During the last decades, sodium-ion batteries (SIBs) have drawn interest since sodium resources are abundant, inexpensive, and available around the earth's crust. Nonetheless, this effort has been mainly focused on half-cell configurations, a preliminary step to evaluate which materials are suitable for future SIBs full-cells. Up to date, few works related to hard carbon (HC)-based SIBs full-cells have been published, and the irreversibility of the HC anode first cycle is still an issue to be solved. Herein, two positive material electrodes, a polyanionic compound (Na3V2O2(PO4)(2)F@C) and a layered oxide (Na2/3Mn0.8Fe0.1Ti0.1O2), were selected due to their favorable theoretical specific capacity and high operating potential. Moreover, the chosen sacrificial salt, to compensate for the Na+ loss for the formation of the Solid Electrolyte Interface (SEI), was Na2C3O5 because of its non-flammable nature and easy process to fully remove the structural water from the hydrated precursor. In full-cell studies using the sacrificial salt, Na3V2O2(PO4)(2)F@C demonstrates excellent long-term cycling stability, retaining 91% of its initial capacity with a discharge capacity of similar to 105 mAh g(- 1) after 200 cycles at 130 mA g(- 1). This research highlights the electrochemical properties and sustainability of these systems, underscoring the potential for developing greener and more environmentally friendly battery alternatives.

LiNi0.5Mn1.5O4/graphite cells offer high energy density and cost advantages but suffer from poor cycling stability, hindering commercialization. This study demonstrates a rational material design approach to achieve long cycle life in LNMO/graphite cells. The LNMO materials are engineered at the particle, surface, and grain boundary levels, forming large spherical secondary particles (D-50 > 14.0 mu m) composed of truncated octahedral primary particles (1.5-6.5 mu m), resulting in dense materials with low surface area (0.20-0.35 m(2) g(-1)). The surface and grain boundary structures were further modified with a SiO2-phase, effectively stabilizing the LNMO/electrolyte interface. These material-level optimizations suppress parasitic side reactions, reduce metal-ion dissolution, and minimize cathode-anode cross-talk, leading to significantly improved cycling stability. The SiO2-900 degrees C material reaches end-of-life (EOL) after 682 cycles and retains 75.2 % of its capacity after 1000 cycles. In comparison, pristine LNMO (P-900 degrees C) reaches EOL after just 400 cycles and retains only 66.6 % capacity after 1000 cycles, demonstrating a 69 % improvement in EOL for SiO2-900 degrees C cell. Post-mortem XPS analyses reveal fewer electrolyte decomposition products on the tailored LNMO materials. Additionally, the graphite anodes paired with SiO2-LNMO exhibit a robust SEI film, unlike the ruptured SEI observed with pristine LNMO, confirming improved interfacial stability.

Anode-free sodium ion batteries (SIBs) promise higher energy density and lower costs, by eliminating the need for an anode host material; however, achieving efficient Na plating/stripping remains a major challenge. Here, three electrolyte classes - carbonate-based, glyme-based, and a localized high-concentration electrolyte-are evaluated for Na plating/stripping on a commercial carbon-coated aluminium current collector. Measurements across a broad temperature and current range (-30°C-+60°C, 0.25-14 mA cm-2-) and studies on the Na growth modes by operando optical microscopy reveal the superior behavior of the glyme-based electrolyte, including a uniform crystalline metal deposition. In anode-free full cells with Na4Fe3(PO4)2P2O7 as cathode, this electrolyte enables superior cycling with 75.3% capacity retention over 400 cycles at areal loadings above 3 mAh cm-2-. Projected energy densities of 290 Wh/kg and 751 Wh/l are calculated at the cell-stack level, exceeding current LiFePO4-based Li-ion batteries. The excellent Na plating/stripping behavior is evidenced by a particularly low initial areal capacity loss (IACL, mAh cm-2). The IACL parameter represents the first cycle Na inventory loss that must be compensated by the cathode. Unlike for conventional Na-ion cells with traditional anodes, the IACL is a constant for anode-free cells. For the given cell, the IACL amounts to only 0.14-0.16 mAh cm-2 (~5% of the 3 mAh cm-2 cathode areal capacity). This highlights the potential of anode-free SIBs using commercially available components.

