Scientists at the University of Maryland have re-designed battery cathodes in an effort to make more efficient, stable and affordable rechargeable sodium, magnesium and aluminium batteries.
The researchers, backed by an international group of collaborators, have used polymeric hexaazatrinaphthalene (PHATN), based on the organic compound pyrazine, as a high-capacity, fast-charging cathode material.
When combined with a sodium ion, the team reported their cathode outperformed polymeric and inorganic cathodes in capacity delivery and retention.
The researchers noted that in sodium‐ion batteries, PHATN delivered a reversible capacity of 220mAh/g−1 at 50mA/g−1, corresponding to the energy density of 440Wh/kg−1, and retained 100mAh/g−1 at 10Ag−1 after 50,000 cycles.
The sodium battery performed up to 3.5V while maintaining a capacity of more than 100mAh/h per gram after 50,000 charge/discharge cycles, claim the researchers.
The team reported similar results in magnesium and aluminium batteries, with PHATN retaining reversible capacities of 110mAh/g−1 after 200 cycles in the former and 92mAh/g−1 after 100 cycles in the later.
The findings were published in the peer-reviewed journal Angewandte Chemie.
Chunsheng Wang, a professor of Chemical and Biomolecular Engineering at the university, said: “Historically, HATN has had poor stability during cycling, posing major challenges.
“We stabilised the material by introducing linkages between the individual molecules forming an organic polymer called polymeric HATN, or PHATN, which offered fast reaction kinetics and high capacities for sodium, aluminium and magnesium ions.”