Graphite Intercalation Compounds Research Articles

Removal of reactive black 5 in water using adsorption and electrochemical oxidation technology: kinetics, isotherms and mechanisms

AbstractIn this work, a novel graphite intercalation compound (GIC) particle electrode was used to investigate the adsorption of Reactive Black 5 (RB5) and the electrochemical regeneration in a three-dimensional (3D) electrochemical reactor to recover its adsorptive capacity. Various adsorption kinetics and isotherm models were used to characterise the adsorption behaviour of GIC. Several adsorption kinetics were modelled using linearised and non-linearised rate laws to evaluate the viability of the sorption process. Studies on the selective removal of RB5 dyes from binary mixture in solution were evaluated. RSM optimisation studies were integrated with ANOVA analysis to provide insight into the significance of selectivity reversal from the salting effect of textile dye solution on GIC adsorbent. A unique range of adsorption kinetics and isotherms were used to evaluate the adsorption process. Non-linear models best simulated the kinetic data in the order: Elovich > Bangham > Pseudo-second-order > Pseudo-first-order. The Redlich–Peterson isotherm was calculated to have a dye loading capacity of 0.7316 mg/g by non-linear regression analysis. An error function analysis with ERRSQ/SSE of 0.1390 confirmed the accuracy of dye loading capacity predicted by Redlich–Peterson isotherm using non-linear regression analysis. The results showed that Redlich–Peterson and SIPS isotherm models yielded better fitness to experimental data than the Langmuir type. The best dye removal efficiency achieved was ~ 93% using a current density of 45.14 mA/cm2, whereas the highest TOC removal efficiency achieved was 67%.

Deciphering Anion-Modulated Solvation Structure for Calcium Intercalation into Graphite for Ca-Ion Batteries.

Co-intercalation reactions make graphite a feasible anode in Ca ion batteries, yet the correlation between Ca ion intercalation behaviors and electrolyte structure remains unclear. This study, for the first time, elucidates the pivotal role of anions in modulating the Ca ion solvation structures and their subsequent intercalation into graphite. Specifically, the electrostatic interactions between Ca ion and anions govern the configurations of solvated-Ca-ion in dimethylacetamide-based electrolytes and graphite intercalation compounds. Among the anions considered (BH4 -, ClO4 -, TFSI- and [B(hfip)4]-), the coordination of four solvent molecules per Ca ion (CN=4) leads to the highest reversible capacities and the fastest reaction kinetics in graphite. Our study illuminates the origins of the distinct Ca ion intercalation behaviors across various anion-modulated electrolytes, employing a blend of experimental and theoretical approaches. Importantly, the practical viability of graphite anodes in Ca-ion full cells is confirmed, showing significant promise for advanced energy storage systems.

Deciphering Anion‐Modulated Solvation Structure for Calcium Intercalation into Graphite for Ca‐Ion Batteries

AbstractCo‐intercalation reactions make graphite a feasible anode in Ca ion batteries, yet the correlation between Ca ion intercalation behaviors and electrolyte structure remains unclear. This study, for the first time, elucidates the pivotal role of anions in modulating the Ca ion solvation structures and their subsequent intercalation into graphite. Specifically, the electrostatic interactions between Ca ion and anions govern the configurations of solvated‐Ca‐ion in dimethylacetamide‐based electrolytes and graphite intercalation compounds. Among the anions considered (BH4−, ClO4−, TFSI− and [B(hfip)4]−), the coordination of four solvent molecules per Ca ion (CN=4) leads to the highest reversible capacities and the fastest reaction kinetics in graphite. Our study illuminates the origins of the distinct Ca ion intercalation behaviors across various anion‐modulated electrolytes, employing a blend of experimental and theoretical approaches. Importantly, the practical viability of graphite anodes in Ca‐ion full cells is confirmed, showing significant promise for advanced energy storage systems.

