Aqueous Aluminum-ion Battery Research Articles

Potassium cobalt hexacyanoferrate nanocubic assemblies for high-performance aqueous aluminum ion batteries

Prussian blue analogues are considered as a class of extremely promising electrode materials for various energy storage devices. Here, the potassium cobalt hexacyanoferrate (K2CoFe(CN)6) with a nanocubic assembled structure was successfully synthesized via a one-step hydrothermal method and low-temperature calcination operation; this material is employed as the working electrode for aqueous aluminum ion batteries (AIBs). To some extent, such a 3D open-framework structure accelerated the electronic and ionic transmission and optimized the electrochemical properties. The as-prepared K2CoFe(CN)6 demonstrated a reversible discharge capacity of 50 mA h g−1 at a of 0.1 A/g and showed a desirable cycling stability, which makes it a feasible electrode material for aqueous AIBs.

Graphene and diglyme assisted improved Al3+ ion storage in MoO3 nanorod: steps for high-performance aqueous aluminum-ion battery

An approach to improve the Al3+ ion storage capacity of MoO3 in aqueous electrolyte is illustrated here. Graphene as conductive additive and diglyme as electrolyte additive play a pivotal and synergistic role in the improvement. Graphene-MoO3 composite exhibits stable capacity of 160 mAh g−1 over 100 cycles in diglyme mixed aqueous electrolyte with v/v mixing ratio of 50:50, whereas it delivers a capacity of only 75 mAh g−1 at the 100th cycle in pristine aqueous electrolyte. Besides, pristine MoO3 also demonstrates improved stability in diglyme mixed aqueous electrolyte.

Investigating FeVO4 as a cathode material for aqueous aluminum-ion battery

Developing an aluminum-ion aqueous battery is extremely attractive for prospects of creating a super cheap, environmentally friendly and safe energy storage system. However, a lack of reversible cathode materials hampers the use of metallic Al as a high-capacity anode in an aqueous electrolyte. As opposed to insertion-type cathodes, the performance of conversion-type cathodes for Al-ion electrochemistry in an aqueous electrolytic environment remains poorly explored. As a first attempt to understand the performance of such conversion type materials for Al-ion intake, we herein report FeVO4 as a potential cathode material with a significantly high capacity of 350 mA h g−1. We use a combination of inhouse and synchrotron-based characterization techniques to confirm Al-ion electrochemical reaction with FeVO4, and also determine how electrolyte pH has a mechanistic influence on the reversibility of aluminum-ion aqueous batteries.

Electrochemically activated spinel manganese oxide for rechargeable aqueous aluminum battery

Aluminum is a naturally abundant, trivalent charge carrier with high theoretical specific capacity and volumetric energy density, rendering aluminum-ion batteries a technology of choice for future large-scale energy storage. However, the frequent collapse of the host structure of the cathode materials and sluggish kinetics of aluminum ion diffusion have thus far hampered the realization of practical battery devices. Here, we synthesize AlxMnO2·nH2O by an in-situ electrochemical transformation reaction to be used as a cathode material for an aluminum-ion battery with a configuration of Al/Al(OTF)3-H2O/AlxMnO2·nH2O. This cell is not only based on aqueous electrolyte chemistry but also delivers a high specific capacity of 467 mAh g−1 and a record high energy density of 481 Wh kg−1. The high safety of aqueous electrolyte, facile cell assembly and the low cost of materials suggest that this aqueous aluminum-ion battery holds promise for large-scale energy applications.

Al3+ ion intercalation in MoO3 for aqueous aluminum-ion battery

While addressing the question of Al3+ ion intercalation/deintercalation in MoO3, we unravel that Al3+ ion preferentially intercalates in MoO3 in certain aqueous electrolytes. The Al3+ ion electrochemistry in MoO3 shows stark contrasting characteristics in different aqueous electrolytes. Although very high initial Al3+ ion storage capacity of 680 mAhg−1 is observed, a stable discharge capacity of approximately 170 mAhg−1 is attained after 20th cycle over the measured time (350th cycle) at a specific current of 2.5 Ag-1 (5 mA cm−2) in AlCl3 aqueous electrolyte. AlCl3 aqueous electrolyte exhibits superior benefits than Al2(SO4)3 and Al(NO3)3 aqueous electrolytes in terms of offering higher Al3+ ion storage capacity, long-term stability, capacity retention and minimized polarization.

Active role of inactive current collector in aqueous aluminum-ion battery

The recent revival of research interest in rechargeable aluminum-ion batteries has opened up avenues to overcome its inherent challenges. While there are fierce attempts to find suitable electrode materials for aluminum-ion batteries, it is very important to carefully evaluate them. We show here that an essential criterion for correct electrochemical evaluation of aqueous aluminum-ion batteries is to appropriately select the current collector. Considering anatase TiO2 as a model electrode material, it is demonstrated that type of current collector could transform an inactive electrode material to an active one. TiO2 could exhibit initial Al3+ ion storage capacity of 256 mAhg−1 at a current density of 4 Ag−1 with graphite current collector, whereas it is only 82 mAhg−1 with titanium current collector at similar current density. Interestingly, no charge/discharge characteristics could be obtained with stainless steel and nickel current collectors at any current densities.

An approach to improve the Al3+ ion intercalation in anatase TiO2 nanoparticle for aqueous aluminum-ion battery

There have been unprecedented research activities to identify electroactive materials for room temperature rechargeable aluminum-ion battery in the last 5 years. Titanium dioxide (TiO2) is emerging as a perspective anode material for aqueous aluminum-ion battery. We address here the phenomenon of Al3+ ion intercalation-deintercalation in anatase TiO2 nanoparticles. The study reveals that graphene significantly improves the electrochemical activity of TiO2 nanoparticles. It is estimated that incorporation of graphene enhances the Al3+ ion diffusion coefficient in TiO2 by 44 times. The graphene-TiO2 nanocomposite delivers an initial discharge capacity of 52 mAh g−1 at a very high current density of 6.25 Ag−1, whereas pristine TiO2 nanoparticle shows negligible capacities at a similar or lower current density. Remarkably, the reversible crystal phase transition of TiO2 to aluminum titanate (Al2TiO5) due to Al3+ ion intercalation-deintercalation is also observed for the first time.

Anatase TiO2 as an Anode Material for Rechargeable Aqueous Aluminum-Ion Batteries: Remarkable Graphene Induced Aluminum Ion Storage Phenomenon

The electrochemical intercalation and extraction of Al3+ ion in anatase TiO2 is illustrated in various aqueous electrolytes in an attempt to demonstrate the viability of TiO2 as an anode material for rechargeable aqueous aluminum-ion batteries. It is well understood that the primary barrier for diffusion of Al3+ ion in TiO2 is the poor electronic conductivity of TiO2. It is revealed that a small fraction of graphene (<2 wt %) could induce ultrafast diffusion of Al3+ ion in TiO2. Estimation shows that graphene remarkably enhances the Al3+ ion diffusion coefficient in TiO2 by 672 times. Discharge capacities in the range of 33–50 mAhg–1 are obtained at a high current rate of 6.25Ag–1for graphene incorporated TiO2. It is also seen that the nature of electrolytes critically influences the Al3+ ion insertion phenomenon. The possibility of reversible crystal phase transition of TiO2 to aluminium titanate due to Al3+ ion intercalation-extraction is also demonstrated for the first time.