Roll up nanowire battery from silicon chips

Abstract

Here we report an approach to roll out Li-ion battery components from silicon chips by a continuous and repeatable etch-infiltratepeel cycle. Vertically aligned silicon nanowires etched from recycled silicon wafers are captured in a polymer matrix that operates as Li þ gel-electrolyte and electrode separator and peeled off to make multiple battery devices out of a single wafer. Porous, electrically interconnected copper nanoshells are conformally deposited around the silicon nanowires to stabilize the electrodes over extended cycles and provide efficient current collection. Using the above developed process we demonstrate an operational full cell 3.4 V lithium-polymer silicon nanowire (LIPOSIL) battery which is mechanically flexible and scalable to large dimensions.polymer electrolyte | core-shell nanowires | energy storage | flexible electronics | waste management S ilicon is a promising anode material in lithium batteries due to its high specific capacity and low operation voltage (1). However, the major concern in using Si-based anodes is the huge volume expansion during the lithiation that leads to a fast degradation of the electrode material and a reduced life cycle of the battery with limited use in real life Li-ion applications. The advent of nanotechnology and successful incorporation of nanostructured materials in energy storage devices has further grown an interest in revisiting Si as an active anode material. The enhancement in the electrochemical performance of nanostructured Si anodes provides novel platforms for the ubiquitous presence of Si in Li-ion batteries (2-4). Through nanostructuring, the active Si pulverization was minimized yielding stable capacity retention. However, this was found insufficient to maintain a uniform electrical interface and adequate mechanical contact between the active Si particles and the conductive additives, calling for the development of new binder materials (5-7). Avoiding binders or conductive additives and enabling a direct contact between Si and the current collector is the other way to maintain the electrical conductivity and mechanical integrity of the electrode. This requires special designs of the current collector complying with the ensuing active material deposition. The optimal alternative so far is provided by the use of nanowires, nanotubes, or hierarchical assemblies directly grown, assembled, or bonded onto the current collector (8-12).Current collectors integrated with Si anodes have been successfully fabricated through chemical or physical vapor deposition methods, room temperature metal assisted chemical etching (MACE), as well as through various top-down methods (8,9,(12)(13)(14)(15). One of the major drawbacks of the respective configurations is the relatively low tap density of the Si nanostructures leading to low mass loading of active material and low volumetric capacities. Moreover, excess of current collector is usually employed in this configuration rendering them less attractive for high-throughput battery manufacturing (16). Low compactio...

Design Considerations for Unconventional Electrochemical Energy Storage Architectures

“…Reproduced with permission. [ 265 ] Copyright 2012, National Academy of Sciences, U.S.A. E). Schematics of the hybrid organic/inorganic selfwound capacitor based on rolled-up nanomembranes altogether with cross-sectional view of a capacitor comprising 13 windings and rolled from a 600 µm long planar capacitor.…”

“…Vlad et al have used a sequential silicon nanowire polymer infi ltration-gel-polymer coatingcathode slurry coating followed by mechanical delamination to build a rolled Li-ion battery (Figure 9 D). [ 265 ] To stabilize the fragile silicon nanowire confi guration, the authors have developed an electroless plating process to apply a thin conformal copper layer around each nanowire. The silicon core-copper shell structure was also found to exhibit enhanced rate performance as compare to bare nanowire confi guration.…”

“…[ 268 ] Again, given the simplicity and less stringent requirements for manufacturing and especially for safe operation, mainly supercapacitor power fi bers have been explored, [ 227,243,248, the Li-ion technology integration being still challenging yet with strong efforts undertaken leading recently to valuable developments. [ 221,233,260,[263][264][265][297][298][299][300][301][302][303] Chemistries other than Li-ion are being explored as well, with fl exible fi ber-type zinc-carbon and zinc-air batteries being recently demonstrated. [ 147,304 ] Furthermore, a few attempts to build integrated energy harvest/storage power fi bers have already been successfully realized; the energy device hybridization techniques are detailed in Section 4.5.…”

Metal-assisted chemical etching of silicon and the behavior of nanoscale silicon materials as Li-ion battery anodes

“…In addition to its high capacity, Si is the second most abundant element in the earth's crust, is environmentally friendly, and is the focus of many worldwide corporations, which also makes it attractive when considering its use as an anode in LIBs. Rolled-up batteries based on Si NWs have even been demonstrated from silicon used in chips [141]. Li 15 Si 4 is the highest lithiated phase achievable for the ambient temperature lithiation of bulk Si and corresponds to a capacity of 3,579 mAh · g -1 [142].…”

Morphology and processing of aligned carbon nanotube carbon matrix nanocomposites

“…The tailorable energy harvesting 1-8 , storage [7][8][9][10][11] , and dissipation [12][13][14][15][16] capabilities of nanowires, nanofibers, and nanotubes make them prime candidates for next generation multifunctional material architectures. By integrating aligned nanofibers with a carbon matrix, materials with high strength, toughness, low density, and extended operating regimes may be synthesized.…”