Kumar international Symposium (8th Intl. Symp. on Sustainable Secondary Battery Manufacturing & Recycling)

Sulfide based solid electrolytes are attracting attention because they have better electrochemical performances compared to other types of solid electrolytes. In addition, they have higher formability enabling favorable interfaces between the active material and solid electrolyte. Even though the sulfide based electrolyte shows better electrochemical characteristics among the various solid electrolytes, it poses some problems that have to be resolved such as poor compatibility of sulfide SEs against oxide-based cathode active materials and its instability against air and moisture.
This study presents the findings of a comparative analysis on the stability of two different sulfide solid electrolytes (SEs) which are glass-ceramic Li7P3S11 and crystalline Li6P5SCl. We synthesized both SEs using the same mechanical milling method in order to compare them under identical conditions. Then, the composite cathodes were prepared by simply mixing the SEs with the active materials and additives. We tried to observe any side reactions that occur during the charging and discharging process. Additionally, electrochemical characterization of the composite cathode were conducted using each SEs. Also, it is aimed to continuously monitor the degradation mechanism of the composite cathodes during the charging and discharging process, as well as evaluate their thermal stability under high-temperature conditions, utilizing X-ray based analytical techniques. The details will be discussed at the meeting.

Current process simulators such as ASPEN, PRO-II, gPROMS etc. do not have thermo-physical and transport property database of the materials used or produced in the battery industry. The process simulators lack physics-based models for modelling unit operations such as mixing, wet milling, coating, drying, calendaring. 

It is thus hard for process simulators to capture the effect of process variables in materials manufacturing or in cell manufacturing units on cell performance. Therefore, the process development and control in the battery industry is mostly done using a trial-and-error approach which makes it time and cost intensive. 

The recent advances in machine learning, artificial intelligence and sensing technologies can be leveraged to reduce the cost, accelerate the development and retuning of plants in the battery industry [1, 2]. The data from the pilot lines or from the manufacturing lines could be used to develop data-based models. 

There are only a few academic groups who have worked on data-based models for cell manufacturing units [2]. However, there is no work on developing data-based models for battery materials manufacturing unit. The biggest bottleneck in developing data-based model for cell manufacturing and battery materials manufacturing units is the availability of feature rich and diverse dataset.

The scarcity of data could be mitigated by coupling multiscale modelling with data driven approach. Multiscale modelling gets computationally intensive when models are built to scale. Plant data still is orders of magnitude expensive and hence exists in much smaller volumes. One possible solution is to build multiscale models with the help of plant data and run these simulations for different scenarios creating a diverse enough dataset [3,4]. The simulated data along with plant data could then be expanded using generative AI to a much larger data set enabling higher accuracies of the data-based model. However, this concept still needs to be tested and validated.

The sustainable advancement of green energy storage technologies hinges on the efficient utilisation of readily available and cost-effective materials. In this context, here, I delve into the eco-friendly conversion of natural minerals and biomass into functional materials tailored for metal-ion energy storage applications. Particular emphasis is placed on the mechanochemical, thermal, and molten salt modification techniques developed at E²MC to nanostructuring minerals such as molybdenum disulfide, ilmenite, and natural graphite, as well as biomass. These processes result in the creation of nanostructured electrode materials with enhanced electrochemical performances for use in Li-ion and/or Na-ion batteries. The phase transformations that occur during these modification processes are explored and their consequential impact on key factors such as metal-ion storage capacity, diffusion coefficients, and surface pseudocapacitive behaviors are discussed. Furthermore, I would underscore the economic benefits stemming from the utilisation of abundant and economical materials in the development of highly efficient battery systems.

