The two major problems with lithium-sulfur batteries stem from the intrinsic inert reaction kinetics of sulfur redox and the unique 'shuttle' mechanism described as that soluble intermediates - polysulfides consisting of lithium-terminated sulfur-chains - diffuse between the cathode and anode, thus being consumed within the battery instead of being utilized. To solve these issues and to improve battery performance relies on not only the electrode materials but also other cell components such as the separator.
A carbon material with high electrical conductivity, high specific surface area, tunable pore structure, mechanically robust framework, and high chemical stability is an important requirement for advanced electrochemical energy storage. However, neither porous carbon or sp2 carbon can full meet these requirements yet. How to create a conductive carbon material with especially large pore volume, and hence large surface area, has therefore been a key focus in electrode research.
Against the double-whammy backdrop of an energy challenge and a climate challenge it is the role of innovative energy technologies to provide socially acceptable solutions through energy savings; efficiency gains; and decarbonization. Nanotechnology It may not be the silver bullet, but nanomaterials and nanoscale applications will have an important role to play. This article provides an overview of the issues and nanomaterials and applications that are being researched in the field of energy.
Researchers have been looking to design catalyst materials that can significantly enhance the performance of oxygen evolution reaction (OER), a key eletrode reaction that is an enabling process for many energy storage options such as direct-solar and electricity-driven water splitting and rechargeable metal-air batteries. However, OER suffers from sluggish kinetics - but a novel material inspired by the pomegranate might change that.
Self-healing of a device is different from material self-healing because the devices contain electronic circuits. Self-healing of a device includes materials self-healing plus alignment of electrodes, which is very difficult but essential. Researchers have now come up with the idea of using magnetic force to assist alignment of electrodes in a circuit, facilitating self-healing of the whole device. To realize this idea, they designed and fabricated an electrically and mechanically self-healable yarn-based supercapacitor by wrapping magnetic electrodes with a self-healing carboxylated polyurethane shell.
According to Planck's law, the emittance of a non-reflective black object - a blackbody - defines the maximum level of thermal emittance from an arbitrary object. Planck's law has been challenged in recent decades by predictions and successful demonstrations of the radiative heat transfer between objects separated by nanoscale gaps that deviate significantly from the law predictions. Researchers have now demonstrated another way to modify the object thermal emission spectrum and to force it to deviate from the one predicted by Planck's law.
Counter intuitive to our idea of 'perfection equals best performance', researchers have shown that defects in nanocarbons could provide a breakthrough for increasing the quantum capacitance. By subjecting graphene layers to a reactive-ion etching process, the team has poked holes into graphene to create holey graphene, which can change the microscopic distribution of electrons and thereby increase the quantum capacitance of graphene by at least fourfold.
The commonly used separators in battery systems are porous polymer membranes, which separate the two electrodes while having little impact on the transportation of ions through the membrane. Polysulfides generated in a lithium-sulfur system can also diffuse freely through the membranes and react with a metal lithium anode, which results in the degradation of the battery's performance. If a novel, ion-selective but highly permeable separator can be developed, the shuttling of polysulfides and self-discharge would be effectively prevented, and both the energy density and power density of lithium-sulfur batteries could be significantly improved.