Three-Dimensional Metal Scaffold Supported Bicontinuous Silicon Battery Anodes

Abstract

Silicon-based lithium ion battery anodes are attracting significant attention because of silicon's exceptionally high lithium capacity. However, silicon's large volume change during cycling generally leads to anode pulverization unless the silicon is dispersed throughout a matrix in nanoparticulate form. Because pulverization results in a loss of electric connectivity, the reversible capacity of most silicon anodes dramatically decays within a few cycles. Here we report a three-dimensional (3D) bicontinuous silicon anode formed by depositing a layer of silicon on the surface of a colloidal crystal templated porous nickel metal scaffold, which maintains electrical connectivity during cycling due to the scaffold. The porous metal framework serves to both impart electrical conductivity to the anode and accommodate the large volume change of silicon upon lithiation and delithiation. The initial capacity of the bicontinuous silicon anode is 3568 (silicon basis) and 1450 mAh g(-1) (including the metal framework) at 0.05C. After 100 cycles at 0.3C, 85% of the capacity remains. Compared to a foil-supported silicon film, the 3D bicontinuous silicon anode exhibits significantly improved mechanical stability and cycleability.

A colloidoscope of colloid-based porous materials and their uses

“…Because the nanoparticles are fully embedded in the matrix, they do not dislodge from the structure, and the efficiency is stable even after hundreds of cycles ( Figure 28B). 62 Alternatively, active electrode materials can easily be grown on conducting supports to produce a layered structure, 26,415,416,425,465 as shown in Figure 29. With hierarchical structures, the charge can quickly travel from the active site to the conducting matrix, where it can be collected before recombination.…”

“…(A) A nickel inverse opal with a conformal silicon layer shown schematically; (B-C) SEM images showing that (B) upon lithiation, the Li x Si fills the pores but the structure remains intact, and (C) after delithiation, the structure remains. 425 Reproduced with permission from the American Chemical Society.…”

“…68,74,419,427 Swelling and shrinking can lead to loss of structural integrity and battery failure. Several groups have investigated using inverse opals to avoid this degradation, especially for MnO 2 465 and MnSiO 4 464 positive electrodes and silicon negative electrodes 74,419,425,427 in Li-ion batteries, as well as for sulfur in Li-S batteries. 68 These studies describe hierarchical structures, where a conducting matrix is covered with an active material.…”

Variation of stress with charging rate due to strain-rate sensitivity of silicon electrodes of Li-ion batteries

“…Fracture of the electrode leads to loss of active material and creates more surface area for solid-electrolyte interphase (SEI) growth, both of which significantly contribute to the fading of the capacity of the system [2][3][4][5]. Fortunately, this mechanical damage can be mitigated by nanostructuring the silicon anodes, as has been successfully demonstrated in nanowires [6,7], thin films [8][9][10][11][12], nanoporous structures [13,14], and hollow nanoparticles [15,16]. Specifically, recent experiments and theories indicate that one can prevent fracture by taking advantage of lithiation-induced plasticity [11,[17][18][19][20][21][22].…”

Mesoporous silicon sponge as an anti-pulverization structure for high-performance lithium-ion battery anodes

“…Methods are needed to prepare bulk Si materials without structural degradation during lithiation/de-lithiation. Recently, porous structured Si and Sibased composites have attracted significant attention 14,[24][25][26][27][28][29][30][31][32] . The idea is to pre-form meso/macropores in the Si structure to accommodate the large volume expansion that accompanies the lithiation process.…”