Lithium-ion batteries are widely used as energy storage devices for electric vehicles and large-scale energy storage systems. Nevertheless, there are growing concerns about the limited availability of lithium resources, which could result in depletion and increased prices in the future. To tackle this issue, scientists have been extensively investigating alternative secondary battery systems that can replace commercial lithium-ion batteries. Sodium-ion batteries have attracted considerable interest among these alternatives due to the abundance of sodium resources and its economic feasibility compared to lithium. [1]
Although hard carbon has been recognized as a reversible anode material that enables sodium-ion insertion and extraction, the demand for high-capacity anode materials is imperative to achieve the desired energy density in sodium-ion batteries. Conversion- and alloy-based materials are considered highly promising alternatives due to their substantial theoretical capacity for sodium storage. [2,3] However, these materials encounter challenges such as notable volume changes of the active components, slow reaction kinetics, and instability at the electrode interfaces during the sodiation and desodiation processes. Overcoming these obstacles is essential to effectively implement these materials in high-performance sodium-ion batteries. [4]
In order to address these challenges, we devised a novel approach in this study, which involved the design of heterostructured anodes with a unique architecture. This was achieved by combining conversion- or alloy-based active materials with a porous silicon oxycarbide (SiOC) nanocoating layer, which is known for its exceptional surface capacitive reactivity and mechanical strength. We synthesized heterostructured composite anodes (MoS₂@SiOC and Sn@SiOC) by controlling the dispersion of precursors in silicon oil and subsequent heat treatment. To investigate the properties of these composites, we conducted extensive physicochemical and electrochemical characterization, as well as post-mortem analysis. Our focus was particularly on understanding how the heterostructure influenced the battery performance of these composites. By adopting this heterostructure approach, we anticipate that new possibilities will arise for the development of innovative and high-performance anode materials for sodium-ion batteries.

A hybrid energy storage system (HESS) can combine the efficiency and quick response of batteries with the energy density and cost of synthetic (e-)fuel storage. Exergy analysis is a valuable tool in optimising the efficiency of the electrochemical process chains needed to produce and consume e‑fuels. In the paper we present our ongoing efforts on using exergy analysis and exergy gravimetric analysis in battery- fuel cell integrated energy systems. A couple of case studies are presented. A hybrid energy storage system case in detail and others briefly.  An algorithm for optimal sizing of HESS-supported electrical grids in various locations, powered purely by renewable energy is introduced [1]. Efficient process chains have been developed for several fuels such as hydrogen, methane and ammonia. These process chains were combined with storage sizing algorithms to make design choices for large scale energy storage in the Netherlands [2]. 

Exergy analysis combined with HESS-sizing algorithms can also be used for exergy gravimetric analysis, which is an approach that seeks to optimise efficiency simultaneously with energy density. This approach can be useful for several applications, particularly weight-sensitive applications such as long-range sustainable transport. The use of exergy-gravimetric approaches for designing an optimal minimized-mass power plant for aircraft applications is presented [3-5]. Additionally, ongoing efforts on using the same approach in developing road transport systems are also introduced

Recycling and reuse of batteries has increased its importance in recent years. In this study, recycling strategies of both lead acid batteries (LABs) and lithium-ion batteries (LIBs) were investigated comprehensively. Pyrometallurgical processes such as smelting and carbothemic reduction and hydrometallurgical processes such as desulphurisation and electrowinning were evaluated in detail for the recovery of lead in spent lead acid batteries [1-3]. Effects of the battery structure and recycling technologies such us hydrometallurgical, bio-hydrometallurgical and solvo-metallurgical methods on the energy and sustainability of lithium ion batteries were discussed [4]. Opportunities, challenges, and future prospects for the recycling of lead acid batteries and lithium ion batteries were evaluated. Recycling plays an important role for the sustainability of lead acid batteries and lithium ion considering the battery characteristics, environmental issues and critical raw materials. Green sustainable recycling and circular economy were emphasized for spent batteries [5-7]. Future perspectives for sustainable recycling of both lead acid batteries and lithium ion batteries were outlined.

Among various battery chemistries, Zn and Al batteries stand out due to their safety, availability, high volumetric capacity, ease of handling and recyclability. [1, 2] Compared to Li/Na battery chemistries, both Zn and Al batteries have been developed using aqueous/ionic liquid electrolytes which has shown relatively stable performance. [3, 4] However, challenges exist in tuning the electrolyte chemistries along with developing suitable cathodes due to multi-ion storage process. In the last couple of years, we have looked into the electrolyte and cathode chemistries for both batteries and have progressed in developing a stable battery system.

