Graphene batteries: Introduction and Market News - Page 43

Researchers at Stanford University developed a new battery technology based on graphene and aluminum. The stanford team claims that their aluminum battery has a number of advantages over lithium: it's flexible, can be charged in a minute instead of hours and is very durable. it's also cheaper and non-reactive (meaning compromising it will not result in sparks like lithium batteries).

The scientists used graphene foam (made by creating a metal foam, then catalyzing graphene formation on its surface) as cathode material and aluminum foil as the anode. The electrolyte the researchers used was a solution of aluminum trichloride dissolved in an organic solvent that also contained chlorine. While this granted better performance (7,500 cycles, much more than the 1,000 expected from a Li-ion battery), the voltage provided by an aluminum-ion battery is only about half of that what you'd get from a lithium-ion cell. Also, the overall power density (the amount of power you can store in a battery in relation to its size) is still insufficient.

Researchers at UCLA’s California NanoSystems Institute have successfully combined laser-scribed graphene and manganese dioxide (which is currently used in alkaline batteries since it holds a lot of charge and is cheap and abundant) to create a new energy storage device with outstanding qualities. The new hybrid supercapacitor stores large amounts of energy, recharges quickly, and can last for more than 10,000 recharge cycles.

The scientists also created a microsupercapacitor that is small enough to fit in wearable or implantable devices. At just a fifth of the thickness of a sheet of paper, it can hold more than twice as much charge as a typical thin-film lithium battery.

Researchers at China's Tsinghua University used ion-selective membranes of ultrathin graphene oxide (GO) to develop a novel, ion-selective but highly permeable separator for significantly improving both the energy density and power density of lithium-sulfur batteries. This resulted in a highly-stable and anti-self-discharge lithium-sulfur cell.

Polysulfides are materials generated at the cathode side, diffuse through the membrane, react with lithium anode, and shuttle back. During the process, polysulfides dissolve and irreversibly react with metal lithium and organic components, inducing the destruction of the cathode structure, depletion of the lithium anode, and loss of active sulfur materials. 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. The researchers' design was of a GO membrane, sandwiched between cathode and anode electrodes, which efficiently prohibited the shuttle of polysulfides through the membrane.

Ohio-based Angstron Materials has developed a group of cost-effective thermal foil products that can be customized for handheld devices and other products. The company says that its foil sheets have been qualified for use by a major mobile electronics company. Such thermal foils can be used for the technology beneath devices' screens that conducts heat away from internal electronic components and batteries to help maintain optimal performance.

Angstron’s thermal foils are available in a variety of grades. The company states that its foils are thinner than other products on the market and so give manufacturers greater design flexibility than competing methods. Angstron’s foil sheets also can be sourced with equivalent or greater thermal conductivity.

Earlier this month, the first mass produced graphene-enhanced phone was rumoured to be near commercial sale by Chinese companies. Now, further details are available as it seems that the device is available on the company's website.

The phone, called the Galapad Settler, is said to use graphene for its touchscreen, as well as casing and battery. 30,000 pieces were made by Chinese graphene company Moxi together with Chinese device maker Galapad, with each device selling for $399 USD.

A team of researchers at the University of California report on the preparation of a graphene hydrogel, which can be converted into solvated graphene frameworks that are stable 3D porous structures offering both fast lithium exchange and high conductivity. Using these frameworks as anode material, it is possible to assemble a lithium coin cell, with excellent capacities surpassing conventional graphite materials.

To prepare the graphene frameworks, the scientists used a modified hydrothermal method to generate free-standing cubes of a graphene hydrogel from graphite oxide. Solvent exchange converted the hydrogel structures into the 3D solvated graphene frameworks, which can be pressed in films needed for the coin cells without losing their porous graphene network. These anodes not only provided for much faster lithium diffusion, but also retained the large surface area and excellent conductivity of graphene sheets.

German scientists at the University of Siegen, along with scientists from the KTH-Royal Institute of Technology in Kista, Sweden, claim that laser annealing can improve the quality of printed graphene (and other 2D materials) inks. This can be beneficial for various applications like flexible electronics devices, including batteries and supercapacitors, transistors, solar cells and displays.

The researchers succeeded in producing uniform, transparent and conductive graphene thin films by simply drop-casting dispersions of the carbon sheet onto a glass surface and combining this drop-casting step with laser annealing. The annealing process involves scanning a laser beam across the surface of the films, which distinctly improves their transparency and how well they conduct electricity.

The American XG Sciences demonstrated full battery cell cycle stability, through more than 400 charge/discharge cycles, with a charge storage capacity of 600 mAh/gram over a broad voltage window in its next generation silicon graphene anode materials for lithium-ion batteries.

The company states that their latest material is the first commercially viable silicon and graphene based anode formulation to achieve this all important performance threshold, with charge storage capacity of up to 4 times today’s typical anodes, first cycle efficiency of 85-90%, low swelling and life that is more than double the company's previous generation. 

Recent news from NanoXplore successful $2.7M financing round, launch of their three tonnes/year production facility have positioned the company as a leading graphene company, and certainly a major player in North America.

The core of the company appears to be their production process, developed in-house. In addition to large capacity, they claim it creates very high quality (low defect) graphene, functionalized during production to facilitate mixing (dispersion) with a broad range of industrial materials. The range of products shows not only high quality graphene powders, but also a couple of unique offerings. Interestingly, they seem open to licensing their production technology.

Researchers from the Bourns College of Engineering at the University of California, Riverside investigated a strategy to improve lithium-sulfur batteries' performance by creating nano-sized sulfur particles, and coating them in glass.

Lithium-sulfur batteries have been attracting attention thanks to their ability to produce up to 10 times more energy than conventional batteries, but one of the main roadblocks to implementing them is a the tendency for lithium and sulfur reaction products (called lithium polysulfides) to dissolve in the battery’s electrolyte and travel to the opposite electrode permanently, which causes the battery’s capacity to decrease over its lifetime. The scientists designed a cathode material in which silica (glass) cages trap polysulfides.. The team used an organic precursor to construct the trapping barrier.