Tang Zilong research group of key laboratory has made new progress in the direction of ultra long life sodium ion battery materials

On March 29, 2020, Professor Tang Zilong's research team of Key Laboratory published the research results entitled "Conversion-Type MnO Nanorods as a Surprisingly Stable Anode Framework for Sodium-Ion Batteries" in Advanced Functional Materials. This study breaks the traditional recognition that the conversion electrode material cannot be used as the structural stability framework of the energy storage battery.

In energy storage materials, nano materials can provide high specific capacity and fast reaction kinetics, but they are prone to change in morphology, leading to a large capacity degradation. Therefore, the composite of nanomaterials and structural stability framework can effectively play the advantages of nanomaterials. However, the currently available structural stability framework is very limited, that is, carbon materials, conductive polymers and titanium-based materials, which are inactive or embedded electrode materials. Nevertheless, the conversion type and alloy type electrode materials are generally considered as the representatives of high capacity electrodes, and the electrochemical stability of their own structure is poor, so they have never been considered as a structural stability framework.

In order to solve this problem, Tang Zilong group took the converted MnO nanorods as the structural stability framework, and the composite materials loaded with high capacity Mo based materials obtained more than 40000 stable cycles in the high rate sodium ion battery at 70c (Fig. 1a ~ c). However, although the composite has a high capacity in lithium-ion batteries, its cycle life is less than 500 times (Fig. 1d ~ e). This shows that the capacity of the electrode material is easy to decay and the structure is not stable. When the service environment of the material is changed and its storage capacity is limited (for example, the manganese oxide in this study has been transformed from the electrode material of high capacity lithium-ion battery to the electrode material of low capacity sodium ion battery), the conversion electrode material can also be used as an excellent structural stability framework. This design strategy is expected to be universal for other alloy type or conversion type electrode materials, and provide a new idea for the synthesis of high-performance functional materials by using the interface / bonding characteristics between the structural stability framework and high-capacity nano materials.

Fig. 1 Comparison of the electrochemical properties of MnO nanorod Mo based composite in Na⁺battery (a ~ c) and Li-ion battery (d ~ e)

The corresponding authors of this paper are Professor Tang Zilong, from Key Laboratory, and Dr. Wang Shitong, from Massachusetts Institute of technology. The research is supported by NSFC.

Paper link:https://onlinelibrary.wiley.com/doi/abs/10.1002/adfm.202001026