In this presentation, I will show the progress in both batteries which involves modification of aqueous electrolytes using ionic liquids/bio-ionic liquids which in-turn changes the electrochemical reactions at the cathode and anode. The addition of ionic liquids leads to dendrite-free metal deposition at the anode and improves the overall battery capacity. By tuning the electrolyte composition, we have improved both the capacity and stabilities of Zn and Al batteries.    

Aqueous zinc ion batteries (AZIBs) have emerged as one of the promising next-generation secondary batteries, offering affordability and inherent safety features. However, AZIBs face limitations associated with the use of water-based electrolytes, which result in low operating voltages and subsequently low energy density. Additionally, challenges such as dendrite growth and hydrogen gas evolution at the interface between the zinc metal anode and electrolyte further hinder the commercialization of AZIBs. To address these issues, this study focuses on implementing two interfacial modification strategies. In the first study, we tried to enhance the depth of discharge (DOD) by using a zinc powder electrode instead of thick zinc foils as the anode, thereby reducing the N/P ratio. However, the high surface area of zinc powder accelerates dendrite growth and corrosion. To address these challenges, we applied a uniform SnO2 coating layer on the zinc powder using the atomic layer deposition (ALD) technique. The SnO2 coating effectively inhibits dendrite growth and corrosion on the zinc powder surface. When we implemented this interfacial modification strategy in a full-cell configuration, we observed an increase in discharge capacity from 163 mAh g-1 to 221 mAh g-1, indicating improved cycling performance. Ultimately, by using zinc powder anodes with a low N/P ratio similar to that of commercial lithium-ion batteries. As a result, by applying SnO2 coating as a protective layer, we not only increased the zinc utilization rate but also achieved an increase in volumetric energy density. Secondly, we introduced tetrabutylammonium iodide (TBAI) as an electrolyte additive to the mildly acidic ZnSO4 electrolyte. This approach combines the zincophobic repulsion effect of cationic TBA+ ions and the corrosion inhibition effect of the anionic I- ions. TBA+ ions form a protective layer on the zinc anode surface, preventing localized deposition of Zn2+ ions. I- ions act as corrosion inhibitors, suppressing the detrimental corrosion at the interface. By effectively addressing these issues at the interface, we achieved improved capacity retention in the full-cell system with a Zn0.25V2O5 cathode. After 5000 cycles, the capacity retention rate increased from 44.7% to 58.3% upon the incorporation of the TBAI additive.

The unique physicochemical properties of tungsten, its alloys and compounds (infusibility, chemical, abrasive and erosion resistance, high mechanical strength, emissive ability, catalytic activity, etc.) determined their widespread use in modern science and technology. This is evidenced by the high growth rates of the tungsten industry throughout the world. An important area of ​​tungsten application is the use of tungsten carbides in the production of cutting and wear-resistant materials. These materials are used in metalworking, the oil, gas, mining, energy, construction, and automotive industries, etc. A promising direction to improve the performance properties of tungsten-based materials is the reduction of the grain size in the material to the nanometer. Analysis of experts on the development of the world market for tungsten carbide indicates the importance of this direction and predicts an increase in carbide production from 2018 to 2028 on average by 4.07% per year in value equivalent [1, 2].

The high-temperature electrochemical synthesis method allows one to obtain both single-phase powders of tungsten, tungsten bronzes, tungsten carbides, and composite materials based on them with carbon and metals (Pt, Co, Ni) in one stage at relatively low temperatures (700 °C) and energy consumption for electrolysis with an average grain size of up to 10 nm and a specific surface area of up to 30 m²/g. The carbon source for the synthesis of carbides is carbon dioxide, which is introduced into the melt under pressure. At the same time, this method is an electrochemical utilizing of carbon dioxide, the content of this greenhouse gas in the Earth’s atmosphere rises catastrophically every year [3]. The method allows one to capture and convert carbon dioxide into new value-added chemical products. Therefore, in addition to technological and applied tasks, this study solves an important environmental problem.