This study introduces an innovative electrolyte for sodium-ion batteries (SIBs), which consists of sodium difluoro(oxalato)borate (NaDFOB) salt, dissolved in the α-methyl-γ-butyrolactone (α-Me-GBL) solvent. α-Me-GBL, is a positional isomer of γ-Valerolactone (GVL) and has properties similar to those of GVL. The electrolyte exhibited a wide electrochemical stability window, strong inhibition of anodic dissolution and excellent electrochemical stability (up to 4.3 V vs. Na+/Na). We showed that its use allows the realization of lab scale SIBs able to retain 97% of their initial capacity after 300 galvanostatic cycles at 0.5C. This outstanding stability is significantly higher than that observed for 1M NaDFOB in GVL. Post-mortem characterizations indicated the formation of thin interphase layers on both anode and cathode surfaces which are maintaining a homogenous elemental distribution across the entire electrode area over the cycling process. These results show that electrolytes containing different positional isomers can have different impact on the electrochemical performance of SIBs. Furthermore, since α-Me-GBL can be synthesized from bio-sources, they are offering novel indication towards the realization of advanced sustainable solvents suitable for SIBs.

This study introduces a dual salt novel electrolyte for sodium-ion batteries (SIBs), consisting of sodium difluoro(oxalato)borate (NaDFOB) and sodium bis(fluorosulfonyl)imide (NaFSI) salts dissolved in the bio-based γ-valerolactone (GVL) solvent. Besides its renewable origin, the electrolyte exhibited strong inhibition of anodic dissolution and excellent electrochemical stability (up to 4.3 V vs. Na+/Na). It delivered outstanding cycling stability, with ∼87 % capacity retention after 100 cycles in P2-Na2/3Al1/9Fe1/9Mn2/3Ni1/9O2 (P2-AFMNO) cathode half cells and ∼80 % retention after 200 cycles in lab- scale full cells with hard carbon anodes when cycled within a wide voltage window of 1.5-4.3 V. Post mortem X-ray photoelectron spectroscopy analysis helped gaining deeper understanding about the decomposition products formed on the interphases. A simple and sustainable water-based process is employed to successfully recover the GVL solvent. The recovery method enabled recover 85 % of GVL solvent from the recycling process. The feasibility of recycling is further demonstrated by reusing the recovered GVL-based electrolyte in full cells, which achieved performance comparable to that of the pristine GVL-based electrolyte and exhibited excellent long-term stability, retaining approximately 83 % of its capacity after 100 cycles.

Alternative conductive additives for lithium-ion batteries, such as carbon nanotubes and graphene, are academically well-established with pursued industrial opportunities while carbon black represents the global standard. However, further advancements are necessary to improve battery performance beyond current industrial metrics. Herein, a mixed-dimensional carbon material is introduced, featuring a network of 1D multi-walled nanotubes with 2D sheetlets, synthesized through a cost-effective process separating methane - a potent greenhouse gas - into carbon and low carbon intensity hydrogen. With proper slurry mixing, this material forms an expansive 3D conductive network within the electrode, enhancing electrical transport and thermal conductivity compared to carbon black electrodes. With only one-third of the carbon content (1 wt%), the electrical conductivity of a LiNi0.5Mn0.3Co0.2O2 cathode is 13 times higher than a carbon black reference, increasing both energy density and rate performance. The thermal conductivity is further improved by 40% (through-plane) and 200% (in-plane), promoting better heat dissipation. This carbon network also effectively retains transition metals during electrochemical cycling, limiting their migration to the anode, and thus reducing overall impedance build-up. The excellent compatibility of this conductive additive with state-of-the-art nickel-rich (85% nickel) layered oxides is also demonstrated, where 11.5 Ah pouch cells display >88% capacity retention after 1000 cycles at C/3.

Sodium-ion batteries (SIBs) are attractive alternatives to lithium-ion batteries owing to their comparable performance, improved safety, and reduced reliance on critical raw materials. Hard carbon (HC) is widely regarded as the most practical anode for SIBs; however, conventional HCs still suffer from limited reversible capacity, poor rate capability, and an incompletely understood Na+ storage mechanism. Here, we investigate hazelnut shell-derived HC synthesized via a sustainable water-washing route, with a particular focus on the effects of particle size and pyrolysis temperature on electrochemical behavior. We demonstrate that smaller particle sizes improve reversible capacity and cycling stability, while uniformly distributed nanoscale inorganic impurities regulate the evolution of pore structure in HC, thereby enhancing Na+ storage. A clear thermodynamic relationship between the sloping and plateau capacities is identified. Operando X-ray diffraction and ex-situ Raman spectroscopy reveal that Na+ storage proceeds through chemisorption in the sloping region and diffusioncontrolled Na clustering within pseudographitic domains in the low-voltage plateau, accompanied by reversible structural disordering. Density functional theory and molecular dynamics simulations further confirm that Na+ preferentially chemisorbs at disordered carbon layers at higher potentials and subsequently forms semimetallic Na clusters within nanopores adjacent to pseudographitic layers at lower potentials, closely linked to the pre-adsorbed Na+ species. These findings provide fundamental mechanistic insight into Na+ storage in biomass-derived HC and offer clear guidelines for optimizing HC anodes toward high-performance SIBs.

