Ruttert Mirco, Holtstiege Florian, Hüsker Jessica, Börner Markus, Winter Martin, Placke Tobias
University of Münster, MEET Battery Research Center, Institute of Physical Chemistry, Corrensstraße 46, 48149 Münster, Germany.
Helmholtz Institute Münster, IEK-12, Forschungszentrum Jülich GmbH, Corrensstraße 46, 48149 Münster, Germany.
Beilstein J Nanotechnol. 2018 Sep 5;9:2381-2395. doi: 10.3762/bjnano.9.223. eCollection 2018.
In this work, silicon/carbon composites are synthesized by forming an amorphous carbon matrix around silicon nanoparticles (Si-NPs) in a hydrothermal process. The intention of this material design is to combine the beneficial properties of carbon and Si, i.e., an improved specific/volumetric capacity and capacity retention compared to the single materials when applied as a negative electrode in lithium-ion batteries (LIBs). This work focuses on the influence of the Si content (up to 20 wt %) on the electrochemical performance, on the morphology and structure of the composite materials, as well as the resilience of the hydrothermal carbon against the volumetric changes of Si, in order to examine the opportunities and limitations of the applied matrix approach. Compared to a physical mixture of Si-NPs and the pure carbon matrix, the synthesized composites show a strong improvement in long-term cycling performance (capacity retention after 103 cycles: ≈55% (20 wt % Si composite) and ≈75% (10 wt % Si composite)), indicating that a homogeneous embedding of Si into the amorphous carbon matrix has a highly beneficial effect. The most promising Si/C composite is also studied in a LIB full cell vs a NMC-111 cathode; such a configuration is very seldom reported in the literature. More specifically, the influence of electrochemical prelithiation on the cycling performance in this full cell set-up is studied and compared to non-prelithiated full cells. While prelithiation is able to remarkably enhance the initial capacity of the full cell by ≈18 mAh g, this effect diminishes with continued cycling and only a slightly enhanced capacity of ≈5 mAh g is maintained after 150 cycles.
在这项工作中，通过水热法在硅纳米颗粒（Si-NPs）周围形成无定形碳基质来合成硅/碳复合材料。这种材料设计的目的是结合碳和硅的有益特性，即与作为锂离子电池（LIBs）负极的单一材料相比，具有更高的比容量/体积容量和容量保持率。这项工作重点研究了硅含量（高达20 wt%）对复合材料的电化学性能、形态和结构的影响，以及水热碳对硅体积变化的耐受性，以检验所应用的基质方法的机遇和局限性。与Si-NPs和纯碳基质的物理混合物相比，合成的复合材料在长期循环性能方面有显著改善（103次循环后的容量保持率：≈55%（20 wt% Si复合材料）和≈75%（10 wt% Si复合材料）），表明将硅均匀嵌入无定形碳基质具有非常有益的效果。还对最有前景的Si/C复合材料在与NMC-111正极组成的LIB全电池中进行了研究；这种配置在文献中很少报道。更具体地说，研究了电化学预锂化对这种全电池设置中循环性能的影响，并与未预锂化的全电池进行了比较。虽然预锂化能够使全电池的初始容量显著提高约18 mAh/g，但随着循环的继续，这种效果会减弱，150次循环后仅维持约5 mAh/g的略微提高的容量。
