5 years ago

Atomistic Simulation Derived Insight on the Irreversible Structural Changes of Si Electrode during Fast and Slow Delithiation

Atomistic Simulation Derived Insight on the Irreversible Structural Changes of Si Electrode during Fast and Slow Delithiation
Yue Qi, James Wortman, Kwang Jin Kim, Sung-Yup Kim
Quantifying the irreversible chemical and structural changes of Si during cycling remains challenging. In this study, a continuous reactive molecular dynamics delithiation algorithm, with well-controlled potential gradient and delithiation rate, was developed and used to investigate the “natural” delithiation responses of an aluminum-oxide coated silicon thin-film. Fast delithiation led to the formation of dense Si network near the surface and nanoporosity inside the a-LixSi, resulting in 141% volume dilation and significant amount of Li trapped inside (a-Li1.2Si) at the end of delithiation process. In contrast, slow delithiation allowed the a-LixSi to shrink by near-equilibrium condition, demonstrating no permanent inner pore with nearly Li-free structure (a-Li0.2Si) and minimal volume dilation (44%). However, even without trapped Li, the delithiated a-LixSi still exhibited higher volume (lower density) than the equilibrium structure with the same Li concentration, despite delithiation rate. The origin of this excess volume is the loss of directly bonded Si–Si pairs, which made the subsequent relithiation faster. On the basis of the atomistic modeling and the quantified degradation mechanism, battery operating guidelines, including the delithiation rate and the depth of charge to avoid trapped Li and coating delamination, were suggested to improve the durability Si electrodes.

Publisher URL: http://dx.doi.org/10.1021/acs.nanolett.7b01389

DOI: 10.1021/acs.nanolett.7b01389

You might also like
Discover & Discuss Important Research

Keeping up-to-date with research can feel impossible, with papers being published faster than you'll ever be able to read them. That's where Researcher comes in: we're simplifying discovery and making important discussions happen. With over 19,000 sources, including peer-reviewed journals, preprints, blogs, universities, podcasts and Live events across 10 research areas, you'll never miss what's important to you. It's like social media, but better. Oh, and we should mention - it's free.

  • Download from Google Play
  • Download from App Store
  • Download from AppInChina

Researcher displays publicly available abstracts and doesn’t host any full article content. If the content is open access, we will direct clicks from the abstracts to the publisher website and display the PDF copy on our platform. Clicks to view the full text will be directed to the publisher website, where only users with subscriptions or access through their institution are able to view the full article.