The lithium-ion batteries (LIBs) industry has expanded quickly despite technological constraints. Additionally, raw materials supply, end-of-life (EoL) management, and the creation of LIB manufacturing policies are receiving attention. All these concerns could be addressed simultaneously by integrating recycling of EoL cells from the early stages of the LIB manufacturing. This article presents perspectives on how to achieve this holistic integration through the means of digitalization. Various challenges of LIB recycling, and different digitalization tools are discussed, shedding light on the latter's potential applications and outcomes. Through the use of the discussed tools to create advanced Digital Twins, it would be possible to screen different recycling processing conditions and materials to achieve higher efficiency, increased safety, at a lower cost. In this regard digitalization of the recycling process for LIB cells, emerges as the key for achieving a collaborative, sustainable, and efficient battery value chain in the European Union. Lastly, in the view of the growing LIB market, this article is thought to be of interest for recycling stakeholders as they move towards a more circular economy model.

Ceramic oxides are promising solid electrolytes for Lithium metal solid-state batteries (SSBs) because of their high ionic conductivity and stability under ambient conditions. Nonetheless, the need for high-temperature densification approaches challenges their processability towards upscaling and their implementation into practical SSB devices. Here, we investigate a High-Pressure Low-Temperature (HPLT) processing technique for the densification of NASICON-based Li1+xAlxTi2-x(PO4)(3) (LATP) solid electrolyte, providing an understanding of several key parameters such as temperature, pressure and time. Our results show that nanometric LATP can be densified using the HPLT technique at 200 degrees C within 2 min delivering an ionic conductivity of 6.15x10(-5) Scm(-1), which is the highest reported value at this temperature without the addition of solvents. On the other hand, by combining HPLT with a short post-heat treatment at 700 or 800 degrees C for 1 hour, highly dense pellets with an ionic conductivity of 10(-4) Scm(-1) can be obtained. This represents a reduction of the densification temperature of 400 degrees C compared to conventional high-temperature sintering and shows the potential of HPLT to overcome current densification constraints derived from the use of very high temperatures.

This work describes the most logical approach to address the imminent scale up and mass industrial manufacturing of solid‐state batteries (SSBs) attending to material, product and production requirements. All the currently used technologies, starting from small lab scale and going to initial prototyping and industrial attempts, are evaluated against exclusion criteria focused on achieving a low‐cost, high throughput, reliable and easily scalable manufacturing process that is in addition environmentally friendly and minimizes risk related to human health and work safety. Batteries that rely on raw materials which are readily available and are ethically produced. Batteries that are manufactured using energy that leaves no carbon footprint and are efficiently reused and recycled, resulting in minimal impact on the earth’s resources and climate. Batteries that do not exist today but will certainly exist tomorrow. The resulting roadmap is used as the benchmark to compare the manufacturing strategies of the main industrial players attempting mass fabrication of SSBs in the next 5–10 years

Temperature-assisted densification methods are typically used in oxide-based solid-state batteries to suppress resistive interfaces. However, chemical reactivity among the different cathode components (which include a catholyte, the conducting additive, and the electroactive material) still represents a major challenge and processing parameters need thus to be carefully selected. In this study, we evaluate the impact of temperature and heating atmosphere in the LiNi0.6Mn0.2Co0.2O2 (NMC), Li1+xAlxTi2-xP3O12 (LATP), and Ketjenblack (KB) system. A rationale of the chemical reactions between components is proposed from the combination of bulk and surface techniques and overall involves a cation redistribution in the NMC cathode material that is accompanied by the loss of lithium and oxygen from the lattice enhanced by LATP and KB, which act as lithium and oxygen sinks. The final result is the formation of several degradation products, starting at the surface, that lead to a rapid capacity decay above 400 °C. Both the reaction mechanism and threshold temperature depend on the heating atmosphere, with the air atmosphere being more favorable compared to oxygen or any other inert gases.

