Polypyrenes as High‐Performance Cathode Materials for Aluminum Batteries

Abstract

The pressing need for low-cost and large-scale stationary storage of electricity has led to a new wave of research on novel batteries made entirely of components that have high natural abundances and are easy to manufacture. One example of such an anode-electrolyte-cathode architecture comprises metallic aluminum, AlCl :[EMIm]Cl (1-ethyl-3-methylimidazolium chloride) ionic liquid and graphite. Various forms of synthetic and natural graphite cathodes have been tested in recent years in this context. Here, a new type of compelling cathode based on inexpensive pyrene polymers is demonstrated. During charging, the condensed aromatic rings of these polymers are oxidized, which is accompanied by the uptake of aluminum tetrachloride anions (AlCl ) from the chloroaluminate ionic liquid. Discharge is the fast inverse process of reduction and the release of AlCl . The electrochemical properties of the polypyrenes can be fine-tuned by the appropriate chemical derivatization. This process is showcased here by poly(nitropyrene-co-pyrene), which has a storage capacity of 100 mAh g , higher than the neat polypyrene (70 mAh g ) or crystalline pyrene (20 mAh g ), at a high discharge voltage (≈1.7 V), energy efficiency (≈86%), and cyclic stability (at least 1000 cycles).

Mesoporous Reduced Graphene Oxide as a High Capacity Cathode for Aluminum Batteries

“…After 100 cycles at 100 mAh g −1 , scanning electron microscopy (SEM) imaging did not reveal changes to the Al surface (Figure S5, Supporting Information). This concurs with previous claims of dendrite‐free operation of ACB in acidic AlCl 3 :[EMIm]Cl melts …”

Unexpected Contribution of Current Collector to the Cost of Rechargeable Al‐Ion Batteries

“…AIBs comprise of a metallic aluminum that serves as the anode and the negative current collector, a chloroaluminate ionic liquid as the electrolyte with a AlCl 3 :EMImCl molar ratio (r)>1 (only in this cases reversible electrodeposition of metallic Al is possible), an Al‐insertion cathode material and a positive current collector. The vast majority of studies have been mainly focused on increasing energy density through the development of new cathode materials, e. g. vanadium oxides, metals sulfides, polymers, MXene, tellurium or graphitic materials amongst others . Most of these studies were carried out using expensive or unpractical materials like glassy carbon, molybdenum (Mo),, tungsten (W), or tantalum (Ta), due to the anodic dissolution of cheap and commonly used current collectors, e. g. Ni, Cu, Ti or stainless steel.…”

Stability of Metallic Current Collectors in Acidic Ionic Liquid for Rechargeable Aluminum‐Ion Batteries

“…Therefore, it is necessary to develop a stable and sustainable current collector. Several research groups have suggested new current collectors ,. However, they can operate only above 0.5 V of the low cutoff voltage.…”