Intercalation of AlCl3 in microcrystalline graphite via high-temperature mechanochemical method for electromagnetic wave absorption

Given their distinct microstructure, Graphite intercalation compounds (GICs) provide significant application potential in the field of electromagnetic wave absorption (EMWA). Herein, microcrystalline graphite (MG) and AlCl3 were employed to fabricate xAlCl3-yMGIC powders via a novelty high-temperature mechanochemical method (HTMC). The impact of AlCl3 addition on the microstructure and EMWA properties, the possible EMWA mechanisms of the xAlCl3-yMGIC powder, were thoroughly evaluated additionally. The results demonstrate that the intercalation of AlCl3 can significantly improve the EMWA properties of the raw MG. Furthermore, the EMWA properties of the xAlCl3-yMGIC powders can be tuned by adapting the AlCl3 contents and the matching thickness. Among them, when the mass ratio of MG to AlCl3 is 1:1 and a sample filling ratio of only 15 wt%, the minimum reflection loss (RLmin) of the AlCl3-MGIC powders attains −37.6 dB at 9.52 GHz and a matching thickness of 1.6 mm, covering an effective absorption bandwidth (EAB, RL < -10 dB) of 8.56 − 10.62 GHz. This work presents an innovative concept for the high-value application of MG in the domains of EMWA and the short-process preparation of GICs.

Superior decomposition of xenobiotic RB5 dye using three-dimensional electrochemical treatment: Response surface methodology modelling, artificial intelligence, and machine learning-based optimisation approaches

The highly efficient electrochemical treatment technology for dye-polluted wastewater is one of hot research topics in industrial wastewater treatment. This study reported a three-dimensional electrochemical treatment process integrating graphite intercalation compound (GIC) adsorption, direct anodic oxidation, and ∙OH oxidation for decolourising Reactive Black 5 (RB5) from aqueous solutions. The electrochemical process was optimised using the novel progressive central composite design–response surface methodology (CCD–NPRSM), hybrid artificial neural network–extreme gradient boosting (hybrid ANN–XGBoost), and classification and regression trees (CART). CCD–NPRSM and hybrid ANN–XGBoost were employed to minimise errors in evaluating the electrochemical process involving three manipulated operational parameters: current density, electrolysis (treatment) time, and initial dye concentration. The optimised decolourisation efficiencies were 99.30%, 96.63%, and 99.14% for CCD–NPRSM, hybrid ANN–XGBoost, and CART, respectively, compared to the 98.46% RB5 removal rate observed experimentally under optimum conditions: approximately 20 mA/cm2 of current density, 20 min of electrolysis time, and 65 mg/L of RB5. The optimised mineralisation efficiencies ranged between 89% and 92% for different models based on total organic carbon (TOC). Experimental studies confirmed that the predictive efficiency of optimised models ranked in the descending order of hybrid ANN–XGBoost, CCD–NPRSM, and CART. Model validation using analysis of variance (ANOVA) revealed that hybrid ANN–XGBoost had a mean square error (MSE) and a coefficient of determination (R2) of approximately 0.014 and 0.998 respectively, for the RB5 removal efficiency, outperforming CCD–NPRSM with MSE and R2 of 0.518 and 0.998, respectively. Overall, the hybrid ANN–XGBoost approach is the most feasible technique for assessing the electrochemical treatment efficiency in RB5 dye wastewater decolourisation.

Influence of Defects and Charges on the Colloidal Stabilization of Graphene in Water.

Mastering graphene preparation is an essential step to its integration into practical applications. For large-scale purposes, full graphite exfoliation appears as a suitable route for graphene production. However, it requires overpowering attractive van der Waals forces demanding large energy input, with the risk of introducing defects in the material. This difficulty can be overcome by using graphite intercalation compounds (GICs) as starting material. The greater inter-sheet separation in GICs (compared with graphite) allows the gentler exfoliation of soluble graphenide (reduced graphene) flakes. A solvent exchange strategy, accompanied by the oxidation of graphenide to graphene, can be implemented to produce stable aqueous graphene dispersions (Eau de graphene, EdG), which can be readily incorporated into many processes or materials. In this work, we prove that electrostatic forces are responsible for the stability of fully exfoliated graphene in water, and explore the influence of the oxidation and solvent exchange procedures on the quality and stability of EdG. We show that the amount of defects in graphene is limited if graphenide oxidation is carried out before exposing the material to water, and that gas removal of water before the incorporation of pre-oxidized graphene is advantageous for the long-term stability of EdG.

Scalable Synthesis of Bilayer Graphene at Ambient Temperature.

