The tremendous efforts made in the research field of solid-state Li-ion batteries have led to considerable advancement of this technology and the first market-ready systems can be expected in the near future. The research community is currently investigating different solid-state electrolyte classes (e.g. oxides, sulfides, halides and polymers) with a focus on further optimizing the synthesis and electrochemical performance. However, so far, the development of sustainable recycling strategies allowing for an efficient backflow of critical elements contained in these batteries into the economic cycle and thus a transition from a linear to a circular economy lags behind. In this contribution, resource aspects with respect to the chemical value of crucial materials, which are used for the synthesis of solid-state electrolytes are being discussed. Furthermore, an overview of possible approaches in relation to their challenges and opportunities for the recycling of solid-state batteries with respect to different solid-state electrolyte classes by means of pyrometallurgy, hydrometallurgy and direct recycling/dissolution-based separation processes is given. Based on these considerations and with reference to previous research, it will be shown that different solid-state electrolytes will require individually adapted recycling processes to be suitably designed for a circular economy and that further improvements and investigations will be required.

In recent years, zinc-ion batteries (ZIBs) have been considered one of the most promising candidates for next-generation electrochemical energy storage systems due to their advantages of high safety, high specific capacity and high economic efficiency. As an indispensable component, the electrolyte has the function of connecting the cathode and the anode, and plays a key role in the performance of the battery. Different types of electrolytes have different effects on the performance of ZIBs, and the use of additives has further developed the research on modified electrolytes, thus effectively solving many serious problems faced by ZIBs. Therefore, to further explore the improvement of ZIBs by electrolyte engineering, it is necessary to summarize the current status of the design of various electrolyte additives, as well as their functions and mechanism in ZIBs. This paper analyzes the challenges faced by different electrolytes, reviews the different solutions of additives to solve battery problems in liquid electrolytes and solid electrolytes, and finally makes suggestions for the development of modified ZIB electrolytes. It is hoped that the review and strategies proposed in this paper will facilitate development of new electrolyte additives for ZIBs.

Conversion/alloying materials (CAMs) represent a potential alternative to graphite as a Li-ion anode active material, especially for high-power applications. So far, however, essentially all studies on CAMs have been dealing with nano-sized particles, leaving the question of how the performance (and the de-/lithiation mechanism in general) is affected by the particle size. Herein, we comparatively investigate four different samples of Zn_0.9Co_0.1O with a particle size ranging from about 30 nm to a few micrometers. The results show that electrodes made of larger particles are more susceptible to fading due to particle displacement and particle cracking. The results also show that the conversion-type reaction in particular is affected by an increasing particle size, becoming less reversible due to the formation of relatively large transition metal (TM) and alloying metal nanograins upon lithiation, thus hindering an efficient electron transport within the initial particle, while the alloying contribution remains essentially unaffected. The generality of these findings is confirmed by also investigating Sn_0.9Fe_0.1O₂ as a second CAM with a substantially greater contribution of the alloying reaction and employing Fe instead of Co as a TM dopant.

Photovoltaic (PV)-integrated flow cells for electrochemical energy conversion and storage underwent a huge development. The advantages of this type of integrated flow cell system include the simultaneous storage of solar energy into chemicals that can be readily utilized for generating electricity. However, most studies overlook the practical challenges arising from the inherent heat exposure and consequent overheating of the reactor under the sun. This work aims to predict the temperature profiles across PV-integrated electrochemical flow cells under light exposure conditions by introducing a computational fluid dynamics–based method. Furthermore, we discuss the effects of the flow channel block architecture on the temperature profile to provide insights and guidelines for the effective remedy of overheating.