Li Distribution Research Articles

Visualizing the Li distribution in an all-solid-state battery composite electrode using combined plasma focused-ion beam microscopy and secondary-ion mass spectroscopy

Using a Li metal anode, the all-solid-state battery (ASSB) promises a step change in specific energy over Li-ion batteries and the potential for increased battery safety. ASSBs rely critically on the efficient movement of Li charge carriers through a Li-conducting solid electrolyte (SE) separator and throughout a composite cathode (CC) comprising active particles, particulate SE, polymeric binder, and carbon. Unfortunately, there is no readily accessible laboratory method to visualise Li distributions at both particle and electrode scales to help understand and optimise Li electrode dynamics in ASSBs. We report a method to map all electrode elements in a 3D volume, including Li, within a typical ASSB composite cathode. The method combines a xenon plasma focused-ion beam (PFIB) for 3D milling, energy dispersive X-ray spectroscopy (EDS) to map non-Li elements, and secondary ion mass spectrometry (SIMS) to map Li. We manipulate 3D EDS and SIMS datasets into a common format and then recombine them in 3D to differentiate the different materials at high resolution. This new approach can be applied to understand and optimise the role of microstructure in controlling ASSB performance.

Tuning solvation behavior within electric double layer via halogenated MXene for reliable lithium metal batteries

Solid electrolyte interphase (SEI)/electrolyte interface is critical in determining the lithium (Li) plating/stripping behavior. The solvation structure of Li-ion is well understood in the bulk electrolyte. Still, the mechanism of how SEI components affect the Li-ion solvation structure and desolvation energy barrier at the SEI/electrolyte interface is still unclear. Herein, Ti3C2 Maxine with single halogenated terminations (−Cl, −Br, −I) are synthesized and used as a model system, because their surface terminations induce a double halide-rich SEI formation (LiF and LiCl/LiBr/LiI). We examine the influence of the interaction strength between different Li halides and Li-ion on coordination number of Li ions and distribution of Li ions within the inner Helmholtz plane (IHP). A solvation sheath with a low solvent coordination number forms near the IHP of the LiBr interphase, improving the kinetics of Li deposition. Accordingly, half-cells utilising Li-carbon fiber/Ti3C2Br2 electrodes exhibit a long lifespan of 12,000 h (1 mA cm−2, 1 mAh cm−2). A pouch cell comprising Li-carbon fiber/Ti3C2Br2 anode and LiFePO4 cathode displays a capacity retention rate of 97 % after 300 cycles even at a low negative to positive electrode capacity ratio of 2.26. Our research provides crucial principles for the design of SEI components in Li metal batteries.

Revealing Gliding-Induced Structural Distortion in High-Nickel Layered Oxide Cathodes for Lithium-Ion Batteries.

After charging to a high state-of-charge (SoC), layered oxide cathodes exhibit high capacities but suffer from gliding-induced structural distortions caused by deep Li depletion within alkali metal (AM) layers, especially for high-nickel candidates. In this study, we identify the essential structure of the detrimental H3 phase formed at high SoC to be an intergrowth structure characterized by random sequences of the O3 and O1 slabs, where the O3 slabs represent Li-rich layers and the O1 slabs denote Li-depleted (or empty) layers that glide from the O3 slabs. Moreover, we adopt two doping strategies targeting different doping sites to eliminate the formation of Li-vacant O1 slabs. First, we introduce direct transition metal (TM) pillars between TMO2 slabs achieved through dopants (e.g., Nb) positioned within AM layers, significantly improving the cycling stability. Second, we introduce indirect Li pillars achieved through dopants located at TM layers to adjust the Li-O bond strength. While this strategy can regulate the uniformity of Li at the slab level, it results in an uneven Li distribution at the particle scale, ultimately failing to enhance the electrochemical performance. Our established research strategy facilitates the realization of diverse pillars between TMO2 slabs through doping, thereby offering guidance for stabilizing high-capacity layered oxide cathodes at high SoC.