Scalable and sustainable lithium-ion battery recycling routes could be crucial for the future economic and ecological landscape of Europe. Although graphite is a critical raw material for the EU, the recycling of graphite from spent cells is currently limited to a small scale and is less developed than the recovery of cathode elements. In this study, we present a process for regenerating anode active material from spent lithium-ion cells with electrochemical performance comparable to that of commercial battery-grade graphite. The study is based on a direct recycling concept that employs green solvents and thermal treatment. The focus is on the direct impact of the applied temperature on the quality of the recycled graphite. The temperature range used for thermal treatment affects the physical and chemical properties of the particles, primarily impacting the surface functionalities, which are crucial for electrochemical performance. We demonstrate the electrochemical performance of regenerated graphite active materials by validating the short closed loop from spent cells to new anodes with high-performance.

A frequently undervalued aspect of lithium-ion battery performance reporting is the specification of the format and area of the tested cells. However, these parameters provide crucial insights into the quality of the electrodes used for cell assembly and the reliability of the data obtained from the investigated systems. Here we focus on the aspects of process standardization and industry collaboration necessary for translating nanoscale electrochemical processes to Ah-scale cells. We examine the role of cell area and format in promoting comparability and standardization in battery research studies with technology readiness levels of 4 or higher. In addition, we discuss the limitations, challenges and expectations associated with measuring and evaluating battery performance exclusively in small cell formats.

Sodium-ion batteries (NIBs) are increasingly recognized as a viable and complementary technology to the Li-ion batteries (LIBs), with progress towards commercialization. However, the performance, stability and safety of these devices need to be further improved. State-of-the-art electrolytes, containing high fluorine content such as sodium hexafluorophosphate (NaPF6), guarantee satisfactory performance with improved SEI stability, but they pose serious environmental and safety concerns. Therefore, the development of less-fluorinated electrolytes that offer safe, sustainable, and promising performance is immensely important. This study investigates a sustainable, low-fluorinated electrolyte, comprising sodium bis(fluorosulfonyl)imide (NaFSI) and sodium difluoro(oxalato) borate (NaDFOB) in propylene carbonate (PC) solvent, for NIBs. The findings underscore that the use of this electrolyte in a laboratory-scale NIB full cell containing hard carbon (HC) and P2-Na2/3Al1/9Fe1/9Mn2/3Ni1/9O2 (P2-AFMNO) cathode, allows the realization of devices which display high performance and stability, i.e., achieving 80 % capacity retention within a wider voltage range of 1.5-4.3 V vs Na+/Na, after 200 cycles. An Xray photoelectron spectroscopy (XPS) analysis revealed the formation of inorganic-rich, robust and stable interfaces on both electrodes, contributing to enhanced stability and lifetime of the NIB demonstrator.

Wetting of lithium-ion battery electrodes with electrolyte represents a challenge that is a mostly neglected aspect of electrode optimization. In the production of large-format cells, the rate of electrolyte wetting after filling is of particular importance, as wetting time often represents a significant bottleneck. This study employs a systematic, quantitative investigation of the wetting behavior of lithium-ion battery electrodes using a tensiometer and considering the Washburn equation. This approach facilitates a fundamental understanding of the wetting behavior of porous electrodes. To consider the influence of microstructural differences and intrinsic electrode properties, two water-based graphite anodes were employed, which exhibit the same microscopic properties but differ in their pore size distribution and binder system. The developed tensiometer method demonstrates that by employing the average pore radius obtained from pore size distribution measurements, it is feasible to consider separately microstructural and material-specific influencing factors of wetting. Further investigation revealed that one of the two electrodes exhibited superior wetting, whereby the improved wetting could be clearly attributed to the used binder system. The findings were verified by contact angle measurements of the individual binder system films, by a drop shape analyzer and by electrochemical impedance spectroscopy measurements in symmetrical pouch cells.

