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Blended positive electrodes consisting of mixtures of LiMn2O4 spinel (LMO) and layered LiNi0.5Mn0.3Co0.2O2 (NMC) have been studied by coupling electrochemical testing to operando synchrotron based X-ray absorption and powder diffraction experiments to shed light on their redox mechanism. Blending NMC with LMO results in enhanced energy density at high rates, with the composition with 25% LMO exhibiting the best electrochemical performance. Tests with a special electrochemical setup detecting the contribution of each blend component indicate that the effective current load on each blend component can be significantly different from the nominal rate and also varies as function of SoC. Operando studies enabled to monitor the evolution of oxidation state and changes in the crystal structure, which are in agreement with the expected behaviour of the individual components considering the material specific electrochemical current loads. These findings should contribute to a deeper mechanistic understanding of blended electrodes to foster a rational driven approach for their design.

We present a battery screening Python pipeline, VOLTA. It allows for a novel battery active material explorative workflow, prioritizing the cell level performance indicators, such as cell capacity and voltage profile. This is achieved by the construction of a starting dataset of both observed and virtual active materials from the Materials Project, the implementation of the physics-based ARTISTIC project pipeline for the assessment of practical electrode properties like porosity and thickness, and the coupling of the electrodes into virtual cells, whose figures of merit such as voltage and capacity are calculated. The screening can be conducted by applying filters to these cell-level properties, achieving a indirect selection of the most suitable active materials. The approach is validated through comparison to current commercial battery technology, and we demonstrate that VOLTA is able to identify promising electrode materials for high energy batteries, like the well-known LiCoO2, LiNiO2 and graphite phases. We also illustrate a case-study, where the pipeline is used to identify suitable low-voltage, realistic virtual batteries obtained by combining entries of the Materials Project battery database (a battery revealing type of task).

Emerging energy storage systems based on abundant and cost-effective materials are key to overcome the global energy and climate crisis of the 21st century. Rechargeable Magnesium Batteries (RMB), based on Earth-abundant magnesium, can provide a cheap and environmentally responsible alternative to the benchmark Li-ion technology, especially for large energy storage applications. Currently, RMB technology is the subject of intense research efforts at laboratory scale. However, these emerging approaches must be placed in a real-world perspective to ensure that they satisfy key technological requirements. In an attempt to bridge the gap between laboratory advancements and industrial development demands, herein, we report the first non-aqueous multilayer RMB pouch cell prototypes and propose a roadmap for a new advanced RMB chemistry. Through this work, we aim to show the great unrealized potential of RMBs.

Synchrotron radiation based techniques are powerful tools for battery research and allow probing a wide range of length scales, with different depth sensitivities and spatial/temporal resolutions. Operando experiments enable characterization during functioning of the cell and are thus a precious tool to elucidate the reaction mechanisms taking place. In this perspective, the current state of the art for the most relevant techniques (scattering, spectroscopy, and imaging) is discussed together with the bottlenecks to address, either specific for application in the battery field or more generic. The former includes the improvement of cell designs, multi-modal characterization and development of protocols for automated or at least semi-automated data analysis to quickly process the huge amount of data resulting from operando experiments. Given the recent evolution in these areas, accelerated progress is expected in the years to come, which should in turn foster battery performance improvements.

Ca2MnO3.5 and CaV2O4 were found to be potentially interesting as positive electrode materials for calcium metal-based high-energy density batteries with DFT-predicted average voltages of 3.7 V and 2.5 V and energy barriers for Ca migration of 1.1 eV and 0.6 eV, respectively. Both compounds were prepared by solid state reaction under reducing atmospheres. Optimum conditions to achieve Ca2MnO3.5 comprised the reduction of Ca2MnO4 under NH3 gas at 420⁰C with a flow rate of 1200 ml/min while CaV2O4 was achieved by reduction of CaV2O6 at 700 ⁰C under H2 flow. Electrochemical oxidation of Ca2MnO3.5 in lithium or calcium cells resulted in the formation of an orthorhombic phase with cell parameter (a= 5.2891(1), b= 10.551(2), c= 12.1422(1)). Operando synchrotron radiation diffraction experiments indicate that the charge compensation mechanism is not related to Ca2+ extraction but to intercalation of F− (originated from electrolyte salt decomposition) into the anion vacancy position, as confirmed by EELS and EDS. This process was found to be irreversible. In the case of CaV2O4, oxidation induces the electrochemical extraction of calcium with the formation of an orthorhombic phase (space group Pbnm) with cell parameters a = 10.72008(9) Å, b = 9.20213(2) Å and c = 2.89418(3) Å. The process was also investigated via operando synchrotron radiation diffraction, with the oxidized phase being found to reintercalate Ca2+ ions upon reduction, with the formation of a solid solution. Preliminary cycling tests reveals a decrease in the polarization after the first cycle and call for further investigation of this system.

