Arrays of Sealed Silicon Nanotubes As Anodes for Lithium Ion Batteries

Abstract

Silicon is a promising candidate for electrodes in lithium ion batteries due to its large theoretical energy density. Poor capacity retention, caused by pulverization of Si during cycling, frustrates its practical application. We have developed a nanostructured form of silicon, consisting of arrays of sealed, tubular geometries that is capable of accommodating large volume changes associated with lithiation in battery applications. Such electrodes exhibit high initial Coulombic efficiencies (i.e., >85%) and stable capacity-retention (>80% after 50 cycles), due to an unusual, underlying mechanics that is dominated by free surfaces. This physics is manifested by a strongly anisotropic expansion in which 400% volumetric increases are accomplished with only relatively small (<35%) changes in the axial dimension. These experimental results and associated theoretical mechanics models demonstrate the extent to which nanoscale engineering of electrode geometry can be used to advantage in the design of rechargeable batteries with highly reversible capacity and long-term cycle stability.

Stable silicon-ionic liquid interface for next-generation lithium-ion batteries

“…Such systems could serve to expedite a smooth transition to an electrified transportation market and enable intermittent renewable energy resources, both of which have been gaining attention in our increasingly carbonconstrained world. The search is on for the next generation of electrode materials that will meet such guidelines in a cost effective and efficient manner [6][7][8] .…”

Soft, thin skin-mounted power management systems and their use in wireless thermography

“…Although schemes in high-frequency or ultrahigh-frequency wireless power transfer satisfy requirements in many important contexts (14,15), opportunities remain for approaches in local generation and/or storage of power in ways that retain overall stretchable characteristics at the system level. Reported approaches to the former involve harvesting based on piezoelectric (16,17), triboelectric (18), and thermoelectric (19) effects; the latter includes batteries (20)(21)(22) and supercapacitors (23,24) enabled by various unusual materials. Complete power management systems that offer both types of functionality, in an actively coordinated fashion and with robust, high-performance operation, represent an important goal.…”

Roll up nanowire battery from silicon chips

“…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.…”

“…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)(9)(10)(11)(12).…”