EES Blog

Scientists in Japan have made an electrode for a lithium-air battery using a pencil. The advance could bring efficient, environmentally friendly and safe batteries for electric vehicles a step closer.

Lithium-air batteries have the potential to produce enough energy to power an electric vehicle, but the amount of energy is a safety concern. Contamination in lithium batteries can result in unstable and high energy reactions, and the current lithium-air batteries are vulnerable to decomposition and burn-out.

Haoshen Zhou and Yonggang Wang at the National Institute of Advanced Industrial Science and Technology in Tsukuba, have designed a battery in which the lithium is encapsulated by an organic electrolyte topped with a ceramic protection layer. The ceramic layer acts as a solid-state electrolyte upon which the team simply drew a 2D cathode using a graphite pencil. Zhou says that ‘removing and redrawing the novel air electrode is simple.’

Read the Chemistry World article by Harriet Brewerton in full

Or read the Energy & Environmental Science paper

To draw an air electrode of a Li–air battery by pencil
Yonggang Wang and Haoshen Zhou,
Energy Environ. Sci., 2011, DOI: 10.1039/c0ee00759e

‘HOT’ paper – Chemically Selective Gas Sweetening Without Thermal-Swing Regeneration

Scientists have reacted anhydrous alkanolamines with H₂S to produce switchable hydrosulfide-based ionic liquids, of which H₂S can be released without thermal heating. H2S removal from natural gas is commonly known as ‘‘gas sweetening,’’ a process that uses either physical or chemical sorbents.

Read the Energy & Environmental Science article today – hot off the press!

Chemically Selective Gas Sweetening Without Thermal-Swing Regeneration
P K Koech, J E Rainbolt, M D Bearden, F Zheng and D J Heldebrant
Energy Environ. Sci., 2011, DOI: 10.1039/ c0ee00839g

Scientists in China have made a biofuel cell that harvests energy from soft drinks such as iced tea and juices.

Energy supply is a hot topic, explains Shaojun Dong, who made the cell with her team at the Chinese Academy of Sciences in Beijing. Biofuel cells (BFCs) convert chemical energy into electrical energy. They are cheap and active at room temperature and near-neutral pH, and show promise for use in green technology. Enzymatic BFCs that use an enzyme to convert sugar energy into electrical energy can be made into portable power sources and implantable medical devices as they generate more power than other BFC types.

BFCs need to be miniaturised and have access to an abundant fuel source to be able to power small electronic devices. Soft drinks are cheap and widely available, Dong explains. Just 1ml of a drink could allow a fuel cell to provide electrical energy for over a month.

Power outputs of the biofuel, from left to right: iced red tea, vegetable juice, fruit juice and aerated water

Scientists from Korea have found that with the use of graphene nanosheets, the fabrication of bendable power sources is possible.

Electronic devices are no longer confined to the home or office. We travel with them, carry them around and even wear them. To make equipment like roll-up displays and wearable devices achievable, the power source that supplies them must also become more flexible.

The major challenge of developing a truly bendable power source has been the shortage of material that is both highly flexible and has superior electronic conductivity. Polymers are typically used, but they can degrade at relatively low temperatures, which makes them less than ideal.

Kisuk Kang from the Korea Advanced Institute of Science and Technology in Daejon, and colleagues, have developed a graphene based hybrid electrode producing a flexible lithium rechargeable battery. The cathode material, in this case V₂O₅, is grown on graphene paper using pulsed laser deposition and graphene paper coated in lithium is used as the anode. The resultant battery is lightweight and flexible enough to be twisted or rolled.

Want to find out more?

Read the rest of the Chemistry World story by Rebecca Brodie

Or view the Energy & Environmental Science article in full:
Flexible energy storage devices based on graphene paper
Hyeokjo Gwon, Hyun-Suk Kim, Kye Ung Lee, Dong-Hwa Seo, Yun Chang Park, Yun-Sung Lee, Byung Tae Ahn and Kisuk Kang,
Energy Environ. Sci., 2011, DOI: 10.1039/c0ee00640h

‘HOT’ Minireview – hot off the press…

Reviewing recent advances in ammonia and hydrazine based electrochemical fuel cells

Most low-temperature fuel cells are based, in some form, on the hydrogen fuel cell, due to its high power density and clean oxidation to yield no carbon-containing products. However, due to issues of compression and storage, research has been on-going into alternative “hydrogen-storage” compounds that can deliver similar performance in a more convenient form.

The nitrogen hydrides, ammonia and hydrazine, have been candidate materials for fuels for nearly 50 years, but rapid advances in the past 5–6 years have shown them to be front-runners in the race for commercial, high-performance, portable fuel cells.

Carbon-free energy: a review of ammonia- and hydrazine-based electrochemical fuel cells
Neil V. Rees and Richard G. Compton
Energy Environ. Sci., 2011, DOI: 10.1039/C0EE00809E

US scientists have proposed a new method to compare the cost of solar energy technology with traditional sources as current methods may not give a realistic result

Seth Darling and colleagues from the Argonne National Laboratory in Illinois have used a simulation that gives distributions of values for variable parameters such as weather, solar panel performance, operating costs and inflation to more accurately reflect the overall cost.

‘For solar energy to make a significant dent in the overall energy mix, its cost will have to be similar to or lower than traditional sources such as fossil fuels,’ says Darling, ‘but to make this comparison, you need to know how to calculate the cost.’

‘The results indicate that the real discount rate is the most relevant factor,‘ says José Goldemberg, an expert on energy and environmental issues from the University of São Paulo, Brazil.

Darling hopes that stakeholders in the energy community will adopt his approach. The biggest challenge, he says, is getting performance data from diverse geographic locations. 

‘We hope that partnerships between the solar energy industry, utility providers and national laboratories will focus on collecting the data and making it accessible to those interested in exploring the potential of solar energy,’ he concludes.

Read more of the Chemistry World feature here…

View the Energy Environmental Science Analysis article:

Assumptions and the levelized cost of energy for photovoltaics
Seth B. Darling, Fengqi You, Thomas Veselka and Alfonso Velosa
Energy Environ. Sci., 2011, DOI: 10.1039/c0ee00698j

With increasing concerns over global warming and the urgent need to reduce CO₂ emissions, scientists in China have developed a new simple and efficient strategy for the reduction of CO_2.

They demonstrate a carbon cycle which is driven simply by the oxidation and reduction of commonly available metals, such as iron.

The cycle begins with the high-yield reduction of CO₂ to formic, via the oxidation of a zero-valent metal under hydrothermal conditions. The metal oxide can then be converted back to the metal using a bio-derived chemical such as glycerin, which is readily available from renewable resources.

The production of formic acid in the cycle is also an added bonus, as this can be used to power fuel cells, which can be applied to small, portable electronics such as cell phones and laptop computers.

This new energy system has many advantages over current methods to reduce CO₂ (such as water-splitting) as it has high yields, no waste products, does not require expensive catalysts or harsh reagents and, as the overall cycle is exothermic, it is expected to have minimal energy requirements.

Read the ‘HOT’ Communication today:

High-yield reduction of carbon dioxide into formic acid by zero-valent metal/metal oxide redox cycles
Fangming Jin, Ying Gao, Yujia Jin, Yalei Zhang, Jianglin Cao, Zhen Wei and Richard L. Smith Jr
Energy Environ. Sci., 2011, DOI: 10.1039/C0EE00661K