Energy storage devices are important components in portable electronics, electric vehicles, and the electrical distribution grid. Batteries have achieved great success as the spearhead of electrochemical energy storage devices but need to be further developed in order to meet the ever-increasing energy demands, especially the new materials and processing method need to be further developed to achieve a sustainable production and usage. Rational design of not only the electrode materials, but also the inactive materials/components for example binder, conductive additives, current collectors are very important in developing high performance, low cost and sustainable lithium-ion battery. Starting from the issues of the current materials and technologies used in the battery cell production, I will introduce some of our recent works about how to design and fabricate sustainable active and inactive materials for the development of high-performance lithium-ion battery and future batteries. Specifically, the binder, sustainable electrode processing, current collector modification, coating strategies, and conductive additives will be discussed, and the use of various advanced characterization techniques (in situ/operando) to understand the materials and their energy storage mechanisms will be covered.

Batteries, essential components of electric vehicles, are the focus of intense research to improve safety, performance, and fast-charging capability. In this context, measuring the potential of each electrode individually is crucial, not only for laboratory characterisation, but also for intelligent management during commercial operation: in particular, monitoring the negative electrode (NE) potential is a direct and effective way to prevent lithium plating under operando conditions [1]. The reference electrode (RE) provides a practical solution for this, and LiFePO₄ (LFP) REs are among the most promising [2]. Nevertheless, obtaining reliable, reproducible, and artefact-free measurements without perturbing normal cell behaviour remains challenging [3]. This work investigates the impact of REs on cell operation, their electrochemical behaviour, and the accuracy of their measurements.

Six NMC811-graphite cell designs were produced to quantitatively compare LFP and lithium REs. Two dedicated designs, in which the RE covered the full active surface of the cell, allowed a detailed investigation of the underlying operating mechanism of the RE and its impact on cell performance. Pronounced disturbances, differing between lithium and LFP REs, revealed distinct mechanisms underlying the observed artefacts. Similar disturbances were also found in cells equipped with standard REs.

However, the measurements exhibited contradictory trends between polarisation and potential-response delay, which could not be explained based on existing literature. To move towards a more fundamental understanding of the phenomena involved, a pseudo-3D Newman model including a LFP RE was simulated using COMSOL Multiphysics. It reproduced the experimental observations, clarified the origin of these apparent contradictions and revealed a competition between polarisation and delay, providing new insight into RE-related artefacts. This analysis enabled the disturbances to be associated with characteristic deviations in the probed potentials.

Moreover, the simulation showed that REs based on insertion materials behave fundamentally differently from what is commonly assumed. Previously unreported artefacts linked to this phenomenon have been uncovered, raising questions regarding measurement reliability, particularly as the RE ages.

All these artefacts may either accumulate or compensate each other, and their magnitude depends on parameters such as temperature and C-rate. Fortunately, they can be considerably reduced by optimising the RE geometry, dimensions, or initial state. Building on these findings, this presentation will provide practical guidelines for designing artefact-minimised REs, enabling more reliable electrode-resolved measurements in both research and commercial applications.

Ag has garnered significant interest as an anode material for advanced Li batteries due to its ability to promote stable Li plating, particularly in all-solid-state battery systems. Nevertheless, the fundamental mechanisms responsible for this stable cycling behavior remain elusive. Here, we adopted atomistic simulations—combining density functional theory with machine-learning–potential molecular dynamics—to elucidate how Li transport kinetics regulate Li plating behavior within the Li–Ag alloy. Our calculations reveal that Li–Ag alloys exhibit pronounced Li surface diffusion characteristics that facilitate smooth, flat Li plating. However, bulk diffusion can be markedly sluggish, rendering the phase transformation kinetically limited. As a result, the phase transition is predominantly governed by the thermodynamic driving force, together with the more facile Li mobility within the amorphous phase. This kinetically moderated phase evolution prevents local Li build-up and maintains spatially uniform plating. Taken together, these insights underscore the essential balance between bulk and surface Li transport, providing guiding principles for the rational design of stable alloy-type Li anodes.

