放电态Li-AgVO_3一次电池作为可充Li-O_2电池再利用研究

Resumption of the Discharged Li-AgVO_3 Primary Batteries for Rechargeable Li-O_2 Batteries

废弃电池中活性材料再利用是目前处理废弃的一次电池既节约又节能的方法.基于此,本工作详细地研究了废弃的Li-AgVO_3一次电池作为可充Li-O_2电池的再利用.结果显示放电后的Li-AgVO_3电池可以作为Li-O_2电池被再次激活.在Li-AgVO_3电池放电过程中,原位生长在钒氧化物电极上的银纳米颗粒可以进一步有效地催化Li-O_2电池中氧还原和氧析出反应(ORR/OER).通过控制Li-AgVO_3一次电池的放电深度,可以得到具有不同尺寸和分布状态的Ag纳米颗粒的银/钒氧化物复合电极.将这些不同放电状态的复合电极作为Li-O_2电池的空气正极并测试了它们的电化学性能.电化学测试结果表明,放电到2.3 V的复合电极电化学性能最优,比容量高达9000 mAh·g_(carbon)^(-1),充放电过电位最低,可稳定循环95周.其优异电化学性能归因于银纳米颗粒合适的尺寸和均匀的分布,明显提高了电极导电能力并为ORR/OER电催化反应提供了丰富的活性位点.

Recycling use is one of the energy and resource saving strategies to dispose depleted batteries, especially primary lithium batteries that employ electrode materials based on expensive and low-abundance elements. In this study, we report in detail the recycling use of discharged Li-AgVO3 primary battery for rechargeable Li-O2 battery. We demonstrate that the discharged Li-AgVO3 cell, in which metallic silver nanoparticles in-situ generated in the vanadium oxide nanowires cathode efficiently catalyze the oxygen reduction/evolution reactions （ORR/OER）, can be resumed as rechargeable Li-O2 cells when they are exposed at O2 atmosphere. By controlling the discharge depths, we obtained different cathodes that were composed of vanadium oxide nanowires and silver nanoparticles. As the electrode was discharged to a lower voltage, more silver nanoparticles with larger particle size were distributed on the surface of vanadium oxides, as a result of the sequential reduction of Ag＋ to Ago and V5＋ to V4＋. Specifically, the average size of formed Ag nanoparticles was 15 nm and 70 nm at ceased discharge voltage of 2.9 V and 2.0 V, respectively, while the formation of V4＋ was observed at discharge voltage lower than 2.3 V. Electrochemical tests indicated that the Li-O2 cells assembled with the AgVO3 cathode discharged to 2.3 V （AgVO3-2.3） exhibited the highest specific capacity （9000 mAh·garbon-1）, the lowest overpotential and robust cycling performance （up to 95 cycles at the current density of 300 mA·gcarbon-1）. The remarkable electrochemical performance of the Li-O2 battery with the AgVO3-2.3 cathode is attributed to the optimization of amount, size and distribution of generated silver nanoparticles that contribute to high electronic conductivity and abundant active sites for the ORR/OER. A combined analysis of electrochemical impedance spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy confirmed that the AgVO3-2.3 cathode enables the reversible formation and decomposition of Li2O2 with lower charge transfer resistance on discharge and charge. The results presented here would provide new insight into the promising recycling application of depleted primary Li-AgVO3 batteries in rechargeable high-capacity Li-O2 batteries.