Two-dimensional materials have been widely used as electrodes for lithium ion batteries (LIB) due to their special physical and chemical properties. MXene has excellent performance and has been extensively explored in energy storage. However, most of the related application research is carried out on multilayer MXene, or with the assistance of carbon materials. The two most unique characteristics of MXene are usually overlooked. It has a large interlayer spacing and rich surface chemistry, which distinguishes MXene from other two-dimensional materials.

Recently, the research group of Professor Weiqiang Han of Zhejiang University published a research paper titled: Rational Design of Pillared SnS/Ti3C2Tx MXene for Superior Lithium-Ion Storage in the internationally renowned academic journal ACS Nano. This paper uses an improved solution phase flocculation method to prepare less The layer of MXene (f-MXene) nanosheet powder avoids the re-stacking phenomenon of f-MXene nanosheets during the preparation process and the oxidation problems during storage. By further using solvothermal reaction and annealing treatment, we successfully synthesized in situ columnar SnS/Ti3C2Tx composites modified with TiO2 nanoparticles. In composite materials, MXenes can act as a conductive network as a buffer matrix for SnS volume expansion, while active SnS nanosheets can give full play to its high capacity advantages and further induce Ti3C2Tx interlayer engineering during the cycle. The columnar SnS/Ti3C2TxMXene composite material shows a significant improvement in electrochemical performance. And the capacity increased significantly in the subsequent cycles, which can be attributed to the "piling effect" of Ti3C2Tx MXenes. The efforts and attempts made in this work can further broaden the development of columnar MXene composites. The first author of this work is Dr. Zhang Shunlong of Zhejiang University.

Figure 1. Schematic diagram of the preparation process of (a) Ti3C2Tx MXene powder with few layers and (b) SnS / Ti3C2Tx composite

Figure 2. Physical characterization XRD pattern and XRS pattern of the sample

Figure 3. SEM and TEM spectra of the sample

Figure 4. Electrochemical performance of SnS / Ti3C2Tx composite

Figure 5. Comparison of electrochemical performance of three samples and SnS / Ti3C2Tx kinetic analysis

In this paper, considering the two most easily distinguishable properties of MXenes, the rich surface chemical composition and large interlayer spacing, the target product columnar SnS/Ti3C2Tx composite was successfully prepared by tightly fixing the SnS nanosheets on the small-layer Ti3C2Tx electrode. CTAB is supported in columnar shape in advance, and then undergoes solvothermal reaction and annealing process. SnS/Ti3C2Tx composites can fully provide high capacity, suppress the volume problem of SnS, and exhibit excellent electrical conductivity and Ti3C2Tx adjustable interlayer engineering can achieve excellent lithium ion storage capacity: they exhibit 1254.3 at 100 mA/g High discharge capacity of mAh/g, it still maintains 866 mAh/g after 300 cycles of 500 mA/g. Even at a higher current density of 5000 mA/g, the specific capacity can reach 787.7 mAh/g, which proves the excellent rate performance of the composite. Due to the "columnar effect" between metal sulfide and MXene, the capacity increase can be observed in the subsequent cycles, which successfully broadens the field of columnar MXene composites, from multi-layer MXene to f-MXenes, from metal oxidation To metal sulfide. It is believed that the pillar support strategy of MXenes will be more widely used in the future, resulting in a series of outstanding research.

Literature link:

https://doi.org/10.1021/acsnano.0c08770

Source: MXene Frontier

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