Enabling the fast charge and discharge of Li-metal solid-state batteries paves the way towards their deployment in electro-mobility applications, which require high-energy and power with safety guaranteed. Solid-state batteries using polyethylene oxide as the polymer matrix are appealing candidates although currently limited to relatively slow rate capability arising from high solid-solid interfacial resistance and sluggish lithium-ion mobility at the solid electrolyte. In this work, the engineering design and optimization of composite electrodes with multi-walled carbon nanotubes lead to high performance Li metal solid-state cells, showing a high-capacity retention at rates up to 4C. The electrode formulations including the elongated architectures exhibit a concerted ionic-electronic diffusion in the catholyte polymer enabling fast Li-ion transport, enhancing the electronic percolation and increasing the interfacial reaction kinetics and exchange current density. The solid-state battery with LiFePO4 electrode shows an unprecedented capacity retention of 92% during 800 cycles at 2C. The promising performance at high-rates of this approach is also extended to electrodes with a high-voltage active material.

One of the main technological challenges oxide-based solid-state batteries face today is the densification of their components to reach good interfacial contact. The most common approach requires co-sintering of the different components (electroactive material, catholyte and conducting additive) at high temperatures which often results in the inter-diffusion of elements that deteriorate the overall cathode performance. In this work, the impact of different carbon grades in the thermal response of LATP-NMC622-Carbon electrodes is evaluated and shown to significantly influence the chemical compatibility between components. By means of a combination of bulk and surface characterization techniques including gas adsorption, X-ray diffraction, X-ray absorption spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy and thermogravimetric analysis, it is shown that carbons with low surface area are more adequate as result in higher oxidation temperatures and hence are less reactive.

Ceramic oxides are promising solid electrolytes for Lithium metal solid-state batteries (SSBs) because of their high ionic conductivity and stability under ambient conditions and against lithium metal anode. Nonetheless, the need for high-temperature densification approaches challenges their processability towards upscaling and their implementation into practical SSB devices. Here, we investigate a High-Pressure Low-Temperature (HPLT) processing technique for the densification of NASICON-based Li1+xAlxTi2-x(PO4)3 (LATP) solid electrolyte, providing an understanding of several key parameters such as temperature, pressure and time. Our results show that nanometric LATP can be densified using the HPLT technique at 200˚C within 2 minutes delivering an ionic conductivity of 6.15 x 10-5 Scm-1, which is the highest reported value at this temperature without the addition of solvents. On the other hand, by combining HPLT with a short post-heat treatment at 700 or 800 ˚C for 1 hour, highly dense pellets with an ionic conductivity of 10-4 Scm-1 can be obtained. This represents a reduction of the densification temperature of more than 400˚C compared to conventional high-temperature sintering and shows the potential of HPLT to overcome current densification constraints derived from the use of very high temperatures.

Self-standing carbon fiber electrodes hold promise for solid-state battery technology owing to their networked structures improving interparticle connectivity, robustness contributing to mechanical integrity, and surface sites confining Li dendrites. We here evaluate carbonized 3D electrospun fibers filled with polymer electrolytes as anodes in solid-state lithium half cells. Microscopic analysis of the cells demonstrates the high wettability of carbon fibers with electrolytes, promoting an intimate contact between electrolytes and fibers. Solid-state cells delivered high initial capacities up to ∼300 mAh g−1, although the latter cycles were characterized by gradual capacity fade (∼100 mAh g−1 in the 100th cycle with nearly 100% coulombic efficiency), attributed to the onset of parasitic reactions increasing the cell resistance and polarization. When these were benchmarked against similar cells but with the liquid electrolyte, it was found that Li storage in these fiber electrodes is intermediate between graphite and hard carbon in terms of lithiation voltage (vs Li/Li+), corroborating with the nature of carbon assessed by XRD and Raman analysis. These observations can contribute to further development and optimization of solid-state batteries with 3D electrospun carbon fiber electrodes.