Miniaturized solid-state batteries provide a powerful platform for exploring the fundamental processes that govern solid–solid electrochemical interfaces, while simultaneously addressing the growing demand for compact and reliable energy storage in applications such as microsensors, implantable devices, and distributed IoT systems. Within this context, Pulsed Laser Deposition (PLD) stands out as a versatile thin film fabrication technique, offering exceptional control over composition, microstructure, and layer thickness across a wide range of electrode and electrolyte materials.

In this talk, we present a PLD-based approach to the fabrication and integration of oxide and phosphate thin film electrodes with solid-state electrolytes, focusing on interface formation and electrochemical behavior in both half-cell and full-cell configurations. Spinel Li₄Ti₅O₁₂ and LiMn2O4 and olivine LiFePO₄ thin films are investigated as model anode and cathodes, respectively, integrated with NASICON-type and LATP electrolytes. By tailoring deposition conditions and lithium supply during growth, distinct phase distributions and lithiation profiles are achieved, which strongly influence interfacial stability and cycling response. In particular, lithium-rich interfacial phases in LiMn₂O₄-based systems are shown to enable extended voltage operation when coupled to LiPON.

By combining multiple electrode chemistries, electrolyte families, and cell configurations, this talk aims to highlight PLD as a powerful tool not only for realizing proof-of-concept thin film solid-state batteries, but also for systematically probing the mechanisms that govern solid-state electrochemical interfaces across emerging material systems.

The performance and durability of lithium metal batteries are strongly influenced by the structure and chemistry of the solid electrolyte interphase (SEI), which forms through electrolyte reduction at the anode. Conventional strategies for creating fluorine rich SEIs rely on large amounts of fluorinated solvents or salts, increasing cost and environmental impact while often compromising electrolyte properties. We introduced a new SEI design concept that uses positively charged, readily reducible fluorinated cations which are electrostatically attracted to the negatively polarized lithium surface. Through this mechanism, we form a robust fluorine containing SEI using only millimolar additive levels, facilitating uniform and dense lithium plating and significantly improving interfacial stability. Building on this strategy, we are expanding the concept to a broader set of custom designed pyridinium-based cations to control SEI chemistry. By tuning functional groups, we aim to establish molecular level relationships between cation structure, SEI composition, and interphase mechanical and transport properties. Ongoing work examines how cation derived interphases form and evolve, how their nanoscale properties influence cycling stability, and how cation solvation environments affect SEI performance.

Mixed ionic–electronic conductors (MIECs) which can host mobile protons have attracted interest for low- to intermediate-temperature (25ºC - 300 ºC) electrochemical technologies e.g. energy-conversion, sensing and information-processing. However, the challenge remains in determining the proton uptake, electronic leakages and chemical stability when in contact with different media.

In this work, we introduce a thin-film materials comparison of proton-active oxides, combining perovskite-type electrodes (LaSr₀.₄Fe₀.₆O₃, SrFe₀.₅Co₀.₅O₃, Ba₀.₉₅La₀.₀₅Fe₀.₈Zn₀.₂O₃) with widely studied proton storing simple oxides (TiO₂ and WO3). Dense electrode films are deposited using pulsed laser deposition, enabling precise control of thickness, texture and interfaces.

The thin films are characterized using PICET (proton insertion coupled with electron transfer)-inspired electrochemical protocols. Materials are characterized both acidic and alkaline aqueous electrolytes to probe proton-coupled redox processes and their associated charge storage. Cyclic voltammetry and galvanostatic charge-discharge are used to map the accessible potential window, charge insertion per unit cell and rate response for each composition. The evolution of current–potential profiles with pH, scan rate and film thickness provide insight into the balance of near-surface reactions and deeper proton insertion, while extended cycling defines voltage ranges that preserve electrochemical response and structural integrity. This yields a comparative view on how Fe/Co-based perovskites w.r.t Ti/W simple oxides operate as proton-responsive MIECs under different chemical environments. MIEC thin films are also combined with proton conducting perovskites like BaCe₀.₈Y₀.₁Yb₀.₁O₃ and BaZr₀.₄Sc₀.₆O₃ to explore proton insertion using air electrode at relevant temperature ranges.

