Son Seoung-Bum, Cao Lei, Yoon Taeho, Cresce Arthur, Hafner Simon E, Liu Jun, Groner Markus, Xu Kang, Ban Chunmei
National Renewable Energy Laboratory 15013 Denver West Parkway Golden CO 80401 USA.
Department of Material Science and Engineering Massachusetts Institute of Technology Cambridge MA 02139 USA.
Adv Sci (Weinh). 2018 Dec 14;6(3):1801007. doi: 10.1002/advs.201801007. eCollection 2019 Feb 6.
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.
硅（Si）因其在地壳中的丰富储量和高容量存储特性，已被公认为是一种很有前景的可替代石墨的材料。然而，其在锂化/脱锂过程中会发生较大的体积变化，进而导致材料破碎、电接触丧失以及电解液过度消耗，这阻碍了它的全面应用。作为应对快速容量衰减的一种对策，通过将硅纳米颗粒容纳在石墨基体中，采用了石墨和硅的复合电极。这种方法涉及两种在电极中与锂发生电化学相互作用的材料，因此需要一种分析方法来确定每种活性材料的个体电化学行为。在这项工作中，建立了一种包括微分图和积分学的方法，以分析两种活性电池之间复杂的相互作用，并研究混合电极中容量衰减的失效机制。为了解决该方法所识别出的性能缺陷，展示了一种醇铝（alucone）表面改性策略，以稳定石墨-硅复合电极的结构和电化学性能。这项工作中建立的综合方法对于多组分复合电极的设计和诊断具有重要意义，预计会引起其他下一代电池系统的高度关注。
