A pomegranate-inspired nanoscale design for large-volume-change lithium battery anodes

Abstract

Silicon is an attractive material for anodes in energy storage devices, because it has ten times the theoretical capacity of its state-of-the-art carbonaceous counterpart. Silicon anodes can be used both in traditional lithium-ion batteries and in more recent Li-O2 and Li-S batteries as a replacement for the dendrite-forming lithium metal anodes. The main challenges associated with silicon anodes are structural degradation and instability of the solid-electrolyte interphase caused by the large volume change (∼300%) during cycling, the occurrence of side reactions with the electrolyte, and the low volumetric capacity when the material size is reduced to a nanometre scale. Here, we propose a hierarchical structured silicon anode that tackles all three of these problems. Our design is inspired by the structure of a pomegranate, where single silicon nanoparticles are encapsulated by a conductive carbon layer that leaves enough room for expansion and contraction following lithiation and delithiation. An ensemble of these hybrid nanoparticles is then encapsulated by a thicker carbon layer in micrometre-size pouches to act as an electrolyte barrier. As a result of this hierarchical arrangement, the solid-electrolyte interphase remains stable and spatially confined, resulting in superior cyclability (97% capacity retention after 1,000 cycles). In addition, the microstructures lower the electrode-electrolyte contact area, resulting in high Coulombic efficiency (99.87%) and volumetric capacity (1,270 mAh cm(-3)), and the cycling remains stable even when the areal capacity is increased to the level of commercial lithium-ion batteries (3.7 mAh cm(-2)).

Metallic Sn‐Based Anode Materials: Application in High‐Performance Lithium‐Ion and Sodium‐Ion Batteries

“…Yolk–shell architectures with inner buffering voids can provide reserved space to hold the expansion of active materials without destroying the protective sheaths, and the inner space is also beneficial to the rapid permeation of electrolyte 135, 136, 137, 138. Lee et al139 synthesized Sn/C york–shell nanospheres with Sn particles encapsulated in hollow spherical carbon shells through a soft template method ( Figure 13 a).…”

Advanced Micro/Nanostructures for Lithium Metal Anodes

“…Compared with the insertion‐host electrode materials (carbon,16 oxide,16 and silicon16, 17 etc. ), there is no host for lithium metal anode during lithium ion plating, rendering the uncontrollable growth of dendrites.…”

Electrode Nanostructures in Lithium‐Based Batteries

“…Further, by utilizing in situ transmission electron microscopy (TEM), the effect of void space on the stability of structure, SEI thickness and performance was observed, and it is found that if the space is not enough for volume expansion then it causes structural disintegration (Figure 6). 52 Further, the use of self‐healing materials is another way to control the volume changes of anode materials, like self‐healing polymer was established to control the structural damages of silicon‐based electrode. Self‐healing polymer recover the cracks or other damages in structure during conversion reaction with Li + 84.…”