- Email: [email protected]
A new spin on energy storage
Nano Energy (2012) 1, 509–513
Available online at www.sciencedirect.com
journal homepage: www.elsevier.com/locate/nanoenergy
NEWS AND OPINIONS
A new spin on energy storage Cordelia Sealy The search is on for the perfect energy storage medium to serve an increasing array of products from wearable electronics to electric vehicles. Batteries can store high densities of energy but deteriorate over repeated charging and discharging. Electrochemical capacitors (ECs) – also known as super capacitors or ultra capacitors – can charge/discharge much more easily and quickly but generally have a much lower energy density. Now researchers from University of California, Los Angeles and Cairo University in Egypt think they may have turned over a new leaf in energy storage using graphene [M.F. El-Kady, et al., Science 335 (2012) 1326]. Richard B.
Figure 1 Etching graphene supercapacitor in a DVD burner: the dark areas on this DVD are laser scribed graphene (LSG), a form of graphene that can be used for battery electrodes. The structure of the device is etched with graphene. (Credit: Maher El-Kady, UCLA.)
Kaner and colleagues used a standard LightScribe DVD optical drive to convert graphite oxide (GO) films into graphene. The graphene films produced by laser reduction technique are mechanically robust, show high electrical conductivity and specific surface area, and can be used as EC electrodes without any additional treatment. EC devices using the graphene electrodes, which the researchers dub laser scribed graphene (LSG) supercapacitors, can store as much energy as conventional batteries but can be charged 100–1000 times faster (Fig. 1). The combination of properties allows the graphene to be used as both the active material and the current collector in the EC device, leading to a simplified and lighter weight device architecture. The liquid electrolyte can even be replaced with a polymer gel to further reduce device thickness and weight, while simplifying the fabrication process because no packaging is required and improving the overall robustness of the device by acting as a glue sticking all the components together. Compared with conventional energy storage devices, the LSG supercapacitor exhibits energy storage densities twothirds higher than AC–EC devices and three orders of magnitude greater than thin-film Li batteries. Moreover, GO can be manufactured at large volumes and low cost, making devices cheap and easy to produce. ‘‘The high performance energy storage along with flexibility and robustness opens the way for lots of possible applications: from roll-up screens, electronic newspapers, to wearable electronics that collect and store energy from body movements,’’ researcher and first author Maher El-Kady told Nano Energy. E-mail address: [email protected] 2211-2855/$ - see front matter http://dx.doi.org/10.1016/j.nanoen.2012.05.007
Available online at www.sciencedirect.com
journal homepage: www.elsevier.com/locate/nanoenergy
NEWS AND OPINIONS
A new spin on energy storage Cordelia Sealy The search is on for the perfect energy storage medium to serve an increasing array of products from wearable electronics to electric vehicles. Batteries can store high densities of energy but deteriorate over repeated charging and discharging. Electrochemical capacitors (ECs) – also known as super capacitors or ultra capacitors – can charge/discharge much more easily and quickly but generally have a much lower energy density. Now researchers from University of California, Los Angeles and Cairo University in Egypt think they may have turned over a new leaf in energy storage using graphene [M.F. El-Kady, et al., Science 335 (2012) 1326]. Richard B.
Figure 1 Etching graphene supercapacitor in a DVD burner: the dark areas on this DVD are laser scribed graphene (LSG), a form of graphene that can be used for battery electrodes. The structure of the device is etched with graphene. (Credit: Maher El-Kady, UCLA.)
Kaner and colleagues used a standard LightScribe DVD optical drive to convert graphite oxide (GO) films into graphene. The graphene films produced by laser reduction technique are mechanically robust, show high electrical conductivity and specific surface area, and can be used as EC electrodes without any additional treatment. EC devices using the graphene electrodes, which the researchers dub laser scribed graphene (LSG) supercapacitors, can store as much energy as conventional batteries but can be charged 100–1000 times faster (Fig. 1). The combination of properties allows the graphene to be used as both the active material and the current collector in the EC device, leading to a simplified and lighter weight device architecture. The liquid electrolyte can even be replaced with a polymer gel to further reduce device thickness and weight, while simplifying the fabrication process because no packaging is required and improving the overall robustness of the device by acting as a glue sticking all the components together. Compared with conventional energy storage devices, the LSG supercapacitor exhibits energy storage densities twothirds higher than AC–EC devices and three orders of magnitude greater than thin-film Li batteries. Moreover, GO can be manufactured at large volumes and low cost, making devices cheap and easy to produce. ‘‘The high performance energy storage along with flexibility and robustness opens the way for lots of possible applications: from roll-up screens, electronic newspapers, to wearable electronics that collect and store energy from body movements,’’ researcher and first author Maher El-Kady told Nano Energy. E-mail address: [email protected] 2211-2855/$ - see front matter http://dx.doi.org/10.1016/j.nanoen.2012.05.007