Solid-state lithium metal batteries (SSLMBs) are considered an auspicious technology to develop high energy density and safe energy storage devices. The double layer polymer electrolyte (DLPE) is a rational approach for engineering high-performance SSLMBs addressing electrolyte requirements with specifically designed polymers at the positive electrode and as separator. In this work, SSLMBs were assembled with poly(propylene carbonate) (PPC), offering stability toward oxidation at the positive electrode, and a gel polymer electrolyte with polyethyleneglycol dimethylether (PEGDME) as separator, offering high ionic conductivity at low temperature and sufficient interfacial stability with Li metal. The electrochemical properties and performance of cells with LiFePO 4 and Li[Ni 0.6 Mn 0.2 Co 0.2 ]O 2 positive electrodes are thoroughly investigated as function of the operating temperature by using a host of characterization techniques. High-voltage cells with an areal capacity of 0.7 mAh·cm −2 cycled at 40 °C exhibit a higher capacity retention than the cells cycled at 70 °C. To understand such differences, a three-electrode setup is applied to discriminate anodic processes from cathodic as function of the temperature. We elucidate the ageing and interfacial evolution for DLPE cells with gel polymer electrolytes paving the way for building performance solid state batteries.

Composite electrolytes, owing to their ability to combine both polymeric and ceramic properties are promising candidates for Solid-State-Batteries (SSBs). In this paper, we assess the effect of ceramic fillers (Li1+xAlxTi2-xP3O12, Li6.55Ga0.15La3Zr2O12 and Al2O3) in a poly(ethylene oxide carbonate)-LiTFSI matrix. First, the role of the filler chemistry on thermal and electrochemical properties is evaluated: reduced polymer crystallinity leads to an increased ionic conductivity at low temperatures; and the ionic conductivity at low temperatures (<30 degrees C) is improved for LLZO filler particles. This behaviour is commonly attributed to new conduction pathways generated within the fillers. However, we also demonstrate that a polymer degradation is induced by the filler chemistry by modifying the polymer chemistry in poly(ethylene glycol), initiated by LiOH that can be found on the LLZO surface. The electrolyte containing LATP or Al2O3 does not induce any degradation. Hence, special attention must be paid to surface impurities, as degradation may occur.

Solid polymer electrolyte batteries with a Li-metal anodeand high-voltage active materials hold promising prospects to increasethe energy density and improve the safety of conventional Li-ionbatteries. An adequate choice of the polymers used for the cathode(catholyte) and for the separator (electrolyte) to create a sufficientenergy gap and improve the chemical compatibility at both the positiveelectrode and Li-metal anode is required. The present work highlightsthe advantages of the double-layer polymer electrolyte approach in cellswith a LiNixMnyCozO2active material, a poly(propylene carbonate)(PPC) catholyte, and a poly(ethylene oxide) (PEO) electrolyte.Replacing PEO in the catholyte with PPC results in a remarkablyimproved cycling performance. In addition, the higher lithium trans-ference number of electrolytes with single lithium ion conductors leads toa smooth cycling of solid-state batteries. Cells with 1 mAh cm-2deliver160 mAh g-1, with a capacity retention above 80% over 80 cycles and a Coulombic efficiency close to 100%.

Solid state lithium metal batteries based on polymer electrolytes hold the most promising prospect to face energy density and safety issues encountered by conventional Li ion batteries. The use of two different polymers, one for the cathode and another one as electrolyte, brings a sufficient energy gap and chemical stability allowing compatibility with the positive electrode and lithium metal anode; thus, achieving remarkable benefits towards high-performance cells. The present work unveils the Li salt interdiffusion occurring between two different dual-ion conducting polymer electrolytes consisting of lithium bis(trifluoromethanesulfonyl)imide] (LiTFSI) dissolved in poly(ethylene oxide) (PEO) and poly(propylene carbonate) (PPC). Combining these polymers within the same device results in cell failure due to the migration of LiTFSI to the more solvating PEO. The replacement of LiTFSI by lithium poly[(4-styrenesulfonyl)(trifluoromethanesulfonyl)imide] (LiPSTFSI), in which the anion is immobilized at a polymeric backbone, proves to overcome salt migration between the polymer phases. LiFePO4 -based solid state lithium metal batteries using LiTFSI fail within the initial cycles, while cells with LiPSTFSI display an outstanding cycling performance, with above 80% capacity retention at C/10, over 120 cycles, and excellent coulombic efficiency of ca. 100%. The rational design and in-depth knowledge provided in this work are highlighted as key elements for the development of high-performance solid state lithium metal batteries.

