Scientists exploring alternatives to lithium-ion batteries are turning their attention to potassium-ion batteries, leveraging the abundance of potassium. However, challenges, such as ionic radius issues leading to suboptimal electrochemical performance, have hindered their commercial development. To overcome these hurdles, researchers are considering the use of NiCo2Se4, a bimetallic selenide, to construct sphere-shaped electrodes.
Published in Energy Materials and Devices, the study, led by Mingyue Wang from Xi’an Jiaotong University in China, focuses on synthesizing NiCo2Se4 through a two-step hydrothermal process. This results in nanotube structures with flower-like clusters, creating channels that facilitate potassium ion and electron transfer. Initially, Ni-Co precursor spheres with solid nanoneedles are prepared and exposed to selenide during a process called selenization.
The Kirkendall effect comes into play during this process, causing the formation of NiCo2Se4 nanotube shells. These hollow tubes, approximately 35 nanometers wide, provide ample space for potassium ions and electrons to transfer. Tests and analyses confirmed the superior electrochemical performance of NiCo2Se4 anodes, showcasing more active sites than other electrode materials. The unique nanotube structure and synergy between the two metals, Ni and Co, contributed to its outperformance, with higher capacity enhancing cyclic stability and high-rate performance.
Wang emphasizes that NiCo2Se4’s nanotube electrode demonstrated superior cyclic stability and rate capability compared to monometallic counterparts like Ni3Se4 and Co3Se4. The co-presence of two metals, Ni and Co, played a pivotal role in this success. The study’s findings provide valuable insights into designing micro/nano-structured binary metal selenides as potassium-ion battery anodes, showcasing extraordinary potassium ion storage performance. This research marks a significant step forward in addressing challenges and advancing the development of potassium-ion batteries as a viable alternative to lithium-ion counterparts.
