New Insight in Understanding Oxygen Reduction and Evolution in Solid-State Lithium–Oxygen Batteries Using an in Situ Environmental Scanning Electron Microscope

Abstract

Via designing a facile microscale all-solid-state lithium-oxygen battery system constructed in an environmental scanning electron microscope, direct visualization of discharge and charge processes of the lithium-oxygen battery is achieved. Different morphologies of the discharge product are observed, including a sphere, conformal film, and red-blood-cell-like shape, with a particle size up to 1.5 μm; whereas upon charge, the decomposition initiates at their surface and continues along a certain direction, instead of from the contact point at the electrode. These new findings indicate that the electron and lithium ion conductivities of Li2O2 could support the growth and decomposition of the discharge product in our system. In addition, our results indicate that various morphologies of Li2O2 arise from the different current density and surface chemistry of CNT, and the growth and decomposition of the particle are related to the uneven distribution of the ionic and electronic conductivities of Li2O2.

Flexible binder-free graphene paper cathodes for high-performance Li-O2 batteries

“…4F and 1C). This observation of the morphology of the discharge products and its growth pattern in accordance with the discharge/charge cycle was consistent with others [17,27,55,56]. The average size of the discharge products during discharge and charge are summarized in Table S2 within the Supporting Information.…”

Rechargeable Solid‐State Li–Air and Li–S Batteries: Materials, Construction, and Challenges

“…Similarly, Zheng et al constructed an SSLAB that consisted of super-aligned CNT (SACNT), native Li 2 O layer electrolyte, and Li anode in an environmental SEM. [115] Their results showed that some discharge products with sizes ranging from 500 nm to 1 µm preferred to grow on CNT-SE-oxygen three-phase interface, while smaller discharge products tended to grow along the CNT. The SEM images in Figure 8 clearly stated that the Li 2 O 2 particle grew on the solid electrolyte-CNT-oxygen triple phase interface during discharge and that the electronic and ionic conductivities of Li 2 O 2 could support this growth.…”

Li 2 O 2 oxidation: the charging reaction in the aprotic Li-O 2 batteries

“…Reprinted with permission from Ref. [32]. Copyright (2014) American Chemical Society The gray shaded region indicates the target conductivity needed to meet performance requirements, as discussed in the text; b proposed two-stage recharge mechanism for a Li-air cell.…”

“…This result is consistent with that of Gerbig et al [33], who experimentally proved that the electronic conduction (*10 -12 S/cm) of bulk Li 2 O 2 was less than its ionic conductivity (*10 -10 S/cm). But Zheng et al [32] drew a different conclusion based on an in situ environmental scanning electron microscope (SEM) of a solid-state Li-O 2 battery. They argued that the oxidation process initiated at the surface of Li 2 O 2 , not at the electrode/Li 2 O 2 or electrolyte/Li 2 O 2 interface (Fig.…”

“…Reproduced from Ref. [25] with permission of The Royal Society of Chemistry work [32], Li 2 O 2 was in situ generated by a microscale allsolid-state Li-O 2 battery built in an environmental SEM. This varied conditions resulted in the different morphology, surface property and charge transport of Li 2 O 2 , which in turn impact the following oxidation process.…”