Enhancing Long-Term Durability of Electrochemical Reactors Producing Formate from CO and Water Designed for Integration with Solar Cells.

Artificial photosynthetic cells producing organic matter from CO and water have been extensively studied for carbon neutrality, and the research trend is currently transitioning from proof of concept using small-sized cells to large-scale demonstrations for practical applications. We previously demonstrated a 1 m size cell in which an electrochemical (EC) reactor featuring a ruthenium (Ru)-complex polymer (RuCP) cathode catalyst was integrated with photovoltaic cells. In this study, we tackled the remaining issue to improve the long-term durability of cathode electrodes used in the EC reactors, demonstrating high Faradaic efficiencies exceeding 80% and around 60% electricity-to-chemical energy-conversion efficiencies of a 75 cm sized EC reactor after continuous operation for 3000 h under practical conditions.

Positive Feedback Mechanism to Increase the Charging Voltage of Li-O Batteries.

The 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.

Synergistic Effect of Binary Electrolyte on Enhancement of the Energy Density in Li-O Batteries.

Enhancement 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.

Publisher Correction: Negative differential resistance as a critical indicator for the discharge capacity of lithium-oxygen batteries.

The original version of this Article contained an error in the title, which was previously incorrectly given as 'Negative differential resistance as a critical indicator for the discharge capacity of lithium-oxygene batteries'. The correct version states 'lithium-oxygen' in place of 'lithium-oxygene'. This has been corrected in both the PDF and HTML versions of the Article.

Negative differential resistance as a critical indicator for the discharge capacity of lithium-oxygene batteries.

In non-aqueous lithium-oxygen batteries, the one-electron reduction of oxygen and subsequent lithium oxide formation both occur during discharge. This lithium oxide can be converted to insulating lithium peroxide via two different pathways: a second reduction at the cathode surface or disproportionation in solution. The latter process is known to be advantageous with regard to increasing the discharge capacity and is promoted by a high donor number electrolyte because of the stability of lithium oxide in media of this type.

A highly efficient LiO oxidation system in Li-O batteries.

A novel indirect charging system that uses a redox mediator was demonstrated for Li-O batteries. 4-Methoxy-2,2,6,6-tetramethylpiperidinyl-1-oxyl (MeO-TEMPO) was applied as a mediator to enable the oxidation of LiO, even though LiO is electrochemically isolated. This system promotes the oxidation of LiO without parasitic reactions attributed to electrochemical charging and reduces the charging time.