This paper examines Vicenta Arnal Yarza's (1902-1960) life and scientific contributions to electrochemistry in the late 1920s and the 1930s. In Spain, this was a time of ambitious programs to modernize and internationalize scientific research, which included the training and career promotion of some women. Vicenta Arnal's pathway shifted from the early years of her international scientific education with top scientists in the field to a domestic career devoted to improving the teaching and popularizing of chemistry under the constraints of the Franco dictatorship, which brought about a dramatic regression in gender equity.

The development of high energy density battery technologies based on divalent metals as the negative electrode is very appealing. Ca and Mg are especially interesting choices due to their combination of low standard reduction potential and natural abundance. One particular problem stalling the technological development of these batteries is the low efficiency of plating/stripping at the negative electrode, which relates to several factors that have not yet been looked at systematically; the nature/concentration of the electrolyte, which determines the mass transport of electro-active species (cation complexes) toward the electrode; the possible presence of passivation layers, which may hinder ionic transport and hence limit electrodeposition; and the mechanisms behind the charge transfer leading to nucleation/growth of the metal. Different electrolytes are investigated for Mg and Ca, with the presence/absence of chlorides in the formulation playing a crucial role in the cation desolvation. From a R&D point-of-view, proper characterization alongside modeling is crucial to understand the phenomena determining the mechanisms of the plating/stripping processes. The state-of-the-art is here presented together with a short perspective on the influence of the cation solvation also on the positive electrode and finally an attempt to define guidelines for future research in the field.

Battery research initiatives and giga-scale production generate an abundance of diverse data spanning myriad fields of science and engineering. Modern battery development is driven by the confluence of traditional domains of natural science with emerging fields like artificial intelligence and the vast engineering and logistical knowledge needed to sustain the global reach of battery Gigafactories. Despite the unprecedented volume of dedicated research targeting affordable, high-performance, and sustainable battery designs, these endeavours are held back by the lack of common battery data and vocabulary standards, as well as, machine readable tools to support interoperability. An ontology is a data model that represents domain knowledge as a map of concepts and the relations between them. A battery ontology offers an effective means to unify battery-related activities across different fields, accelerate the flow of knowledge in both human- and machine-readable formats, and support the integration of artificial intelligence in battery development. Furthermore, a logically consistent and expansive ontology is essential to support battery digitalization and standardization efforts, such as, the battery passport. This review summarizes the current state of ontology development, the needs for an ontology in the battery field, and current activities to meet this need.

Several Hard carbon||Na3V2(PO4)2F3 full-cells in 18650-format are assembled to demonstrate the possible use of SIBs in stationary applications. The cell aging process is investigated in two different conditions: (i) continuous cycling at different current rates, and (ii) storage at different states-of-charge at various temperatures. The obtained results reveal that the cell degradation depends strongly on the temperature, current rates applied in cycling conditions, or state-of-charge of the storage test. Under cycling conditions, the continuous sodiation/desodiation may induce significant mechanical deformation, leading to the detachment of active materials from the current collector. Furthermore, the post-mortem analysis shows that reaction rate and aging process are not homogeneous along the electrode roll. The XRD analysis shows that Na3V2(PO4)2F3 structure is robust; nevertheless, the material cannot recover the initial Na+ content as the cycling progresses, which is the main cause for capacity loss in the positive electrode. The solid-electrolyte interphase present on the hard carbon surface was characterised using XPS. The hard carbon electrode cannot be detected during this study, evidencing the formation of a relatively thick (>5 nm) passivating layer composed of carbonate salts and NaF, which are the main products of electrolyte decomposition.

Defects in crystalline structures play a vital role in their properties, so their proper characterization is essential to understanding and improving the behaviour of the materials. In this work, their presence in Ca4Fe9O17 has been analysed. Its structure exhibits three different iron coordination topologies and can be described as layers of corner-sharing FeO5 bipyramids stacked along the c axis together with layers of edge-sharing FeO6 octahedra, both being linked by FeO4 tetrahedra. The relative position of the FeO4 tetrahedra generates three possible stacking directions, which results in stacking faults when more than one is combined. Structural refinement using the Rietveld method in X-ray and neutron powder diffraction data was not possible due to significant mismatches between the observed and calculated integrated intensities for several peaks resulting from this atomic disorder. Selected area electron diffraction (SAED) and high-resolution scanning transmission electron microscopy (HR-STEM) images confirm the local defective nature of the material. The FAULTS software enabled a successful refinement of the structure considering a high concentration of planar defects, conferred by the existence of three possible stacking directions in the crystal structure, all of them confined in the basal plane.

