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Herein, thermal decomposition experiments of lithium peroxide (Li2O2) were performed to prepare a precursor (Li2O) for sacrificing cathode material, Li2NiO2. The Li2O2 was prepared by a hydrometallurgical reaction between LiOH·H2O and H2O2. The overall reaction during annealing was found to involve the following three steps: (1) dehydration of LiOH·H2O, (2) decomposition of Li2O2, and (3) pyrolysis of the remaining anhydrous LiOH. This stepwise reaction was elucidated by thermal gravimetric and quantitative X-ray diffraction analyses. Furthermore, over-lithiated lithium nickel oxide (Li2NiO2) using our lithium precursor was synthesized, which exhibited a larger yield of 90.9% and higher irreversible capacity of 261 to 265 mAh g?1 than the sample prepared by commercially purchased Li2O (45.6% and 177 to 185 mAh g?1, respectively) due to optimal powder preparation conditions.

In-situ Raman spectroscopy is applied, for the first time, to elucidate the reaction products of oxygen reduction in two types of ionic liquids: 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (C 2mimTFSI) and 1-butyl-1-methylpyrr

When aprotic Li–O2batteries discharge, the product phase formed in the cathode often contains two different morphologies, that is, crystalline and amorphous Li2O2. The morphology of Li2O2impacts strongly on the electrochemical performance of Li–O2cells in terms of energy efficiency and rate capability. Crystalline Li2O2is readily available and its properties have been studied in depth for Li–O2batteries. However, little is known about the amorphous Li2O2because of its rarity in high purity. Herein, amorphous Li2O2has been synthesized by a rapid reaction of tetramethylammonium superoxide and LiClO4in solution, and its amorphous nature has been confirmed by a range of techniques. Compared with its crystalline siblings, amorphous Li2O2demonstrates enhanced charge-transport properties and increased electro-oxidation kinetics, manifesting itself a desirable discharge phase for high-performance Li–O2batteries.

Aprotic Li-O2 batteries have attracted a great deal of attention because of their potential to offer much higher energy density than those provided by commercialized lithium-ion batteries. However, their reversible operation is plagued by serious side-reactions from liquid electrolytes and/or carbon-based materials. Recently, carbon-free materials have been proposed and utilized to construct stable cathodes for Li/O2 chemistry. Different from most of the previously reported metal-based carbon-free cathodes, herein we report a non-metal-based carbon-free cathode support consisting of mesoporous boron-doped carbon nitride (m-BCN) and demonstrate its excellent stability and activity for Li/O2 chemistry. Benefiting from the introduction of evenly distributed RuO2 nanoparticles (1-2 nm) in the pores of the boron-doped carbon nitride support, excellent cycle stability with a low overpotential (141 cycles with a pristine Li anode which is extended to 227 cycles after replacing it with a new Li anode at 0.5 mA cm-2) and superior rate capability (1.28 mA h cm-2 at 1 mA cm-2) are obtained. This impressive performance is ascribed to the enhanced stability and activity of such designed cathodes, which is supported by the fact that reversible formation and decomposition of Li2O2 with no accumulation of Li2CO3 is detected during cycling. These results demonstrate that manipulating cathode materials towards stable reaction interfaces is essential for alleviating the formation of by-products and improving the performance of Li-O2 batteries.