This work reports on the synthesis of layered manganese oxides (δ-MnO2) and their possible application as cathode intercalation materials in Al-ion and Zn-ion batteries. By using a one-pot microwave-assisted synthesis route in 1.6 M KOH (MnVII:MnII = 0.33), a pure layered δ-MnO2 birnessite phase without any hausmannite traces was obtained after only a 14 h reaction time period at 110 °C. Attempts to enhance crystallinity level of as-prepared birnessite through increasing of reaction time up to 96 h in 1.6 M KOH failed and led to decreases in crystallinity and the emergence of an additional hausmannite phase. The influence of MnII:OH− ratio (1:2 to 1:10) on phase crystallinity and hausmannite phase formation for 96 h reaction time was investigated as well. By increasing alkalinity of the reaction mixture up to 2.5 M KOH, a slight increase in crystallinity of birnessite phase was achieved, but hausmannite formation couldn’t be inhibited as hoped. The as-prepared layered δ-MnO2 powder material was spray-coated on a carbon paper and tested in laboratory cells with Al or Zn as active materials. The Al-ion tests were carried out in EMIMCl/AlCl3 while the Zn-Ion experiments were performed in water containing choline acetate (ChAcO) or a ZnSO4 solution. Best performance in terms of capacity was yielded in the Zn-ion cell (200 mWh g−1 for 20 cycles) compared to about 3 mAh g−1 for the Al-ion cell. The poor activity of the latter system was attributed to low dissociation rate of tetrachloroaluminate ions (AlCl4−) in the EMIMCl/AlCl3 mixture into positive Al complexes which are needed for charge compensation of the oxide-based cathode during the discharge step.

Recently, rechargeable aluminum batteries have received much attention due to their low cost, easy operation, and high safety. As the research into rechargeable aluminum batteries with a room-temperature ionic liquid electrolyte is relatively new, research efforts have focused on finding suitable electrode materials. An understanding of the environmental aspects of electrode materials is essential to make informed and conscious decisions in aluminum battery development. The purpose of this study was to evaluate and compare the relative environmental performance of electrode material candidates for rechargeable aluminum batteries with an AlCl3/EMIMCl (1-ethyl-3-methylimidazolium chloride) room-temperature ionic liquid electrolyte. To this end, we used a lifecycle environmental screening framework to evaluate 12 candidate electrode materials. We found that all of the studied materials are associated with one or more drawbacks and therefore do not represent a “silver bullet” for the aluminum battery. Even so, some materials appeared more promising than others did. We also found that aluminum battery technology is likely to face some of the same environmental challenges as Li-ion technology but also offers an opportunity to avoid others. The insights provided here can aid aluminum battery development in an environmentally sustainable direction.

In aluminium (Al) symmetric cell, potentials during Al deposition on an Al foil at 1 mA cm−2 were 60–70 mV higher in TEA‐AlCl3 electrolyte compared to those measured with EMIMCl‐AlCl3 reference. Because of higher electrochemical stability of TEA‐AlCl3 solution, cut‐off voltage of charging step in AIB full‐cell was set to 2.45 V compared to 2.40 V for the reference cell. During long‐term cycling at 1 A g−1, the specific capacity of the AIB cell employing TEA‐AlCl3 increased from 60 to 94 mAh g−1 (57 %) after 1000 cycles while that of cell with EMIMCl‐AlCl3 was quite constant at about 60 mAh g−1. This behaviour was explained by continuous decreasing in Al electrode potential at End‐of‐Charge state (EOC) during deposition reaction (charging step) in TEA‐AlCl3 allowing an increase in graphite electrode potential and consequently in AIB cell capacity over the whole experiment. This increase in capacity was accompanied by a raise of defect sites in graphite material.

Lithiumfreie Systeme könnten helfen, den Bedarf an elektrochemischen Energiespeichern zu decken. Aluminium‐Graphit‐Batterien nutzen bieten eine hohe Leistungsdichte und sind langlebig. Sie sind allerdings noch in einer frühen Entwicklungsphase. Es fehlen etwa korrosionsfreie Elektrolyte.

Carbon xerogels were synthesized using a soft-template route with resorcinol as the carbon source and sodium carbonate as the catalyst. The influence of the resorcinol to catalyst ratio in the range of 500–20,000 on pore structure, graphitic domains, and electronic conductivity of as-prepared carbon xerogels, as well as their performance in an aluminium ion battery (AIB), was investigated. After carbonization steps of the polymers up to 800 °C, all carbon samples exhibited similar specific volumes of micropores (0.7–0.8 cm³ g−1), while samples obtained from mixtures with R/C ratios lower than 2000 led to carbon xerogels with significantly higher mesopore diameters up to 6 nm. The best results, in terms of specific surface (1000 m² g−1), average pore size (6 nm) and reversible capacity in AIB cell (28 mAh g−1 @ 0.1 A g−1), were obtained with a carbon xerogel sample synthetized at a resorcinol to catalyst ratio of R/C = 500 (CXG500). Though cyclic voltammograms of carbon xerogel samples did not exhibit any sharp peaks in the applied potential window, the presence of both oxidation and a quite wide reduction peak in CXG500–2000 cyclic voltammograms indicated pseudocapacitance behaviour induced by diffusion-controlled intercalation/de-intercalation of AlCl4− ions into/from the carbon xerogel matrix. This was confirmed by shifting of the (002) peak towards lower 2θ angle values in the XRD pattern of the CXG500 electrode after the charging step in AIB, whereas the contribution of pseudocapacitance, calculated from half-cell measurements, was limited to only 6% of overall capacitance.