This research was conducted under the innovation program H2020 FETOPEN-1-2016-2017 (CARBAT, grant agreement no. 766617). The objective of the CARBAT project is the development of a calcium metal rechargeable battery. This work aims to establish a reliable was to evaluate cathode active material for calcium reversible intercalation and shows the potential use of TiS2 as reversible cathode material for calcium batteries at room temperature.

This research was conducted under the innovation program H2020 FETOPEN-1-2016-2017 (CARBAT, grant agreement no. 766617). The objective of the CARBAT project is the development of a calcium metal rechargeable battery. Fe-based oxides have shown to be attractive as cathodes, among calcium ferrites, DFT calculations on Ca4FeO17 have predicted a calculated average voltage of 4.16 V, a theoretical specific capacity of 230 mA h g−1 and the lowest energy barrier for Ca migration so far predicted for an existing oxide (0.72 eV). This dataset contains the raw x-ray diffraction data as well as the electrochemical i-v curves collected for pristine and electrochemically oxidized samples of Ca4Fe9O17.

Water based electrolytes enable very high ionic conductivity, and are particularly attractive for high power density batteries. The main advantages of water-based electrolytes are their lower cost and nonflammability, while their principal disadvantage is the limited thermodynamic electrochemical window of water. Yet, the latter is currently being challenged, through the use of highly concentrated electrolytes (“water in salt concept”). Strong research focus is currently placed on rechargeable M-ion batteries (M ¼ Li, Na) mimicking the organic Li-ion or Na-ion batteries, which will despite falling shorter in energy density exhibit cost advantages. Moreover, they should be expected to deliver very attractive power densities. The main challenge at this stage is the development of new negative electrodes able to operate at lower potentials. A more challenging topic is divalent ion concepts (M ¼ Zn) using a Zn metal anode which could, in principle, deliver higher energy density, but for which issues still remain related to (i) developing appropriate positive electrode materials for reversible Zn ion insertion and (ii) side reactions involving mostly H+ or OH species, which are not yet mastered.

This Review flows from past attempts to develop a (rechargeable) battery technology based on Ca via crucial breakthroughs to arrive at a comprehensive discussion of the current challenges at hand. The realization of a rechargeable Ca battery technology primarily requires identification and development of suitable electrodes and electrolytes, which is why we here cover the progress starting from the fundamental electrode/electrolyte requirements, concepts, materials, and compositions employed and finally a critical analysis of the state-of-theart, allowing us to conclude with the particular roadblocks still existing. As for crucial breakthroughs, reversible plating and stripping of calcium at the metal-anode interface was achieved only recently and for very specific electrolyte formulations. Therefore, while much of the current research aims at finding suitable cathodes to achieve proof-of-concept for a full Ca battery, the spectrum of electrolytes researched is also expanded. Compatibility of cell components is essential, and to ensure this, proper characterization is needed, which requires design of a multitude of reliable experimental setups and sometimes methodology development beyond that of other next generation battery technologies. Finally, we conclude with recommendations for future strategies to make best use of the current advances in materials science combined with computational design, electrochemistry, and battery engineering, all to propel the Ca battery technology to reality and ultimately reach its full potential for energy storage.

Current societal challenges in terms of energy storage have prompted an intensification in the research aiming at unravelling new high energy density battery technologies. These would have the potential of having disruptive effects in the world transition towards a less carbon-dependent energy economy through transport, both by electrification and renewable energy integration. Aside from controversial debates on lithium supply, the development of new sustainable battery chemistries based on abundant elements is appealing, especially for large-scale stationary applications. Interesting alternatives are to use sodium, magnesium or calcium instead of lithium. While for the Na-ion case, fast progresses are expected as a result of chemical similarities with lithium and the cumulated Li-ion battery know-how over the years, for Ca and Mg the situation is radically different. On the one hand, the possibility to use Ca or Mg metal anodes would bring a breakthrough in terms of energy density; on the other, development of suitable electrolytes and cathodes with efficient multivalent ion migration are bottlenecks to overcome.

The impact of energy production by conventional technologies on the environment and human health has promoted transition policies towards a new model for the energy sector. In this context, it is essential to identify the key challenges which favour the global implementation of a clean, safe and efficient energy system, focused on the ways in which energy is produced and stored, and the management of existing resources and their emissions.