Electrochemical-mechanical coupled interfacial degradation model of Ternary polymer composite cathodes in all-solid-state batteries

Despite significant attention focused on the composite cathode composed of active particles, which is considered to increase the interfacial areas and satisfy high areal load, suffers from interfacial issues. In this article, we formulate an electrochemical-mechanical model of LiNixMnyCozO2 (NMC) composite cathode coupling the relations between interfacial degradation, charge transformation, diffusion transport, and mechanical deformation under cyclic loads. Based on the transition state theory, we regard the interfacial degradation as an energy barrier dependent on the interfacial debonding state. Physical mismatch due to chemical expansion results in interfacial current distinction, anisotropic Li diffusion and excessive local stress. Compared to single-crystal NMC particles, the effect of interfacial separation and internal cracks triggers an extremely nonuniformity of Li distribution within random orientation polycrystalline-type particles. The external pressure in the range of operation can cause mechanical deformation to fill in the interface vacancies, which effectively alleviates the rapid growth of damage and provides a better cyclic performance. Moreover, soft polymer-based solid electrolytes take advantage of their flexible property to deal with solid-solid contact, providing considerable maintenance of interface stability. This present framework reveals the failure mechanism with electrochemical-mechanical coupled relations for composite cathode materials and broadens the design guidance toward improving interfacial integrity.

Enhancing Lithium Conductivity Using High-Valence Cations in Cubic Spinel Halide Solid Electrolytes.

Halide solid electrolytes for all-solid-state batteries have recently emerged as competitors to oxide and sulfide solid electrolytes due to their excellent electrochemical properties. This ab initio study unveils the dynamic nature of Li2Sc2/3Cl4, a rare superionic conductor among cubic spinel halide materials. Li ions in Li2Sc2/3Cl4 prefer to occupy some of the tetrahedral 8a, octahedral 16c, and octahedral 16d sites, leading to disordered Li distribution. Li ions in Li2Sc2/3Cl4 diffuse through the single-ion diffusion mechanism rather than the concerted diffusion mechanism, providing a high conductivity of 1.36 mS cm-1. Li ions at the 16d site diffuse as actively as those at the 8a/16c site, an unexpected result that runs counter to the conventional view. In Li2MgCl4, the same cubic spinel as Li2Sc2/3Cl4, Li ions at the 8a/16c site diffuse actively, but those at the 16d site are almost immobile, resulting in a very low conductivity of 5.3 × 10-4 mS cm-1. The extremely higher conductivity in Li2Sc2/3Cl4 than in Li2MgCl4 is because the concentration of Sc3+/Mg2+ cations blocking the movement of Li ions at the 16d site is lower in Li2Sc2/3Cl4 than in Li2MgCl4. Designing cubic spinel materials containing high-valence cations is proposed as a way to increase conductivity by reducing the concentration of multivalent cations that impede Li diffusion. This study sheds new light on how to control conductivity using site-dependent Li mobility in solid electrolytes.

Lithium Volatilization and Phase Changes during Aluminum-Doped Cubic Li6.25La3Zr2Al0.25O12 (c-LLZO) Processing

Stabilized Li6.25La3Al0.25 Zr2O12 (cubic LLZO or c-LLZO) is a Li+-conducting ceramic with ionic conductivities approaching 1 mS-cm. Processing c LLZO so that it is suitable for use as a solid state electrolyte in all solid state batteries, however, is challenging due to the formation of secondary phases at elevated temperatures. The work described in this manuscript examines the formation of one such secondary phase La2Zr2O7 (LZO) formed during sintering c LLZO at 1000 °C. Specifically, spatially resolved Raman spectroscopy and X-ray Diffraction (XRD) measurements have identified gradients in Li distributions in the Li ion (Li+)-conducting ceramic Li6.25La3Al0.25 Zr2O12 (cubic LLZO or c-LLZO) created by thermal processing. Sintering c-LLZO under conditions relevant to solid state Li+ electrolyte fabrication conditions lead to Li+ loss and the formation of new phases. Specifically, sintering for 1 h at 1000 °C leads to Li+ depletion and the formation of the pyrochlore lanthanum zirconate (La2Zr2O7 or LZO), a material known to be both electronically and ionically insulating. Circular c-LLZO samples are covered on the top and bottom surfaces, exposing only the 1.6 mm-thick sample perimeter to the furnace’s ambient air. Sintered samples show a radially symmetric LZO gradient, with more LZO at the center of the pellet and considerably less LZO at the edges. This profile implies that Li+ diffusion through the material is faster than Li+ loss through volatilization, and that Li+ migration from the center of the sample to the edges is not completely reversible. These conditions lead to a net depletion of Li+ at the sample center. Findings presented in this work suggest new strategies for LLZO processing that will minimize Li+ loss during sintering, leading to a more homogeneous material with more reproducible electrochemical behavior.

