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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.

El Premi Nobel de Química 2019 va ser atorgat a John B. Goodenough, M. Stanley Whittingham i Akira Yoshino pel «desenvolupament de les bateries d’ió liti». L’origen d’aquesta tecnologia és l’estudi dels compostos d’intercalació, que ben aviat van mostrar el seu potencial per a l’emmagatzemament d’energia electroquímica. Malgrat els reptes que va caldre superar, la tecnologia va arribar al mercat el 1990 i no només ha fet possible la revolució de l’electrònica portàtil, sinó que a més avui en dia és essencial en l’electrificació del transport i sembla que en el futur ho serà també en altres camps.Paraules clau: Bateries, bateries de liti, Premi Nobel de Química., The Nobel Prize in Chemistry 2019 was awarded jointly to John B. Goodenough, M. Stanley Whittingham and Akira Yoshino for the development of lithium-ion batteries. This technology is rooted in the study of intercalation compounds, for which the potential in electrochemical energy storage was soon harnessed. Despite the challenges encountered, the technology reached the market in 1990. Besides powering the revolution in portable electronics, lithium-ion batteries are essential in transport electrification and would seem to have a bright future in alternative applications.Keywords: Batteries, lithium-ion batteries, Nobel Prize in Chemistry.

The present invention relates to a calcium-based secondary cell containing:an electrolyte arranged between the negative electrode and the positive electrode and comprising a calcium salt of a fluorine-containing anion of formula (XFn)m− wherein n is a positive integer of at most 6 and m is a positive integer of at least 1 and ma positive-electrode active material at the positive electrode which is a one-dimensional structure accommodating Ca2+ ions and has the formula (1): Can+2Me1(n+1)−y−zMe2yMe3zO3n+3 (1) wherein:Me1, Me2, Me3 are different transition metals;1≤n and n is not necessarily an integer;0≤y and y is not necessarily an integer;0≤z and z is not necessarily an integer.

The currently emerging sodium-ion battery technology is in need of an optimized standard organic solvent electrolyte based on solid and directly comparable data. With this aim we have made a systematic study of “simple” electrolyte systems consisting of two sodium salts (NaTFSI and NaPF6) dissolved in three different alkyl carbonate solvents (EC, PC, DMC) within a wide range of salt concentrations and investigated: (i) their more macroscopic physico-chemical properties such as ionic conductivity, viscosity, thermal stability, and (ii) the molecular level properties such as ion-pairing and solvation. From this all electrolytes were found to have useful thermal operational windows and electrochemical stability windows, allowing for large scale energy storage technologies focused on load levelling or (to a less extent) electric vehicles, and ionic conductivities on par with analogous lithium-ion battery electrolytes, giving promise to also be power performant. Furthermore, at the molecular level the NaPF6-based electrolytes are more dissociated than the NaTFSI-based ones because of the higher ionic association strength of TFSI compared to PF6− while two different conformers of DMC participate in the Na+ first solvation shells – a Na+ affected conformational equilibrium and induced polarity of DMC. The non-negligible presence of DMC in the Na+ first solvation shells increases as a function of salt concentration. Overall, these results should both have a general impact on the design of more performant Na-conducting electrolytes and provide useful insight on the very details of the importance of DMC conformers in any cation solvation studies.

A study of the Solid Electrolyte Interphase (SEI) on hard-carbon (HC) electrodes in sodium half-cells is presented. Electrochemical performances over > 100 cycles were compared with two different salts (NaPF6, NaTFSI) and two different electrolyte additives (FEC, DMCF) in a mixture of EC and DMC solvents. The best electrochemical performances were observed with NaPF6 salt in conjunction with 3% FEC. The DMCF additive had a detrimental effect in all electrolyte combinations. The chemical characterization of the SEI was carried out by X-ray Photoelectron Spectroscopy (XPS) and showed that the best electrochemical behavior was related to an SEI composition based on sodium ethylene dicarbonate and NaF, whereas poorer electrochemical performances were associated to either low NaF or high Na2CO3 content. The results reported herein provide an insight on the SEI chemistry on hard carbon electrodes in sodium cells after long-term cycling, as a complement to previous studies dealing with the first cycles.