A high cut-off voltage is required for nickel-rich layered oxide LiNixCoyMnzO2 (NCM) to meet the high energy density requirement of lithium-ion batteries in electric vehicles. However, such a high voltage application leads to an unstable interface between NCM and liquid electrolytes. To stabilize the interface, the facile wet impregnation method has been developed to apply an ultra-thin Al2O3 coating layer on the NCM particles. This coating layer was found to have a strong interaction with the NCM and resulted in Al-doped NCM at the surface structure of NCM. The change of surface structure can not only reduce the surface resistance of lithium diffusion of LiNi0.5Co0.2Mn0.3O2 (NCM523), but also stabilize the solid electrolyte interface between NCM523 and the electrolyte with the cut-off voltage of 4.5 V vs. Li/Li+. Compared to other coating methods, wet impregnation coating can provide an ultra-thin and uniform coating with surface doping on NCM particles. Furthermore, this scalable coating method can be applied to various electrode materials without adding much additional cost.

Solid-state batteries are the holy grail for the next generation of automotive batteries. The development of solid-state batteries requires efficient electrolytes to improve the performance of the cells in terms of ionic conductivity, electrochemical stability, interfacial compatibility, and so on. These requirements call for the combined properties of ceramic and polymer electrolytes, making ceramic-rich polymer electrolytes a promising solution to be developed. Aligned with this aim, we have shown a surface modification of Ga substituted Li7La3Zr2O12 (LLZO), to be an essential strategy for the preparation of ceramic-rich electrolytes. Ceramic-rich polymer membranes with surface-modified LLZO show marked improvements in the performance, in terms of electrolyte physical and electrochemical properties, as well as coulombic efficiency, interfacial compatibility, and cyclability of solid-state cells.

High-voltage Li metal solid-state batteries are in the spotlight as high energy and power density devices for the next generation of batteries.

Aiming to improve the sustainability of materials for lithium‐ion batteries (LIBs), this work reports on the development of novel membranes based on iota‐carrageenan biopolymer and their suitability as separator in LIBs applications. The membranes are prepared by freeze‐drying and its morphology, thermal, mechanical, and electrochemical properties are evaluated as a function of polymer concentration in the solution. Porous membranes with a degree of porosity above 90% and different interconnected pore sizes between 50 and 70 µm for both polymer concentrations are obtained. The electrochemical parameters of the membranes are influenced by the carrageenan polymer concentration, being 1.34 mS cm ‐1 , 3, 7, and 0.48 for ionic conductivity, tortuosity, MacMullin number, and lithium transference number, respectively, for the membrane prepared from the 4 wt% carrageenan content solution. The half‐cells cathodic prepared with the developed membranes show good cyclability and rate capability. The discharge capacity values obtained with the membrane prepared from 4 wt% carrageenan content are 145 and 25 mAh g ‐1 at C/10‐ and 1C‐rates, respectively, demonstrating excellent battery cycling performance and long‐term stability. Thus, this work demonstrates that iota‐carrageenan biopolymer membranes developed by freeze‐drying can be used as separators for a next generation of more sustainable batteries.

