Hierarchical porous silicon structures with extraordinary mechanical strength as high-performance lithium-ion battery anodes

Abstract

Porous structured silicon has been regarded as a promising candidate to overcome pulverization of silicon-based anodes. However, poor mechanical strength of these porous particles has limited their volumetric energy density towards practical applications. Here we design and synthesize hierarchical carbon-nanotube@silicon@carbon microspheres with both high porosity and extraordinary mechanical strength (>200 MPa) and a low apparent particle expansion of~40% upon full lithiation. The composite electrodes of carbon-nanotube@silicon@carbon-graphite with a practical loading (3 mAh cm −2) deliver~750 mAh g −1 specific capacity, <20% initial swelling at 100% state-of-charge, and~92% capacity retention over 500 cycles. Calendered electrodes achieve~980 mAh cm −3 volumetric capacity density and <50% end-of-life swell after 120 cycles. Full cells with LiNi 1/3 Mn 1/3 Co 1/3 O 2 cathodes demonstrate >92% capacity retention over 500 cycles. This work is a leap in silicon anode development and provides insights into the design of electrode materials for other batteries.

Recent Advances in Silicon‐Based Electrodes: From Fundamental Research toward Practical Applications

“…When compared to nano-Si electrodes, micrometer porous Si spheres demonstrated significantly improved electrochemical performance, tap density, cycling lifetime, specific capacity, and rate capability. [223,224] Porous, amorphous Si (a-Si) particles were synthesized by a combination of solvothermal and Mg reduction methods (Figure 12e). [225] The final Si materials were highly porous, with pore sizes ranging from 10 to 50 nm (Figure 12f-i).…”

Effect of Size and Shape on Electrochemical Performance of Nano-Silicon-Based Lithium Battery

“…This deleterious volume change stimulated the development of Si nanomaterials, because Si at the nano scale can withstand swelling without fracture during LiB cycling. This has been demonstrated for a variety of morphologies including Si nanoparticles (SiNP) [6][7][8][9][10][11], Si nanowires (SiNW) [3,[12][13][14], Si nanotubes [15,16], and Si porous nanomaterials [17][18][19]. However, nanostructuration can be a costly process that needs to be carefully optimized for a dedicated application.…”

Ultrathin Silicon Nanolayer Implanted NixSi/Ni Nanoparticles as Superlong‐Cycle Lithium‐Ion Anode Material

“…[ 25 ] Recently, hierarchical carbon nanotube@silicon@carbon microspheres with both high porosity and mechanical strength (>200 MPa) and a low apparent particle expansion of ≈40% upon full lithiation have been reported. [ 26 ]…”