Angell Michael, Pan Chun-Jern, Rong Youmin, Yuan Chunze, Lin Meng-Chang, Hwang Bing-Joe, Dai Hongjie
Department of Chemistry, Stanford University, Stanford, CA 94305.
Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan.
Proc Natl Acad Sci U S A. 2017 Jan 31;114(5):834-839. doi: 10.1073/pnas.1619795114. Epub 2017 Jan 17.
In recent years, impressive advances in harvesting renewable energy have led to a pressing demand for the complimentary energy storage technology. Here, a high Coulombic efficiency (∼99.7%) Al battery is developed using earth-abundant aluminum as the anode, graphite as the cathode, and a cheap ionic liquid analog electrolyte made from a mixture of AlCl and urea in a 1.3:1 molar ratio. The battery displays discharge voltage plateaus around 1.9 and 1.5 V (average discharge = 1.73 V) and yielded a specific cathode capacity of ∼73 mAh g at a current density of 100 mA g (∼1.4 C). High Coulombic efficiency over a range of charge-discharge rates and stability over ∼150-200 cycles was easily demonstrated. In situ Raman spectroscopy clearly showed chloroaluminate anion intercalation/deintercalation of graphite (positive electrode) during charge-discharge and suggested the formation of a stage 2 graphite intercalation compound when fully charged. Raman spectroscopy and NMR suggested the existence of AlCl, AlCl anions and [AlCl·(urea)] cations in the AlCl/urea electrolyte when an excess of AlCl was present. Aluminum deposition therefore proceeded through two pathways, one involving AlCl anions and the other involving [AlCl·(urea)] cations. This battery is a promising prospect for a future high-performance, low-cost energy storage device.
近年来，可再生能源采集方面取得的显著进展引发了对配套储能技术的迫切需求。在此，开发了一种高库仑效率（约99.7%）的铝电池，该电池以储量丰富的铝为阳极，石墨为阴极，并采用由氯化铝和尿素按1.3:1摩尔比混合制成的廉价离子液体类似物电解质。该电池在1.9伏和1.5伏左右显示出放电电压平台（平均放电电压 = 1.73伏），在100毫安/克（约1.4库仑）的电流密度下，阴极比容量约为73毫安时/克。在一系列充放电速率下都很容易证明其具有高库仑效率，并且在约150 - 200次循环中具有稳定性。原位拉曼光谱清楚地表明，在充放电过程中，石墨（正极）存在氯铝酸根阴离子的嵌入/脱嵌，并表明在完全充电时形成了2阶石墨嵌入化合物。拉曼光谱和核磁共振表明，当存在过量的氯化铝时，在氯化铝/尿素电解质中存在AlCl、AlCl阴离子和[AlCl·(尿素)]阳离子。因此，铝的沉积通过两条途径进行，一条涉及AlCl阴离子，另一条涉及[AlCl·(尿素)]阳离子。这种电池对于未来高性能、低成本的储能装置来说前景广阔。