Overall, this study identifies favorable compositional and microstructural features that govern proton-enabled MIEC behavior. We explored the comparison of proton insertion in MIEC perovskites with simple oxides in different media and proton uptake by hydrogenation of materials with air electrode. The results outline design principles for oxide thin films with tailored protonic and electronic transport, suitable for integration in next-generation intermediate temperature energy storage devices as well as memory devices.

Thin film solid-state batteries (TFSSB) can act as model system to enable mechanistic insights into battery materials, which would often be obscured by additives and complex microstructure in composite electrodes. TFSSBs use pure materials, have well-defined geometry (parallel layers of known thickness and area) and compact size.^1,2 Their architecture also allows for relatively easy investigations of buried interfaces that would be challenging to measure in bulk cells that have multi-phase components with often random structure.³

Transition-metal fluorides (TMFs) represent a promising class of high-energy cathodes but remain poorly understood due to their complex reaction pathways and instability in conventional liquid electrolyte cells. Using co-evaporated TM–LiF heterostructures with LiPON solid-state electrolyte, we systematically explore how the choice of TM (TM = Cr, Mn, Fe, Co, Ni, Cu) in TMF cathodes influences their electrochemical performance.⁴

We use a combination of galvanostatic cycling, impedance spectroscopy, and post-mortem STEM/EELS/EDX to elucidate the interplay between structure, chemistry and performance. Our best performers differ a lot in terms of their charge-discharge profiles and degradation performance. Briefly, in Fe-LiF, prolonged cycling leads to C-rate dependent restructuring that results in more beneficial nanostructure and increase in available capacity (from 150 to 210 mAh/g at 6C).⁵ We propose for the first time Cr-LiF cathodes, which show higher initial capacity of 433 mAh/g and similar nano-restructuring. However, the new nanostructure reduces electrochemical performance, which then plateaus at 208 mAh/g after 1500 cycles. Cr-LiF also demonstrates good rate capability with 357 mAh/g at 5C and 192 mAh/g at 8C.⁶ Moreover, I will discuss the prospects of using interfacial conversion reactions and job-sharing mechanisms to further boost the ion storage capacity and C-rate of thin-film cathodes and our recent results in that field.^7,8

Owing to their high energy density and relatively low costs, Ni-rich Li[Ni_xCo_yMn_1–x–y]O₂ (NCM) based cathode active materials are of high interest for conventional lithium-ion batteries (LIBs) as well as for next-generation all-solid state batteries (ASSB). However, the active materials suffers from parasitic side reactions mainly occurring at the interface with the liquid or solid electrolyte, which results in capacity fading and impedance rise and, thus, hinders large-scale application. One feasible approach to tackle this issue are surface coatings, which can stabilize the interface as they prevent direct contact between electrolyte and cathode active material.

The presentation will provide examples of how thin surface coatings can enhance the performance of NCM-based cathodes in both lithium-ion and all-solid-state batteries, and how the structural properties of these coatings influence their functionality.[1-3] It will be shown that the design of efficient coatings involves certain requirements: while the coating must inhibit direct contact between the active material and the electrolyte to suppress surface degradation, it must simultaneously provide sufficient ionic conductivity to facilitate ion transport across the interphase. In addition, it will be demonstrated that thin-film model systems offer valuable insights into the fundamental mechanisms governing coating functionality.[4,5]

Oxygen stoichiometry in mixed ionic-electronic conductors (MIECs) can be used to control a wide range of materials functionalities, from electrical conductivity to optical and magnetic properties [1]. Moreover, by appropriately choosing MIEC materials with a wide electrochemical stability window, oxygen incorporation/release can be used for charge storage, in analogy with Li-ion battery electrodes. In the present contribution, I will show our recent results related to precise oxygen control in MIEC thin films using advanced electrochemical methods, and demonstrate how this strategy can be implemented for the precise tuning of materials functionalities and for the realization of new generation of oxygen-based devices including an all-solid-state oxygen-ion battery (OiB) [2]. These batteries can deliver continuous and reliable operation in intermediate and high temperature environments (>250 ºC), where state-of-the-art Li-based devices fall short, and they present high stability towards a variety of environmental conditions – including oxygen and humidity, while delivering competitive performance (OCV > 1V, electrode capacity > 60 mAh g^-1). Advances in technology development, including electrolyte miniaturization, electrode engineering, and technology scale-up, which are being achieved within the European project “OxyBatt”, will be shown.

