the MnO2 core and the Li(Ni,Mn)2O4 spinel shell are prepared by mechanical treatment using an attrition-type mill, whereas the concentration-gradient spinel particles with an average composition of LiNi0.32Mn1.68O4 are produced by calcination of their core@shell particles as a precursor. The concentration-gradient LiNi0.32Mn1.68O4 spinel cathode exhibits the high discharge capacity of 135.3 mA h g−1, the wide-range plateau at a high voltage of 4.7 V and the cyclability with a capacity retention of 99.4% after 20 cycles. Thus, the facile preparation route of the core@shell and concentration-gradient particles may provide a new opportunity for the discovery and investigation of functional materials as well as for the cathode materials for LIBs.

No MeSH data available.


First charge-discharge curves at a constant current of 0.1 C of the concentration-gradient spinel cathodes prepared by calcination at various temperatures.
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Figure 6: First charge-discharge curves at a constant current of 0.1 C of the concentration-gradient spinel cathodes prepared by calcination at various temperatures.

Mentions: The electrochemical performances of the concentration-gradient spinel powders were tested using a coin-type half-cell employing Li metal as the anode. Figure 6 shows the first charge-discharge curves of the concentration-gradient spinel cathodes, measuring at a constant current density of 14.6 mA g−1 (0.1 C rate for LiNi0.5Mn1.5O4) in a voltage range of 3.0–5.0 V. There are two noteworthy features in our concentration-gradient spinels compared with the reported core@shell and concentration-gradient spinels [21, 27]. One is a high specific discharge capacity. The theoretical values for the LiNi0.5−xMn1.5+xO4 (0 ≤ x ≤ 0.5) spinels are 146.7–148.2 mA h g−1. The concentration-gradient spinel prepared by calcination at 700 °C provided the highest discharge capacity of 135.3 mA h g−1, whereas that at 600 °C was 120.2 mA h g−1. The low discharge capacity at 600 °C is caused by a remaining MnO2 phase. This high capacity will lead to an increase of the energy density on the practical applications. The other feature is the presence of an electrochemically active region at a high voltage of 4.6–4.7 V. A capacity of about 90 mA h g−1 was delivered by this high-voltage region. The operation voltages of LiMn2O4 and LiNi0.5Mn1.5O4 spinels are 4.1 V and 4.7 V, which are attributed to the redox couples of Mn3+/Mn4+ and Ni2+/Ni4+, respectively [9, 15]. Therefore, the concentration-gradient LiNi0.32Mn1.68O4 spinels had a close property to the LiNi0.5Mn1.5O4 spinel.


Facile preparation of core@shell and concentration-gradient spinel particles for Li-ion battery cathode materials
First charge-discharge curves at a constant current of 0.1 C of the concentration-gradient spinel cathodes prepared by calcination at various temperatures.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC5036501&req=5

Figure 6: First charge-discharge curves at a constant current of 0.1 C of the concentration-gradient spinel cathodes prepared by calcination at various temperatures.
Mentions: The electrochemical performances of the concentration-gradient spinel powders were tested using a coin-type half-cell employing Li metal as the anode. Figure 6 shows the first charge-discharge curves of the concentration-gradient spinel cathodes, measuring at a constant current density of 14.6 mA g−1 (0.1 C rate for LiNi0.5Mn1.5O4) in a voltage range of 3.0–5.0 V. There are two noteworthy features in our concentration-gradient spinels compared with the reported core@shell and concentration-gradient spinels [21, 27]. One is a high specific discharge capacity. The theoretical values for the LiNi0.5−xMn1.5+xO4 (0 ≤ x ≤ 0.5) spinels are 146.7–148.2 mA h g−1. The concentration-gradient spinel prepared by calcination at 700 °C provided the highest discharge capacity of 135.3 mA h g−1, whereas that at 600 °C was 120.2 mA h g−1. The low discharge capacity at 600 °C is caused by a remaining MnO2 phase. This high capacity will lead to an increase of the energy density on the practical applications. The other feature is the presence of an electrochemically active region at a high voltage of 4.6–4.7 V. A capacity of about 90 mA h g−1 was delivered by this high-voltage region. The operation voltages of LiMn2O4 and LiNi0.5Mn1.5O4 spinels are 4.1 V and 4.7 V, which are attributed to the redox couples of Mn3+/Mn4+ and Ni2+/Ni4+, respectively [9, 15]. Therefore, the concentration-gradient LiNi0.32Mn1.68O4 spinels had a close property to the LiNi0.5Mn1.5O4 spinel.

View Article: PubMed Central - PubMed

ABSTRACT

Core@shell and concentration-gradient particles have attracted much attention as improved cathodes for Li-ion batteries (LIBs). However, most of their preparation routes have employed a precisely-controlled co-precipitation method. Here, we report a facile preparation route of core@shell and concentration-gradient spinel particles by dry powder processing. The core@shell particles composed of the MnO2 core and the Li(Ni,Mn)2O4 spinel shell are prepared by mechanical treatment using an attrition-type mill, whereas the concentration-gradient spinel particles with an average composition of LiNi0.32Mn1.68O4 are produced by calcination of their core@shell particles as a precursor. The concentration-gradient LiNi0.32Mn1.68O4 spinel cathode exhibits the high discharge capacity of 135.3 mA h g−1, the wide-range plateau at a high voltage of 4.7 V and the cyclability with a capacity retention of 99.4% after 20 cycles. Thus, the facile preparation route of the core@shell and concentration-gradient particles may provide a new opportunity for the discovery and investigation of functional materials as well as for the cathode materials for LIBs.

No MeSH data available.