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Lithium oxygen batteries (LOBs) are considered promising next‐generation lithium batteries owing to their high theoretical specific energy density. However, several issues must be addressed for realizing the practical applications of LOBs. Among them, the evolution of singlet oxygen (1O2)—which undergoes vigorous reactions that compromise the stability of the system—is a key challenge. The high overpotential induced by low‐conductivity lithium peroxide necessitates the use of a redox mediator (RM) to facilitate the charging process; however, RMs can also be degraded by 1O2, which limits their efficacy in the long term. Recently, it was revealed that certain RMs play a role in suppressing the generation of 1O2. In this review, the relationship between the RM and 1O2 is described. Based on recent understandings, clear insight into RM reactions toward 1O2 and possible future research directions will be provided. [ABSTRACT FROM AUTHOR]

Lithium-oxygen batteries are in fact the only rechargeable batteries that can rival internal combustion engines, in terms of high energy density. However, they are still under development due to low-efficiency and short lifetime issues. There are problems of side reactions on the cathode side, high reactivity of the Li anode with solution species, and consumption of redox mediators via reactions with metallic lithium. Therefore, efforts are made to protect/block the lithium metal anode in these cells, in order to mitigate side reactions. However, new approach is required in order to solve the problems mentioned above, especially the irreversible reactions of the redox mediators which are mandatory to these systems with the Li anode. Here, optimized bicompartment two solution cells are proposed, in which detrimental crossover between the cathode and anode is completely avoided. The Li metal anode is cycled in electrolyte solution containing fluorinated ethylene carbonate, in which its cycling efficiency is excellent. The cathode compartment contains ethereal solution with redox mediator that enables oxidation of Li2O2 at low potentials. The electrodes are separated by a solid electrolyte membrane, allowing free transport of Li ions. This approach increases cycle life of lithium oxygen cells and their energy efficiency. [ABSTRACT FROM AUTHOR]

• The TiC-cloth for Li-O 2 battery cathodes prepared using easily available T-shirts. • Coating with perpendicularly aligned TiC suppress the carbon cathode decomposition. • The TiC-cloth provides abundant space to accommodate discharge products. • The TiC-cloth offers catalytic properties during recharge process. • The TiC-cloth demonstrates excellent cycling stability with high capacity. To overcome the theoretical energy density limit of current lithium-ion batteries (LIBs), lithium-oxygen (Li-O 2) batteries based on electrochemical formation and decomposition of lithium peroxide (Li 2 O 2) have received much attention. However, critical cathode-related issues such as carbon decomposition, irreversible accumulation of Li 2 O 2 , and subsequent cathode passivation severely restrict the performance of Li-O 2 batteries. To manage these issues, this paper reports a perpendicularly aligned TiC-coated carbon cloth (TiC-cloth) for Li-O 2 battery cathodes prepared by a facile carbothermal method using easily available T-shirts as a substrate and growth of TiC on the outer surface. Coating with perpendicularly aligned TiC protects the carbon surface and increases the surface area to accommodate Li 2 O 2. After verification of the successful coating, electrochemical tests of Li-O 2 batteries were conducted, and the results were compared against TiC nanoparticle electrode casted manually onto carbonized T-shirts. The TiC-cloth affords enhanced oxygen reduction/evolution activity and cyclability for Li-O 2 batteries compared with the TiC nanoparticles. Analyses demonstrate that this improvement arises from the reversible formation and decomposition of Li 2 O 2 grown along the shape of the TiC on the carbonized T-shirts without carbon decomposition. The study reported here will be a keystone for the intelligent design of stable and efficient cathodes for Li-O 2 batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] • PIPL-H was developed to protect Li metal in batteries using aqueous electrolytes. • Facile fabrication of PIPL-H enabled uniform coating and high reproducibility. • Pre-impregnated high-concentration solution showed enhanced hydrophobicity. • PIPL-H effectively enhanced electrochemical performance during long-term cycling. Aqueous electrolytes have been considered as alternatives for solving thermal safety issues of batteries caused by the high flammability of non-aqueous electrolytes. However, the use of low-potential anodes for high energy density batteries using aqueous electrolytes is limited by the narrow electrochemical stability window of water (1.23 V). Therefore, an artificial protective layer is required to compensate for the potential difference between the electrolyte and anode: however, using selectively conducting Li ions while suppressing water penetration during cycling tests in batteries is a key problem that has not yet been solved. In this study, a pre-impregnated protective layer using a Li ion conductive high concentration solution in a hydrophobic polymer framework (PIPL-H) was developed for the reversible use of Li metal in batteries using aqueous electrolyte. PIPL-H minimizes hydrogen evolution reactions by preventing direct contact between the water molecules and the Li metal. PIPL-H enabled a Li symmetric cell without increasing polarization for 1000 h, as well as a full cell using LiMn 2 O 4 with 88.2 % capacity retention for up to 60 cycles. These results provide a new perspective into protective layers that enable stable operation without being constrained by the limited cathodic stability of aqueous electrolytes. [ABSTRACT FROM AUTHOR]