Si Electrodes for Li-Ion Batteries—A New Way to Look at an Old Problem

Abstract

High-capacity Si-based electrodes could replace carbon-based electrodes in the next generation of Li-ion batteries. Although Si-based electrodes have large gravimetric capacities, they typically suffer from poor cyclability. One reason for the poor cyclability is large volume expansion associated with 3.75 mol of Li reacting with 1 mol of Si. A theoretical approach to design electrodes that can accommodate this large volume expansion is discussed. It is shown that experimental results agree well with the theoretical approach. We show that Si-based electrodes with a relatively low Si content ͑Ͻ33 wt %͒ and high binder content ͑33-56 wt %͒ cycle at large capacities ͑ϳ660 mAh/g͒ for hundreds of cycles. No special electrode processing or cycling procedures are required to achieve high capacities with good cyclability.

Graphene/Na carboxymethyl cellulose composite for Li-ion batteries prepared by enhanced liquid exfoliation

“…Since contribution of capacity of CSP and graphene to capacity of composite much smaller than capacity of Si, decrease of capacity of CSP and graphene at high currents was neglected. It can be seen that Si shows the typical high irreversible capacity at the first cycle in the presence of both binders [42,57]. The highest capacity was reached with graphene/NaCMC composite at 1611 mAh/g after 10 cycles, which is almost 30% higher than the capacity of Si electrode in the presence of NaCMC alone (1246 mAh/g) and without graphene.…”

“…This ratio was suggested to be optimal by Beattie et al in [57] in terms of increasing cyclability of Si which can be compromised due to its high volume expansion/contraction as a result of alloying/dealloying reactions during cycling. The final graphene content was 8.78 wt% and Si content was 33.3 wt%.…”

Evaluating the performance of nanostructured materials as lithium-ion battery electrodes

“…The first is that Si suffers from structural changes induced on cycling, characterised by the formation of amorphous Li15Si4 and LiySi phases, leading to reduced cycling performance [12][13][14]. In addition, Si suffers from a large (± 400%), volume change during the (de)alloying process, the strain of which potentially leads to pulverisation of the local structure and electrical disconnect from the current collector; such an effect results in a marked loss of capacity and cycle performance [15]. Numerous examples in the literature have demonstrated the associated volume change on the local structure of the Si anode [16][17][18].…”

“…Composite Si nanowires having core-shell morphologies, or those with surface modification features, have also been proposed to enhance the cycling ability of Si nanowires, by further accommodating the strain associated with the alloying process. Carbon coated Si nanowire arrays [30,31], mesoporous Si/C nanowires [32] [15,[49][50][51]. The addition of alginate, a polysaccharide derived from brown algae, significantly enhanced the cycling performance of Si-based nanopowders, achieving a highly stable capacity of 1200 mA h g -1 after 1300 cycles (Fig.…”

Microstructural evolution induced by micro-cracking during fast lithiation of single-crystalline silicon

“…Because of their high power densities, lithium-ion batteries are employed in applications that are especially sensitive to weight and size, such as portable electronic devices and electric vehicles [1][2][3][4][5][6]. Generally, graphite-based materials are used for anodes due to their low cost and stable performance, but they have a limited capacity of 372 mAh/g [7].…”