Predicting the performance of lithium adsorption and recovery from unconventional water sources with machine learning

Selective lithium (Li) recovery from unconventional water sources (UWS) (e.g., shale gas waters, geothermal brines, and rejected seawater desalination brines) using inorganic lithium-ion sieve (LIS) materials can address Li supply shortages and distribution issues. However, the development of high-performance LIS materials and the optimization of recovery-related operating parameters are hampered by the variety of production methods, intricate procedures, and experimental expenses. Machine learning (ML) techniques offer potential solutions for enhancing LIS material development. We collected literature data on Li adsorption, categorizing 16 parameters into adsorbent parameters, operating parameters, and solution components. Three tree-based algorithms—Random Forest (RF), Gradient Boosting Decision Trees (GBDT), and Extreme Gradient Boosting (XGBoost)—were used to evaluate the impact of these parameters on lithium adsorption. The grouped random splitting method limited data leakage and mitigated overfitting. XGBoost demonstrated the best performance, with an R² of 0.98 and a root-mean-squared error (RMSE) of 1.72. The SHAP values highlighted that operating parameters were the most influential, followed by adsorbent parameters and coexisting ion concentrations. Therefore, focusing on optimizing operating parameters or making targeted improvements on LIS based on operating conditions will enhance LIS performances in UWS. These insights are crucial for optimizing Li adsorption processes and designing effective inorganic LIS materials.

Enhancing Li-ion diffusivity of Li1.3Al0.3Ti1.7(PO4)3 through liquid-electrolytes-induced secondary crystallization

Solid electrolytes (SEs) offer promising avenues for improving both the energy density and safety of lithium-ion batteries (LIBs). However, the grain boundary resistance remains a significant hurdle that impact the performance of LIBs, particularly when utilizing SEs in powder form. In this study, we introduce a novel approach to reduce grain boundary resistance in Li1.3Al0.3Ti1.7(PO4)3 (LATP) via secondary crystallization induced by liquid electrolytes (LEs). By immersing nano-sized LATP powders in LiPF6/carbonates LEs, rapid aggregation and recrystallization into bulk micrometer-sized particles occur within minutes under ambient conditions. This secondary crystallization process alters the Li distribution within LATP bulk phase, substantially reducing the grain boundary resistance and enhancing Li-ion diffusivity. Consequently, the assembled LATP-modified commercial LiNi0.89Co0.07Mn0.04O2 cathode using LiPF6 electrolyte delivers a remarkable discharge capacity of 105.4 mAh g−1 at 4C, significantly superior to the bare electrode (44.7 mAh g−1). The recrystallized LATP enhances the transport properties and pathways of Li+ ions within the cathode material, especially at high current densities. Multinuclear and multi-dimensional solid-state NMR analysis reveal that active F− ions released from the hydrolysis of LiPF6 electrolytes act as mineralizing agent, facilitating rapid agglomeration and secondary growth of LATP grains. Our findings underscore the efficacy of secondary crystallization using LEs as a promising strategy for eliminating grain boundary resistance and facilitating fast Li-ion conduction of SEs, thereby advancing LIB performance.

Investigation of Lithium Deposition in Tri-Layer Llzo Garnet Structure As a Function of Cell Cycling Using Nuclear Reaction Analysis Method

A key challenge of lithium metal batteries is the volumetric expansion of battery after several charging cycles due to the non-uniform deposition of lithium on anode. This leads to lithium dendrite formation compromising battery safety, and poor lifetime. We adapted tri-layer (porous-dense-porous) Al-doped Lithium Lanthanum Zirconium Oxide (LLZO) host (separator) via tape casting. During cycling lithium is deposited in the porous structure preventing dendrite formation. XRD analysis of annealed host structure confirmed presence of cubic phase LLZO which provides higher ionic conductivity. We measured Li distribution on LLZO host structure before and after different cell cycling conditions and investigated the failure mechanism. We performed concentration depth profiles of 7Li and 6Li isotopes by Nuclear Reaction Analysis (NRA) using two different methods: Proton Induced Gamma-ray Emission (PIGE) and Proton Induced Alpha-particle Reaction (Particle-Particle reaction) and compared the results for accuracy. Depth profile of 7Li confirmed 33 at % Li at 0.44µm thickness before cycling which was increased after cycling. The Gaussian distribution of NRA data indicated a uniform Li depth profile in the dense layer. Through electrochemical testing, we measured that Li capacity loss after 5 and 25 charging cycles with 0.1C rate, 1.51mAh and 2.89mAh, respectively, in tri layered LLZO separator.

