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International audience; This roadmap presents the transformational research ideas proposed by "BATTERY 2030+", the European large-scale research initiative for future battery chemistries. In this paper we outline a "chemistry-neutral" roadmap to advance battery research, particularly at low TRL, with a time horizon of about ten years. The roadmap is centered around six themes: 1) accelerated materials discovery platform, 2) battery interface genome, with the integration of smart functionalities such as 3) sensoring and 4) self-healing processes. Beyond chemistry related aspects we also include crosscutting research regarding 5) manufacturability and 6) recyclability. This roadmap should be seen as an important enabling complement to the many global battery roadmaps which focus on expected ultrahigh battery performance, especially for the future of transports. Batteries are used in many other applications and are considered to be one of Europe's key technologies necessary to reach the climate goals. Currently the market is dominated by lithium-ion batteries, which performs well in most applications, but despite new generations coming in near time, soon will approach their performance limits. Without major breakthroughs, battery performance and production requirements will not be sufficient to enable the building of a climate-neutral society. Through our "chemistry neutral" approach we aim to create a generic toolbox transforming the way we develop and design batteries, which later benefit into the development of specific battery chemistries and technologies. The goal is to integrate modeling and high-through-put experimental results in a closed integrated loop and manage the large amounts of data we generate to learn more about complex processes on different levels affecting the function of a battery cell or a battery system. Based on this we suggest concrete actions with the ambition to be part of and support the implementation of the European Green Deal, the UN Sustainable Development Goals, as well as the European Strategic Action plan on Batteries and the Strategic Energy Technology Plan.

Future optimized lithium-sulfur batteries may promise higher energy densities than the current standard. However, there are many barriers which hinder their commercialization. In this review we describe how ionic liquids (ILs) and their polymers are utilized in different components of the battery to address some of these issues. For example, IL-based electrolytes have the potential to reduce the solubility of polysulfides compared to conventional organic electrolytes. Polymerizing ILs directly on the surface of the Li-metal anode is suggested as an approach to protect the surface of this electrode. Finally, using poly(ionic liquids) (PILs) as binders for the cathode active material may increase the performance of the cathode as compared to polyvinylidene difluoride (PVdF) and could inhibit swelling-induced degradation. These results demonstrate the advantages of ILs and their polymers for improving the performance of Li−S batteries.

For the design of light-metal-sulfur batteries and for the understanding of their performance, knowledge on the stable crystalline polysulfides is very important. We confronted experimental and ab initio crystal structure prediction studies on the stability of Na polysulfides. The selected evolutionary-based structure-prediction algorithm was able to quickly and correctly predict the thermodynamically stable crystalline forms of Na polysulfides with small unit cells. For Na polysulfides with large unit cells, the algorithm correctly proposed short unbranched polysulfide chains to be energetically favorite structural motifs, but could not find proper three-dimensional structures in the limited number of generations. Experimentally, the polysulfides were studied by X-ray diffraction and 23 Na solid-state NMR spectroscopy. Complemented by calculations of the isotropic chemical shifts and quadrupolar coupling constants, NMR spectroscopy proved to be an excellent tool for the examination of Na polysulfides, because it allowed easy distinction and quantification of components in the samples.

Aluminum 3D thin film anodes fully integrated with a separator are fabricated by sputtering and enable rechargeable aluminum metal batteries with high power performance. The 3D thin film anodes have an approximately four to eight times larger active surface area than a metal foil, which significantly both reduces the electrochemical overpotential, and improves materials utilization. In full cells with organic cathodes, that is, aluminum metal-organic batteries, the 3D thin film anodes provide 165 mAh g(-1)at 0.5 C rate, with a capacity retention of 81% at 20 C, and 86% after 500 cycles. Post-mortem analysis reveals structural degradation to limit the long-term stability at high rates. As the multivalent charge carrier active here is AlCl2+, the realistic maximal specific energy, and power densities at cell level are approximate to 100 Wh kg(-1)and approximate to 3100 W kg(-1), respectively, which is significantly higher than the state-of-the-art for Al batteries.

