Amorphization of germanium selenide driven by chemical interaction with carbon and realization of reversible conversion-alloying reaction for superior K-ion storage

Chemical interaction with carbon has been employed to establish electron conduction pathways through intimate contact with anode materials. It is highly plausible that the strong chemical interaction can change the crystallinity as well as bonding nature of anode materials. This highlights the importance of chemical interaction with carbon and its effects on the material and electrochemical properties of anode materials. However, this is not yet investigated. This study is the first report on the amorphization of layered structured GeSe induced by the chemical interaction and its implications on the electrochemical properties for K-ion batteries. The charge storage mechanism of GeSe/CNT composite, investigated using ex-situ X-ray diffraction, indicates that reversible conversion-alloying reaction of GeSe is realized by the amorphization, which is closely linked with weakening of Ge–Se bonds derived from the strong chemical interaction and a concomitant increase in K-ion diffusion. As a result, the GeSe/CNT composite exhibits excellent electrochemical properties. Similar amorphization driven by chemical interaction is also observed for other layered structured anode materials. This study provides new insights on the chemical interaction of layered anode materials with carbon. Our findings could effectively be used to realize reversible conversion reaction for other anode materials for advanced secondary batteries.