2 research outputs found
Improving the Cycle-life of Naphthoquinone-based Active Materials by Their Polymerization for Rechargeable Organic Batteries
No full textAbstractTo increase the cycle-stability of rechargeable batteries using an organic positive-electrode material, we synthesized a polymer from a 5,8-dihydroxy-1,4-naphthoquinone (DHNQ) skeleton, which potentially undergoes a four-electron transfer redox reaction. The polymeric material (PDHNQ) was synthesized by the condensation reaction between DHNQ and formaldehyde under acidic media conditions. The initial capacity of the electrode using the monomer (DHNQ), 193 mAh/g, quickly decayed to 56 mAh/g after 100 cycles. On the other hand, the electrode incorporating the prepared PDHNQ showed the higher initial discharge capacity of 256 mAh/g and a longer cycle-life, retaining about 133 mAh/g after 100 cycles
Long Cycle-life Organic Electrode Material based on an Ionic Naphthoquinone Derivative for Rechargeable Batteries
No full textAbstractThe applicability of the redox reactions of 5,8-dihydroxy-1,4-naphthoquinone (1) and its lithium salt, 5,8-dihydroxy-1,4-naphthoquinone dilithium salt (2), as positive electrode active materials for rechargeable lithium batteries was investigated. The prepared electrodes showed initial discharge capacities of 170 mAh g(1)−1 with an average voltage of 2.2 V vs. Li+/Li, and 247 mAh g(2)−1 with an average voltage of 2.1 V vs. Li+/Li for 1 and 2, respectively. The obtained discharge capacities correspond to their two-electron redox behaviors. While the electrode using 1 suffered from a poor cycle-stability, the one using 2 underwent many cycles; i.e., after a small drop in the capacity at the first cycle, the capacity of the latter electrode hardly decayed during the subsequent 100 cycles. The effects of the introduction of ionic groups on the physical properties including the cycle stability were discussed along with quantum chemistry calculation results
