Title: Nanostructuring Strategies for Silicon-based Anodes in Lithium-ion Batteries: Tuning Areal Silicon Loading, SEI Formation/Irreversible Capacity Loss, Rate Capability Retention and Electrode Durability Show Chinese title

Title: 硅基负极的纳米结构策略：调节面密度硅负载、SEI形成/不可逆容量损失、倍率能力保持和电极耐久性

Abstract: Silicon is one of the most promising anode materials for Lithium-ion batteries. Silicon endures volume changes upon cycling, which leads to subsequent pulverization and capacity fading. These drawbacks lead to a poor lifespan and hamper the commercialization of silicon anodes. In this work, a hybrid nanostructured anode based on silicon nanoparticles (SiNPs) anchored on vertically aligned carbon nanotubes (VACNTs) with defined spacing to accommodate volumetric changes is synthesized on commercial macroscopic current collector. Achieving electrodes with good stability and excellent electrochemical properties remain a challenge. Therefore, we herein tune the active silicon areal loading either through the modulation of the SiNPs volume by changing the silicon deposition time at a fixed VACNTs carpet length or through the variation of the VACNT length at a fixed SiNPs volume. The low areal loading of SiNPs improves capacity stability during cycling but triggers large irreversible capacity losses due to the formation of the solid electrolyte interphase (SEI) layer. By contrast, higher areal loading electrode reduces the quantity of the SEI formed, but negatively impacts the capacity stability of the electrode during the subsequent cycles. A higher gravimetric capacity and higher areal loading mass of silicon is achieved via an increase of VACNTs carpet length without compromising cycling stability. This hybrid nanostructured electrode shows an excellent stability with reversible capacity of 1330 mAh g-1 after 2000 cycles. Show Chinese abstract

Abstract: 硅是锂离子电池中最有前景的负极材料之一。 硅在循环过程中会经历体积变化，这会导致随后的粉碎和容量衰减。 这些缺点导致寿命较差，并阻碍了硅负极的商业化。 在这项工作中，在商业宏观电流收集器上合成了一种基于硅纳米颗粒（SiNPs）的混合纳米结构负极，这些SiNPs锚定在具有定义间距的垂直对齐碳纳米管（VACNTs）上，以适应体积变化。 实现具有良好稳定性和优异电化学性能的电极仍然是一个挑战。 因此，我们通过改变固定VACNTs地毯长度下的硅沉积时间来调节活性硅的面载量，或者通过改变固定SiNPs体积下的VACNT长度来调节面载量。 较低的SiNPs面载量在循环过程中提高了容量稳定性，但由于固体电解质界面（SEI）层的形成，会导致较大的不可逆容量损失。 相比之下，较高的面载量电极减少了SEI的形成量，但在后续循环中对电极的容量稳定性产生了负面影响。 通过增加VACNTs地毯长度，在不损害循环稳定性的前提下实现了更高的硅质量比容量和更高的面载量质量。 这种混合纳米结构电极表现出优异的稳定性，在2000次循环后具有1330 mAh g-1的可逆容量。