Although lithium-oxygen batteries (LOBs) hold the promise of high gravimetric energy density, this potential is hindered by high charging voltages. To ensure that the charging voltage remains low, it is crucial to generate discharge products that can be easily decomposed during the successive charging process. In this study, we discovered that the use of amide-based electrolyte solvents containing a fluorinated moiety can notably establish a sustained voltage plateau at low-charging voltages at around 3.
View Article and Find Full Text PDFThe rational design of a stable and catalytic carbon cathode is crucial for the development of rechargeable lithium-oxygen (LiO ) batteries. An edge-site-free and topological-defect-rich graphene-based material is proposed as a pure carbon cathode that drastically improves LiO battery performance, even in the absence of extra catalysts and mediators. The proposed graphene-based material is synthesized using the advanced template technique coupled with high-temperature annealing at 1800 °C.
View Article and Find Full Text PDFAlthough sufficient tolerance against attack by superoxide radicals (O ) has been mainly recognized as an important property for Li-O battery (LOB) electrolytes, recent evidence has revealed that other critical factors also govern the cyclability, prompting a reconsideration of the basic design guidelines of LOB electrolytes. Here, we found that LOBs equipped with a N,N-dimethylacetamide (DMA)-based electrolyte exhibited better cyclability compared with other standard LOB electrolytes. This superior cyclability is attributable to the capabilities of quenching O and forming highly decomposable Li O .
View Article and Find Full Text PDFThe large overpotential of nonaqueous Li-O batteries when charging causes low round-trip efficiency and decomposition of the electrode materials and electrolyte. The origins of this overpotential have been enthusiastically explored to date; however, a full understanding has not yet been reached because of the complexity of multistep reaction mechanisms. Here, we applied structural and electrochemical analysis techniques to investigate the reaction step that results in the increase of the overpotential when charging.
View Article and Find Full Text PDFPrior to the practical application of rechargeable aprotic Li-O batteries, the high charging overpotentials of these devices (which inevitably cause irreversible parasitic reactions) must be addressed. The use of redox mediators (RMs) that oxidatively decompose the discharge product, LiO, is one promising solution to this problem. However, the mitigating effect of RMs is currently insufficient, and so it would be beneficial to clarify the LiO reductive growth and oxidative decomposition mechanisms.
View Article and Find Full Text PDFEnhancement of the discharge capacity of lithium-oxygen batteries (LOBs) while maintaining a high cell voltage is an important challenge to overcome to achieve an ideal energy density. Both the cell voltage and discharge capacity of an LOB could be controlled by employing a binary solvent electrolyte composed of dimethyl sulfoxide (DMSO) and acetonitrile (MeCN), whereby an energy density 3.2 times higher than that of the 100 vol % DMSO electrolyte was obtained with an electrolyte containing 50 vol % of DMSO.
View Article and Find Full Text PDFACS Appl Mater Interfaces
September 2020
Various electrolyte components have been investigated with the aim of improving the cycle life of lithium-oxygen (Li-O) batteries. A tetraglyme-based electrolyte containing dual anions of Br and NO is a promising electrolyte system in which the cell voltage during charging is reduced because of the redox-mediator function of the Br/Br and NO/NO couples, while the Li-metal anode is protected by LiO formed via the reaction between Li metal and NO. To maximize the potential of this system, the fundamental factors that limit the cycle life should be clarified.
View Article and Find Full Text PDFData-driven material discovery has recently become popular in the field of next-generation secondary batteries. However, it is important to obtain large, high quality data sets to apply data-driven methods such as evolutionary algorithms or Bayesian optimization. Combinatorial high-throughput techniques are an effective approach to obtaining large data sets together with reliable quality.
View Article and Find Full Text PDF