Graphene and graphene-based materials have attracted great attention in energy storage applications for batteries and supercapacitors owing to their unique properties of high mechanical flexibility, large surface area, chemical stability, superior electric and thermal conductivities that render them great choices as alternative electrode materials for electrochemical energy storage systems. A recent review article summarizes the progress in graphene and graphene-based materials for four energy storage systems, i.e., lithium-ion batteries, supercapacitors, lithium-sulfur batteries and lithium-air batteries.
Nanotechnology has the potential to deliver the next generation lithium-ion batteries (LIBs) with improved performance, durability and safety at an acceptable cost. However, several challenging bottlenecks remain to build the ideal nanostructured electrodes for ultrafast rechargeable LIBs. To overcome these challenges, researchers developed a mechanical force-driven method to prepare elongated bending titania-based nanotubes for high-rate LIBs.
A three-dimensional crumpled graphene-encapsulated nickel sulfide electrode is reported as a superior high-energy lithium storage material. Compared with an electrode without crumpled graphene encapsulation, the optimized electrode yields significant improvements, especially in the cycling stability and rate capability. This enhanced performance is attributed to the 3D framework providing high continuous electron pathway and more free space for charge and mass transfer, and the stabilizing effect of the crumpled graphene based stretchy shell.
Sulfur is a very intriguing solution for the design of high energy density storage devices. The lithium-sulfur battery theoretically delivers an energy density which is 3-5 times higher than traditional lithium-ion batteries. Unfortunately, several obstacles so far have prevented the practical demonstration of sulfur-based cathodes for Li-S batteries. Among them, the most important one is the rapid capacity fading. Researchers have now developed a novel strategy towards highly stable Li-S batteries by building a strongly coupled interface between surface- mediated carbon hosts and various sulfur-containing guests.
Nanotechnology has the potential to deliver the next generation lithium-ion batteries (LIBs) with improved performance, durability and safety at an acceptable cost. At present, there is a great deal of interest to upgrade the existing LIBs with improved properties and arrive at a battery technology that would permit smart-storage of electric energy. Futuristic smart electric grids that can provide an uninterruptible power supply to a household for 24 hours can replace the currently used lead acid battery systems by performing better in terms of longer back up time and reduced space requirements. With the advent of next generation LIBs, electric vehicles are expected to cover longer distances with shorter charging times; mobile phones and laptops are expected to be charged within minutes and last longer.
Renewable and high-capacity energy systems like fuel cells and metal-air batteries are key components in any scenario on future energy systems free of fossil fuels. The performance of fuel cells largely depends on the oxygen reduction reaction - the process that breaks the bonds of the oxygen molecules - which is substantially affected by the activity of the cathode catalyst. Researchers have now demonstrated the synthesis of a novel N-doped graphene/single-walled carbon nanotube hybrid material by a facile and cost-favorable one-step CVD method.
Almost all strategies for solar energy harvest and solar energy storage that exist today are developed as independent technologies. For instance, a solar cell generates electricity from the absorption and conversion of sunlight, while the storage of the produced electricity has to be implemented with another set of energy utilization solutions such as batteries/supercapacitors and fuel cells. With quite an ingenious solution, researchers have now demonstrated a hybrid, multifunctional material system that allows for simultaneous solar power generation (respectively hydrogen production), electrical energy storage, and chemical sensing.
A new class of high-density, rechargeable batteries has the potential to address the 'range anxiety' that is inherent to current electric vehicles by drastically increasing their battery capacity: molten air batteries have up to 50 times the storage capacity of lithium-ion batteries. These batteries reversibly use oxygen from the air to store energy via a molten salt and multiple electrons stored per molecule at the counter electrode.