A comparative study of the reduction of TiS2 in diverse electrolyte formulations involving Ca(BF4)2 and Ca(TFSI)2 salts was carried out at different temperatures (from 25 °C to 100 °C). While for the former salt intercalation of calcium is only observed at high temperatures, calcium intercalated phases are also observed for the latter even at room temperature. The nature of the electrolyte does also have an impact on the relative amounts of the phases formed. Since Ca(TFSI)2 based electrolytes do not enable calcium plating, cycling was attempted using activated carbon as counterelectrode, and the reversibility of the process was ascertained. Even if corrosion of stainless steel current collectors and side reactions do still prevent proper cyclability, the results achieved should contribute to the establishment of reliable and viable cell set-up and methodology for the unambiguous study of the intercalation process in multivalent battery systems.

Sustainability combined with high energy density prospects makes Fe-based oxides attractive as cathodes for calcium rechargeable batteries. This work presents a DFT evaluation of the CaFe2+nO4+n (0 < n < 3) family, for which both the average intercalation voltage and the theoretical specific capacity decrease with the increasing n value. The term n = 1/4, Ca4Fe9O17, meets the most appealing characteristics: 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). To overcome the previously reported synthesis difficulties, we employed a novel synthesis procedure in sealed quartz tubes followed by quenching in water. The XRD and SAED patterns of the prepared Ca4Fe9O17 powder reveal a certain degree of stacking defects along the c axis. Attempts to deinsert Ca ions from Ca4Fe9O17 by chemical means (NO2BF4 in ACN) and in electrochemical Ca cells were unsuccessful, although some hints of oxidation are observed in Li cells with the LP30 electrolyte. The suitability of Ca4Fe9O17 as a Ca cathode is pending further studies utilizing Ca-electrolytes with high anodic stability.

[EN] The present invention relates to a calcium-based secondary cell containing: - an electrolyte arranged between the negative electrode and the positive electrode and comprising a calcium salt of a fluorine-containing anion of formula (XFn)m-, wherein n is a positive integer of at most 6 and m is a positive integer of at least 1 and m < n, - a positive-electrode active material at the positive electrode which is a one-dimensional structure accommodating Ca2+ ions and has the formula (1): Can+2Me1(n+1)-y-zMe2yMe3zO3n+3, wherein: Me1, Me2, Me3 are different transition metals; 1 ≤ n and n is not necessarily an integer; 0 ≤ y and y is not necessarily an integer; 0 ≤ z and z is not necessarily an integer, [FR] La présente invention porte sur un accumulateur à base de calcium contenant : - un électrolyte agencé entre l'électrode négative et l'électrode positive et comprenant un sel de calcium d'un anion contenant du fluor de formule (XFn)m", n étant un entier positif égal à 6 au plus et m étant un entier positif égal à au moins 1 et m < n, - un matériau actif d'électrode positive à l'électrode positive qui est une structure unidimensionnelle accueillant des ions Ca²⁺ et qui a la formule (1) : Can+2Me1(n+1)-y-zMe2yMe3zO3 n+3 (1) : Me1, Me2, Me3 étant des métaux de transition différents; 1 < n et n n'étant pas nécessairement un entier; 0 < y et y n'étant pas nécessairement un entier; 0 < z et z n'étant pas nécessairement un entier

To mark the occasion of Nature Chemistry turning 10 years old, we asked scientists working in different areas of chemistry to tell us what they thought the most exciting, interesting or challenging aspects related to the development of their main field of research will be — here is what they said.

Rechargeable battery technologies based on the use of metal anodes coupled to multivalent charge carrier ions (such as Mg2+, Ca2+ or Al3+) have the potential to deliver breakthroughs in energy density radically leap-frogging the current state-of-the-art Li-ion battery technology. However, both the use of metal anodes and the migration of multivalent ions, within the electrolyte and the electrodes, are technological bottlenecks which make these technologies, all at different degrees of maturity, not yet ready for practical applications. Moreover, the know-how gained during the many years of development of the Li-ion battery is not always transferable. This perspective paper reviews the current status of these multivalent battery technologies, describing issues and discussing possible routes to overcome them. Finally, a brief section about future perspectives is given.