Eutectic Nano-Droplet Template Injection into Bulk Silicon to Construct Porous Frameworks with Concomitant Conformal Coating as Anodes for Li-Ion Batteries

Abstract

Building porosity in monolithic materials is highly desired to design 3D electrodes, however ex-situ introduction or in-situ generation of nano-scale sacrificial template is still a great challenge. Here Al-Si eutectic droplet templates are uniformly injected into bulk Si through Al-induced solid-solid convection to construct a highly porous Si framework. This process is concomitant with process-inherent conformal coating of ion-conductive oxide. Such an all-in-one method has generated a (continuously processed) high-capacity Si anode integrating longevity and stable electrolyte-anode diaphragm for Li-ion batteries (e.g. a reversible capacity as large as ~1800 mAh/g or ~350 μAh/cm2-μm with a CE of ~99% at 0.1 C after long-term 400 cycles).

Highly Reversible Conversion Anodes Composed of Ultralarge Monolithic Grains with Seamless Intragranular Binder and Wiring Network

“…This strategy of constructing an intragrain binder can be extended to broader material systems, especially for expansible conversion and alloying electrodes. NO 6 , Alfa Aesar 95%, denoted TDA-1) of 145.5 mg were dissolved in deionized water of 30 mL. The pH value of the TDA-1 solution was adjusted to 1.5 by adding 6 M aqueous HCl, which is very important for the formation of the polyoxometalate-based complex with a sheetlike morphology.…”

“…Insertion-type anodes, for example, graphite, Li 4 Ti 5 O 12 , and Nb 2 O 5 , can show good rate performance and long cycling life even without intentional nanostructuring. − However, their reversible capacities are still limited and usually less than 300 mAh/g due to single-electron (or fewer electron) transfer. Conversion or alloying anodes enable a much higher capacity close to or exceeding 1000 mAh/g as long as their low conductivity is compensated and volume expansion is suppressed. , Different from Li 4 Ti 5 O 12 and Nb 2 O 5 , the marginal lithiation in conversion materials does not lead to a remarkable upgrade of bulk electron conductivity, whereas the deep lithiation often triggers a phase segregation with the generation of more grain boundaries, which likely passivate the migration of Li ions to the next electroactive particle. , Nanoengineering enables surface nonstoichiometry or defect enrichment and likely delays (or suppresses) the occurrence of phase transformation reaction and the evolution of volume. This factor is favorable for the improvement of bulk conductivity and charge transfer across heterostructures.…”

“…Conversion or alloying anodes enable a much higher capacity close to or exceeding 1000 mAh/g as long as their low conductivity is compensated and volume expansion is suppressed. 5,6 Different from Li 4 Ti 5 O 12 and Nb 2 O 5 , the marginal lithiation in conversion materials does not lead to a remarkable upgrade of bulk electron conductivity, whereas the deep lithiation often triggers a phase segregation with the generation of more grain boundaries, which likely passivate the migration of Li ions to the next electroactive particle. 7,8 Nanoengineering enables surface nonstoichiometry or defect enrichment and likely delays (or suppresses) the occurrence of phase transformation reaction and the evolution of volume.…”

Different Dimensional Nanostructured Silicon Materials: From Synthesis Methodology to Application in High‐Energy Lithium‐Ion Batteries

“…Because of the abundant pore structures, pSi can greatly reduce the destructive effect on the active material structure due to volume change during charge and discharge . Recently, some pSi materials can be obtained by the templating and etching methods and show good electrochemical performance .…”

Biomass‐Derived Poly(Furfuryl Alcohol)–Protected Aluminum Anode for Lithium‐Ion Batteries

“…However, it undergoes a volume variation of ≈97% and, although this is comparatively low with regard to other popular candidates such as metallic Sn (≈200%–300%) and metalloid Si (≈300%), this phenomenon leads to a fast capacity decay due to the electrode deterioration . Accordingly, many approaches have been studied to alleviate the volume change concern, including the fabrication of composites, nanoparticles, nanowires, nanorods, 3D frameworks, and yolk–shell structures; however, using Al foil directly as both the anode and current collector seems to be the best way to save costs in manufacturing . In addition, the corrosion of Al foil under nonaqueous electrolytes has been intensively studied, which can be delayed through the use of a protective layer, as shown by AlPO 4 coating used by Gao et al As such, to accommodate the Al volume change during cycling and resist electrode corrosion, we think a flexible polymeric protecting layer might provide dual benefits toward enhanced Al anode functionality.…”