The current boom of safe and renewable energy storage systems is driving the recent renaissance of Zn‐ion batteries. However, the notorious tip‐induced dendrite growth on the Zn anode restricts their further application. Herein, the first demonstration of constructing a flexible 3D carbon nanotube (CNT) framework as a Zn plating/stripping scaffold is constituted to achieve a dendrite‐free robust Zn anode. Compared with the pristine deposited Zn electrode, the as‐fabricated Zn/CNT anode affords lower Zn nucleation overpotential and more homogeneously distributed electric field, thus being more favorable for highly reversible Zn plating/stripping with satisfactory Coulombic efficiency rather than the formation of Zn dendrites or other byproducts. As a consequence, a highly flexible symmetric cell based on the Zn/CNT anode presents appreciably low voltage hysteresis (27 mV) and superior cycling stability (200 h) with dendrite‐free morphology at 2 mA cm−2, accompanied by a high depth of discharge (DOD) of 28%. Such distinct performance overmatches most of recently reported Zn‐based anodes. Additionally, this efficient rechargeability of the Zn/CNT anode also enables a substantially stable Zn//MnO2 battery with 88.7% capacity retention after 1000 cycles and remarkable mechanical flexibility.

Oxygen-deficient α-Fe2 O3 nanorods with outstanding capacitive performance are developed and demonstrated as novel negative electrodes for flexible asymmetric supercapacitors. The asymmetric-supercapacitor device based on the oxygen-deficient α-Fe2 O3 nanorod negative electrode and a MnO2 positive electrode achieves a maximum energy density of 0.41 mW·h/cm(3) ; it is also capable of charging a mobile phone and powering a light-emitting diode indicator.

The development of high-capacity, Earth-abundant, and stable cathode materials for robust aqueous Zn-ion batteries is an ongoing challenge. Herein, ultrathin nickel cobaltite (NiCo O ) nanosheets with enriched oxygen vacancies and surface phosphate ions (P-NiCo O ) are reported as a new high-energy-density cathode material for rechargeable Zn-ion batteries. The oxygen-vacancy and surface phosphate-ion modulation are achieved by annealing the pristine NiCo O nanosheets using a simple phosphating process. Benefiting from the merits of substantially improved electrical conductivity and increased concentration of active sites, the optimized P-NiCo O nanosheet electrode delivers remarkable capacity (309.2 mAh g at 6.0 A g ) and extraordinary rate performance (64% capacity retention at 60.4 A g ). Moreover, based on the P-NiCo O cathode, our fabricated P-NiCo O //Zn battery presents an impressive specific capacity of 361.3 mAh g at the high current density of 3.0 A g in an alkaline electrolyte. Furthermore, extremely high energy density (616.5 Wh kg ) and power density (30.2 kW kg ) are also achieved, which outperforms most of the previously reported aqueous Zn-ion batteries. This ultrafast and high-energy aqueous Zn-ion battery is promising for widespread application to electric vehicles and intelligent devices.

Advanced flexible batteries with high energy density and long cycle life are an important research target. Herein, the first paradigm of a high-performance and stable flexible rechargeable quasi-solid-state Zn-MnO battery is constructed by engineering MnO electrodes and gel electrolyte. Benefiting from a poly(3,4-ethylenedioxythiophene) (PEDOT) buffer layer and a Mn -based neutral electrolyte, the fabricated Zn-MnO @PEDOT battery presents a remarkable capacity of 366.6 mA h g and good cycling performance (83.7% after 300 cycles) in aqueous electrolyte. More importantly, when using PVA/ZnCl /MnSO gel as electrolyte, the as-fabricated quasi-solid-state Zn-MnO @PEDOT battery remains highly rechargeable, maintaining more than 77.7% of its initial capacity and nearly 100% Coulombic efficiency after 300 cycles. Moreover, this flexible quasi-solid-state Zn-MnO battery achieves an admirable energy density of 504.9 W h kg (33.95 mW h cm ), together with a peak power density of 8.6 kW kg , substantially higher than most recently reported flexible energy-storage devices. With the merits of impressive energy density and durability, this highly flexible rechargeable Zn-MnO battery opens new opportunities for powering portable and wearable electronics.

the developing trend of modern electronic technologies, [6] and significant efforts have been devoted to transforming these energy storage systems to their light, flexible, small, and thin counterparts. [7] The flexible battery market is forecast to increase rapidly from $69.6 million in 2015 to $958.4 million in 2022. [8] Lithium-ion batteries (LIBs) historically and presently dominant the markets of rechargeablebattery for portable devices because of the lightness of lithium and high energy density of the battery systems. [9,10] Nonetheless, LIBs are marred by the high cost and the shortage of lithium resources. Moreover, the aprotic electrolytes used in LIBs are generally toxic and flammable. This fact causes great safety issues for LIBs, especially when they are used in wearable/implantable applications in close contact with human body. It is highly challenging to assemble flexible LIBs due to the requirement of a highly reliable protective packaging to avoid the electrolyte leakage and reconcile with the washing need of wearable devices in practical applications. [3] Moreover, due to the high barrier encapsulation, the volumetric performance would be severely restricted, especially when LIBs are miniaturized. In this context, it is highly desirable to prepare flexible "beyond Li-based" batteries with safe, low-cost, and eco-friendly aqueous electrolytes. [11] As alternatives for LIBs, multivalent ion battery technologies (Zn-ion battery, ZIB, Mg-ion battery, and Al-ion battery) are of high interest for electrochemical energy storage. In comparison with LIBs operating with single-electron transfer, multivalent ion batteries employ multielectron transfer during the charge/ discharge processes, thus delivering much higher volumetric energy densities. [12][13][14] Since the first utilization of Zn in batteries in 1799, [15] Zn metal has captured increasing attention as an ideal anode material. In earlier studies, Zn anodes were widely explored in many alkaline battery systems, such as alkaline zinc-MnO 2 batteries, [16] zinc-nickel batteries, [17][18][19][20] zinc-silver batteries, [21] and zinc-air batteries. [22][23][24] Zn metal is able to offering both high gravimetric and high volumetric capacities (820 and 5855 mAh cm −3 ). [25] Moreover, Zn has the merits of low cost, low-toxicity, abundance in earth crust (≈300 times higher than for lithium), environmental benignity, easily recyclable, and intrinsic safety. [14,26] These advantages directly drove the recent renaissance of Zn anode based batteries. [15] However, the use of corrosive alkaline electrolyte leads to the Zn-dendritic (sharp, needle-like metallic protrusions) growth [27,28] and soluble ZnO 2 2− formation on Zn anode, which poison the cathode and result in the rapid capacity To keep pace with the increasing pursuit of portable and wearable electronics, it is urgent to develop advanced flexible power supplies. In this context, Zn-ion batteries (ZIBs) have garnered increasing attention as favorable energy storage devices for flexible electronics, ...