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Lithium-ion batteries are the most ubiquitous energy storage devices in our everyday lives. However, their energy storage capacity fades over time due to chemical and structural changes in their components, via different degradation mechanisms. Understanding and mitigating these degradation mechanisms is key to reducing capacity fade, thereby enabling improvement in the performance and lifetime of Li-ion batteries, supporting the energy transition to renewables and electrification. In this endeavor, surface analysis techniques are commonly employed to characterize the chemistry and structure at reactive interfaces, where most changes are observed as batteries age. However, battery electrodes are complex systems containing unstable compounds, with large heterogeneities in material properties. Moreover, different degradation mechanisms can affect multiple material properties and occur simultaneously, meaning that a range of complementary techniques must be utilized to obtain a complete picture of electrode degradation. The combination of these issues and the lack of standard measurement protocols and guidelines for data interpretation can lead to a lack of trust in data. Herein, we discuss measurement challenges that affect several key surface analysis techniques being used for Li-ion battery degradation studies: focused ion beam scanning electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and time-of-flight secondary ion mass spectrometry. We provide recommendations for each technique to improve reproducibility and reduce uncertainty in the analysis of NMC/graphite Li-ion battery electrodes. We also highlight some key measurement issues that should be addressed in future investigations.

The lack of knowledge on electrochemical reaction pathways for Al/S batteries prevents the development of practical approaches to mitigate the irreversibility and poor cycling performances of this appealing secondary battery system, which is, in theory, scalable, inexpensive, and energy-dense. Different from the Li/S system, Al/S batteries use ionic liquids (ILs) as electrolytes. The choice of the IL, i.e., whether the IL is based on a conventional EMImCl-based electrolyte or in a deep eutectic mixture of aluminum chloride with urea (or any of its derivatives), strongly affects the electrochemical energy-storage performance of the cell. To shed some light on the Al/S battery chemistry, here, we present the computational electrochemistry research work to determine the most favorable reaction pathways and thermodynamically stable reaction intermediates. We also discuss the effect of the coordination of ionic species (originated from aluminum-containing deep eutectic electrolytes) with polysulfide intermediates, which lead to alterations in the reaction pathway and electrochemical behavior of the Al/S system. The spectroscopic signatures from various reaction intermediates are also reported and validated via comparison with experimental observations.

Electrochemical energy storage has been instrumental for the technological evolution of human societies in the 20th century and still plays an important role nowadays. In this introductory chapter, we discuss the most important aspect of this kind of energy storage from a historical perspective also introducing definitions and briefly examining the most relevant topics of electrochemical energy storage associated with the use of nanomaterials.

The high abundance and low cost of aluminum and sulfur make the Al–S battery an attractive combination. However, significant improvements in performance are required, and increasing the thickness and sulfur content of the sulfur electrodes is critical for the development of batteries with competitive specific energies. This work concerns the development of sulfur electrodes with the highest sulfur content (60 wt %) reported to date for an Al–S battery system and a systematic study of the effect of the sulfur electrode thickness on battery performance. If low‐cost electrolytes made from acetamide or urea are used, slow mass transport of the electrolyte species is identified as the main cause of the poor sulfur utilization when the electrode thickness is decreased, whereas complete sulfur utilization is achieved with a less viscous ionic liquid. In addition, the analysis of very thin electrodes reveals the occurrence of degradation reactions in the low‐cost electrolytes. The new analysis method is ideal for evaluating the stability and mass transport limitations of novel electrolytes for Al–S batteries., Thick and thicker! The thickness of the cathode and viscosity of the electrolyte affect the rate of transport of electrolyte species inside the porous sulfur electrode in Al–S batteries and cause poor sulfur utilization in deep eutectic solvents, whereas complete sulfur utilization is achieved with a less viscous ionic liquid. In addition, the analysis of the effect of cathode thickness on battery performance and the electrochemistry of carbon additives provides evidence of the degradation of deep eutectic solvents in Al–S batteries.

