High-Energy Density Aqueous Zinc–Iodine Batteries with Ultra-long Cycle Life Enabled by the ZnI₂ Additive

Abstract

Aqueous zinc−iodine batteries, featuring high energy density, safety, and cost-effectiveness, have been regarded as a promising energy storage system. Nevertheless, poor cycling stability and dissolution of iodine/polyiodide have greatly limited the development of zinc−iodine batteries. Here, iodine encapsulated by hierarchical porous carbon is employed as a positive material to assemble high-performance zinc−iodine batteries. Meanwhile, the utilization of the ZnI 2 additive in the electrolyte can enhance the capacity and cycling stability of as-assembled devices because the existence of polyiodide (I 3 − and I 5 − ) can effectively inhibit the dissolution of iodine. Thanks to the high conductivity and interconnected structure of the prepared carbon material, the asassembled zinc−iodine batteries deliver an excellent specific capacity of 360.6 mA h g −1 at 0.5 C, a superb durability (∼98.4% retention of the initial capacity at a high density of 50 C after 35,000 cycles), and an ultra-high energy/power density of 422.6 W h kg −1 /21.6 kW kg −1 . Significantly, the mechanism of the constructed device was investigated by ex-situ Raman and ex-situ X-ray diffraction. Besides, when coupling carbon@I 2 electrodes with the hydrogel electrolyte to assemble quasi-solid-state zinc−iodine batteries, the as-built device can well service for an electronic clock.

Development of long lifespan high-energy aqueous organic||iodine rechargeable batteries

“…Major success has been achieved in the development of various aqueous metal||I 2 batteries, e.g., Fe||I 2 16 , Al||I 2 17 and Zn||I 2 3 , 5 , 6 , 18 – 24 . However, these batteries are affected by the detrimental (electro)chemical behavior of the metal electrode upon cycling 3 – 6 , 12 – 21 , 25 . The dendrite growth and corrosion of the metal anodes cause rapid attenuation of the capacity and short circuit; the iodine anionic species lead to the formation of electrochemically inactive complexes with the metal anode, which induces the irreversibility of the I 2 cathode and limited lifespan, similar to the shuttle effect in lithium-sulfur batteries 3 , 4 , 26 .…”

Aqueous organic anode//iodine cascadable battery with ultra-long lifespan, high energy and power density

“…2d). Impressively, the voltage plateau of the PTCDI//I 2 full cell is of considerable superiority to that of all reported aqueous rechargeable Zn//I 2 , 3,5,6,[18][19][20][21]47 Fe//I 2 16 , Al//I 2 , 17 H 2 //I 2 , 48 and most aqueous rechargeable K + full battery systems (ARKFBs), [38][39][40][41][42] making it a promising prospect for high-energy output (Fig. 2e).…”

“…Fe//I 2 , 16 Al//I 2 17 and Zn//I 2 . 3,5,6,[18][19][20][21][22][23][24] However, the intrinsic disadvantages of these batteries have also been recognized. 3−6, 12−21, 25 The inevitable dendrite growth and corrosion of the metal anodes cause rapid attenuation of capacity and short circuit; the leak-out iodine anionic species lead to formation of electrochemically inactive complexes with the metal anode, which induces the irreversibility of I 2 cathode and limited lifespan, similar to the shuttle effect in lithium-sulfur batteries.…”

“…3,4,26 To address these issues, enormous efforts have been dovoted to modifying the metal anode and anchoring iodine species onto the cathode rmly, 5,6,12,14,16,27,28 leading to signi cant improvement. The best results obtained from the developed aqueous metal//I 2 batteries are 35000 cycles at 10.55 A g − 1 , 23000 cycles at 6 A g − 1 , 6000 cycles at 1.92 A g − 1 for cycling, 6, 18, 21 109100 W kg − 1 at 179 Wh kg − 1 and 410 Wh kg − 1 at 110 W kg − 1 for Ragone performance, 20,21 and 140 mAh g − 1 at 21 A g − 1 and 419 mAh g − 1 at 2 A g − 1 for rate performance. 3,21 However, it remains highly challenging to substantially boost the performance of metal//I 2 batteries.…”

“…The best results obtained from the developed aqueous metal//I 2 batteries are 35000 cycles at 10.55 A g − 1 , 23000 cycles at 6 A g − 1 , 6000 cycles at 1.92 A g − 1 for cycling, 6, 18, 21 109100 W kg − 1 at 179 Wh kg − 1 and 410 Wh kg − 1 at 110 W kg − 1 for Ragone performance, 20,21 and 140 mAh g − 1 at 21 A g − 1 and 419 mAh g − 1 at 2 A g − 1 for rate performance. 3,21 However, it remains highly challenging to substantially boost the performance of metal//I 2 batteries. A novel alternative system has been proposed recently, i.e.…”