Tailoring particle size/morphology for the stable cathode performance of polygonal-shaped Li(Ni,Mn)2O4 single crystals

We regulate the particle size and crystallographic facet of single-crystal (SC) Li(Ni,Mn)2O4 (LNMO) cathode materials via flux-selective molten salt method. By simply adjusting Li2MoO4 or LiI as sintering aids, we synthesized size controlled SC particles, both small and large, and comparatively investigated their electrochemical behavior focusing on the lithiation/delithiation reactivity in conjunction with the particle size and surface planes. Considering the growth mechanism of a SC particles with a specific crystal plane, such particle size control is not determined solely by the synthetic condition but must also consider the interfacial energy of the crystal planes in conjunction with the fluxes what we used. While the initial charge capacity is similar, the given cathode using a small SC LNMO (using LiI) with uniform particle sizes (≤5 μm) exhibits outstanding rate capability with stable capacity retention under changing current density, which indicates stable lithium transport during the repetitive electrochemical reactions. The dependency of the impedance response with change in the electrode resistances as well as the stability during the cycle reactions in conjunction with the post-mortem Li distribution by using laser-induced breakdown spectroscopy as a function of porosity change and cell degradation are thoroughly discussed from the standpoint of regulated particle property.

High-resolution Li depth profiling in a thin-film all-solid-state battery using TOF-ERDA

A quantitative understanding of the Li distribution inside all-solid-state Li-ion batteries is important for improving the performance of batteries. We constructed a time-of-flight (TOF) elastic recoil detection analysis (ERDA) system for operando measurements of thin-film Li-ion batteries. The TOF-ERDA measurement provides elementally resolved spectra with a depth resolution much higher than that of conventional stopper-foil ERDA. The Li depth profiles in a cathode film and solid electrolyte were obtained quantitatively to a depth of 100 nm using a 9-MeV Cu ion beam with reflection geometry. In this study, we conducted TOF-ERDA for a thin-film battery having a cathode made from LiCoO2, an oxide-based solid electrolyte [lithium aluminum titanium phosphate (LATP)], and an anode made from Fe2(MoO4)3 to demonstrate the ability of the measurement system and reveal the Li distribution near the interface with improved resolution. The depth resolution at the interface (30 nm from the surface) was estimated to be 12–14 nm. We quantitatively obtained the Li density in the LiCoO2 cathode and the variation in the Li distribution around the LiCoO2/LATP interface and inside the LATP electrolyte upon charging/discharging. TOF-ERDA is thus a powerful tool for the high-resolution quantitative depth analysis of Li in thin-film batteries in operando.

Lithium, rotation and metallicity in the open cluster M35

Context. Lithium (Li) abundance is an age indicator for G, K, and M stellar types, as its abundance decreases over time for these spectral types. However, despite all of the observational efforts made over the past few decades, the role of rotation, stellar activity, and metallicity in the depletion of Li is still unclear. Aims. Our purpose is to investigate how Li depletion is affected by rotation and metallicity in G and K members of the roughly Pleiades-aged open cluster M35. Methods. We have collected an initial sample of 165 candidate members observed with the WIYN/Hydra spectrograph. In addition, we have taken advantage of three previous spectroscopic studies of Li in M35. As a result, we have collected a final sample of 396 stars observed with the same instrument, which we have classified as non-members, possible non-members, possible members, and probable members of the cluster. We have measured iron abundances, Li equivalent widths, and Li abundances for the 110 M35 members added to the existing sample by this study. Finally, rotation periods for cluster members have been obtained from the literature or derived from Zwicky Transient Facility light curves. Results. We have confirmed that fast G and K rotators are Li-rich in comparison with slow rotators of similar effective temperature. This trend, which is also seen in previous studies, is more evident when binaries are not taken into account. Furthermore, while we derived an average metallicity of [Fe/H] = −0.26 ± 0.09 from our spectra, the distribution of Li in M35 is similar to those observed for the Pleiades and M34 open clusters, which have solar metallicity and slightly different ages. In addition, we have shown that an empirical relationship proposed to remove the contribution of the Fe I line at 670.75 nm to the blended feature at 670.78 nm overestimates by 5–15 mÅ the contribution of this iron line for M35 members. Conclusions. M35 fast G and K rotators have depleted less Li than their slower counterparts. Furthermore, a 0.2−0.3 dex difference in metallicity appears to make little difference in the Li distributions of open clusters with ages between 100 and 250 Myr.