The Lithium–Sulfur battery is considered to be one of the main candidates for the “post-lithium-ion” battery generation, because of its high theoretical specific capacity and inherently low cost. The role of the electrolyte is particularly important in this system and remarkable battery performances have been reported by tuning the amount of salt in the electrolyte. To further understand the reasons for such improvements we chose the lithium bis(trifluoromethanesulfonyl)imide in 1,3-dioxolane electrolyte as a model salt-solvent system for a systematic study of conductivity and viscosity over a wide range of concentration from 10-5 up to 5 molal. The experimental results, discussed and interpreted with reference to the theory of electrolyte conductance, lead to the conclusion that triple ions formation is responsible for the highest molal conductivity values before reaching the maximum at 1.25 molal. At higher concentrations, the molal conductivity drops quickly due to a rapid increase in viscosity and the salt–solvent system can be treated as a diluted form of molten salt.

The term supercapacitor (or ultracapacitor) is used to indicate an electrochemical capacitor capable of storing charge through a capacitive process occurring in the electrical double layer formed at the interface between an electronic conductor (i.e., the electrode) and an electrolytic solution (e.g., non-aqueous electrolyte). The increasing demand for improved electrochemical energy storage systems continually boosts research efforts toward new materials, configurations and production processes, both for batteries and supercapacitors. The development of hybrid devices (e.g., where one electrode stores charge through a faradaic process and the other through a non-faradaic process) has also exploited progress in both the battery and supercapacitor fields. However, not all investigated materials are promising or industry-relevant, contrary to the claims in many research works. For example, complications related to the upscaling of lab-scale experiments hamper the exploitation at industrial scale. For these reasons, it is essential to define the best-practice methods to obtain reasonable predictions for supercapacitor materials and device testing. Also, many battery electrode materials are explored as supercapacitor electrode materials. However, not all battery materials can be considered as candidate electrode materials for hybrid devices. Only those materials with a suitable crystal structure for high rate capability and good cycling stability are appropriate.

Operando Raman spectroscopy is a well-established technique for monitoring chemical changes in active materials during electrochemical cycling of alkali-ion cells. To date, however, its application to the study of commercial electrodes under realistic operating conditions has been severely limited by cell design constraints. We present here an improved configuration for performing operando Raman spectroscopy on coated metal foil electrodes used in standard laboratory cell testing. Electrochemical modeling predicts much improved lithiation homogeneity compared to a previously used configuration; this observation is validated experimentally for a commercially-sourced graphite electrode. The new configuration delivers improved electrochemical performance at higher specific currents than was previously possible, ensuring that Raman measurements at a single location are representative of the entire electrode. Finally, the broad applicability of the configuration is demonstrated through a study of hard carbon sodium-ion negative electrodes over 50 cycles. These results provide a new configuration for performing reliable, validated operando Raman spectroscopy on commercial battery electrodes, as well as establishing a general methodological framework for the validation of operando spectroscopic techniques to ensure that their performance is relevant to the practical systems to which they are applied.

Casein from bovine milk is evaluated in this work as binding agent for electrochemical double layer capacitors (EDLCs) electrodes. It is demonstrated that casein provides excellent adhesion strength to the current collector (1187 kPa compared to 51 kPa achieved with PVdF), thus leading to mechanically stable electrodes. At the same time, it offers high thermal stability (above 200 °C) and electrochemical stability in organic electrolytes. Apparently though, the casein-based electrodes offer lower electronic conductivity than those based on other state-of-the-art binders, which can limit the rate performance of the resulting EDLC. In the attempt of improving the electrochemical performance, it is found that the application of a pressing step can solve this issue, leading to excellent rate capability (up to 84% capacitance retention at 50 mA cm −2 ) and cycling stability (96.8% after 10,000 cycles at 10 mA cm −2 ) in both PC- and ACN-based electrolytes. Although the adhesive power casein is known since ancient times, this report presents the first proof of concept of its employment in electrochemical power sources.

In this manuscript we report about the realization and testing of a high-voltage electrochemical double layer capacitor (EDLC) prototype (IES prototype), which has been assembled using innovative electrode and electrolyte components. The IES prototype displays a nominal capacitance of 4 F, a maximum voltage of 3.2 V and its maximal energy and power are in the order of 37 Wh kg −1 and 65 kW kg −1 , respectively. Furthermore, it also displays good cycling stability, high capacitance retention after 80 h float test and acceptable self-discharge. Taking into account substantial improvements of the cell design and assembly procedure, the performance of the IES prototype indicates that the components utilized in this device might be suitable alternatives to the state-of-the-art materials used in high energy EDLCs.

