Traditionally, the size of electrode materials in supercapacitors is reduced to nanometers to enable high surface area and more room for storing more amounts of energy. But the microscopic electron distribution in nanocarbons limits the total amount of stored energy through a property called 'quantum capacitance'.
Although a lot of charge could be stored in the pores on nanocarbons due to their high surface area, their inherently low quantum capacitance reduces the net energy that could be drawn from supercapacitors. Researchers have controllably added nitrogen atoms to graphene to achieve carbon supercapacitors ready for practical applications.
The fact that temperature differentials (heat) are ubiquitously present in our environment makes thermoelectric energy harvesting a highly attractive research field. New work highlights the fabrication of flexible thermoelectric materials and modules by merging colloidal nanomaterials (quantum dots) that can be tuned for efficient heat-to-electricity energy conversion with naturally abundant cellulose paper that are low in cost and have inherently low thermal conductivity.
Sodium-ion batteries (SIBs) represent an attractive alternative to lithium-ion batteries, owing to the fact that sodium resources are practically inexhaustible and evenly distributed around the world while the ion insertion chemistry is largely identical to that of lithium. Researchers have now rationally designed and fabricated a sodium ion full battery where both of the cathode and anode materials possessed very unique two-dimensional nanostructured architecture. The 2D nanostructured architecture results in excellent rate capability and stable cycling performance.
Although developed only recently, inorganic halide perovskite quantum dot systems have exhibited comparable and even better performances than traditional quantum dots in many fields. They are expected to be applied in display and lighting technologies. Researchers now have reported an interesting cyclable surface dissolution and recrystallization phenomenon of inorganic perovskite crystals. This allows them to freely change size between nanometer and micrometer scales, and can be used to healing the defects inside perovskite films and hence improve the performances of optoelectronic devices.
Self-powered nanotechnology based on these nanogenerators aims at powering nanodevices and nanosystems using the energy harvested from the environment in which these systems are suppose to operate. An interesting approach comes from a group of Chinese scientists who propose to scavenge the large amounts of wasted wind energy in cities: they propose hybridized nanogenerator that consists of a solar cell and a triboelectric nanogenerator, which can be utilized to individually or simultaneously scavenge solar and wind energies.
Today, the best performing battery in terms of specific energy and specific power is the secondary lithium-metal (Li-metal). However, uncontrolled dendrite growth during Li depositing/stripping in rechargeable Li metal based batteries has prevented their practical applications over the past 40 years. To address this issue, researchers have now proposed a novel method of modulating the lithium ion adsorption to suppress lithium dendrite growth by employing glass fiber as solid electrolytes with plenty of polar functional groups as the interlayer between Li metal anode and routine polymer separator.
Lithium-sulfur (Li-S) batteries, which employ sulfur as cathode and metallic lithium as anode materials, have been extensively studied as promising alternatives to the widely used lithium-ion batteries because - theoretically - they can render 3-6 times higher energy density. In practice, though, it has proven challenging to approach that theoretical value. Specifically, the rapid capacity fading, low Coulombic efficiency, and irreversible loss of active materials have impeded large-scale commercial use of Li-S batteries. Researchers now have shown that trapping lithium polysulfide species on (nanoscale) host materials is an effective way to overcome these challenges.
To explore the intrinsic mechanisms of the electrochemical reactions of porous graphene oxide in situ, the single-nanowire electrochemical probe is an effective tool. Although graphene is usually used as an additive in active materials to improve the electrochemical performance, how graphene influences the electrochemical performance and reaction mechanisms of electrode materials is under dispute. To address these issues, researchers have explored single-nanowire electrochemical devices to investigate the capacitance, ion diffusion coefficient, and charge storage mechanisms of graphene.