Effects of Graphene Interface on Potassiation in a Graphene–Selenium Heterostructure Cathode for Potassium-Ion Batteries
Effects of Graphene Interface on Potassiation in a Graphene–Selenium Heterostructure Cathode for Potassium-Ion Batteries
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DOI：
10.1021/acsaem.3c00989
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发表时间：
2023-04
影响因子：
6.4
通讯作者：
Vidushi Sharma;D. Datta
中科院分区：
文献类型：
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作者：
Vidushi Sharma;D. Datta
硒（Se）阴极是一种令人兴奋的新兴钾离子电池（KIB）高能量密度存储系统，其中钾化反应了解较少。在这里，我们提出了一个原子级的KxSe阴极封闭在六方晶格的碳（C）的多层石墨烯基质和多壁碳纳米管（MW-CNTs）的特性的调查。将KxSe阴极中由石墨烯衬底引导的微结构变化与无石墨烯阴极进行对比。研究了石墨烯对长链多硒化物（Se-Se-Se =-2.82eV和Se-Se =-2.646eV）的结合亲和力以及诱导Se和K之间反应性的能力。此外，以K2 Se作为最终放电产物，计算了石墨烯包围的KxSe阴极反应中间体的嵌入电压。我们的研究结果表明，一个单步反应附近的电压为1.55 V之间的K和Se阴极。我们的研究结果表明，在更高的电压（~ 2 V）下操作可能导致形成反应中间体，其中K的嵌入/脱嵌可能是一个挑战，因此导致电池中不可逆的容量损失。主要问题是长链聚硒化物与石墨烯的高结合能，其在低K浓度下阻碍K储存和Se-Se键解离。与不含石墨烯的阴极的比较突出了货车德瓦尔斯（vdW）石墨烯界面可以在KxSe阴极的原子结构和电化学中带来的实质性变化。
Selenium (Se) cathodes are an exciting emerging high energy density storage system for Potassium ion batteries(KIB), where potassiation reactions are less understood. Here, we present an atomic-level investigation of KxSe cathode enclosed in hexagonal lattices of carbon(C) characteristic of multilayered graphene matrix and multiwalled carbon nanotubes (MW-CNTs). Microstructural changes directed by graphene substrate in KxSe cathode are contrasted with graphene-free cathode. Graphene's binding affinity for long-chain polyselenides (Se-Se-Se = -2.82 eV and Se-Se = -2.646 eV) and ability to induce reactivity between Se and K are investigated. Furthermore, intercalation voltage for graphene enclosed KxSe cathode reaction intermediates are calculated with K2Se as the final discharged product. Our results indicate a single-step reaction near a voltage of 1.55 V between K and Se cathode. Our findings suggest that operating at higher voltages (~2V) could result in the formation of reaction intermediates where intercalation/deintercalation of K could be a challenge, and therefore cause irreversible capacity losses in the battery. Primary issues are the high binding energy of long-chain polyselenides with graphene that discourage K storage and Se-Se bond dissociation at low K concentrations. A comparison with graphene-free cathode highlights the substantial changes a van der Waals (vdW) graphene interface can bring in atomic-structure and electrochemistry of the KxSe cathode.