Electrochemical impedance spectroscopy (EIS) is a widely applied non-destructive method of characterisation of Li-ion batteries. Despite its ease of application, there are inherent challenges in ensuring the quality and reproducibility of the measurement, as well as reliable interpretation and validation of impedance data. Here, we present a focus review summarising best metrological practice in the application of EIS to commercial Li-ion cells. State-of-the-art methods of EIS interpretation and validation are also reported and examined to highlight the benefits and drawbacks of the technique.

Sodium-ion batteries (NIBs) are an attractive alternative to lithium-ion batteries (LIBs) because of the natural abundance of sodium resources [1]. Owing to their similar working principles to LIBs, NIBs also offer the advantage of utilizing the same manufacturing protocols and methodology as LIBs, and as such minimal additional capital costs are required for existing LIB manufacturers to switch to NIB technology. Since the sodium storage mechanism of hard carbon (HC) was demonstrated by Stevens and Dahn in 2000 [2], it has become the state-of-the-art anode material for NIBs due to its good cycling stability, low working potentials, small voltage hysteresis and relatively low cost. However, the storage mechanism for high performance is not fully understood due to the complexity of the HC structure. The prevalent problem of under-estimated capacity of HC in half-cell tests indicates that this conventional test method requires improvement. Furthermore, half-cell studies are generally carried out in two-electrode configuration, where the counter electrode (CE) acts also as reference electrode (RE). This provides reliable results only if the passage of current does not significantly perturb the potential of the CE [3]. In this study, we present an in-depth investigation of the electrochemical behavior of a range of HC-based working electrodes (WE) in three-electrode half-cell configuration, with a pure Na metal CE and a concentric Na metal coaxial ring RE. The use of a separate RE allows simultaneous data acquisition for both WE and CE, during galvanostatic cycling and electrochemical impedance spectroscopy measurements. Using this approach, the electrochemical performance, including cycling stability, rate capability and electrochemical impedance, is measured in a reliable manner to assess the capacity and cyclability of HC. In addition, the effect of four different types of electrolyte solution on the electrochemical behavior is analysed and discussed to inform electrolyte selection from a full-cell perspective (Figure 1). Reference s : [1] C. Vaalma, D. Buchholz, M. Weil, S. Passerini, Nat. Rev. Mat., 3 (2018) 18013. [2] J. R Dahn, D. A. Stevens, J. Electrochem. Soc., 4 (2000) 147. [3] R. Raccichini, M. Amores, G. Hinds, Batteries., 5 (2019) 12. Figure 1

Use of a reference electrode (RE) in Li-ion batteries (LIBs) aims to enable quantitative evaluation of various electrochemical aspects of operation such as: (i) the distinct contribution of each cell component to the overall battery performance, (ii) correct interpretation of current and voltage data with respect to the components, and (iii) the study of reaction mechanisms of individual electrodes. However, care needs to be taken to ensure the presence of the RE does not perturb the normal operation of the cell. Furthermore, if not properly controlled, geometrical and chemical features of the RE can have a significant influence on the measured response. Here, we present a comprehensive review of the range of RE types and configurations reported in the literature, with a focus on critical aspects such as electrochemical methods of analysis, cell geometry, and chemical composition of the RE and influence of the electrolyte. Some of the more controversial issues reported in the literature are highlighted and the benefits and drawbacks of the use of REs as an in situ diagnostic tool in LIBs are discussed.

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The paper gives guidelines for the publication of results related to batteries.

The scientific community is continuously committed to the search for new high energy electrochemical storage devices. In this regard, lithium metal batteries, due to their very high electrochemical energy storage capacity, appear to be a highly appealing choice. Unfortunately, the use of lithium metal as the anode may lead to some safety hazards due to its uneven deposition upon charging, resulting in dendrite growth and eventual shorting of the battery. This issue may be successfully addressed by using intrinsically safer electrolytes capable of establishing a physical barrier at the electrode interface. The most promising candidates are solid electrolytes, either polymeric or inorganic. The main purpose of this review is to describe the present status of worldwide research on these electrolyte materials together with a critical discussion of their transport properties and compatibility with metallic lithium, hoping to provide some general guidelines for the development of innovative and safe lithium metal batteries.

