No abstract

Although the theoretical energy densities of lithium-oxygen batteries (LOBs) far exceed those of lithium-ion batteries, the practical values of the LOBs are usually much lower because of the use of large electrolyte excesses. Thus, to realize LOBs with a high practical energy density, the electrolyte amount should be minimized without compromising their performance. To address this challenge, we herein investigate the influence of several electrolyte filling techniques on the performance of LOBs, revealing that the battery discharge/charge profiles are strongly influenced by the uniformity of electrolyte distribution in the porous carbon electrode. The obtained results show the importance of electrolyte filling technology for realization of practical high-energy-density LOBs and facilitate their further development.

Self-standing porous carbon electrodes mainly composed of mesopores with a three-dimensional hexagonal array exhibited superior lithium–oxygen battery performance under low electrolyte/areal capacity (E/C < 10 g A−1 h−1) conditions.

Lithium−oxygen batteries (LOBs) are promising nextgeneration rechargeable batteries due to their high theoretical energy densities. The optimization of the porous carbon-based positive electrode is a crucial challenge in the practical implementation of LOB technologies. Although numerous studies have been conducted regarding the relationships between LOB performance and the physicochemical properties of carbon electrodes, most of these studies evaluate the performances of the electrodes under unrealistic conditions with inappropriate technological parameters. In this study, we prepared carbon gel-based self-standing membranes as positive electrodes and evaluated their performances in LOBs under lean-electrolyte, high-areal-capacity conditions. We clarified the following three crucial points: (1) The nanometer-sized pores exhibited limited effects in improving the cycle performance, although they contributed in enhancing the discharge capacity. (2) The macro-sized pores displayed positive effects in enhancing the discharge capacity. (3) The crystallinity and/or surface functional groups influence the discharge potential and cycle life. The results of this study suggest the significance of controlling the physicochemical properties of a porous carbon-based positive electrode in preparing a LOB with a practically high energy density and an extended cycle life.