A new kind of Al-ion battery with carbon paper as the cathode, high-purity Al foil as the anode and ionic liquid as the electrolyte is proposed in this work. The significance of the presented battery is going to be an extremely high average voltage plateau of ca. 1.8 V vs. Al(3+)/Al.

may offer noteworthy cost saving and safety improvement compared to its counterparts. Additionally, aluminum has a very negative redox potential (≈1.676 V vs standard hydrogen electrode (SHE)) and a small electrochemical equivalent (0.336 g Ah −1 ), which make it one of the ideal elements for rechargeable batteries. However, the previous efforts have encountered numerous issues over the past few years, such as the cathode material disintegration, [12,14] low discharge voltage, [8] capacitive behavior without discharge voltage plateaus. [15,16] There is no doubt that some of recent works have explored a series of new electrode materials, such as V 2 O 5 , [8] TiO 2 , [9] fluorinated natural graphite, [15] polymers, [16] and Prussian blue analogues (PBAs). [12] The previous work has revealed that Al ions can insert into TiO 2 nanotube arrays and PBAs in aqueous solution. But the discharge capacity of these materials is too low. Very recently, the works from our group at University of Science and Technology Beijing (USTB) and Dai and co-workers at Stanford University found that rechargeable aluminum-ion batteries using graphite materials cathode had a very high charge/discharge voltage plateau around 2.0 V versus Al 3+ /Al. [12,17] The charge/discharge reaction happens through the intercalation and deintercalation of AlCl 4 − into interlayer space of graphite materials.Herein, we report for the first time, the design of Ni 3 S 2 / graphene microflakes composite as a novel cathode material for rechargeable aluminum-ion batteries. The battery runs through the electrochemical deposition and dissolution of aluminum at the anode, and the intercalation and deintercalation of Al 3+ cations in the cathode. The unique advantage of Ni 3 S 2 /graphene microflakes composite lies in the low charge-transfer impedance, which represents a high rate of intercalation and deintercalation of ions. Additionally, we find that there is a dissociation process of Al 2 Cl 7 − during charge process, and the active material transforms from monocrystal to polycrystal at the same time. The battery exhibits a high discharge voltage plateau (≈1.0 V vs Al/AlCl 4 − ), a discharge capacity of over 60 mA h g −1 , a high coulombic efficiency of about 99% , and a high rate capability, suggesting that it is a favorable cathode material for high-performance aluminumion batteries.

On the basis of low-cost, rich resources, and safety performance, aluminum-ion batteries have been regarded as a promising candidate for next-generation energy storage batteries in large-scale energy applications. A rechargeable aluminum-ion battery has been fabricated based on a 3D hierarchical copper sulfide (CuS) microsphere composed of nanoflakes as cathode material and room-temperature ionic liquid containing AlCl and 1-ethyl-3-methylimidazolium chloride ([EMIm]Cl) as electrolyte. The aluminum-ion battery with a microsphere electrode exhibits a high average discharge voltage of ∼1.0 V vs Al/AlCl, reversible specific capacity of about 90 mA h g at 20 mA g, and good cyclability of nearly 100% Coulombic efficiency after 100 cycles. Such remarkable electrochemical performance is attributed to the well-defined nanostructure of the cathode material facilitating the electron and ion transfer, especially for chloroaluminate ions with large size, which is desirable for aluminum-ion battery applications.

An ultrafast rechargeable multi-ions battery is presented, in which multi-ions can electrochemically intercalate into graphite layers, exhibiting a high reversible discharge capacity of ≈100 mAh g and a Coulombic efficiency of ≈99% over hundreds of cycles at a high current density. The results may open up a new paradigm for multi-ions-based electrochemical battery technologies and applications.

A flower-like vanadium sulfide/reduced graphene oxide (VS /rGO) composite was prepared by a typical hydrothermal method and it was investigated as cathode for aluminum-ion batteries with non-inflammable and non-explosive ionic-liquid electrolytes. The charge/discharge performance measurements were performed in a voltage range of 0.1-2.0 V versus Al/AlCl , which gave an initial charge/discharge specific capacity af approximately 491.57 and 406.94 mA h g , respectively, at a current density of 100 mA g . Additionally, in the cycling performance, the discharge capacity was observed to remain over 80, 70, and 60 mA h g at current densities of 100, 200, and 300 mA g after 100 cycles, respectively. The result of a coulombic efficiency over 90 % after 100 cycles and high retained capacity indicate that the composite is a favorable cathode material for new rechargeable aluminum-ion batteries.