Flat Monolayer Graphene Cathodes for Li–Oxygen Microbatteries

Abstract

Miniature batteries can accelerate the development of mobile electronics by providing sufficient energy to power small devices. Typical microbatteries commonly use thin-film inorganic electrodes based on Li-ion insertion reaction. However, they rely on the complicated thin-film synthesis method of inorganics containing many elements. Graphene, one atomic layer thick carbon sheet, has diverse physical and chemical properties and is compatible with conventional micron-scale device fabrication. Here, we study the use of chemical vapor deposition (CVD) grown monolayer graphene in a two-dimensional configuration, as a future Li−oxygen microbattery cathode. By maximizing the dissolution of discharge intermediates, we obtain 2610 Ah/g graphene of capacity corresponding to 20% higher areal cathode energy density and 2.7 times higher cathode specific energy than that can be derived from the same volume or mass of conventional Li-ion battery cathode material. Furthermore, a clear observation on the discharge reaction on composite electrodes and their role in the charging reaction was made, thanks to the two-dimensional monolayer graphene Li−oxygen battery cathode. We demonstrate an easy integration of two-dimensional CVD graphene cathode into microscale devices by simply transferring or coating the target device substrate with flexible graphene layers. The ability to integrate and use monolayer graphene on arbitrary device substrates as well as precise control over a chemical derivation of the carbon interface can have a radical impact on future energy-storage devices.

Miniaturized Energy Storage Devices Based on Two‐Dimensional Materials

“…[29,76,77] Oh et al reported the use of monolayer graphene grown by means of CVD as af uture lithium-oxygen MB cathode. [78] Ac apacity of 0.088 mAh cm À2 ,c orresponding to an arealc athode energy density of 20 %h igher, was achieved, which was 2.7fold highert han that of conventional LIB cathode materials with the same volumeo rm ass. Additionally,t hey also showed af acile integrationo f2 DC VD graphene into microdevices by transferring them onto desired substrates, such as silicon, glass, and polymers.…”

“…Oh et al. reported the use of monolayer graphene grown by means of CVD as a future lithium–oxygen MB cathode . A capacity of 0.088 mAh cm −2 , corresponding to an areal cathode energy density of 20 % higher, was achieved, which was 2.7‐fold higher than that of conventional LIB cathode materials with the same volume or mass.…”

Recent Advances in High‐Performance Microbatteries: Construction, Application, and Perspective

“…And when it comes to the miniaturized one, some techniques came in handy. Take Li‐O 2 MB as an example, a flat monolayer graphene cathode (less than 1 nm) fabricated by chemical vapor deposition was reported by Oh et al [ 92 ] Commercial substrate such as wafer or stainless steel exhibited satisfactory performance, and such monolayer design in 2D configuration offered a good observation platform for monitoring the growth of Li 2 O 2 , thus the miniaturized design suited the requirements of catalytic effect (Figure 5d,e).…”

Graphene Materials for Miniaturized Energy Harvest and Storage Devices

“…Apart from Li ions microbatteries, Dahyun et al [ 80 ] reported a Li–oxygen microbattery by using flat monolayer graphene as cathode and Li metal as anode (Figure 5h). Compared with traditional lithium‐ion battery cathode materials of the same volume or mass, the areal capacity was up to 2610 Ah g −1 , the cathode areal energy density and specific energy are increased by 20% and 2.7 times, respectively (Figure 5i).…”