Metal-Coated Polymer Fiber Mesh as an Ultralightweight Gas-Diffusible Current Collector for High-Energy-Density Rechargeable Lithium–Oxygen Batteries

Abstract

Lithium−oxygen batteries (LOBs) have received great attention as nextgeneration energy storage devices owing to their superior theoretical energy densities. Although there has been considerable technological progress in the field of LOBs, the development of gas diffusion layer materials at the positive oxygen electrode is limited despite their importance in providing an oxygen supply needed to achieve practical power densities. In the present study, we demonstrate the concept of a gas-diffusible current collector, which combines the functions of oxygen mass transport and electron transfer with minimal mass loading. To verify this concept, we fabricated a Ni-coated polymer fiber mesh and investigated its applicability in LOBs. LOB cells equipped with an ultralightweight gas-diffusible current collector exhibit a performance equivalent to that of cells equipped with conventional heavy components at 0.4 mA/cm 2 current density and 4.0 mAh/cm 2 areal capacity. We believe that the concept of an ultralightweight gasdiffusible current collector demonstrated in this study opens future directions in the search for metal−air batteries with high energy and power densities.

New Insights into Fundamental Processes and Physical Degradation Mechanisms in Rechargeable Lithium‐Oxygen Batteries Providing Suitably High Energy Densities

“…Using such a setup, the concept of a gas-diffusible current collector was recently demonstrated, which combines the functions of oxygen mass transport and electron transfer with minimal mass loading. [7] For the gas-diffusible current collector for high energy density LOB, the following three factors are crucial: (i) light weight, (ii) high electrical conductivity to function as an electron transport channel, and (iii) suitable structure for an oxygen transport channel. To verify this concept, nickel-coated polymer fiber meshes were fabricated, in which the PET fiber with diameter of 27 μm is fully covered with nickel with 0.5 μm thickness (Figure 2d-2g).…”

“…And then, oxygen gas further transports to inside of cell in the horizontal direction. Using such a setup, the concept of a gas‐diffusible current collector was recently demonstrated, which combines the functions of oxygen mass transport and electron transfer with minimal mass loading [7] . For the gas‐diffusible current collector for high energy density LOB, the following three factors are crucial: (i) light weight, (ii) high electrical conductivity to function as an electron transport channel, and (iii) suitable structure for an oxygen transport channel.…”

“…In contrast, an LOB designed to produce a high energy density may include a thin separator and have an electrode distance of less than 20 μm. Recent work using a three electrode setup was able to deconvolute the over‐potentials associated with the positive oxygen electrode and negative lithium metal electrode and demonstrated that deterioration of the latter was the main reason for the limited cycle lifespan of an LOB having a high energy density [7] . In addition, assessments using in situ mass spectrometry have established that the reaction efficiency of the lithium electrode decreases over time primarily because of the cross‐over of compounds such as H 2 O and CO 2 from the positive oxygen electrode side (Figure 3a).…”

Evaluation of performance metrics for high energy density rechargeable lithium–oxygen batteries

“…Actually, a recent study demonstrated the use of a gas-diffusible current collector that combines the functions of oxygen mass transport and electron transfer. 9 The application of such a novel concept for the practical design of LOBs may benefit from a detailed analysis of the cell performance at low E / C values.…”

Developments, Novel Concepts, and Challenges of Current Collectors: From Conventional Lithium Batteries to All‐Solid‐State Batteries

“…However, as the mature commercial Li‐ion batteries (LIBs) are approaching their maximum limit of energy density, there is a pressing need for new cell technologies that can meet the growing demands for energy density and power density in today's storage systems [5] . In addition to lithium metal batteries (LMBs) which are undergoing commercialization, advanced lithium‐sulfur batteries (LSBs), lithium‐air batteries (LABs), and anode‐free lithium batteries (AFLBs) have been developed [6–10] . The global market for lithium batteries is expected to experience sustained growth for a considerable period of time, while safety concerns mainly regarding the flammability of the organic liquid electrolytes currently in use have been frequently raised [11] .…”