In this work, we develop for the first time a facile chemical lithiation-assisted exfoliation approach to the controllable and scalable preparation of bilayer graphene. Biphenyl lithium (Bp-Li), a strong reducing reagent, is selected to realize the spontaneous Li-intercalation into graphite at ambient temperature, forming lithium graphite intercalation compounds (Li-GICs). The potential of Bp-Li (0.11 V vs Li/Li+), which is just lower than the potential of stage-2 lithium intercalation (0.125 V), enables the precise lithiation of graphite to stage-2 Li-GICs (LiC12). Intriguingly, the exfoliation of LiC12 leads to the bilayer-favored production of graphene, giving a high selectivity of 78%. Furthermore, the mild intercalation-exfoliation procedure yields high-quality graphene with negligible structural deterioration. The obtained graphene exhibits ultralow defect density (ID/IG ∼ 0.14) and a considerably high C/O ratio (∼29.7), superior to most current state-of-the-art techniques. This simple and scalable strategy promotes the understanding of chemical Li-intercalation methods for preparing high-quality graphene and shows great potential for layer-controlled engineering.

The Behavior of the Intercalant AlCl4 Anion during the Formation of Graphite Intercalation Compound: An X‐ray Absorption Fine Structure Study

This work aims to study the insertion of anion in the crystalline structure of oriented pyrolytic graphite (PG) at the point of view of the anion itself. The electronic and atomic structures of the anion at different intercalation stages are studied. In particular double‐edge (bicolor) X‐ray absorption spectroscopy at the Al and Cl K‐edges is carried out, highlighting a contraction of the anion bonding at the highest intercalation degree obtained electrochemically (stage 3), while the electronic population changes for both the edges upon cycle.

Diglyme as a Promoter for the Electrochemical Formation of Quaternary Graphite Intercalation Compounds Containing two Different Types of Solvents

AbstractCo‐intercalation using ether‐based electrolytes renders graphite as a promising anode material in sodium‐ion batteries (SIBs). While most research on electrochemical solvent co‐intercalation in graphite has focused on linear ethers such as mono‐, di‐, tri‐, tetra‐, and penta‐glyme, we herein investigate the possibility of reversible electrochemical co‐intercalation with alternative solvents, especially cyclic ethers tetrahydrofuran (THF) and 1,3‐dioxolane (DOL), which show no signs of co‐intercalation on their own. We demonstrate, however, that this reaction becomes feasible when incorporating diethylene glycol dimethyl ether (2G, diglyme) as an additive. Operando X‐ray diffraction and ex‐situ ss‐NMR techniques are employed comprehensively to understand the co‐intercalation reaction of these cyclic ethers, along with Na+‐glymes, into graphite during cycling. When using these mixed electrolytes i. e., THF/2G and DOL/2G, the voltage profiles changes compared to the pure glyme‐based electrolyte, while showing comparable specific capacities and good long‐term durability. Overall, we propose that even trace amounts of diglyme prompt the co‐intercalation of THF and DOL into graphite layers. This leads to the formation of quaternary graphite intercalation compounds (q‐GICs), expanding beyond the realm of ternary graphite intercalation compounds (t‐GICs).

Relaxation Analysis of Silicon Monoxide-Graphite Composite Anode

Relaxation analysis based on X-ray diffraction has been carried out on SiO-graphite composite anode of the lithium-ion battery, focusing on the lithium migration during the relaxation accompanied by the stage change of lithium graphite intercalation compound (Li-GIC). After the termination of electrochemical lithium insertion, XRD peaks of Li-GIC change from stage I into stage II during the relaxation. Due to the slower reaction for lithiation of SiO in comparison with the intercalation of Li-GIC, lithium migration from Li-GIC toward SiO to change the Li-GIC from stages I into II toward the equilibrium lithium distribution. The stage change is more apparent for higher current density at the charging, presumably due to the core–shell model of lithium concentration of SiO after charging.

Li Dynamics in Mixed Ionic-Electronic Conducting Interlayer of All-Solid-State Li-metal Batteries.