A graphene-based composite containing Sn and Sb is synthesized and characterized. Structural and morphological characterizations demonstrate the achievement of multilayer graphene with anchored SnSb nanoparticles. The composite is tested as active material for lithium-ion battery anodes and, as a result of the use of poly acrylic acid binder and vinylene carbonate electrolyte additive, remarkable electrochemical performance are achieved in terms of stable cycling stability and specific gravimetric capacity (468 mAh g−1 after 75 cycles with a capacity retention of about 80%). Moreover, impedance spectroscopy analysis further demonstrates the enhanced stability obtained by using, together with vinylene carbonate electrolyte additive, poly acrylic acid binder instead of poly vinylidene difluoride.

The electrochemical properties of graphene are strongly depending on its synthesis. Between the different methods proposed so far, liquid phase exfoliation turns out to be a promising method for the production of graphene. Unfortunately, the low yield of this technique, in term of solid material obtained, still limit its use to small scale applications. In this article we propose a low cost and environmentally friendly method for producing multilayer crystalline graphene with high yield. Such innovative approach, involving an improved ionic liquid assisted, microwave exfoliation of expanded graphite, allows the production of graphene with advanced lithium ion storage performance, for the first time, at low temperatures (

Tin oxide (SnO) is considered one of the most promising metal oxides for utilization as anode material in sodium ion batteries (SIBs), because of its ease of synthesis, high specific gravimetric capacity, and satisfactory cycling performance. However, to aim at practical applications, the Coulombic efficiency during cycling needs to be further improved, which requires a deeper knowledge of its working mechanism. Here, a microflower-shaped SnO material is synthesized by means of an ultrafast ionic liquid-assisted microwave method. The as-prepared SnO anode active material exhibits excellent cycling performance, good Coulombic efficiency as well as a large capacity delivered at low potential, which is fundamental to maximize the energy output of SIBs. These overall merits were never reported before for pure SnO anodes (i.e., not in a composite with, for example, graphene). Additionally, by combining ex situ XRD and XPS, it is clearly demonstrated for the first time that the Sn-Na alloy, which is formed during the initial sodium sodiation, desodiates in two successive but fully separated steps. Totally different from the previous report, the pristine SnO phase is not regenerated upon desodiation up to 3 V vs Na/Na

Since its first isolation in 2004, graphene has become one of the hottest topics in the field of materials science, and its highly appealing properties have led to a plethora of scientific papers. Among the many affected areas of materials science, this 'graphene fever' has influenced particularly the world of electrochemical energy-storage devices. Despite widespread enthusiasm, it is not yet clear whether graphene could really lead to progress in the field. Here we discuss the most recent applications of graphene - both as an active material and as an inactive component - from lithium-ion batteries and electrochemical capacitors to emerging technologies such as metal-air and magnesium-ion batteries. By critically analysing state-of-the-art technologies, we aim to address the benefits and issues of graphene-based materials, as well as outline the most promising results and applications so far.

The electrochemical behavior of a composite anode based on tin oxide nanoparticles embedded in electrically conductive graphene matrix is reported. The composite has been synthetized through microwave reduction of poly acrylic acid functionalized graphene oxide and a tin oxide organic precursor both dispersed in ethylene glycol. The poly acrylic functionalization of graphene oxide partially prevent the re-stacking of the graphene layers. In addition, poly acrylic acid acts as a surfactant favoring an optimized dispersion of the metal and, after thermal decomposition, contributes in creating a carbon layer for an improved conductivity. The final product morphology reveals a composite in which SnO 2 nanoparticles are homogenously distributed into the reduced graphene oxide matrix. Graphene/SnO 2 nanocomposite electrodes, prepared using Super-P carbon as conducting additive and polyvinylidenedifluoride as binder, exhibit high rate capability and cycle life during galvanostatic charge/discharge tests. After more than 140 cycles, mostly performed at 500 mA g −1 , the electrodes show a remarkable stable specific capacity of about 430 mAh g −1 with a Coulombic efficiency close to 100%.The morphological stability of the electrode is also confirmed by impedance spectroscopy analysis, which shows solid-electrolyte interphase related resistance values constant up to 100 cycles.