Sustainable Anionic Redox by Inhibiting Li Cross-Layer Migration in Na-Based Layered Oxide Cathodes.

The irrational utilization of an anionic electron often accompanies structural degradation with an irreversible cation migration process upon cycling in sodium-layered oxide cathodes. Moreover, the insufficient understanding of the anionic redox involved cation migration makes the design strategies of high energy density electrodes even less effective. Herein, a P3-Na0.67Li0.2Fe0.2Mn0.6O2 (P3-NLFM) cathode is proposed with the in-plane disordered Li distribution after an in-depth remolding of the Li ribbon-ordered P3-Na0.6Li0.2Mn0.8O2 (P3-NLM) layered oxide. The disordered Li sublattice in the transition metal slab of P3-NLFM leads to the dispersed |O2p orbitals, the lowered charge transfer gap, and the suppressed phase transition at high voltages. Then the enhanced Mn-O interaction and electronic stability are disclosed by the crystal orbital Hamilton population (COHP) analysis at high voltage in P3-NLFM. Furthermore, ab initio molecular dynamics (AIMD) simulation suggests the order/disorder of the transition metal layer is highly correlated with the stability of the Li sublattice. The cross-layer migration and loss of Li in P3-NLM are suppressed in P3-NLFM to enable the high reversibility upon cycling. As a result, the P3-NLFM delivers a high capacity of 163 mAh g-1 without oxygen release and an enhanced capacity retention of 81.9% (vs 42.9% in P3-NLM) after 200 cycles, which constitutes a promising approach for sustainable oxygen redox in rechargeable batteries.

Diffusion-Optimized Long Lifespan 4.6V LiCoO2: Homogenizing Cycled Bulk-To-Surface Li Concentration with Reduced Structure Stress.

Increasing the charging cut-off voltage (e.g., 4.6V) to extract more Li ions are pushing the LiCoO2 (LCO) cathode to achieve a higher energy density. However, an inhomogeneous cycled bulk-to-surface Li distribution, which is closely associated with the enhanced extracted Li ions, is usually ignored, and severely restricts the design of long lifespan high voltage LCO. Here, a strategy by constructing an artificial solid-solid Li diffusion environment on LCO's surface is proposed to achieve a homogeneous bulk-to-surface Li distribution upon cycling. The diffusion optimized LCO not only shows a highly reversible capacity of 212mAhg-1 but also an ultrahigh capacity retention of 80% over 600cycles at 4.6V. Combined in situ X-ray diffraction measurements and stress-evolution simulation analysis, it is revealed that the superior 4.6V long-cycled stability is ascribed to a reduced structure stress leaded by the homogeneous bulk-to-surface Li diffusion. This work broadens approaches for the design of highly stable layered oxide cathodes with low ion-storage structure stress.

Research on the energy properties and the storage stability of Al–Si–Li ternary alloy powders

To solve the problems of storage stability and compatibility of the Al–Li alloy powders, a series of Al–Si–Li alloy powders containing two-phase structure were prepared based on Al–Si–Li ternary phase diagram. The energy release, attenuation and compatibility of the Al–Si–Li alloy powders were studied by oxygen bomb calorimeter, XRD, SEM, TG-DSC and SIMS. As the content of the AlSiLi intermetallic compound phase increased, the measured mass combustion enthalpies increase before decreasing. When the proportion of the AlSiLi intermetallic compound phase is 20 wt.% (denoted as 20%-ASL), it has the maximum mass combustion enthalpy (31729 J⋅g−1) which is higher than the theoretical mass enthalpy of the pure aluminum powder (31000 J⋅g−1). The aging test of the 20%-ASL alloy powder show that its measured mass combustion enthalpy only decreased by 5.5 % (from 31739 J⋅g−1 to 29921 J⋅g−1), along with the thermal oxidation weight gain decreasing from 95.82 % to 80.04 %, while mass combustion enthalpy of the Al–Li alloy powder with the same Li content decreased by 17.5 % (from 30325 J⋅g−1 to 25031 J⋅g−1), and the weight gain decreased from 96.68 % to 41.05 %. This indicates that the AlSiLi phase effectively improves the oxidation resistance and storage stability of the Al–Li alloy powders. To explain this, surface Li distribution of the 20%-ASL alloy powder was analyzed by SIMS. The results show that the AlSiLi phase can immobilize Li inside the particles to reduce surface Li content from 2.920 × 106 to 1.439 × 106 and improve its oxidation resistance, thereby improving its storage stability and compatibility.