Lithium-rich antiperovskites have emerged as a promising class of solid electrolytes due to their high lithium content, structural tunability, and potential for fast ion transport. This presentation examines how defect chemistry, lattice topology, and anion sublattice dynamics collectively govern lithium mobility in antiperovskite materials. Using a combination of first-principles modeling and data-driven analysis, we identify dominant transport pathways and quantify the role of vacancies, rotational disorder, and low-dimensional conduction motifs in enabling superionic behavior. These insights are distilled into simple design rules for engineering antiperovskites with enhanced ionic conductivity and improved thermodynamic stability. Building on this mechanistic understanding, the talk further introduces a high-throughput computational framework for identifying chemically stable interlayers for halide solid electrolytes, aimed at mitigating interfacial reactivity with electrodes. By screening candidate interlayer materials across thermodynamic and electrochemical stability metrics, we establish transferable criteria for interphase selection. Together, these efforts link crystal chemistry, ion transport, and interfacial stability, providing a predictive framework for the rational design of solid electrolytes and interlayers for durable solid-state battery architectures.

The rapid growth of battery industry required for global transition to emission-free economy created a new challenge – can we provide alternatives to the modern Li-ion batteries? This challenge calls for new materials, chemistries and non-conventional approaches. However, the design of new materials, their efficient implementation in a battery, possible recycling pathways strongly depends on the operating mechanism, i.e. what kind of chemical transformations a material undergoes in a battery cell. In many cases, understanding of failed or well performing materials can greatly assist in optimization and design of new better performing analogues. Our recent work demonstrated that operando methods can be used not only for the analysis of active materials, but also for analysis of other chemical and mechanical processes in batteries, such as relaxation and mechanical deformation of active components.  In the present talk, the operando X-ray based methods for characterization of battery materials will be discussed illustrating the potential benefits and challenges associated with the use of those techniques.

We present a comprehensive and versatile methodology for the acquisition, preliminary interpretation, and advanced modeling of impedance spectra of lithium-ion insertion electrodes. Using a Ni-rich NMC cathode as a model system, we outline the essential experimental requirements for obtaining reliable impedance data and demonstrate how rigorous characterization of active material particles, electrode morphology, and porosity contributes to the consistency and interpretability of electrochemical impedance spectroscopy (EIS) results. Particular attention is given to common experimental pitfalls and typical misinterpretations of impedance features that often arise in studies of porous insertion electrodes.

A key contribution of this work is the introduction and application of a scaling-based normalization approach for impedance parameters.[1] We show that simple mass-normalized Nyquist plots, together with the assumption of ideal capacitive behavior, enable a fast preliminary estimation of the total chemical insertion capacitance, C_total. Importantly, we experimentally confirm for Ni-rich NMC that C_total obtained from sufficiently low-frequency impedance measurements is quantitatively equivalent to the differential capacitance C_d(x) extracted from the equilibrium OCV curve.[1] This demonstrates that low-frequency EIS can directly probe the thermodynamic properties of single-phase insertion materials in realistic porous electrodes.

In the second step, we systematically analyze impedance spectra of a dedicated series of NMC cathodes with increasing electrode mass loading using an advanced physics-based transmission line model (TLM). We verify theoretically predicted scaling laws for all model parameters and demonstrate how electrode geometry governs the detectability and magnitude of individual impedance contributions.[2] The results highlight a critical practical implication: for a given mass loading, only a subset of impedance processes emerge above the measurement sensitivity threshold. Consequently, accurate parameter extraction typically requires impedance spectra collected from electrodes spanning a wide and well-controlled range of masses. Moreover, the analysis reveals an unexpected additional diffusion feature—predominantly visible in thin electrodes—which we attribute to ion diffusion within micropores inside the NMC aggregates. Overall, this integrated methodology provides experimenters with directly applicable tools, scaling relations, and modeling strategies for developing intuitive and physically grounded interpretations of impedance responses in porous Li-ion insertion cathodes.