Up to date, research on sodium-ion batteries (SIBs) has primarily focused on half-cell configurations, a crucial but preliminary step in evaluating suitable materials for full-cell SIBs. To date, the literature on hard carbon (HC)-based full-cell SIBs remains limited, and the irreversibility associated with the first cycle of HC anodes presents a significant challenge for the commercialization of hard carbon-based SIBs. This work evaluates sodium mesoxalate as a sacrificial salt (SS) in the cathode to compensate for biomass-based hard carbon first cycle irreversibility in two full-cell systems versus Na3V2(PO4)3@C and Na3V2O2(PO4)2F@C. This sacrificial salt is selected due to its nonflammability, low cost, and ease of dehydration. Full-cell studies utilizing the sacrificial salt-containing cathodes and biomass-derived hard carbon anodes demonstrate to achieve outstanding specific capacity and rate capability at low and moderate rates (from 9 to 130 mA g-1) for the fluorophosphate cell chemistry but poorer electrochemical results for the NASICON-based system. Finally, Life Cycle Assessment methodology is applied to the sacrificial salt containing full-cells to evaluate and compare the environmental footprint of these SS full-cells based on a sustainable anode with polyanionic cathode chemistries.

In this work, the characterization of novel electrolytes based on the combination of propylene carbonate (PC) solvent with sodium bis(fluorosulfonyl)imide (NaFSI) and sodium difluoro(oxalato)borate (NaDFOB), as well as their application in sodium‐ion batteries (SIBs) is presented. The results show that dual‐salt electrolytes have a wide electrochemical stability window, excellent transport properties, and mostly suppress anodic dissolution. When combined with P2‐Na 2/3 Al 1/9 Fe 1/9 Mn 2/3 Ni 1/9 O 2 (P2‐AFMNO) cathode electrode for SIBs operating at 4.3 V vs Na + /Na, they enable high performance and stability. XPS investigation revealed that this performance is related to the formation of a thin and homogeneous cathode electrolyte interphase (CEI) at the electrode surface.

Lithium-ion battery cathode materials such as LiNi0.5Mn1.5O4 (LNMO) are very sensitive to water, which has so far hindered the successful commercialization of aqueous electrode processing strategies. Herein, a detailed investigation of the surface and bulk reactivity of ordered LNMO with water and an aqueous solution of phosphoric acid to decipher the reaction mechanism and the impact on the eventual electrochemical behavior is presented. The comprehensive analysis via, for instance, neutron diffraction and synchrotron X-Ray diffraction, X-Ray absorption spectroscopy, magic-angle spinning nuclear magnetic resonance spectroscopy, thermogravimetric analysis coupled with mass spectrometry, high-resolution transmission electron microscopy, and X-Ray photoelectron spectroscopy reveals that the (acidic) water treatment particularly affects a very thin layer at the particle surface, while the bulk material remains largely unaffected. Nonetheless, when processed classically with N-methyl-2-pyrrolidone and polyvinylidene fluoride into electrodes, the significant impact of this layer on the electrochemical behavior highlights the important impact of the material surface on the eventually achievable performance in battery cells.

Combining high-voltage cobalt-free LiNi0.5Mn1.5O4 (LNMO) with fluorine-free water-soluble binders holds the promise of achieving more sustainable and environment-friendly lithium-ion batteries (LIBs). However, achieving high mass loading electrodes with lithium transition metal oxides as the active material remains a challenge. Herein, 2-hydroxyethyl cellulose (HEC) is proposed as suitable binding agent, crosslinked via citric acid with guar gum (GG). The incorporation of HEC is pivotal for realizing a homogeneous dispersion of the electrode components, which is essential for the mechanical properties. Hence, the advantageous combination of co-crosslinked HEC and GG allows for the simultaneous optimization of electrochemical and mechanical properties, enabling the preparation of well performing high mass loading LNMO electrodes with about 15 mg cm-2, providing a capacity retention as good as reference electrodes employing polyvinylidene difluoride as binder. Coupling these electrodes with graphite-based negative electrodes enables lithium-ion cells with an areal capacity of ~2.2 mAh cm-2 and a capacity retention of 82 % after 200 cycles, rendering this system promising for the realization of water-processed, F-free, high-voltage cathodes.