Electrodeposited Lithiophilic Zn Thin Film on the Current Collector for Improved Cyclability of Anode-Free Lithium Metal Battery

Anode-free lithium metal batteries (AFMBs) are recently presented as the new generation of Li metal batteries benefiting high gravimetric and volumetric energy densities due to the zero excess lithium. However, poor electrochemical stability and maximum cyclability of around 40-50 cycles due to the zero excess Lithium prevent the AFLMBs to be functional1. Here, lithiophilic electrodeposited Zn thin film on the current collector is reported in order to decrease the lithium nucleation overpotential and improve the plating/stripping process during alloying and dealloying. Moreover, columbic efficiency is increased by applying more zinc coated on the cupper current collector and by providing a more hospitable site for Li nuclei to plate2. Due to the alloy formation of Li-Zn, more conformal Li growth on the current collector is provided and homogeneous Li distribution and smooth morphology are observed by SEM images. The cells in different zinc thin layer coating are cycled with different current densities as well as long-term cycling by galvanostatic cycling charge-discharge cycling. As a result, increasing the thin film thickness up to 1 micron significantly enhances the electrochemical stability of the cells such as higher columbic efficiency and cyclability, lower Li nucleation overpotential. Finally, the Li-ion chemical diffusion coefficients DLi, are evaluated by galvanostatic intermittent titration technique (GITT) and electrochemical impedance spectroscopy (EIS) and the results are compared to each other3.References Maddukuri, S. et al. On the challenge of large energy storage by electrochemical devices. Electrochim Acta 354, 136771 (2020).Merso, S. K. et al. An in-situ formed bifunctional layer for suppressing Li dendrite growth and stabilizing the solid electrolyte interphase layer of anode free lithium metal batteries. J Energy Storage 56, 105955 (2022).Xie, J. et al. Determination of Li-ion diffusion coefficient in amorphous Zn and ZnO thin films prepared by radio frequency magnetron sputtering. Thin Solid Films 519, 3373–3377 (2011).

(Invited) Neutrons as a Powerful Tool for Better Understanding Electrochemistry on Various Length and Time Scales

Today, sophisticated methods are applied to gain a deeper understanding of processes in in-situ electrochemistry. There are few ways to study electrochemically relevant processes on different length and/or time scales without affecting the processes themselves. Probes that cover a sufficient volume of the sample non-destructively and are sensitive to the important charge carriers are in great demand. For such purposes, neutrons are an ideal candidate to perform this task because they have relatively high sensitivity to the light chemical elements, can distinguish neighboring elements of the periodic table, have a large beam cross-section, and possess high penetration depth for many types of materials.Therefore, many open questions are addressed to unique neutron techniques tailored to solve the open problems. This article gives an overview of some examples to show the advantages of using neutrons for special questions on different length and time scales [1]. For surface investigations of electrodes, the neutron depth profiling method (NDP) is suitable for characterizing the Li distribution up to the nano range [2]. Neutron diffraction is a powerful tool to better understand cylindrical cells at the atomic level, e.g. during the intercalation process [3]. Another strong field of neutrons is the monitoring of the wetting process during the electrolyte filling of prismatic hard case cells on the macroscopic length scale using the neutron imaging technique [4].

Towards Operando Secondary Ion Mass Spectrometry Imaging of Lithium Redistribution in Solid-State Lithium-Ion Batteries: Correlation of Structural, Chemical and Electrochemical Characteristics

