The results of the laboratory analysis of Core EMB058-11-9 from Pomeranian Bay, southern Baltic Sea

The results of the laboratory analysis for the article: "Littorina and post-Littorina sedimentological processes in the Odra Channel in light of multidisciplinary investigations of a sediment core, Pomeranian Bay, southern Baltic Sea

Detection and Signal Processing for Near-Field Nanoscale Fourier Transform Infrared Spectroscopy

Researchers from a broad spectrum of scientific and engineering disciplines are increasingly using near-field infrared spectroscopic techniques to characterize materials nondestructively and with nanoscale spatial resolution. However, sub-optimal understanding of a technique's implementation can complicate data interpretation and even act as a barrier to enter the field. Here we outline the key detection and processing steps involved in producing scattering-type near-field nanoscale Fourier transform infrared spectra (nano-FTIR). The largely self-contained work (i) explains how normalized complex-valued nano-FTIR spectra are generated, (ii) rationalizes how the real and imaginary components of spectra relate to dispersion and absorption respectively, (iii) derives a new and generally valid equation for spectra which can be used as a springboard for additional modeling of the scattering processes, and (iv) provides an algebraic expression that can be used to extract the sample's local extinction coefficient from nano-FTIR. The algebraic expression is validated with nano-FTIR and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectra on samples of polystyrene and Kapton

The Effect of the SEI Layer Mechanical Deformation on the Passivity of a Si Anode in Organic Carbonate Electrolytes

The solid electrolyte interphase (SEI) on a Si negative electrode in carbonate-based organic electrolytes shows intrinsically poor passivating behavior, giving rise to unsatisfactory calendar life of Li-ion batteries. Moreover, mechanical strains induced in the SEI due to large volume changes of Si during charge–discharge cycling could contribute to its mechanical instability and poor passivating behavior. This study elucidates the influence that static mechanical deformation of the SEI has on the rate of unwanted parasitic reactions at the Si/electrolyte interface as a function of electrode potential. The experimental approach involves the utilization of Si thin-film electrodes on substrates with disparate elastic moduli, which either permit or suppress the SEI deformation in response to Si volume changes upon charging–discharging. We find that static mechanical stretching and deformation of the SEI results in an increased parasitic electrolyte reduction current on Si. Furthermore, attenuated total reflection and near-field Fourier-transform infrared nanospectroscopy reveal that the static mechanical stretching and deformation of the SEI fosters a selective transport of linear carbonate solvent through, and nanoconfinement within, the SEI. These, in turn, promote selective solvent reduction and continuous electrolyte decomposition on Si electrodes, reducing the calendar life of Si anode-based Li-ion batteries. Finally, possible correlations between the structure and chemical composition of the SEI layer and its mechanical and chemical resilience under prolonged mechanical deformation are discussed in detail

Composite Cathode Design for High-Energy All-Solid-State Lithium Batteries with Long Cycle Life

All-solid-state batteries (ASSBs) consisting of a 4 V class layered oxide cathode active material (CAM), an inorganic solid-state electrolyte (SE), and a lithium metal anode are considered the future of energy storage technologies. To date, aside from the known dendrite issues at the anode, cathode instabilities due to oxidative degradation of the SE and reactivities between the SE and CAM as well as loss of mechanical integrity are considered to be the most significant barriers in ASSB development. In the present study, we address these challenges by developing composite cathode structures featuring two key design elements: (1) a halide SE with high oxidative stability to enable direct use of an uncoated 4 V class CAM and (2) a single-crystal (SC) CAM to eliminate intergranular cracking associated with volume changes and mechanical instability. We demonstrate exceptional performance achieved on such ASSB cells incorporating an uncoated SC-LiNi0.8Co0.1Mn0.1O2 (NMC811) CAM, a Li3YCl6 (LYC) SE, and a Li–In alloy anode, delivering a high discharge capacity of 170 mAh/g at C/5 and an impressive capacity retention of nearly 90% after 1000 cycles. Through comparative studies on polycrystalline and single-crystal NMC811 composite cathodes, we reveal the working mechanism that enables such stable cycling in the latter cell design. The study highlights the importance of proper cathode composite design and provides key insights in the future development of better-performing ASSB cells

