Flexible Metal–Air Batteries: Progress, Challenges, and Perspectives

Abstract

rigidity and bulk. Consequently, ideal flexible energy storage and conversion systems should be stable when undergoing frequent mechanical strain, such as bending, twisting, and other deformation modes on a long-term basis. In addition to the mechanical properties, security is paramount and cannot be ignored, especially under various deformation conditions.In response, much progress has been made to develop high-performance flexible energy storage and conversion systems in the past few years, for example, solar cells, [13][14][15][16][17][18][19][20] flexible chemical batteries, [21][22][23][24][25][26][27] and flexible supercapacitors, [28][29][30][31][32][33][34][35] to meet the aesthetic demands of flexible electronic. Among the various types of flexible energy storage and conversion systems, the lithium-ion battery is most widely used and recognized due to its relatively high energy density. Though the battery performance has been greatly improved compared with its first generation introduced by Sony, [36,37] the energy density still cannot satisfy the energy requirements of advanced electronic devices. Obviously, the development of lightweight, high-energy-density flexible energy storage and conversion systems for future flexible electronics is highly significant. Among the various energy storage and conversion systems, metal-air (metaloxygen) batteries have been identified as suitable candidates since the exhausted material (oxygen) is stored outside the battery. This endows these systems with high energy density and they could therefore meet the requirements of advanced electronic devices. [37][38][39][40] Different from the intercalation and conversion reactions of commercial lithium-ion batteries, metalair batteries are based on the oxygen-reduction reaction (ORR) and oxygen-evolution reaction (OER), and usually operate in an open system. Depending on the anode that is used, metal-air batteries can be divided into zinc-air, aluminum-air, lithiumair, potassium-air, sodium-air, and so on. The theoretical specific energies, volumetric energy densities, and nominal theoretical cell voltages of the various metal anodes in metal-air batteries are shown in Figure 1. [41][42][43][44] Due to the extreme sensitivity toward water, lithium-air, potassium-air, and sodium-air batteries are often operated nonaqueous systems, and therefore batteries can operate in a high voltage platform. Different from nonaqueous system, the magnesium, aluminum, zinc, and iron anodes are all compatible with aqueous electrolytes and have energy densities comparable to lithium-air batteries, and have also been widely investigated; here, we label them as aqueous systems. In addition, it should be noted that a hydrophobic protecting layer is also needed in the aqueous Flexible metal-air batteries, which are a promising candidate for implantation in wearable or rolling-up electronic devices, have attracted much attention recently due to their relatively high energy density. Various flexible metalair batteries have been developed recently, i...

In Situ CVD Derived Co–N–C Composite as Highly Efficient Cathode for Flexible Li–O2 Batteries

“…Simultaneously, the random deposition of discharge product would block the permeation path for oxygen and electrolyte within the cathode, resulting in serious decay in the capacity and cycling stability of the battery. All these above challenges limit the practical application of Li–O 2 batteries . Therefore, preparing an effective cathode with high bifunctional catalysts would be conductive to improving the performances of Li–O 2 battery.…”

Sodium‐Ion Hybrid Battery Combining an Anion‐Intercalation Cathode with an Adsorption‐Type Anode for Enhanced Rate and Cycling Performance

“…Exploiting rechargeable battery technologies with enhanced performance as well as low cost and environmental friendliness has become a global and urgent demand since the explosive growth of portable electronic devices, electric vehicles as well as large‐scale energy storage . Meanwhile, the limited and uneven distribution of lithium resource has stimulated extensive investigations of energy storage devices based on other abundant metal ions, such as Na + , K + , Al 3+ ,, etc.…”

The Recent Advance in Fiber‐Shaped Energy Storage Devices

“…As a result, the fiber-shaped lithium-air battery exhibited a cyclability of 100 cycles at 500 mAh g −1 (Figure 5b). [61] A waterproof polyethylene (PE) film was introduced to the battery system as well as a redox mediator LiI through the combination of the PE film and LiI, [65] the parasitic conversion of reaction product Li 2 O 2 to electrochemically inert Li 2 CO 3 was retarded dramatically. [64] To achieve a more stable cyclability in fiber-shaped Li-air batteries, efforts have been devoted to developing novel electrolyte and packaging technologies.…”