Aluminum‐ion batteries (Al‐ion batteries) have become a potential energy storage system, owing to their excellent cycling performance, three‐electron‐redox properties, and safety performance. Until now, great progress has been made in Al‐ion batteries. However, the Al‐ion battery system still encounters various problems, such as high electrolyte price, harsh working environment, low discharge platforms, and inferior capacity. Here, we prepared a novel Al‐ion battery with AlCl3/Imidazole hydrochloride (ImidazoleHCl) as the electrolyte, aluminum as the negative electrode, and commercial graphite as the positive electrode. The battery achieves a high specific discharge capacity of 129 mA h g−1 at a current density of 0.5 A g−1 and 105 mA h g−1 with a high coulombic efficiency of 99 % at the current density of 4 A g−1 after 1000 cycles. The mechanism of AlCl4− intercalation/de‐intercalation is proved by Raman, XRD and EDS studies. ImidazoleHCl is a promising electrolyte and this work provides a new insight for the Al‐ion battery system.

The illustration of the electrochemical process for high capacity aluminum ion batteries based on polythiophene/graphite composite cathode materials.

In this paper, we designed a novel rechargeable Al−Ni battery. Nickel foil was firstly used as a cathode material for aluminum batteries and realized a reversible electrode reaction in a weak Lewis acidic electrolyte. Al−Ni battery can provide a high discharge capacity of more than 0.4 mA h cm−2 and exhibit excellent stability. Furthermore, the electrode reaction mechanism and proposed reasonable reaction equations of Al−Ni battery was studied deeply. We also explored the failure process of Al−Ni batteries and obtained the composition of side reaction products. This Al−Ni battery could offer a high reversible capacity of 0.66 mA h at a current density of 0.5 mA cm−2. Even at 1 mA cm−2, it still delivers a capacity of 0.415 mA h (0.27 mA h cm−2) after 100 cycles.

Aluminum-ion batteries based on AlCl3/caprolactam (CPL) and AlCl3/urea/CPL electrolytes exhibit worthwhile performances.

Aluminum batteries (ABs) have been considered as a viable candidate for new‐generation energy‐storage devices due to its low cost and high theoretical volumetric capacity. Despite these advantages, the large‐scale application of ABs is constrained by scarce options of suitable cathode materials. Herein, three‐dimensional nanostructured α‐MnSe microspheres with porous properties are reported as a cathode for ABs. The nanosized and porous structure of α‐MnSe could offer numerous open channels and the short ionic transport path, which would efficiently mitigate volume changes and enhance electrochemical reaction kinetics. Moreover, the pseudocapacitive characteristic of Al3+ storage in α‐MnSe contributes to the fast kinetics of the cathode. It is demonstrated that the reversible Al3+ insertion/extraction occurs in the α‐MnSe cathode during the cycling process. The resulting aluminum battery based on the α‐MnSe cathode, AlCl3/[EMIm]Cl ionic liquid electrolyte, and aluminum anode exhibits an ultrahigh reversible capacity of 408 mA h g−1 at 0.2 A g−1. Even for a current density at 1 A g−1, a discharge capacity of 131 mA h g−1 could be retained with a Coulombic efficiency of 97 % over 150 cycles. This strategy has referential significance in aspects of the selection of compatible cathode for ABs.

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Subsynchronous oscillation (SSO) phenomena caused by interactions between controllers of Doubly-fed induction generators (DFIGs) and series capacitor compensators has been well recognized. However, SSO can also happen on a DFIG-based wind farm without series compensation as reported in a recent real event. This paper firstly analyzes the recorded voltage waveform during this SSO event. Then an equivalent model of the system including the wind farm, static synchronous compensator (STATCOM) and the power grid was established. The paper derives the subsynchronous frequency response of the DFIG converter together with the STATCOM in detail and gives the criterion for SSO to occur, which is verified by both time domain simulation and spectrum analysis. The methodology adopted in this paper can be generalized to analyze the causes of a type of SSO that involves DFIGs and STATCOM but not series compensation. The paper also provides practical suggestions on adjustments of control parameters with the DFIG and STATCOM to prevent this type of SSO.