Two variants of electrochemical synthesis were realized:

1. Joint electro-reduction of oxygen-containing compounds of tungsten and carbon with doping agents Pt, carbon in chloride-oxide melts.

2. Electro-reduction of oxygen-containing tungsten compounds that are found in chloride melts in the solid phase.

Physico-chemical properties of the synthesized materials (phase and chemical composition, morphological and structural features, thermal stability, electro-catalytically activity) were studied and the correlation of properties with electrolysis conditions was established. Evaluation of the catalytic activity of the materials obtained was done in the reaction of hydrogen evolution in acidic solutions.

Electrochemical energy storage devices can offer a number of great potentials for meeting future energy demands, such as of renewable energy, electric vehicles, portable electronics, that require high energy density, high power density and long cycle life. Among the various electrode materials available for energy storage devices, graphene, a one-atom-thick, two-dimensional sp² carbon structure, has attracted considerable interest as a next-generation electrode material. This can be attributed to a number of interesting properties of graphene, such as its good mechanical/chemical stability, high electrical/thermal conductivity, and a large surface area due to its high surface-to-volume ratio.[1] The combination of these unique physical and chemical properties means that graphene has significant potential to act as an electrochemically active material for use in energy storage devices such as Li-ion batteries and electrochemical capacitors.[2,3]
In this study, we report on the synthesis and electrochemical characterization of nanoperforated graphene-based electrode materials for energy storage applications. More details will be discussed at the meeting.

Hybrid organic-inorganic perovskites have attracted significant attention in the past two decades owing to their enormous application potential in energy. Like their oxide counterparts, these hybrid organic-inorganic systems exhibit abundant phase transitions which can often lead to significant changes in the electrical, magnetic, and optical properties that are of vital importance for the design and fabrication of functional devices. However, the atomistic driving forces and underlying mechanism need to be well understood for these hybrid perovskite systems. In this talk, I shall present our recent advances in the thermally and pressure-driven phase transitions and their microscopic mechanisms of some three-dimensional and two-dimensional hybrid organic-inorganic perovskites. At the same time, I shall discuss the symmetry alternation at the interface and corresponding atomic origin of some two-dimensional hybrid organic-inorganic perovskites.

The advent of printed large area electronics has started delivering exciting innovations over the last few years. A key enabler for fully thin devices are printed energy storage devices. Over the last few years, Zinergy has embarked on a mission to develop simple, low cost, printed energy storage devices which are compatible with other printed electronic devices. 

Printing is a very versatile technique for batteries. It allows to control not only size and shape of devices, but also via thickness control and ink formulations there is a toolkit to adapt the battery´s energy and power requirements to a large set of applications, optimising for energy, power or mechanical properties. Printing batteries allows a degree of freedom in design generally not possible with more traditional production methods. 

In this paper we discuss the use of a printed co-planar battery electrode layout, constructed in a polymer casing which allows the in-situ observation of electrode/electrolyte dynamics. The effects during discharge at various current rates was done by visual time lapsed observation of the formation of compound residues which crystallise and re-dissolve during the discharge process. An aqueous, acidic Zinc/MnO₂ system is used and the spatial observation of reactants allows also the visualisation of electrolyte/ion movement. In addition, it is noted that the presence of the separator plays a critical role in providing nucleation sites for crystallisation. Electrical discharge curves and optical measurements are complemented with in-situ X-ray synchrotron data, allowing the observation of the components formed and as a result provide a better understanding of the discharge process, leading to and overall improved battery design. 

This paper provides an overview of the learnings from in situ measurements of co-planar aqueous zinc batteries, and it is hoped that this system may be more generally applied to observe reaction dynamics in different battery systems, contributing to the electrochemical energy storage field in general.