Nano-FTIR Spectroscopy of the Solid Electrolyte Interphase Layer on a Thin-Film Silicon Li-Ion Anode

Si anodes for Li-ion batteries are notorious for their large volume expansion during lithiation and the corresponding detrimental effects on cycle life. However, calendar life is the primary roadblock for widespread adoption. During calendar life aging, the main origin of impedance increase and capacity fade is attributed to the instability of the solid electrolyte interphase (SEI). In this work, we use ex situ nano-Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy to characterize the structure and composition of the SEI layer on amorphous Si thin films after an accelerated calendar aging protocol. The characterization of the SEI on non-washed and washed electrodes shows that brief washing in dimethyl carbonate results in large changes to the film chemistry and topography. Detailed examination of the non-washed electrodes during the first lithiation and after an accelerated calendar aging protocol reveals that PF6– and its decomposition products tend to accumulate in the SEI due to the preferential transport of PF6– ions through polyethylene oxide-like species in the organic part of the SEI layer. This work demonstrates the importance of evaluating the SEI layer in its intrinsic, undisturbed form and new strategies to improve the passivation of the SEI layer are proposed

The Interaction of Li⁺ with Single-Layer and Few-Layer Graphene

The interaction of Li+ with single and few layer graphene is reported. In situ Raman spectra were collected during the electrochemical lithiation of the single- and few-layer graphene. While the interaction of lithium with few layer graphene seems to resemble that of graphite, single layer graphene behaves very differently. The amount of lithium absorbed on single layer graphene seems to be greatly reduced due to repulsion forces between Li+ at both sides of the graphene layer

The Formation Mechanism of Fluorescent Metal Complexes at the Li_<i>x</i>Ni_0.5Mn_1.5O_4−δ/Carbonate Ester Electrolyte Interface

Electrochemical oxidation of carbonate esters at the Li_<i>x</i>Ni_0.5Mn_1.5O_4−δ/electrolyte interface results in Ni/Mn dissolution and surface film formation, which negatively affect the electrochemical performance of Li-ion batteries. Ex situ X-ray absorption (XRF/XANES), Raman, and fluorescence spectroscopy, along with imaging of Li_<i>x</i>Ni_0.5Mn_1.5O_4−δ positive and graphite negative electrodes from tested Li-ion batteries, reveal the formation of a variety of Mn^II/III and Ni^II complexes with β-diketonate ligands. These metal complexes, which are generated upon anodic oxidation of ethyl and diethyl carbonates at Li_<i>x</i>Ni_0.5Mn_1.5O_4−δ, form a surface film that partially dissolves in the electrolyte. The dissolved Mn^III complexes are reduced to their Mn^II analogues, which are incorporated into the solid electrolyte interphase surface layer at the graphite negative electrode. This work elucidates possible reaction pathways and evaluates their implications for Li⁺ transport kinetics in Li-ion batteries

Lithium Diffusion in Graphitic Carbon

Graphitic carbon is currently considered the state-of-the-art material for the negative electrode in lithium ion cells, mainly due to its high reversibility and low operating potential. However, carbon anodes exhibit mediocre charge/discharge rate performance, which contributes to severe transport-induced surface structural damage upon prolonged cycling and limits the lifetime of the cell. Lithium bulk diffusion in graphitic carbon is not yet completely understood, partly due to the complexity of measuring bulk transport properties in finite-sized nonisotropic particles. To solve this problem for graphite, we use the Devanathan−Stachurski electrochemical methodology combined with ab initio computations to deconvolute and quantify the mechanism of lithium ion diffusion in highly oriented pyrolytic graphite (HOPG). The results reveal inherent high lithium ion diffusivity in the direction parallel to the graphene plane (∼10⁻⁷−10⁻⁶ cm² s⁻¹), as compared to sluggish lithium ion transport along grain boundaries (∼10⁻¹¹ cm² s⁻¹), indicating the possibility of rational design of carbonaceous materials and composite electrodes with very high rate capability