TAGS: New Energy Solutions
Researchers from Skoltech, D. Mendeleev University, and the Institute of Problems of Chemical Physics of RAS have synthesized and tested new polymer-based cathode materials for lithium dual-ion batteries. The tests showed that the new cathodes withstand up to 25,000 operating cycles and charge in a matter of seconds, thus outperforming lithium-ion batteries. The cathodes can also be used to produce less expensive potassium dual-ion batteries.
Promising Technology in Use
The team used a promising post-lithium dual-ion technology based on the electrochemical processes involving the electrolyte’s anions and cations to attain a manifold increase in the charging rate as compared to lithium-ion batteries. Another plus is that the cathode prototypes were made of polymeric aromatic amines which can be synthesized from various organic compounds.
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Our previous research addressed polymer cathodes for ultra-fast high-capacity batteries that can be charged and discharged in a few seconds, but we wanted more,” says Filipp A. Obrezkov, a Skoltech PhD student.
Researchers used various alternatives, including linear polymers, in which each monomeric unit bonds with two neighbors only. In this study, researchers studied new branched polymers where each unit bonds with at least three other units. Together they form large mesh structures that ensure faster kinetics of the electrode processes. Electrodes made of these materials display even higher charge and discharge rates.
The Russian team studied the dual-ion batteries in which the electrochemical processes involved the electrolyte’s cations (i.e. lithium cations) and anions that get in and out of the anode and cathode material’s structures, respectively.
Novel Feature to Use Potassium Electrolytes
Another novel feature is that, in some experiments, the scientists used potassium electrolytes instead of expensive lithium ones to obtain potassium dual-ion batteries.
The team synthesized two novel copolymers of dihydrophenazine with diphenylamine (PDPAPZ) and phenothiazine (PPTZPZ) which they used to produce cathodes. As anodes, they used metallic lithium and potassium. Since the key features of these battery prototypes called half-cells are driven by the cathode, the scientists assemble them in order to quickly assess the capabilities of new cathode materials.
While PPTZPZ half-cells showed average performance, PDPAPZ turned out to be more efficient: Lithium half-cells with PDPAPZ were quick to charge and discharge, while displaying good stability and retaining up to a third of their capacity even after 25,000 operating cycles. If a regular phone battery were as stable, it could be charged and discharged daily for 70 years.
PDPAPZ potassium half-cells exhibited a high energy density of 398 Wh/kg. For comparison, the value for common lithium cells is 200-250 Wh/kg, the anode and electrolyte weights included. Thus, the Russian team demonstrated that polymer cathode materials can be used to create efficient lithium and potassium dual-ion batteries.
Source: Skoltech