Investigation of Supercapacitors using Molecular Dynamics Simulations

In today’s modern society, a wide range of electronic products, including mobile phones, laptops, cameras, pacemakers, hearing aids and electric vehicles, heavily rely on the energy storage technology behind them. Among promising candidates as future energy storage devices are batteries and electric double-layer supercapacitors (EDLSC). A striking difference between these two systems is that no chemical reactions occur on the electrodes of an EDLSC and energy is stored via ion adsorption on the electrodes, whereas energy is generated through chemical reactions involving the electrodes of a battery. Batteries are suitable for long-term energy storage whereas EDLSCs are ideal for repeated short-term power delivery, such as repetitive breaking in electric vehicles. In general, batteries possess high energy density whereas EDLSCs have high power density. However, energy storage devices often need to meet both power density and energy density requirements, so developing devices that achieve both is of importance. To advance the utility of EDLCS, it is vital to understand the molecular-level formation of charge layers in the vicinity of electrodes, or the electric double layers (EDLs) as this is a key factor for their performance.This project investigates the molecular-level behaviour of ionic liquids in the EDLs in response to applied potential difference.

在当代社会，从手机、笔记本电脑、相机、心脏起搏器、助听器到电动汽车在内的各类电子产品，均高度依托其背后的储能技术。电池与双电层超级电容器（electric double-layer supercapacitors, EDLSC）是极具潜力的下一代储能装置候选方案。这两类储能系统的显著区别在于：双电层超级电容器的电极表面不会发生化学反应，其储能依靠电极表面的离子吸附作用；而电池则通过涉及自身电极的化学反应来释放能量。电池适用于长期储能，而双电层超级电容器则非常适合反复短时功率输出场景，例如电动汽车的重复制动过程。通常而言，电池具备较高的能量密度，而双电层超级电容器则拥有更高的功率密度。然而，实际应用中的储能装置往往需要同时满足功率密度与能量密度的双重要求，因此开发兼具二者优势的储能装置具有重要意义。为提升双电层超级电容器的实用价值，理解电极附近电荷层（即双电层（electric double layers, EDL））的分子级形成机制至关重要，这也是影响其性能的关键因素。本项目旨在研究外加电势差作用下，离子液体在双电层中的分子级行为。