Innovations in lithium-ion batteries rely crucially on the availability of advanced characterization techniques. High-resolution chemical imaging of low-Z elements e.g., lithium (Li) is often difficult in many conventional chemical analysis techniques such as Energy-Dispersive X-ray Spectroscopy. High-resolution Secondary Ion Mass Spectrometry (SIMS) imaging is a well-known technique for the analysis of all elements including isotopes. For this reason, SIMS imaging is used in numerous studies related to Li-ion battery research. While direct imaging of Li in post-mortem battery components is helpful to understand parts of the degradation mechanisms, a complete dynamic view of the evolution of the Li distribution at high resolution during operation (‘operando’) of batteries is required to fully understand the local interfacial processes, charge transport characteristics and the degradation mechanisms. A few reports presenting operando Time-of-Flight SIMS imaging of batteries have recently been published [1], but the lateral resolution demonstrated in these reports is not adequate to study local processes that occur at nanoscale.In order to demonstrate operando SIMS chemical imaging with sub-20 nm lateral resolution, we developed a novel operando methodology suitable for Focused Ion Beam (FIB)-SIMS imaging and analysis (see Fig. 1). An in-house designed magnetic-sector mass spectrometer [2] attached to a ThermoFisher SCIOS Ga+ FIB is used for SIMS chemical imaging. A special operando sample holder was designed to enable electrochemical cycling of batteries within the FIB-SIMS instrument. The micromanipulator inside the FIB (typically used for preparing thin lamellae for Transmission Electron Microscopy) is used to contact one of the battery electrodes through the operando sample holder and complete the electrical circuit. An external potentiostat is then connected to the instrument to drive the charging/discharging of batteries. The proof-of-concept experiments were performed using Li|Li7La3Zr2O12|Li symmetric half-cells. Galvanostatic cycling was performed in-situ inside the FIB-SIMS instrument until the sample failed. SIMS chemical mapping revealed a redistribution of Li during cycling. Lithium rich phases appeared during cycling which likely percolated through grain-boundaries and pores of the solid electrolyte causing a short-circuit failure. These results validate our methodology for operando analysis of Li-ion batteries with the possibility to obtain SIMS chemical images with sub-20 nm lateral resolution [3].This work was funded by the Luxembourg National Research Fund (FNR) through the grant INTER/MERA/20/13992061 (INTERBATT).[1] Y. Yamagishi, et al., J. Phys. Chem. Lett. 2021, 12, 19, 4623–4627[2] O. De Castro, et al., Analytical Chemistry, 2022, 94, 30, 10754–10763.[3] L. Cressa, et al., Analytical Chemistry, 2023, under review. Figure 1

Facilitating the Systematic Nanoscale Study of Battery Materials by Atom Probe Tomography through in‐situ Metal Coating

AbstractThrough its capability for 3D mapping of Li at the nanoscale, atom probe tomography (APT) is poised to play a key role in understanding the microstructural degradation of lithium‐ion batteries (LIB) during successive charge‐ and discharge cycles. However, APT application to materials for LIB is plagued by the field induced delithiation (deintercalation) of Li‐ions during the analysis itself that prevents the precise assessment of the Li distribution. Here, we showcase how a thin Cr‐coating, in‐situ formed on APT specimens of NMC811 in the focused‐ion beam (FIB), preserves the sample's integrity and circumvent this deleterious delithiation. Cr‐coated specimens demonstrated remarkable improvements in data quality and virtually eliminated premature specimen failures, allowing for more precise measurements via. improved statistics. Through improved data analysis, we reveal substantial cation fluctuations in commercial grade NMC811, including complete grains of LiMnO. The current methodology stands out for its simplicity and cost‐effectiveness and is a viable approach to prepare battery cathodes and anodes for systematic APT studies.

Investigating the geochemical behavior and exploration potential of lithium in brines; a case study of Bam salt plug, Zagros Zone, southern Iran

Lithium (Li) is a scarce and technologically important element; the demand for which has recently increased due to its extensive consumption, particularly in manufacturing of Li-ion batteries, renewable energy, and electronics. Li is extracted from brines, pegmatite, and clay minerals; though extraction from brines is economically preferred. More than 200 salt plugs are in the Zagros Mountains which represent potential sources for Li exploration. This preliminary study collected first data on the abundance of Li in the salt plugs in southern Iran, and investigated Li distribution during evaporation of halite-producing brine ponds. The XRD analysis of powdered samples showed that gypsum and halite are the dominant solid phases in the ponds in which Li is concentrated in gypsum, while halite is depleted of Li. ICP-MS and ICP-OES analyses showed that Li in brines is concentrated during the evaporation by factors up to 28 with total contents up to 40 mg kg‒1. The Mg/Li ratio was higher than 70, which makes the brine unsuitable for conventional evaporation extraction techniques which require Mg/Li ratios of less than 6. Considering that 25 mg kg‒1 is a suitable concentration of Li for exploration purposes, the results of this study suggest that with the advancement of extraction techniques, the depletion of presently used high-grade Li reserves, the increasing demand for lithium, the need for extraction from diverse sources, and the exploration of new resources, the salt plug brines have an exploratory potential for Li in the future.