One of the most pressing environmental concerns facing humanity today is the limitation of carbon dioxide emissions. In the field of natural gas sweetening, carbon capture is equally critical. The solubility of carbon dioxide (CO₂) and ethane (C₂H₆) in three ionic liquids (ILs) with the same anion, [C₃C₁pip][FSI], [C₃C₁pyrr] [FSI] and [N1223][FSI], was measured at (303.15, 323.15, and 343.15) K and at pressures up to 1.1 MPa.Experimental data were correlated with Peng-Robinson (PR) equation of state using three different mixing rules: (i) van der Waals one (vdW1, based on a single binary interaction parameter), (ii) van der Waals two (vdW2, based on two binary interaction parameters), and (iii) Wong-Sandler mixing rules combined with NRTL model. Henry's law constants, enthalpy and entropy for the absorption of Carbon dioxide and ethane in these ILs were also estimated. No significant change was found in the values of Henry's law constants of C₂H₆ in these three ILs which indicates a negligible effect of cations of these ILs on C₂H₆ solubility. The selectivity towards carbon dioxide (CO₂) over C₂H₆ for these ILs was also reported. [FSI]-based ILs seem to have higher selectivity than all the other ILs, except for [C₄C₁Im][BF4] and possibly [C₄C₁Im][PF6], which may qualify them as promising solvents for CO₂ removal from natural gas streams.

Lithium-ion batteries (LIBs) represent a massive shift beginning from personal electronic to energy storage in electrification of transportation, uninterrupted power supply and in supporting power generation from renewable energy technologies. Next generation of research in LIBs are making rapid progress in low-to zero cobalt cathodes, solid state batteries, safety, increased energy and power densities, fast charging and the use of 2D materials and metallic lithium as the anode. (1-3))
Looking into the near future, many other battery chemistries are also staking their claims within a mix of battery chemistry portfolios. In addition to LIBs, aspects of Lead Acid, Li-S, Sodium, Zinc, Aluminium, Potassium, and Redox battery systems will be discussed. Understanding battery chemistry basics is critical to unlocking the issues of energy, power, costs, safety, resources, and sustainability, as this talk will explore.(4,5)
• Some key areas of progress in the Battery Revolution will be addressed:
• Acceleration of research & innovation.
• Use of Artificial Intelligence & Machine Learning.
• Battery Supply Chain – implication for resources; Life Cycle Analysis.
• Optimization of Materials and Energy with minimal environmental degradation with the battery eco-system.
• Re-use, Recovery, Recycling and Upgrading of Battery Materials.

Lithium-ion batteries (LIBs) represent a massive shift beginning from personal electronic to energy storage in electrification of transportation, uninterrupted power supply and in supporting power generation from renewable energy technologies. Next generation of research in LIBs are making rapid progress in low-to zero cobalt cathodes, solid state batteries, safety, increased energy and power densities, fast charging and the use of 2D materials and metallic lithium as the anode.
Looking into the near future, many other battery chemistries are also staking their claims within a mix of battery chemistry portfolios. In addition to LIBs, aspects of Lead Acid, Li-S, Sodium, Zinc, Aluminium, Potassium, and Redox battery systems will be discussed. Understanding battery chemistry basics is critical to unlocking the issues of energy, power, costs, safety, resources, and sustainability, as this talk will explore.
• Some key areas of progress in the Battery Revolution will be addressed:
• Acceleration of research & innovation.
• Use of Artificial Intelligence & Machine Learning.
• Battery Supply Chain – implication for resources; Life Cycle Analysis.
• Optimization of Materials and Energy with minimal environmental degradation with the battery eco-system.
• Re-use, Recovery, Recycling and Upgrading of Battery Materials.