With the growing demand for high-energy-density lithium-ion batteries, silicon oxide (SiO) has emerged as a promising anode material due to its high specific capacity. However, its use entails high irreversible losses and mechanical stress. Pre-lithiated SiO (Li-SiO) blended with graphite enables electrodes with rather low irreversible losses, high specific capacity, and less mechanical stress. However, so far, insights about processing Li-SiO are missing in literature. This work deals with Gr/SiO negative electrodes containing 20 wt% SiO in the active mass. We investigate the effects of different suspension formulations on their rheological properties and the electrochemical performance of the electrodes. Our findings prove superior electrochemical properties of anodes made from Li-SiO compared to pristine SiO. However, we show that the basicity of suspensions containing Li-SiO causes challenges for their processability. The integration of single-walled carbon nanotubes is shown to be essential for counteracting the adverse effects and enabling electrodes with enhanced adhesion, reduced irreversible losses, and stable cycling. A good cell performance is demonstrated with electrodes containing as much as 96.8% of active mass. Our findings provide essential insights into the correlation between formulation, processability, and electrochemical performance of Gr/SiO blends, supporting the development of industrial-scale production processes.

This study systematically investigates the feasibility of replacing conventional sodium hexafluorophosphate (NaPF6) in carbonate-based electrolytes with sodium bis(fluorosulfonyl)imide (NaFSI) and sodium bis(trifluoromethanesulfonyl)imide (NaTFSI) in a 1,1,2,2-tetraethoxyglyoxal (TEG):propylene carbonate (PC) solvent system tested with hard carbon (HC) anode materials for sodium-ion batteries (SIBs). The influence of electrolyte composition and cycling conditions on the evolution of the solid electrolyte interphase (SEI) and overall electrochemical performance of the HC is comprehensively evaluated by means of electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy. The SEI chemical composition, transport properties, and stability are thoroughly characterized. The results demonstrate that the HC tested in NaFSI/TEG:PC electrolyte exhibits superior performance compared to both the conventional NaPF6/ethylene carbonate (EC):PC system and the NaTFSI/TEG:PC-based alternative, achieving higher initial coulombic efficiencies (ICEs), lower interfacial resistance, and enhanced Na+ transport properties. The improved electrochemical stability of the HC in NaFSI/TEG:PC electrolyte is attributed to the formation of a bilayered SEI, comprising an inorganic-rich inner layer and an organic-rich outer layer. These findings underscore the pivotal role of electrolyte formulation in enhancing the HC SEI characteristics and cycling performance, thereby positioning NaFSI in TEG:PC chemistry as a promising electrolyte candidate for next-generation SIBs.

LiNi0.5Mn1.5O4 (LNMO) is a promising next-generation cathode material for lithium-ion batteries (LIBs) due to its high-energy and high-power density. However, its commercial adoption is hindered by the unstable LNMO/ electrolyte interface due to high operating voltages and structural degradation arising from Jahn-Teller distortion and metal-ion dissolution resulting in poor cycling stability. Additionally, the high-temperature calcination beyond 700 degrees C often results in secondary phases such as rock salt NiO, Li1-xNixO, Ni6MnO8 or Li2MnO3, whose precise chemical compositions and their influence on electrochemical performance remain unclear. Traditional analytical techniques such as X-ray diffraction (XRD) or neutron diffraction face challenges in resolving these secondary phases due to low phase fractions and overlapping reflections with the LNMO phase. Here, we address these challenges using correlative Raman-Scanning electron microscopy (Raman-SEM) to characterize secondary phases in LNMO materials that were synthesized under various synthesis conditions and evaluated their impact on the electrochemical performance. Our results reveal the synthesis-dependent emergence of three distinct secondary phases in LNMO materials synthesized at 1000 degrees C, a phenomenon that, to our knowledge, has not been previously reported. Specifically, LNMO synthesized at 900 degrees C shows the coexistence of Ni6MnO8 and Li2MnO3 phases, while synthesized at 1000 degrees C also exhibits a Mn3O4 phase. Furthermore, an increased amount of these secondary phases in LNMO led to a lower discharge capacity due to their electrochemical inactive nature. However, these phases do not negatively impact the rate capability or the long-term cycling performance of the LNMO materials. These insights are crucial for advancing the development of LNMO cathode materials for nextgeneration LIBs.