Lithium transition metal silicates, Li2MSiO4 (M = Fe, Mn, Co), have attracted much interest as positive electrodes for Li-ion batteries due to their high theoretical capacities and their rich crystal chemistry. Low (β) and high (γ) temperature forms of these tetrahedral structures differ in the ordering/distribution of cations within tetrahedral sites of an hcp based packing of oxygen. We have carried out VT powder neutron and X-ray diffraction on Li2MSiO4 (M = Fe, Mn) to characterize the rich polymorphism observed across the Li2MSiO4 (M = Fe, Mn) system as a function of temperature. For Li2FeSiO4 below 500 °C a βII phase was observed with slight Li/Fe disorder. Above this temperature there was a sluggish transition to the γs phase, which was observed up to ca. 820 °C, with the γII polymorph seen at highest temperatures. Excellent agreement with phases obtained by quenching was observed, except that the γ phases exhibit a statistical distribution of Li/Fe, in contrast to the well-ordered structures of quenched phases. The Li2MnSiO4 polymorphism is less complex, the βII phase is stable from room temperature to 750 °C, at which temperature it transforms to the γ structure with disordered Li/Mn.

We demonstrate the importance of effective separation between the sulfur cathode and the lithium anode in Li–S batteries. Improved cycling stability is obtained by using fluoro-functionalized reduced graphene oxide (rGO) as a separator between the sulfur cathode and the lithium anode. The thickness of the hydrophobic interlayer is found to be 1–2 μm. The possible mechanism is checked with analytical techniques and suggests that improvement in the capacity stability can be attributed to the reduced reactivity of long-chain polysulfides with the metallic lithium and to the homogenous distribution of end-discharge products during cycling. The importance of the effective separation of lithium and sulfur is proven by using commercially available lithium conductive ceramics. Good cycling stability over 350 cycles with a coulombic efficiency above 99.95 % is achieved, which demonstrates the possibility of long cycle life with proper separation of lithium and sulfur cathode.

Battery watch: UV/Vis spectrophotometry is demonstrated as a powerful analytical method for the in situ study of polysulfides. Through the interactions that occur between different chain-length polysulfide molecules and the UV/Vis radiation, quantitative and qualitative determination of the polysulfides formed during Li-S battery operation can be achieved.

