The commercialization of silicon (Si) anodes is sluggish due to the poor electrochemical performance of Si-based full cells (FCs). In order to break this limitation, this work investigates the effect of cathode type on the electrochemical performance of Si-based FCs and its mechanism. Based on electrochemical and spectral characterization , NCM523 is more suitable for assembling Si-based FCs to achieve high-rate and long-cycle. This is mainly because that the cathode type has an impact on the distribution of electrolyte decomposition products, while NCM523 is beneficial to the formation of more conductive organic components in the Si anode, and more LiF in the FC that can prevent electrolyte erosion. This work contributes to a basic comprehension of the electrochemical performance and SEI formation of Si-based FCs, and the results are helpful to the development and application of Si anodes.
The extremely high chemical reactivity of lithium metal (Li°) electrodes and its enormous volume change during repetitive cycles cause continuous interfacial degradations in prevailing organic electrolytes, thus deteriorating the cycling performances of rechargeable lithium metal batteries (LMBs). Herein, departing from traditional wisdom on the design of electrolyte components, a super SEI-forming anion (SSA), as an efficient percussor for building stable interphases on Li° electrode, is proposed. Comprehensive investigations related to the unique anion chemistry of SSA reveal that the sulfonate and polyfluoroalkyl functionalities synergistically contribute to uniform spatial distributions of designer interfacial species, greatly improving the surface coverage property and conformal ability of the resulting interphases. Consequently, the incorporation of SSA leads to significant improvements in the cyclability of Li° electrode (exceeding 575 mAh cm −2 before failure) and the corresponding rechargeable Li°||LiFePO 4 cells [a five-time increase in lifespan as compared to the benchmark cell with the popular SEI-forming anion bis(fluorosulfonyl)imide (FSI)]. The present work offers a paradigm shift to tame the notorious interfacial issues via upgraded anion chemistry, which can promote the practical development of rechargeable LMBs and other kinds of metal batteries.
Nanostructure of CuO plays a critical role in Li-ion battery (LIB) applications of CuO/graphene oxide (GO) nanocomposites. Morphological evolution of CuO/GO anode material provides essential information for developing the performance of LIBs. But, the nanostructural evolution of the CuO/GO anode materials have not been previously studied by in situ electrochemical-synchrotron radiation techniques. In this paper, different CuO morphology in preparation of CuO/GO nanocomposites could be controlled by increasing the reactive time at 83 °C. In situ synchrotron X-ray diffraction and small angle X-ray scattering (SAXS) are employed to characterize the structural behavior of CuO/GO samples during the first cycle. The CuO(-511) Bragg peak demonstrates a more significant shift toward higher angles due to the incorporation of Li + in the CuO crystal lattice . SAXS indicates that the formation and growth of SEI are observed with lithiation dose, and subsequently some cracks occur. The in situ electrochemical-synchrotron techniques could be implemented to help further understand the electrochemical behaviors and conversion mechanism of anode materials.
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