A crucial additional consideration arises when aiming to quantitatively interpret impedance parameters in terms of fundamental physical properties. All passive TLMs constructed from R-C elements are grounded in the Nernst–Planck (NP) framework. Accordingly, each circuit element represents a linear response of the part of studied system to the corresponding driving forces associated with gradients of electric potential and salt concentration. It is, however, well established that the classical Nernst–Planck formulation is strictly valid only under two limiting conditions: (i) thermodynamically ideal behavior and (ii) infinitely dilute electrolytes.[3] Real non-aqueous battery electrolytes - used in Li-ion, Na-ion, and analogous insertion systems - substantially deviate from these ideal assumptions. As a result, TLM parameters derived under NP-based assumptions do not necessarily map directly onto physically meaningful transport and thermodynamic quantities.

A more realistic description of battery electrolytes is provided by the Concentrated Solution Theory (CST) framework, pioneered by Newman.[4] CST accounts for non-ideal thermodynamic factors, salt–solvent and ion-ion interactions, and composition-dependent transport coefficients. In this work, we discuss the conceptual and practical implementation of a correction (alignment) step in which NP-derived electrolyte parameters are translated into their CST-consistent counterparts. One of the most prominent examples is the cation transference number, which appears both in NP and CST descriptions but differs quantitatively due to non-ideal thermodynamic and transport behavior. Using representative Li-ion insertion electrolytes, we demonstrate that this alignment step is essential for obtaining physically sound and quantitatively meaningful interpretations of impedance-derived electrolyte parameters in insertion electrodes and full cells.

Sodium-ion batteries are attracting attention as cost-effective and sustainable energy-storage systems. Their performance—including energy density, power capability, cycle life, and safety—depends strongly on the choice and design of cathode active materials (CAMs). Among CAM families, polyanionic compounds are particularly versatile due to their structural diversity and intrinsic stability. These materials, generally represented as NaxMy(XzO₃z₊₁), combine redox-active transition metals with various polyanion groups. The strong covalent character and high electronegativity of these anions enhance the inductive effect, stabilizing the Na–O framework and enabling relatively high operating voltages. The flexibility to incorporate different transition metals and polyanion types—including phosphates, pyrophosphates, silicates, carbonates, and sulfates—provides multiple avenues for tuning electrochemical properties.

Na₄Fe₃(PO₄)₂(P₂O₇) (NFPP) is a representative polyanionic cathode, notable for its earth-abundant composition and stable framework. Its structure of PO₄³⁻ and P₂O₇⁴⁻ groups forms one-dimensional Na⁺ diffusion channels, allowing reversible sodium intercalation. This architecture supports a theoretical capacity of 129 mAh g⁻¹ at an average voltage of ~3.0 V vs. Na⁺/Na. Partial substitution of Fe by Mn has been investigated in recent studies. While Mn substitution appears to enable participation of the Mn²⁺/Mn³⁺ redox couple and may influence the operating voltage, its effects on Na⁺ mobility, capacity, rate performance, and long-term structural stability remain uncertain and require further systematic study.

Synthesis conditions remain a critical factor in determining phase purity and electrochemical performance. Solid-state preparation can lead to secondary phases, emphasizing the importance of precursor composition, reaction control, and carbon-coating strategies. These considerations highlight the broader need for careful compositional and structural design when developing NFPP-based polyanionic cathodes—whether pristine or Mn-substituted—for sodium-ion battery applications.

Aqueous ion batteries represent a promising technology for large-scale stationary energy storage, offering inherent safety, material sustainability, and low maintenance requirements. However, their practical implementation faces significant challenges, primarily related to the compatibility of electrode materials with water-based electrolytes. Beyond the restricted electrochemical stability window, electrode degradation arises from the strong solvating power and complex acid–base chemistry of aqueous systems.