Lithium-metal (Li0) anodes potentially enable all-solid-state batteries with high energy density. However, it shows incompatibility with sulfide solid-state electrolytes (SEs). One strategy is introducing an interlayer, generally made of a mixed ionic-electronic conductor (MIEC). Yet, how Li behaves within MIEC remains unknown. Herein, we investigated the Li dynamics in a graphite interlayer, a typical MIEC, by using operando neutron imaging and Raman spectroscopy. This study revealed that intercalation-extrusion-dominated mechanochemical reactions during cell assembly transform the graphite into a Li-graphite interlayer consisting of SE, Li0, and graphite-intercalation compounds. During charging, Li+ preferentially deposited at the Li-graphite|SE interface. Upon further plating, Li0-dendrites formed, inducing short circuits and the reverse migration of Li0. Modeling indicates the interface has the lowest nucleation barrier, governing lithium transport paths. Our study elucidates intricate mechano-chemo-electrochemical processes in mixed conducting interlayers. The behavior of Li+ and Li0 in the interlayer is governed by multiple competing factors.

Fe3O4-modified FeCl3/graphite intercalation compound confinement architecture for unleashing the high-performance anode potential of lithium-ion batteries.

The ferric trichloride (FeCl3)-intercalated graphite intercalation compound (GIC) has high reversible capacity and bulk density, making it a promising anode material for lithium ion batteries. However, its practical application has been limited by the poor cycle performance due to chloride dissolution and shuttling issues. Herein, FeCl3-GIC is used as the precursor material to synthesize a nano-Fe3O4-modified intercalation material by a solvothermal method. The Fe3O4 moiety at the edge of FeCl3-GIC provides a robust chemical anchoring effect on the chlorides. Together with the two-dimensional graphite layer, it forms a confinement space, which effectively immobilizes soluble chlorides. Attributed to the distinctive structural design, the Fe3O4-FeCl3/GIC 25% C electrode offers a high reversible capacity of 691.4 mA h g-1 at 1000 mA g-1 after 400 cycles. At 2000 and 5000 mA g-1, the reversible specific capacity of the Fe3O4-FeCl3/GIC 25% C electrode is 345.6 and 218.3 mA h g-1, respectively. This work presents an innovative method to improve the lifespan of GIC.

Melaminin Yerinde Polimerizasyonu ile Grafit Katmanlarının Genişletilmesi Üzerine Bir Çalışma

Graphene, renowned for its honeycomb lattice structure formed by densely packed sp2 hybridized carbon atoms, possesses exceptional electronic, thermal, chemical, and mechanical properties. The van der Waals-coupled graphene layers give rise to the well-known AB stacking, forming graphite. Despite the existence of several methods for graphite production, the production of graphene on a large scale remains challenging due to the lack of efficient techniques and the introduction of structural defects during the production process. Exfoliated graphite (EG), a potential solution, is typically derived from the thermal treatment of graphite intercalation compounds (GICs). Melamine, notably displaying significant expansion properties at low temperatures, has been used as an intercalation compound in limited studies. This study investigates the potential of melamine to induce the expansion of graphene layers when incorporated into graphite and subjected to thermal treatment. Raman and X-ray diffraction analyses were employed to assess structural changes.

Investigation of Heteroatom Doped Graphene Anode for High-Capacity Alkali Metal-Ion Batteries

