Enhanced electrochemical discharge of Li-ion batteries for safe recycling.

The recycling of spent lithium-ion batteries (LIBs) is crucial to sustainably manage resources and protect the environment as the use of portable electronics and electric vehicles (EVs) increases. However, the safe recycling of spent LIBs is challenging, as they often contain residual energy. Left untreated, this can trigger a thermal runaway and result in disasters during the recycling process. For efficient recycling, it is important to withdraw any leftover energy from LIBs, regardless of the processing method that follows the discharge. The electrochemical discharge method is a quick and inexpensive method to eliminate this hazard. This method works by immersing batteries in an aqueous inorganic salt solution to discharge LIBs completely and efficiently. Previously, research focus has been on different inorganic salt solutions that release toxic or flammable gaseous products during discharge. In contrast, we present an entirely new approach for electrochemical discharge - the utilization of an Fe(ii)-Fe(iii) redox couple electrolyte. We show that this medium can be used for efficient LIB deep discharge to a voltage of 2.0 V after rebound, a level that is low enough for safe discharge. To accomplish this, periodic discharge methods were used. In addition, no corrosion on the battery casing was observed. The pH behavior at the poles was also investigated, and it was found that without convection, gas evolution during discharge cannot be avoided. Finally, it was discovered that the battery casing material plays a vital role in electrochemical discharge, and its industrial standardization would facilitate efficient recycling.

Awareness increases acceptance and willingness to pay for low-carbon fuels amongst marine passengers.

One of the main applications discussed in decarbonising the marine sector is via alternative fuels, such as methanol and ammonia, produced from renewable hydrogen. These alternative, low-carbon fuels often come with increased prices and operational expenses for the vessel operators, which are ultimately reflected in the passengers' costs. Therefore, it is important to assess passengers' familiarity with expressions linked to decarbonisation and their willingness to pay this 'green premium' for alternative fuels. To assess these, we ran a survey-based study and collected close to 2000 answers through different channels from marine passengers, specifically from those travelling in the Northern European region on roll-on/roll-off passenger (RoPax) vessels. We found that most of the passengers prioritise environmental friendliness in marine fuels and are concerned about environmental issues. However, there seems to be a lack of knowledge about fuels and fuel technologies. Familiarity with certain alternative fuel-related expressions results in a more positive view of them. The observed willingness to pay is affected by the level of education, income, and place of residence, in addition to the level of concern about environmental issues, frequency of travel and spending on trips. Close to 80% of passengers are willing to increase their spending if the vessel is powered by a low-carbon, alternative fuel. As the results indicate that the more passengers know about alternative fuels and their benefits, the more willing they are to pay for them, it is recommended that RoPax operators invest in educating them.

A multi-dimensional indicator for material and energy circularity: Proof-of-concept of exentropy in Li-ion battery recycling.

Recycling processes are an important stage in the raw material life cycle, as it enables the transition from a linear economy into a circular one. However, the currently available indicators of productivity in recycling technologies respond to the needs of a linear economy. In this work, a parameter called "exentropy" is proposed, offering the possibility to simultaneously account for mass preservation and the energy efficiency of transformative stages. As a proof-of-concept of this indicator, the analysis of a lithium-ion battery recycling process under various concentrations of a leaching reagent (i.e., 0.1M, 1M, and 2M) is presented. It is shown that, when the energy or mass dimensions are considered independently, the processes considered optimal may have conflicting characteristics. In contrast, the multi-dimensional analysis identified the process option offering the best compromise for both material and energy preservation, an aspect closer to the goals of the circular economy.

Eco-design for perovskite solar cells to address future waste challenges and recover valuable materials.

Photovoltaic development should be steered by the circular economy. However, it is not. In case of perovskite photovoltaics even current environmental directives divert from profitably recycling. Here, we study the profitability of noble metals recovery from wasted perovskite solar cells depending on recycling routes. Our results show that substrates play a major role in the recovery of precious metals and in contrast to previous research even recycling carbon-based devices could reach profitability. Going beyond the recovery of valuable elements, our findings show that revival of the perovskite solar cells is strongly dependent on the device architecture, so far viable for mesoscopic structures with carbon back contacts. Perovskite solar cells are still at the development stage, but the window of opportunity to ensure eco-design will close with market entry, and device complexity might compromise profitability recycling and even result in failure of recovery critical materials. Therefore, its eco-design should be prioritized by materials researchers to develop devices, where valuable components can be separated and liberated with safe and low energy processes.

Challenging the concept of electrochemical discharge using salt solutions for lithium-ion batteries recycling.

The use of lithium-ion batteries (LIB) has grown significantly in recent years, making them a promising source of secondary raw materials due to their rich composition of valuable materials such as Co, Ni and Al. However, the high voltage and reactive components of LIBs pose safety hazards during crushing stages in recycling processes, and during storage and transportation. Electrochemical discharge by immersion of spent batteries in salt solutions has been generally accepted as a robust and straightforward discharging step to address these potential hazards. Nonetheless, there is no clear evidence in the literature to support the use of electrochemical discharge in real systems, neither are there clear indications of the real-world limitations of this practice. To that aim, this work presents a series of experiments systematically conducted to study the behavior of LIBs during electrochemical discharge in salt solutions. In the first part of this study, a LIB sample was discharged ex-situ using Pt wires connected to the battery poles and submerged into the electrolyte solution on the opposite end. The evolution of voltage in the battery was measured for solutions of NaCl, NaSO4, FeSO4, and ZnSO4. The results indicate that, among the electrolytes used in the present study, NaCl solution is the most effective for LIBs discharge. The discharge of LIB using sulfate salts is however only possible with the aid of stirring, as deposition of solid precipitated on the electrodes hinder the electrochemical discharge. Furthermore, it was found that the addition of particulates of Fe or Zn as sacrificial metal further enhances the discharging rate, likely due to an increased contact area with the electrolyte solution. While these findings support the idea of using electrochemical discharge as a pre-treatment of LIBs, severe corrosion of the battery poles was observed upon direct immersion of batteries into electrolyte solutions. Prevention of such corrosion requires further research efforts, perhaps focused on a new design-for-recycling approach of LIBs.

New analytical methodology for analysing S(IV) species at low pH solutions by one stage titration method (bichromatometry) with a clear colour change. Could potentially replace the state-of-art-method iodometry at low pH analysis due higher accuracy.

A new, faster and more reliable analytical methodology for S(IV) species analysis at low pH solutions by bichromatometry is proposed. For decades the state of the art methodology has been iodometry that is still well justified method for neutral solutions, thus at low pH media possess various side reactions increasing inaccuracy. In contrast, the new methodology has no side reactions at low pH media, requires only one titration step and provides a clear color change if S(IV) species are present in the solution. The method is validated using model solutions with known concentrations and applied to analyses of gaseous SO2 from purged solution in low pH media samples. The results indicate that bichromatometry can accurately analyze SO2 from liquid samples having pH even below 0 relevant to metallurgical industrial processes.