Framework materials such as Na SuperIonic CONductors (NASICON) and Prussian Blue Analogues (PBAs) have attracted considerable attention due to their structural diversity, chemical stability, and low cost. A deep understanding of degradation mechanisms and strategies for their mitigation is essential to unlock the full potential of these materials and enable efficient aqueous battery systems.

Among NASICON-type compounds, NaTi₂(PO₄)₃ (NTP) stands out as one of the most suitable negative electrodes for aqueous electrolytes, owing to its favorable redox potential of -0.62 V vs SHE. Nevertheless, parasitic reactions significantly limit its Coulombic efficiency, induce self-discharge, and reduce charge capacity. To elucidate these degradation pathways, we performed operando monitoring of local pH, complemented by solid-state NMR, XRD, and EDX analyses. Our findings reveal that both hydrogen evolution (HER) and oxygen reduction (ORR) occur during NTP cycling, contributing to pH increase. While HER remains negligible under mildly alkaline conditions, chemical ORR driven by O₂ reacting with Ti^(III) species plays a dominant role. Interestingly, NTP exhibits minimal capacity loss at pH 7, but degradation becomes pronounced at pH 10, even in oxygen-free environments. We demonstrate that the time NTP spends in alkaline solution largely determines its stability at low cycling rates. Furthermore, only a fraction of the observed capacity fade is attributable to NTP decomposition; most losses stem from electronic contact failure within the electrode structure, caused by the growth of aqueous interphase layers composed primarily of amorphous TiO(OH)(H₂PO₄)·nH₂O phases. These insights suggest that careful control of local oxygen concentration and pH can enable highly stable NTP operation in simple, low-concentration aqueous electrolytes.

Prussian Blue Analogues, with their open framework and large cavities, are particularly appealing for multivalent ion storage, such as Zn²⁺ insertion. Zn-rich phases like KₓZn₂[Fe(CN)₆] (x → 0) show promise as positive electrodes for aqueous Zn-ion batteries. We investigated the synthesis–structure–property relationships of KₓZn₂[Fe(CN)₆], focusing on phase formation, Fe^(II/III) oxidation states, and hydration levels. Electrochemical performance was assessed via operando XRD in ZnSO₄ aqueous electrolytes, revealing previously unreported aspects of phase evolution during synthesis and cycling. These findings provide critical insights for optimizing PBA-based electrodes in next-generation aqueous Zn-ion batteries.

Electrolyte is one of the biggest contributors to the battery safety. In the state-of-the-art Li and Na-ion battery electrolytes, carbonate-based solutions and fluorine-containing salts are typically used. However, due to the flammability of the carbonates and the harmful environmental effects of fluorine, the safety risks related to these electrolytes are considerable. The use of fluorine-containing salts is often justified with their good ionic conductivities, good ionic dissociation and their ability to passivate the aluminium current collector. However, it has recently been shown that alternatives with similar properties exist¹, and that the use of fluorine-based anions is not as well-justified as it was before.

One of the most promising fluorine-free electrolytes for Na-ion batteries consists of sodium bis(oxalate)borate (NaBOB) salt dissolved in triethyl phosphate (TEP)². NaBOB, however, is not without issues as it tends to decompose on the negative electrode during the first cycle. Some of this can be prevented by e.g. using additives³ but overall the issue is not understood well. In this work, the effect of the passivating electrolyte additives and different formation protocols on the formation, electrolyte performance and hard carbon sodiation are investigated. A modified formation protocol starting with a high C-rate step in the beginning of the charge to bypass NaBOB decomposition is proved to be more effective in improving the initial Coulombic efficiency of 0.35 M NaBOB-TEP than the additives. When a conventional formation protocol is used, the additives 1,3,2-dioxathiolane 2,2,-dioxide (DTD) and prop-1-ene-1,3-sultone (PES) are reduced before NaBOB which stabilizes the solid electrolyte interphase (SEI) and the cell cycling. However, the modified formation protocol bypasses the positive SEI formation capability of PES and DTD, preventing the traditional SEI formation. Meanwhile 1,4-butane sultone (BS), a less reactive additive, benefits from the changes in the formation step similarly to the baseline NaBOB-TEP without additives. In addition, the electrolyte salt and additives and are observed to affect the sodiation reaction potentials on the hard carbon.

