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• A flexible aqueous Al-ion battery was reported for the first time. • The flexible Al-ion battery exhibits exceptional flexibility and safety. • The Al-ion battery delivers excellent electrochemical cycling stability. • This work paves the way for Al-ion battery application in wearable electronics. With the fast development of flexible and wearable electronics, the design of secondary energy storage system based on aqueous metal ion battery with outstanding flexibility, safety and low cost is critical for their practical application. As low-cost alternatives to lithium ion battery, multivalent metal ion technologies including Mg2+, Zn2+, Ca2+, and Al3+ are investigated increasingly in the past few years. The investigation based on Al-ion chemistry is also underway considering the aluminum's advantages of natural abundance, small ion size together with three-electron-redox properties. Herein, a flexible aqueous Al-ion battery is successfully fabricated for the first time with copper hexacyanoferrate cathode and polypyrrole (PPy) coated MoO 3 anode sandwiched by gel electrolyte. The as-assembled Al-ion battery based on intercalation chemistry exhibits an excellent cycling stability of 83.2% capacity retention after 100 cycles and good rate capability benefiting from the conductive PPy coating layer on MoO 3 anode. Besides, the battery demonstrates impressive flexibility and safety to sustain various deformations and mechanical abuse including bending, squeezing, folding, twisting as well as arbitrary drilling and tailoring into any desired shapes. Obviously, the flexible aqueous Al-ion battery developed in this study paves the way of multivalent metal ion battery as energy storage device towards various wearable electronics. [ABSTRACT FROM AUTHOR]

The rechargeable Lithium-Sulfur battery has been regarded as a promising candidate for the next generation energy storage devices owing to its high energy density, low cost and environment friendliness. The further development of Li-S battery, however, is still hindered by capacity decay and kinetics sluggish caused by the poor electrochemical activity and polysulfide shuttle effect. Herein, a nitrogen-doped porous carbon framework is synthesized by a facial strategy, delivering large special surface area and narrow pore size distribution. As a result, the composited cathode with sulfur loading of 62% shows an excellent rate performance and extreme cycling stability (100 cycles at 1.0 C and 457 mAh g −1 after 500 cycles at 2.0 C), which demonstrates that the N-doped porous carbon host can effectively improve the transport of electron and ion, entrap the dissolved polysulfide, thus improving the electrochemical performance significantly in rate performance and cycle stability. [ABSTRACT FROM AUTHOR]