Energy storage at the micro-/nanoscale
Large-area rolled-up nanomembrane capacitor arrays
Miniaturization of electronic devices and reduction of their footprint areas are essential ingredients towards efficient development of energy autonomous systems and electronic circuitry. We demonstrate the feasibility of fabricating ultracompact energy storage elements employing rolled-up nanotechnology. These elements highlight the flexibility and high yield of the parallel fabrication process, which results in a substantial reduction in the device dimensions and better integration of the devices into future miniaturized electronic systems.
R. Sharma et al., Adv. Energy Mater. 4, 1301631 (2014) URL PDF
Multichannel anodes for lithium-ion batteries
We employed rolled-up nanotechnology to fabricate sandwich-stacked SnO2/Cu hybrid nanosheets as multichannel anodes for lithium-ion batteries with the use of carbon black as inter-sheet spacer. The sandwich-stacked SnO2/Cu hybrid nanosheets exhibit significant improvement in cyclability compared to SnO2 nanosheets and SnO2/Cu hybrid nanosheets. By employing a direct self-rolling and compressing approach, a much higher effective volume efficiency is achieved as compared to rolled-up hollow tubes. This synthesis approach presents a promising route to design multichannel anodes for high performance Li-ion batteries.
New battery research: rolled-up trilayer nanomembranes improve durability and lifetime
We report a new type of tubular configuration made from naturally rolled-up C/Si/C trilayer nanomembranes. A high capacity of ~2000 mAh g-1 can be retained at a current density of 50 mA g-1 without discernible decay, and the capacity can keep ~1000 mAh g-1 even after 300 cycles at 500 mA g-1 with almost 100% capacity retention. The trilayer structure design provides a stable conductive network and prevents Si pulverization and aggregation during cycling, thus guaranteeing superior electrochemical performance.
Rolling their own for energy storage devices
We report a novel hybrid tubular structure composed of multilayer Ge and Ti nanomembranes with superior reversible capacity by rolled-up nanotech. The intrinsic strain accommodated in the Ge/Ti bilayer nanomembranes is efficiently released by a self-rolling process that thus offers a minimization of the whole system energy. The high conductivity, fast lithium ion diffusion and good volume tolerance of the material are evaluated by single tube devices. The proof of concept in this work paves the way for integration of microbatteries for chip-scale applications.
This work was highlighted in:
Renewable Energy (May, 2013) URL
Rolled-up nanotech for lithium energy storage devices
Self-wound nanomembranes out of functional multilayers are designed to improve lithium storage performance. The intrinsic strain is relaxed by rolling; the composite components are uniformly dispersed; the micro/nanohierarchical structure assumes a mixed ion/electron conduction network; and conventional nanomembrane deposition techniques allow for various material combinations, suitable to meet different demands of lithium ion batteries. This work represents a further step towards extending the broad range of applications possible through rolled-up nanotech.
Self-wound ultra-compact energy storage elements
We have demonstrated the self-assembly of ultra-compact energy storage devices based on self-wound three-dimensional hybrid organic/inorganic nanomembranes. Such ultra-compact elements exhibit capacitances per footprint area higher than their state-of-the-art planar counterparts and reach specific energies comparable to supercapacitors. The combination of self-assembled organic monolayers with inorganic capacitor materials leads to elements with small footprints, remarkable performance and properties strongly correlated with the organic materials incorporated. Our results represent a breakthrough for local on-chip energy storage and energy supply for autonomous systems at the micro- and nanoscale.
- New Scientist Magazine (June 26, 2010) URL
- smartgrid (June 27, 2010) URL
- Freie Presse (August 3, 2010)
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First Swiss roll micro-supercapacitor
Winding layers into batteries is an industry-standard to manufacture commercial batteries on the macroscale. On the micro- and nanoscale, however, applying external forces to roll-up layers is not possible any more. Here, we engineer strain in ultra-thin layers by deposition, which causes the layers to wind up automatically upon their release from a substrate. We demonstrate a redox Swiss roll micro-supercapacitor consisting of a self-rolled multilayered nanomembrane with an electrochemical active layer at either the outer or inner surface for different proton diffusion paths. The Swiss roll micro-supercapacitor is ideally suited to achieve high performance (e.g. capacity and life time) in a microscale power source and is helpful for studying charge transfer at the electrolyte/electrode interface.
This work was highlighted by Chemical Communications as a “Hot article”.