Recycling has become an absolute necessity. Spent Lithium-ion batteries (LIBs) are hazardous waste but a potential source of purified minerals. The industrial focus on LIB recycling is mostly centered on costly and scarce cathode materials recovery. Graphite is often overlooked as it fails to generate useful revenue. Herein, the waste LIBs are recycled following an all-components-recovery route that minimizes cross-contamination. However, the surface of the recovered graphite is covered with solid electrolyte interphase (SEI) formed during its first life application. Solvent wash followed by thermal treatment revives graphite for second-life applications. Three important things to consider here are the interaction of solvent media with the preformed SEI, the role of leftover SEI in forming the second-life SEI, and the effect of regenerated SEI on second-life electrochemistry. Therefore, the nature of the solvent plays a vital role in the overall process. Utilizing water is the go-to alternative but the obtained electrochemistry from water-washed graphite is below the mark. Organic solvent dimethyl carbonate (DMC) modifies the chemical composition of the interphase in such a way that it improves second-life electrochemistry. Strong inorganic acid HCl results in the highest carbon purity and makes recovered graphite suitable for non-electrochemical applications too. Electrochemically superior DMC-washed graphite is repurposed into a dual-ion full cell that delivers an average voltage of 4.5 V and an energy density of 110 Wh kg^-1.

Spent lithium-ion batteries (LIBs) rank second in volume after lead-acid batteries in the total number of used batteries [1]. The volume of this type of hazardous waste now amounts to hundreds of kilotons. More than half of such waste is currently not recycled [2]. The main reason for the need to recycle LIB waste is currently its danger to the environment.

When recycling electronics and household appliances waste, used LIBs contain cathode materials such as LiCoO₂ (LCO), LiNi_1-x-yMn_xCo_y (NMC); LiMn₂O₄ (LMO), LiFePO₄ (LFP), etc. The mixture of cathode materials in this case contains valuable Co components (up to half the mass), significant amounts of Ni, Li, Mn. The peculiarities of this material include the variability of its composition, which must be taken into account in the work. The physicochemical characteristics of such materials are given in [3].

The objective of the research is to develop a low-cost method for leaching valuable components from a mixture of cathode materials. A solution of sulfuric acid with additives of the reducing agent hydrogen peroxide was used. The dependence of the efficiency of the process on the concentration of acid, reducing agent, phase ratio, temperature, leaching kinetics was studied, and the optimal parameters for its implementation were determined. It was found that at a concentration of sulfuric acid 4 mol/l, hydrogen peroxide 2 mol/l, temperature 80⁰C in 3 hours. The degree of leaching of all the above elements is more than 99%.

Further processing of the resulting solution should be aimed at obtaining lithium compounds and precursors of NMC-type cathode materials, which will significantly reduce the cost of LIB disposal compared to the isolation of individual compounds.

In this presentation we celebrate the contributions of distinguished scientist Professor R Vasant Kumar in the field of battery recycling and upcycling battery-active materials.
A green hydrometallurgical process for the recycling of lead-acid battery paste has been developed. The background intellectual property, invented by Professor R Vasant Kumar, was licensed to Ever Resource where Dr Fox and colleagues worked in partnership with Professor Kumar to scale up the technology.
The technology uses chelating organic acids to capture lead in the form of a metal-organic framework (MOF). The intermediate MOF is converted into highly advanced, nanostructured, battery-grade oxides which exhibit enhanced energy and power densities, among other properties. In a recent 3rd party-trial, it has been shown that energy densities can increase by as much as 40% - this is due to the high surface area of the oxides made by the process.
By controlling the conditions, we have been able to convert the MOF into battery alpha oxide; beta oxide; and controlled mixtures of alpha and beta. Moreover, it is possible to produce red lead or lead sesquioxide as the final product. This level of control could enable fine-tuning of battery plate for specific applications (e.g. more power in automotive batteries, more cycling for stationary batteries and renewable energy storage, etc). Meanwhile, the quantity of lead in these leady oxides can be controlled to anything from negligible (less than 1% lead) to greater than 20%.
The wet chemistry has been scaled up to 5 tonnes per hour continuous treatment of spent paste (modular), while the life-cycle analysis shows potential for reducing the carbon footprint of traditional recycling by approximately 85% and waste by more than 90%. The process saves considerable energy by not relying on a traditional furnace or electro-process – saving the equivalent of at least 3,000 tonnes of coal per 10,000 tonnes of batteries processed.