The drastic growth of Li-ion batteries (LIBs) in global electronic market and low crustal abundance of Li demands for more abundant alternatives such as sodium and potassium having similar electrochemical properties. Sodium-ion battery (SIB) and potassium-ion battery (PIB) can be used “side-by-side” to LIB which can help battery technology progress efficiently. 1Graphite has been a commercial anode in LIB due to its low cost, high abundance, high electrical conductivity, with a theoretical storage capacity (LiC6) of 372 mAh g-1. In contrast the utilization of graphite in SIBs and PIBs is challenging. This is due to the large radius and unstable graphite-intercalation compounds (NaC64) giving very low theoretical capacity of 30 mAh g-1. In PIBs, graphite exhibits a theoretical capacity of 279 mAh g-1 but suffers from poor stability due to huge volume expansion (60%) in fully potassiated state (KC8). Thus, focus is now shifted on to class of amorphous carbon materials such as hard carbon, soft carbon, graphene etc. with variations in micro-structures, larger interlayer spacing, and defect rich sites promoting enhanced capacity and stability even at high current densities. 2 In my presentation I will be discussing about the synthesis of heteroatom doped graphene with high charge storage and stability for LIB, SIB and PIB compared to graphite. The heteroatom doped graphene exhibits nearly 1000 mAh g-1 (LIB), 380 mAh g-1 (SIB) and 379 mAh g-1 (PIB) at a low current density of 25 mAg-1. Additionally, the elastic nature of ultrathin graphene nanosheets aids in attaining long term cyclability at 1 A g-1 with high-capacity retention of 83% for 300 cycles (LIB), 73% for 400 cycles (SIB) and 91% for 600 cycles (PIB). The enhanced stability in case of PIB, is attributed to optimizing solid electrolyte interphase (SEI) components and improving interfacial reaction kinetics at high current densities. Choice of high concentrated electrolyte (HCE) over conventional KPF6 in EC:DEC determines the nature of SEI and thereby helps in achieving cycling stability. The stability in SEI is characterized via voltage profile and understanding chemical composition by ex-situ X-ray photoelectron spectroscopy. Robust SEI in HCE is due to difference in anion structure studied by Raman spectroscopy.Furthermore, the charge-discharge mechanism, alkali ion diffusion kinetics and structure-activity relationship of electrode materials was investigated using various techniques like cyclic voltammetry profiles at different scan rates and Galvanostatic intermittent titration technique (GITT). Additionally, deeper insights into the fundamental understanding of interfacial and bulk behavior were provided with the help of in-situ Raman spectroscopy and in-situ potentiostatic electrochemical impedance spectroscopy (PEIS) analysis. The investigation of peak area and shift in D (defect) and G (graphitic) band analyzed from in-situ Raman studies helped in understanding the evolution and reversibility of alkali ion storage behavior during charging and discharging. PEIS analysis gave us a thorough understanding of the evolution of stable SEI on charging-discharging and after cycling, which helps us to understand the long-term stability in LIB, SIB and PIB.

Significance of electrolyte additive molecule structure in stabilizing interphase in LiNi0.8Co0.1Mn0.1O2/artificial graphite pouch cells at high temperature

Electrolyte additives are pivotal for stable cycling of rechargeable lithium ion batteries (LIBs), which dictate the creation of the protective interphases on electrodes. Many additives have been proposed but less knowledge is available on the relationship between their molecular structure and interphase stability. This research compares three electrolyte additives with systematic changes in their cyclic ethylene sulfate structures, i.e. 1,3,2−dioxathiolane−2,2−dioxide (DTD), 4−methyl−1,3,2−dioxathiolane−2,2− dioxide (MDTD) and 4−propyl−[1,3,2] dioxathiolane−2,2−dioxide (PDTD) to investigate their effects on the performance of LiNi0.8Co0.1Mn0.1O2/artificial graphite lithium ion pouch cells at high temperature. Comprehensive characterizations reveal that all these additives exhibit similar oxidative and reductive activity, but they lead to diverse long−term cycling performance at 55 °C. The sulfate species derived from the propyl functionalized PDTD form the most effective cathode and anode interphases in preventing electrolyte decomposition and improving cycling capabilities, with capacity retention of 85 % after 900 cycles at 55 °C. Meanwhile, a super stable (3000 cycles), high−capacity (1668 mAh) pouch cell is constructed at 25 °C. This work paves a road to design electrolyte additive more efficiently for high−energy−density LIBs at elevated temperature.

FeSe2 Graphite Intercalation Compound as Anode Materials for Sodium Ion Batteries

FeSe₂ Graphite Intercalation Compound as Anode Materials for Sodium Ion Batteries

Reversible Insertion of [AlCl4 ]- Superhalides in Graphite.

Graphite-based dual-ion batteries are with potential higher energy density, making them a unique candidate in energy storage systems. However, anion insertion into graphite in aqueous environment remains a significant challenge. Herein, we report that the reversible insertion of Al-Cl superhalide into expanded graphite (EG) delivers an ultrahigh specific capacity of ~171 mAh g-1 from an aqueous deep eutectic solvent (DES) gel electrolyte of 50 m ChCl+5 m AlCl3 . High-resolution transmission electron microscopy (HRTEM), Raman spectra and X-ray diffraction (XRD) show that the EG generates turbostratic structure during Al-Cl superhalide (de)insertion instead of presenting typical graphite intercalation compounds (GIC), thus attributing to the high capacity during Al-Cl superhalide insertion.

