A stable polyradical, poly (2,2,6,6-tetramethylpiperidinyloxy methacrylate) (PTMA), was synthesized,and its structure was determined by infrared, ultraviolet-visible, and ESR spectroscopy. Cyclic voltammograms ofthe PTMA polyradical electrodes were obtained by using a three-electrode cell at a scan rate of 5 mV/s within a po-tential range of 3.2-4. 0 V. The results show that the shape of oxidation peak is very similar to that of reductionpeak, and oxidation peak current is equal to the corresponding reduction peak current, which suggest that PTMApossesses an excellent reversibility. The difference of the anodic peak potential (Ea,p =3.66 V, vs Li/Li+ ) and ca-thodic peak potential(Ec,p =3.58 V, vs Li/Li+ ) is estimated at 80 mV, which is extremely less than that of the oth-er organic positive materials in lithium second batteries such as organosulfide compounds, leading to a capability forhigh current capability in the charging and discharging process of the battery. The maximum discharge specific ca-pacity of PTMA is 78.4 mA @ h/g at the constant discharge current of 0.3 mA (0.2 C rate), the coulombic efficien-cy is about 95%, and the charging and discharging curves of the batteries have an obvious plateau at 3.65 V and3.56 V, respectively. The discharging specific capacity of the battery decreased is about 2% after 100 cycles. ThePTMA/Li button batteries exhibite an excellent stability.
展开▼