The results indicate that when additives and modified formation protocols are used together, the investigation for the best-performing additive system should be done using the intended cycling protocol, because the protocol affects the additive performance.

Aqueous Zn–MnO₂ batteries with mildly acidic electrolytes are emerging as a promising alternative to Li-ion systems for large-scale energy storage, offering low cost, high safety, and competitive energy density. These advantages stem from the high capacity and reversibility of Zn metal in aqueous electrolytes, combined with the abundance and environmental benefits of MnO₂, a material long used in primary alkaline batteries. Recent demonstrations of rechargeability in mildly acidic media have expanded the potential of Zn/MnO₂ chemistry for sustainable energy storage.

Despite this progress, the underlying mechanisms remain debated. Our operando (XAS, XRD) and ex situ (TEM, SEM, TXM) studies indicate that electrolytic MnO₂ dissolution–precipitation dominates over intercalation, although voltage profiles and capacities vary with active material and electrolyte composition, as well as cell architecture [1]. The precipitated Mn phases are highly defective and poorly crystalline, with properties strongly influenced by pH, additives, and electrode texture. These insights enable the rational design of cells that exploit Mn oxide precipitation and dissolution as the primary charge-storage mechanism.

Building on this understanding, we present a Zn–MnO₂ flow cell architecture where cycling induces dynamic porosity changes within the electrode, impacting mass transport and reaction distribution. Experimental results are complemented by a 2D COMSOL model based on a porous electrode framework, exploring the effects of diffusion coefficients, electrode thickness, porosity gradients, and Zn geometry on voltage profiles, efficiency, and rate capability. This modelling approach provides design guidelines that are challenging to obtain experimentally and demonstrates the value of macro-scale simulation for optimizing Zn–MnO₂ battery performance. Our findings highlight the potential of aqueous Zn-based systems as safe, cost-effective solutions for grid-scale storage and beyond.

Zinc-Air Batteries (ZABs) have gained significant attention as a promising solution for sustainable energy storage, owing to their high theoretical energy density (1000-1300 Wh kg⁻¹) and the use of non-toxic, inexpensive, and abundant materials. ZABs are particularly suited for low-consumption applications with long energy durability. However, their widespread application remains hindered by challenges such as the inherent instability of traditional liquid electrolytes, particularly issues with leakage and evaporation. [1,2] This work presents the development of agarose-based gel polymer electrolytes (GPEs) as a potential solution to enhance the performance, mechanical stability, and longevity of ZABs.

Two primary approaches were explored to improve the GPE properties; (1) increasing the agarose concentration and (2) introducing boric acid (BA) as a crosslinker. A comprehensive experimental protocol was employed, compression tests, ionic conductivity measurements, and accelerated aging under elevated temperatures. The findings demonstrate that increasing the agarose concentration significantly improves the mechanical strength of the gels, with compression tests showing enhanced resilience compared to lower concentrations, without affecting the electrochemical performance (i.e., conductivity and zinc utilization). Together with crosslinking with BA, this resulted in gels with exceptional stability, ensuring the GPE maintained its structural integrity without degradation under accelerated ageing conditions.

In addition, ionic conductivity tests revealed that agarose gels, both crosslinked and non-crosslinked, exhibited ionic conductivities comparable to traditional liquid electrolytes. Accelerated ageing tests showed that new agarose gels outperformed previous formulations in long-term stability, maintaining promising performance even under harsh conditions.

These results highlight the potential of crosslinked and non-crosslinked agarose-based GPEs as promising advancement for ZABs. With superior mechanical properties, high ionic conductivity, and excellent long-term stability, these gels offer a robust solution to address key limitations of traditional liquid electrolytes, thereby enhancing the performance and scalability of GPEs for next-generation energy storage technologies.