The basic requirement for many high-rate insertion battery materials is that they are prepared in a nanostructured form. In this way, the surface area can be maximized and the solid-state transport length minimized. Both features help minimize the electrode resistance, that is, the electrode polarization at a given current density. However, if we try to prepare the active material in the form of a nanopowder (with a particle size that approaches 10 nm or even smaller), there will be a huge tendency towards particle agglomeration, either during the synthesis itself and/or during further steps of electrode preparation. Of course, agglomerated particles do not allow access of electrons and/or ions to the whole surface of individual primary nanoparticles, which annihilates the very concept of nanostructuring. The problem of agglomeration can be avoided using two approaches. The first is to prepare the active matter in the form of a porous material with the thin walls of the pores (to provide short solid-state diffusion paths). The electrolyte in the pores provides a fast ionic supply to the walls of the pores. To allow for a fast electron supply, the porous material has to be decorated on all surfaces (external and especially internal) with an appropriate electronic conductor. The second approach that prevents excessive particle agglomeration is the use of in situ organic precursors that, during the heating step, form thin surface films. Carbon surface nanofilms have been particularly popular, because they not only suppress particle agglomeration but also provide electronic paths to and around active particles. Despite their extensive use, however, carbon films still exhibit several weaknesses. The first is that most carbon precursors need to be heated to temperatures up to 600–700 8C to transform into well-conductive carbon film. The second issue is that most carbon precursors only partly limit the growth of active particles: in most cases the final active particle size is still above 50 nm. Only when an excessive amount of carbon precursor is used, can the particle size reach the range of 10–15 nm. However, in this case, the amount of carbon in the final composite is very large (usually about 15wt% or, equivalently, more than 30 vol%). This huge amount of native carbon not only decreases the energy density but also limits the rate of charge and mass transport. In certain cases, a deficiency of carbon precursors is also their reductive nature, which may negatively affect the preparation of certain active compounds. In the present work, we show a new strategy towards stabilization of active particle size and morphology during heating: instead of carbon, we use stabilizers that form covalent bonds on an active particle surface. Indeed, we show that certain ceramic precursors completely suppress any morphological change or growth of an initial nanopowder until about 500 8C. Thereby, the amount of precursor can be so small that it does not even form any visible surface film. Thus, they are conceptually and structurally not related to well-known ceramic coatings that serve to protect active matter during electrochemical testing. Our approach does not decrease the energy density nor hinder the kinetics. The only potential drawback with respect to carbon coatings is that the ceramic additive, of course, does not improve the electronic conductivity. Still, we demonstrate that for typical insertion materials, such as titania, this deficiency is more than compensated for by its excellent stabilization of particle size and morphology of the initial nanopowders. It is not only a novel route towards material preparation but also demonstrates the importance of ionic wiring. The effect of size and morphology stabilization using ceramic precursors (hereafter termed ‘ceramic stabilizers’) will be demonstrated on hydrated titania nanotubes. The latter are interesting from various viewpoints: they have a convenient aspect ratio that guarantees that the native material retains sufficient porosity that is, as long nanotubes, once appropriately dispersed; and they do not tend to spontaneously agglomerate at room temperature (as may be the case with spherical, cubical, and other morphologies). The next interesting feature of titania nanotubes is that they can be transformed into various other structures, such as TiO2-B, [14–16] anatase, or rutile, depending on the heat-treatment procedure. We chose to use the conditions at which the nanotubes are fully transformed into the anatase phase. Even if the anatase structure is less convenient for lithium insertion than the TiO2-B structure, [14–16] we show that the use of ceramic stabilizers can produce anatase phases that exhibit a greater high-rate performance than the best results published on TiO2-B. The initial titania nanotubes had outer diameters of 8–11 nm, inner diameters between 4 and 7 nm, and lengths of several hundred nanometers. Their Brunauer–Emmett–Teller (BET) surface area was 250m g . After heating to 480 8C, these

Li2FeSiO4 (I) is prepared by hydrothermal synthesis using stoichiometric quantities of SiO2, FeCl2, and LiOH (autoclave, 200 °C, 6 h).

The structural degradation of Li2MSiO4 (M: Mn, Co) cathode materials upon lithium removal is inherent to the distorted hexagonal oxygen packing of the known polymorphs, where M ions are constrained to occupy tetrahedral sites.

LiMnPO4 particles with a size of 15—20 nm embedded in a carbon matrix are prepared as cathode materials for Li ion batteries from solutions of Mn(OAc)2, citric acid, and H3PO4 (Ar, 700 °C, 1 h) avoiding the presence of Li in the first step, followed by mixing the product with LiOH and thermal treatment at 700 °C for 12 h in Ar.

A new polymorph of the title compound is synthesized by solid state reaction of Li2SiO3, Fe1-xO, and Fe (900 °C, 7 d followed by quenching to 25 °C).

The thermodynamic stability of Li2MnSiO4 polymorphs and their electrochemical properties as electrode for Li batteries are investigated combining experimental and computational methods. Three possible Li2MnSiO4 forms have been considered crystallizing in Pmnb, Pmn21 (β-Li3PO4 derivatives) and P21/n (γ-Li3PO4 derivative) space groups (S.G.). We have first demonstrated that the relative stability of β- and γ-Li3PO4 polymorphs is well-reproduced by density functional theory (DFT) methods (LDA, GGA). For Li2MnSiO4, the Pmnb form is predicted to be 2.4 meV/f.u. and 65 meV/f.u. more stable than the Pmn21 and P21/n forms, respectively (GGA + U results). Computational results indicate that the denser Pmn21 polymorph can be obtained by high pressure/high temperature treatment of the other polymorphs or their mixtures. A sample of Li2MnSiO4 prepared at 900 °C consists of a mixture of polymorphs, as detected by XRD and confirmed by means of SAED and 6Li MAS-NMR. As expected from DFT results, exposing the as-prepared...