Used as a bare active material or component in hybrids, graphene has been the subject of numerous studies in recent years. Indeed, from the first report that appeared in late July 2008, almost 1600 papers were published as of the end 2015 that investigated the properties of graphene as an anode material for lithium-ion batteries. Although an impressive amount of data has been collected, a real advance in the field still seems to be missing. In this framework, attention is focused on the most prominent research efforts in this field with the aim of identifying the causes of such relentless progression through an insightful and critical evaluation of the lithium-ion storage performances (i.e., 1st cycle irreversible capacity, specific gravimetric and volumetric capacities, average delithiation voltage profile, rate capability and stability upon cycling). The "graphene fever" has certainly provided a number of fundamental studies unveiling the electrochemical properties of this "wonder" material. However, analysis of the published literature also highlights a loss of focus from the final application. Hype-driven claims, not fully appropriate metrics, and negligence of key parameters are probably some of the factors still hindering the application of graphene in commercial batteries.

A graphene/silicon nanocomposite has been synthesized, characterized and tested as anode active material for lithium-ion batteries. A morphologically stable composite has been obtained by dispersing silicon nanoparticles in graphene oxide, previously functionalized with low-molecular weight polyacrylic acid, in eco-friendly, low-cost solvent such as ethylene glycol. The use of functionalized graphene oxide as substrate for the dispersion avoids the aggregation of silicon particles during the synthesis and decreases the detrimental effect of graphene layers re-stacking. Microwave irradiation of the suspension, inducing reduction of graphene oxide, and the following thermal annealing of the solid powder obtained by filtration, yield a graphene/silicon composite material with optimized morphology and properties. Composite anodes, prepared with high-molecular weight polyacrylic acid as green binder, exhibited high and stable reversible capacity values, of the order of 1000 mAh g −1 , when cycled using vinylene carbonate as electrolyte additive. After 100 cycles at a current of 500 mA g −1 , the anode showed a discharge capacity retention of about 80%. The mechanism of reversible lithium uptake is described in terms of Li–Si alloying/dealloying reaction. Comparison of the impedance responses of cells tested in electrolytes with or without vinylene carbonate confirms the beneficial effects of the additive in stabilizing the composite anode.

The properties of high quality few-layers graphene, produced though multisteps process involving microwave irradiation of expandable graphite, are presented. Such innovative approach fulfills all desirable requirements (so far missing in the conventional methods, e.g. Hummers method) of being reproducible, low-cost, environmental friendly, with high yield, and scalable. When used as anode material the so-obtained graphene (hereinafter GRAL), differently from the commonly employed reduced graphene oxide, is able, similarly to graphite, to intercalate/de-intercalate Li ions in the few-layers structure. Its peculiar features such as (i) presence of few defects, (ii) small sheets size, and (iii) nanometric thickness, enable the negative electrode to work at considerably lower temperatures than conventional graphite. During galvanostatic charge-discharge experiments (specific current of 50 mA g-1), performed in a temperature range comprised between +20°C and -30°C, GRAL exhibits remarkable capacity retention with comparison to commercial graphite. At temperatures above 0°C, GRAL performs quite similarly to graphite. However, at lower temperatures, graphite suffers from dramatic capacity decay resulting on only 9% of capacity retention at -30°C. On the contrary, GRAL is able to retain 65% and 34% of the room temperature capacity when operating at -20°C and -30°C, respectively. The outstanding performances of this novel few-layers graphene are confirmed also by the very promising low temperature stability, with a coulombic efficiency close to 100%.

We unravel the role of flake dimensionality on the lithiation/de-lithiation processes and electrochemical performance of anodes based on few-(FLG) and multi-layer graphene (MLG) flakes prepared by liquid phase exfoliation (LPE) of pristine graphite. The flakes are sorted by lateral size (from 380 to 75 nm) and thickness from 20 (MLG) to 2 nm (FLG) exploiting a sedimentation-based separation in centrifugal field and, finally, deposited onto Cu disks for the realization of four binder-free anodes. The electrochemical results show that decreasing lateral size and thickness leads to an increase of the initial specific capacity from ≈590 to ≈1270mAhg −1 . However, an increasing irreversible capacity is also associated to the reduction of flakes’ size. We find, in addition, that the preferential Li ions storage by adsorption rather than intercalation in small lateral size (