New Template Synthesis of Anomalously Large Capacity Hard Carbon for Na‐ and K‐Ion Batteries

AbstractHard carbon (HC) is a promising negative‐electrode material for Na‐ion batteries. HC electrochemically stores Na+ ions, resulting in a non‐stoichiometric chemical composition depending on their nanoscale structure, including the carbon framework, and interstitial pores. Therefore, optimizing these structures for Na storage by altering the synthesis conditions can enhance the capacity of Na‐ion batteries. In this study, HCs using MgO, ZnO, and CaCO3 as nanopore templates are systematically investigated, and the ZnO template is found to be particularly effective. By optimizing the concentration of ZnO embedded in the carbon matrix, utilizing a blend of zinc gluconate, and zinc acetate as starting materials, the optimal ZnO‐template HC demonstrates a reversible capacity of 464 mAh g−1 (corresponding to NaC4.8) with high initial coulombic efficiency of 91.7% and low average potential of 0.18 V versus Na+/Na. Thus, a Na‐ion battery full cell consisting of Na5/6Ni1/3Fe1/6Mn1/6Ti1/3O2 and the optimized ZnO‐template HC demonstrates a remarkable energy density of 312 Wh kg−1, comparable to that of a Li‐ion battery with LiFePO4 and graphite. Moreover, the ZnO‐template HC in a K half‐cell also displays a significant capacity of 381 mAh g−1, that is, KC5.8 where the alkali content is higher than stage‐1 graphite intercalation compounds, LiC6 and KC8.

Solvent Co-Intercalation for Electrochemical Energy Storage

One of the major differences between sodium- and lithium-ion batteries (SIBs and LIBs) is how the ions electrochemically react with graphite, where large amounts of lithium can be stored in the graphite galleries, but sodium cannot form thermodynamically stable, high capacity binary graphite intercalation compounds (b-GICs).[1] In 2014, however, it was discovered that graphite had a much greater capacity to reversibly store sodium-ions than previously thought – but only when using ether based electrolytes.[2] The increased storage capabilities in ether based electrolytes comes about by the formation of a ternary graphite intercalation compound (t-GIC), whereby the sodium-ion is intercalated along with it solvation shell. Thus, graphite can store solvated sodium-ions, but not bare ones. This unconventional mechanism is already known to occur for certain solvents, such as propylene carbonate, but was always thought to be accompanied by complete destruction of the graphite.[3]Since then, several studies have been conducted on electrochemical solvent co-intercalation for energy storage,[4] but the topic is still unexplored. Several fundamental questions have received quite conflicting answers – Especially with regards to the SEI and the reaction mechanism - the system displaying both clear staging in graphite, with at least one well defined plateau for stage I formation, but also large pseudocapacitive features. Following development on electrochemical double-layers and confined electrolytes,[5] it appears in systems where reversible electrochemical co-intercalation occurs the system will display both clear faradaic and non-faradaic properties. This is indeed what is seen, as the system offers a moderate amount of energy density, similar to batteries, while still being highly reversible and extremely fast, even at low temperatures, similar to capacitors.[6,7] Moreover, the reaction is tunable by altering the electrolyte composition - opening up for a great deal of exploration.[8] These properties, along with using abundant materials, makes the system applicable to problems where both the properties of capacitors and batteries are needed, such as in grid storage.This talk purport to summarize our research activity on electrochemical solvent co-intercalation phenomena, ranging from fundamental questions such as how to detect solvent co-intercalation, to the nature of the electrochemical reaction. We also present our work on using solvent co-intercalation in full cells, as well as a new type of battery where both the anode and cathode operate by a solvent co-intercalation mechanism – the solvent co-intercalation battery (CoIB).[9] References [1] O. Lenchuk, P. Adelhelm, D. Mollenhaur, Phys. Chem. Chem. Phys., 21 (2019) 19378-19390.[2] B. Jache, P. Adelhelm, Angewandte Chemie, 126 (2014) 10333-10337.[3] K. Xu, Chemical reviews 104 (2004), 4303-4418[4] J. Park, Z-L. Xu, K. Kang, Frontiers in Chemistry, 8 (2020), 2296-2646[5] S. Fleischmann, Y. Zhang, X. Wang, P. T. Cummings, J. Wu, P. Simon, Y. Gogotsi, V. Presser, V. Augustyn, Nature Energy, 7 (2022),222-228.[6] J. Chen, Y. Peng, Y. Yin, Z. Fang, Y. Cao, Y. Wang, X. Dong, Y. Xia, Angew. Chem. Int. Ed. 60 (2021) 23858.[7] Z-L. Xu, G. Yoon, K-Y. Park, H. Park, O. Tamwattana, S. J. Kim, W. M. Seong, K. Kang, Nat. Commun. 10 (2019) 2598.[8] B. Jache, J. O. Binder, T. Abe, P. Adelhelm, Phys. Chem. Chem. Phys., 18 (2016) 14299-14316[9] G. A. Ferrero, G. Åvall, K. A. Mazzio, Y. Son, K. Janßen, S. Risse, P. Adelhelm, Adv. Energy Mater. 12 (2022) 2202377