We present herein a systematic study of solvent co-intercalation during electrochemical reduction of titanium disulfide in lithium cells using state of the art in situ cells and synchrotron X-ray diffraction. To understand the role of the electrolyte components, four salts (LiBF4, LiBOB, LiPF6 and LiTFSI) and three solvents (ethylene carbonate, propylene carbonate and dimethyl carbonate) were investigated. Various types of in situ cells were assembled and X-ray diffraction patterns were collected in operando upon cycling. Co-intercalated phase formation was found to be triggered by the presence of propylene carbonate and to be electrochemically driven. This co-intercalated phase is formed in the early stages of reduction, with cell parameters a = 3.514 Å, c = 17.931 Å, corresponding approximately to a tripling of the pristine TiS2 cell along the c-axis. This phase does not seem to evolve upon further oxidation and hence induces an overall loss of capacity. Whereas the nature of the anion does not appear to influence the co-intercalated phase formation, the content of propylene carbonate in the electrolyte is clearly correlated to both its amount and the extent of capacity loss.

Physical mixtures (i. e. blends) of two or more active materials are often used in commercial batteries to achieve better performance than what can be attained with a single component. This approach has been empirically driven and found to result in relevant synergistic improvements that are unfortunately poorly understood at a fundamental level. Indeed, internal redox processes (which induce structural changes in the components) can take place in blended electrodes that are severely influenced by electrode kinetics. These are in turn affected by temperature and also electrode formulation. Despite difficulties ahead, efforts to understand such issues are needed to pave the way for a rational electrode design enabling optimized performance which ideally could be tuned to match specific application requirements.

BATTERY 2030+ targets the development of a chemistry neutral platform for accelerating the development of new sustainable high-performance batteries. Here, a description is given of how the AI-assisted toolkits and methodologies developed in BATTERY 2030+ can be transferred and applied to representative examples of future battery chemistries, materials, and concepts. This perspective highlights some of the main scientific and technological challenges facing emerging low-technology readiness level (TRL) battery chemistries and concepts, and specifically how the AI-assisted toolkit developed within BIG-MAP and other BATTERY 2030+ projects can be applied to resolve these. The methodological perspectives and challenges in areas like predictive long time- and length-scale simulations of multi-species systems, dynamic processes at battery interfaces, deep learned multi-scaling and explainable AI, as well as AI-assisted materials characterization, self-driving labs, closed-loop optimization, and AI for advanced sensing and self-healing are introduced. A description is given of tools and modules can be transferred to be applied to a select set of emerging low-TRL battery chemistries and concepts covering multivalent anodes, metal-sulfur/oxygen systems, non-crystalline, nano-structured and disordered systems, organic battery materials, and bulk vs. interface-limited batteries.

Hard carbon materials were prepared from different precursors (phenolic resin and commercially available cellulose and lignin) under different pyrolysis and processing conditions using industrially adapted syntheses protocols. The study of their microstructural features enabled to assess that the nature of the precursor and the temperature of pyrolysis are the major factors determining the carbon yield and the surface area, the latter one having a major effect on the electrochemical capacity. Finally, the presence of surface groups and physisorbed water can also play a role both on the maximum reversible capacity achievable (by influencing the interaction of sodium ions with the hard carbon surface) and the irreversible capacity. Phenolic resin combining high carbon yield (~50%), tap density (0.7 gcm-3) and reversible capacity (249 mAh/g) was found to be the precursor producing the most suitable hard carbon for practical use in Na-ion batteries. Cellulose can be a good candidate as well, the lower carbon yield being counterbalanced by its lower price and higher capacity (280 mAh/g).

The electrochemical oxidation of a transition metal oxide through calcium extraction is achieved for the first time. The 1D framework of Ca3Co2O6 is maintained upon oxidation and the new phase formed exhibits a modulated structure. The process occurs at high potential and is partially reversible, which opens prospects for a calcium battery proof-of-concept.

A comparative study of the electrochemical intercalation of Ca2+ and Mg2+ in layered TiS2 using alkylcarbonate-based electrolytes is reported, and for the first time, reversible electrochemical Ca2+ insertion is proved in this compound using both X-ray diffraction and differential absorption X-ray tomography at the Ca L2 edge. Different new phases are formed upon M2+ insertion that are structurally characterized, their amount and composition being dependent on M2+ and the experimental conditions. The first phase formed upon reduction is found to be the result of an ion-solvated intercalation mechanism, with solvent molecule(s) being cointercalated with the M2+ cation. Upon further reduction, new non-cointercalated calcium-containing phases seem to form at the expense of unreacted TiS2. The calculated activation energy barriers for Ca2+ migration in TiS2 (0.75 eV) are lower than those previously reported for Mg (1.14 eV) at the dilute limit and within the CdI2 structural type. DFT results indicate that the expansion of the interlayer space lowers the energy barrier and favors a different pathway for Ca2+ migration.