Interfacially Induced Cascading Failure in Graphite‐Silicon Composite Anodes

Abstract

Silicon (Si) has been well recognized as a promising candidate to replace graphite because of its earth abundance and high‐capacity storage, but its large volume changes upon lithiation/delithiation and the consequential material fracturing, loss of electrical contact, and over‐consumption of the electrolyte prevent its full application. As a countermeasure for rapid capacity decay, a composite electrode of graphite and Si has been adopted by accommodating Si nanoparticles in a graphite matrix. Such an approach, which involves two materials that interact electrochemically with lithium in the electrode, necessitates an analytical methodology to determine the individual electrochemical behavior of each active material. In this work, a methodology comprising differential plots and integral calculus is established to analyze the complicated interplay among the two active batteries and investigate the failure mechanism underlying capacity fade in the blend electrode. To address performance deficiencies identified by this methodology, an aluminum alkoxide (alucone) surface‐modification strategy is demonstrated to stabilize the structure and electrochemical performance of the graphite‐Si composite electrode. The integrated approach established in this work is of great importance to the design and diagnostics of a multi‐component composite electrode, which is expected to be high interest to other next‐generation battery system.

Integration of Graphite and Silicon Anodes for the Commercialization of High‐Energy Lithium‐Ion Batteries

“…Thus, the rate of capacity fading at the initial cycling is closely connected with the characteristics of the Si, such as the size, the crystallinity, and the specific architecture for mitigating the Si‐based failure mechanism . Sufficient graphite is crucial for reducing the interparticle electrical resistance, despite the associated loss of specific capacity, otherwise the capacity fading would be accelerated, like with the Si electrode in which graphite is not blended …”

The critical role of carbon in marrying silicon and graphite anodes for high‐energy lithium‐ion batteries

“…Meanwhile, the huge difference in the volume changes of graphite and Si during cycling would result in electrical contact loss for graphite, leading to additional deterioration. A recent investigation on Si/G composite revealed that graphite loses its intrinsic capacity after cycling, because the graphite particles become isolated from the electrical network due to the deterioration of the microstructure of the electrodes caused by volume expansion of the Si particles, cracks, and excessive SEI formation at the interface …”

“…A recent investigation on Si/G composite revealed that graphite loses its intrinsic capacity after cycling, because the graphite particles become isolated from the electrical network due to the deterioration of the microstructure of the electrodes caused by volume expansion of the Si particles, cracks, and excessive SEI formation at the interface. 13 The repeated volume changes of Si during cycling process can seriously change the morphology of Si/G composite. It has been reported that the Si nanoparticles turn into nanoporous structure with very large surface area as a result of repeated cycling, which leads to electrode swelling with rearrangement of the electrode components, and thus disrupts the electrode.…”

Silicon Anodes for High‐Performance Storage Devices: Structural Design, Material Compounding, Advances in Electrolytes and Binders

“…At a current density of 0.1 C, the cycle was 200 cycles, and the specific capacity remained at 740 mAh g −1 . Excessive electrolyte consumption causes rapid capacity decay …”