Lithium solid-state batteries (SSBs) are considered as a promising solution to the safety issues and energy density limitations of state-of-the-art lithium-ion batteries. Recently, the possibility of developing practical SSBs has emerged thanks to striking advances at the level of materials; such as the discovery of new highly-conductive solid-state electrolytes. Consequently, the focus in research has progressively shifted towards the integration of the various components, the battery's functionality at full cell level, and the scalability of the fabrication processes. Considering these points, the development of SSBs still faces formidable challenges. This review covers the recent advances in SSB development, stressing the importance of full cell integration. The most relevant materials and fabrication processes are briefly summarized and their potential applications in SSBs are examined. The main challenges and strategies for full cell integration are then discussed highlighting the most promising materials and the best suited processing techniques. Particular attention is paid on the mutual compatibility of the cell components, the properties of the interfaces within the cell (anode-electrolyte, cathode-electrolyte, intra-electrolyte) and the strategies applied to stabilize and minimize the resistance of these interfaces via compatible processing.

Unlocking the full potential of solid-state electrolytes (SSEs) is key to enabling safer and more-energy dense technologies than today's Li-ion batteries. In particular, composite materials comprising a conductive, flexible polymer matrix embedding ceramic filler particles are emerging as a good strategy to provide the combination of conductivity and mechanical and chemical stability demanded from SSEs. However, the electrochemical activity of these materials strongly depends on their polymer/ceramic interfacial Li-ion dynamics at the molecular scale, whose fundamental understanding remains elusive. While this interface has been explored for nonconductive ceramic fillers, atomistic modeling of interfaces involving a potentially more promising conductive ceramic filler is still lacking. We address this shortfall by employing molecular dynamics and enhanced Monte Carlo techniques to gain unprecedented insights into the interfacial Li-ion dynamics in a composite polymer-ceramic electrolyte, which integrates polyethylene oxide plus LiN(CF3SO2)2 lithium imide salt (LiTFSI), and Li-ion conductive cubic Li7La3Zr2O12 (LLZO) inclusions. Our simulations automatically produce the interfacial Li-ion distribution assumed in space-charge models and, for the first time, a long-range impact of the garnet surface on the Li-ion diffusivity is unveiled. Based on our calculations and experimental measurements of tensile strength and ionic conductivity, we are able to explain a previously reported drop in conductivity at a critical filler fraction well below the theoretical percolation threshold. Our results pave the way for the computational modeling of other conductive filler/polymer combinations and the rational design of composite SSEs.

Natural polymers are a promising alternative for reducing the environmental impact of batteries. For this reason, it is still necessary to study their behavior and implement its use in these devices, especially in separator membranes. This work reports on new separator membranes based on silk fibroin (SF) and silk sericin (SS) prepared by salt leaching method. The effect of the different SS relative content on the physiochemical properties of the membranes and on the electrochemical performance of the corresponding batteries with lithium iron phosphate (LFP) as cathodes has been reported. It is observed that the increasing of SS content leads to a decrease of the overall crystallinity of the membranes. All SF/SS membranes presented a well-defined porosity above 75% with a uniform distribution of interconnected micropores. The electrolyte uptake and the ionic conductivity are dependent on the relative SS content. The addition of 10 wt% of SS into SF membranes, induce a high ionic conductivity of 4.09 mS.cm = 1 and high lithium transference number (0.52), due to the improvement of the Li+ ions conduction paths within the blended structure. Charge/discharge tests performed in Lithium/C-LFP half-cells reveal a discharge capacity of 85 mAh.g = 1 at 2C after 100 cycles for batteries with a SF/SS separator, containing a 10 wt% of SS, which suggests a stabilizing effect of Sericin on discharge capacity. Further, a 50% and 35% of capacity of retention and capacity fade, respectively, is observed. The presented SF/SS membrane show high electrochemical stability, being suitable for implementation in a next generation of sustainable battery systems. This could allow the SS valorization considering that 150,000 tons of SS are abandoned each year, reducing the contamination of environmental effluents. (c) 2021 Elsevier Inc. All rights reserved.