Prelithiated Carbon Nanotube-Embedded Silicon-based Negative Electrodes for High-Energy Density Lithium-Ion Batteries

Abstract

Multi-walled carbon Nanotubes (MWCNTs) are hailed as beneficial conductive agents in Silicon (Si)-based negative electrodes due to their unique features enlisting high electronic conductivity and the ability to offer additional space for accommodating the massive volume expansion of Si during (de-)lithiation. However, both MWCNTs and Siirreversibly consume an enormous amount of Li inventory to principally form a Solid Electrolyte Interphase (SEI) and due to other parasitic reactions, which results in lowering the Coulombic Efficiency (CE), rapid decrease in reversible capacity, and shorter battery life.To tackle these hurdles, electrochemical prelithiation is adopted as a taming strategy to mitigate the large capacity loss (nearly reducing the first irreversible capacity by ≈60%) of MWCNT-Si/Graphite (Gr) negative electrode-based full-cells. In contrast, a yardstick negative electrode utilizing commercially used Super P (Super P-Si/Gr) showed a reduction of ≈47% after in vitro pre-doping with lithium, which is considerably smaller compared to that of MWCNTs-based electrode design. Furthermore, the Initial CE, life cycle, and rate capability are enhanced by prelithiation. Interestingly, prelithiation brings more impact on MWCNTs -Si/Gr than with Super P-Si/Gr design. An in-depth analysis using X-ray photoelectron spectroscopy (XPS), RAMAN Spectroscopy, Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR FTIR), laser microscopy, and Scanning Electron Microscopy (SEM) reveal deeper insights into the differences in SEI layer between prelithiated MWCNTs and their Super P-based electrode counterparts.