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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.


Schematic illustration of the formation process for the core@shell and concentration-gradient spinel particles.
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Figure 1: Schematic illustration of the formation process for the core@shell and concentration-gradient spinel particles.

Mentions: As illustrated in figure 1, the concentration-gradient spinel particles were synthesized via mechanical synthesis of the MnO2@Li(Ni,Mn)2O4 core@shell particles and a following calcination step. At the beginning, the MnO2@Li(Ni,Mn)2O4 core@shell particles as a precursor were prepared by mechanical treatment of the raw materials using an attrition-type mill. Recently, we demonstrated the mechanical synthesis of LiNi0.5Mn1.5O4 using Li2CO3, NiO and MnO2 as raw materials [29]. The formation of LiNi0.5Mn1.5O4 arises from a solid-state reaction at the particle surface of MnO2, which is induced by the mechanical stresses and frictional heat applied to a powder layer. If the raw MnO2 particles with a micrometer scale are used on the mechanical treatment, the formation of a spinel phase as the shell and the survival of a MnO2 phase as the core is predicted. Hence, the MnO2 particles with the median size of 43 μm estimated from the particle size distribution were used as the raw material.


Facile preparation of core@shell and concentration-gradient spinel particles for Li-ion battery cathode materials
Schematic illustration of the formation process for the core@shell and concentration-gradient spinel particles.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 1: Schematic illustration of the formation process for the core@shell and concentration-gradient spinel particles.
Mentions: As illustrated in figure 1, the concentration-gradient spinel particles were synthesized via mechanical synthesis of the MnO2@Li(Ni,Mn)2O4 core@shell particles and a following calcination step. At the beginning, the MnO2@Li(Ni,Mn)2O4 core@shell particles as a precursor were prepared by mechanical treatment of the raw materials using an attrition-type mill. Recently, we demonstrated the mechanical synthesis of LiNi0.5Mn1.5O4 using Li2CO3, NiO and MnO2 as raw materials [29]. The formation of LiNi0.5Mn1.5O4 arises from a solid-state reaction at the particle surface of MnO2, which is induced by the mechanical stresses and frictional heat applied to a powder layer. If the raw MnO2 particles with a micrometer scale are used on the mechanical treatment, the formation of a spinel phase as the shell and the survival of a MnO2 phase as the core is predicted. Hence, the MnO2 particles with the median size of 43 μm estimated from the particle size distribution were used as the raw material.

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.