Dual-Protective Artificial Layer on Lithium Metal Anodes for Improved Electrochemical Performance – an in-Depth Morphological and Electrochemical Characterization

The energy density of traditional lithium ion batteries (LIB) based on graphite intercalation compounds as negative active material is approaching the theoretical limit and are restricting the increasing demand of high energy battery systems for various mobile and stationary applications.[1] Consequently, the implementation of active materials with high specific energies became prerequisite for future battery technologies. Therein, lithium metal is one of the most promising anode active materials to replace state-of-the-art graphite active materials, due to its high theoretical capacity and low electrode potential.[2]However, poor cycling performance, low Coulombic efficiency, and the uncontrollable Li dendrite growth during lithium electrodeposition/dissolution processes remain as predominant challenges.[3] Several approaches were proposed to eliminate dendrite formation by implementing a mechanically and electrochemically stable artificial solid electrolyte interphase or artificial protective coatings (aPC) by in-situ or ex-situ surface modifications.[4] These designed aPCs should feature an increased and uniform Li-ion flux, mechanical robustness and/or protection against electrolyte decomposition, during substantial volume changes upon electrodeposition/dissolution. However, aPCs fail to support long term cycling stability in lithium metal batteries since they cannot cover all requirements.[5] Therefore, it is crucial to design and understand dual- and multilayer system that address multiple aforementioned requisites.[6] In this contribution, a dual-protective artificial layer is constructed on Li metal by physical vapor deposition consisting of an intermetallic LiZn-layer, providing a uniform Li-ion flux, and an inorganic Li3N-layer, which is electron-blocking, thus reveal surface protective properties. In addition to electrochemical characterization, the Li electrodeposition/dissolution behavior was investigated by cryo-FIB/SEM analysis to unravel the mechanism behind the enhanced cycling stability in symmetrical Li||Li cells and cells with a layered oxide-based positive electrode.[1] R. Schmuch, R. Wagner, G. Hörpel, T. Placke, M. Winter, Nature Energy 2018, 3, 267.[2] J. Liu, Z. Bao, Y. Cui, E. J. Dufek, J. B. Goodenough, P. Khalifah, Q. Li, B. Y. Liaw, P. Liu, A. Manthiram, Y. S. Meng, V. R. Subramanian, M. F. Toney, V. V. Viswanathan, M. S. Whittingham, J. Xiao, W. Xu, J. Yang, X.-Q. Yang, J.-G. Zhang, Nature Energy 2019, 4, 180.[3] T. Placke, R. Kloepsch, S. Dühnen, M. Winter, Journal of Solid State Electrochemistry 2017, 21, 1939.[4] N. Delaporte, Y. Wang, K. Zaghib, Frontiers in Materials 2019, 6.[5] D. Lin, Y. Liu, Y. Cui, Nature Nanotechnology 2017, 12, 194.[6] S. Lee, K.-s. Lee, S. Kim, K. Yoon, S. Han, M. H. Lee, Y. Ko, J. H. Noh, W. Kim, K. Kang, Science Advances 2022, 8, 1.