Chemistry World : Making graphene supercapacitors with a DVD writer

Posted by Andreas Christodoulou

Description :

Imagine having an energy storage device that stores as much energy as a conventional battery, yet, can be charged 100 to 1000 times faster. 

Supercapacitors store charge in electrochemical double layers whereas batteries store charge through electrochemical reactions. Although supercapacitors can charge and discharge much faster than batteries, they are still limited by low energy densities and slow rate capabilities. 

Researchers at UCLA have successfully used an inexpensive precursor (graphite oxide) to produce high-performance graphene-based supercapacitors using a computerized LightScribe DVD drive. 

These devices exhibit ultrahigh energy density values in different electrolytes approaching those of batteries, yet they can be charged in seconds. 

The devices can be charged and discharged for more than 10,000 cycles without losing much in performance compared with a normal life-time of less than 1000 cycles typical for batteries. Additionally, the devices are completely flexible and maintain excellent performance under high mechanical stress.

Read more at :

http://www.rsc.org/chemistryworld/News/2012/March/graphene-dvd-player-burn-supercapacitor.asp

Check also :

UF : Researchers envision a promising new technique - Writing graphene circuitry with ion "pens"

*by andreascy*

Will Super Capacitors and Batteries be Coupled to a Hybrid Soon?

Posted by Andreas Christodoulou

Description :

Almost everyone is familiar with the annoying need to replace the battery or to charge it. It can be the notebook during a presentation, a wireless or cellular phone stopping during a very important conversation with a customer, or a camera in the middle of taking pictures. There are endless incidents of that kind that we face as consumers and users. 

In Industrial Electronics there are many, most harmful battery failures, causing disturbances and security threats. From one side, batteries are not capable supplying high current pulses, from the other side most communication devices are power hungry, demanding high current pulses. Batteries are aimed to supply voltage continuously while delivering high current pulses is damaging their chemistry and shortening life time.

Many electronic devices are using communication protocols that are defined by various current pulses like GSM , Zigbi and WiFi. Other electronic devices such as digital camera or Smartphone need high current during a snapshot to operate the shutter, the flash led or data transmission. One of the best existing solutions today for extending battery life is Pulse Supercapacitors (SC).

A pulse supercapacitor is an “Energy storage” component with high capacitance and low internal resistance (ESR) that unlike a battery is built to deliver pulses of current almost endlessly (hundreds of thousands of charge/discharge cycles) and can be calmly recharged by a battery during the standby time between the pulses.

Hybrids of Battery and SC are coming more and more popular and recognized by the engineers. There are three limiting issues though :

1. Size and shape

Most of Pulse SCs in the market are cylindrical and large in size to be integrated in the miniature trendy market.

2. Environment friendliness

Some of the Pulse SCs contain organic electrolytes and solvents are harmful, flammable and not accepted environmentally (i.e. Acetonitrile which is used in organic electrolyte based SCs).

3. Cost

Pulse SCs are known to be expensive and as so, are not able to join most of consumer electronics bills of materials.

All these three issues were challenged by Cellergy Ltd. Cellergy manufactures its SCs by implementing Printing technology that enables to build flat, thin and in a wide range of sizes down to 12X12.5 mm, yet the smallest form factor of Pulse SCs in the market. Their SCs contain aqueous electrolyte and are green products.

Cellergy’s patented manufacturing process is based on Automation and Robotics, which helps to reduce costs to a level that enables them to be integrated not only in industrial products but also in consumer electronics. Partial list of Cellergy’s SCs applications can show the large penetration into the electronic industry. Check it out :

(a) Industrial Electronics :

- Automated metering (AMR)

- GSM/GPRS Modules

- M2M communication

- Active RFID for animals tracking, vehicles tracking, prisoners tracking, medical equipment tracking, and container tracking, etc.

- Medical drug delivery pumps

- Fuel Automated payment solutions

- Wireless computers mouse and keyboards

- Home security

- Home Automation

- Electronic locks

- Irrigation control

Energy harvesting for sensors

- Energy harvesting for mechanical movement operations

- LaserRangefinders for civil and for military applications

- Military pulse applications

- Cellular communication and led flash

(b) Consumer Electronics :

- Personal Pagers

- Sound improvement of loudspeakers

- Wireless audio devices

- PDA’s

Supercapacitors contribute to a breakthrough in power management design. The combination of batteries and supercapacitors enables the transmission of pulses of the many electronic devices surrounding us, and results in extending the life of batteries of those devices, thus lowering end customer expenses and making it affordable for use.

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*by andreascy*

World's first energy-storage membrane outstrips existing rechargeable batteries and supercapacitors

Posted by Andreas Christodoulou

Description :

A Singaporean Research team has come up with a novel and highly efficient energy storage system which looks certain to replace all known forms of energy storage once manufacturing is underway

Researchers from the NUS Nanoscience and Nanotechnology Initiative (NUSNNI) have developed the world's first energy-storage membrane, answering the need for cost-effective and environmentally friendly energy storage and delivery solutions. 

The research team, led by Principal Investigator Dr Xie Xian Ning, used a polystyrene-based polymer to deposit the soft, foldable membrane converted from organic waste which, when sandwiched between and charged by two graphite plates, can store charge at 0.2 farads per square centimetre. This capability was well above the typical upper limit of 1 microfarad per square centimetre for a standard capacitor. The cost involved in energy storage is also drastically reduced with this invention, from about US$7 to store each farad using existing technologies based on liquid electrolytes to about US$0.62 per farad. 

Dr Xie said: "Compared to rechargeable batteries and supercapacitors, the proprietary membrane allows for very simple device configuration and low fabrication cost. Moreover, the performance of the membrane surpasses those of rechargeable batteries, such as lithium ion and lead-acid batteries, and supercapacitors." 

Supported by grants from the Singapore-MIT Alliance for Research & Technology (SMART) and the National Research Foundation, the research took about one and a half years to reach its current status and the team has also successfully filed a US patent for this novel invention. 

The discovery has also attracted the attention of scientific journals worldwide, and was featured in Energy & Environmental Science and highlighted by renowned international journal Nature. 

"With the advent of our novel membrane, energy storage technology will be more accessible, affordable, and producible on a large scale. It is also environmentally-friendly and could change the current status of energy technology," Dr Xie said. 

Going forward, the team will explore more applications for this efficient energy storage solution. It is also looking into opportunities to work with venture capitalists to commercialise the invention.

As usual there is no mention of how much energy it takes to create the membrane. However we can assume that it will scale fairly significantly based on the description of the base ingredients.

*by andreascy*