“Carbon‐Glue” Enabled Highly Stable and High‐Rate Fe₃O₄ Nanorod Anode for Flexible Quasi‐Solid‐State Nickel–Copper//Iron Alkaline Battery

Abstract

The practical application of iron oxide anode in rechargeable alkaline batteries is greatly hampered by the poor electrochemical stability and low rate capability. In addition, flexible solid‐state iron anode‐based rechargeable batteries with distinctive counter electrode coupling are quite lacking. Herein, an interesting “carbon glue” penetration strategy toward Fe3O4 nanorod film anode is proposed. This design not only immobilizes the nanorods and maintains strong adhesion with the current collector but also ensures continuous electrically conductive pathway, resulting in dramatically increased stability (≈99% capacity retention after 1000 cycles) and excellent rate performance (1.2 min charging with ≈70.6% initial capacity kept). By pairing with a new‐type Ni0.49Cu0.51O nanowire array cathode, a unique 1.2 V flexible rechargeable nickel–copper//iron alkaline battery is further assembled, which stores energy based on redox electrochemistry of transition metal ions. It delivers high volumetric energy and power densities (7.21 mWh cm−3; 299.30 mW cm−3), and demonstrates outstanding stability up to 5000 cycles. In particular, with the utilization of quasi‐solid‐state electrolyte, the device still maintains good performance upon substantially bending and twisting. This work presents a new concept to design high stability iron anode‐based alkaline batteries and further pushes forward the development of emerging flexible energy storage systems.

Electrolyte Concentration Regulation Boosting Zinc Storage Stability of High-Capacity K0.486V2O5 Cathode for Bendable Quasi-Solid-State Zinc Ion Batteries

“…5i. The maximum volumetric energy density of 8.38 mWh cm −3 is achieved, much better than those of flexible Ni//Fe batteries (3.34 mWh cm −3 at 18.67 mW cm −3 ) [45] and thin film Li battery [46], and comparable with previous flexible Ni//Zn batteries (7.76 mWh cm −3 at 11 mW cm −3 ) [1]. It is noticed that the average operating voltage (~ 0.75 V) of our device is lower than those of previous alkaline batteries (given in Fig.…”

Surface and Interface Engineering of Nanoarrays toward Advanced Electrodes and Electrochemical Energy Storage Devices

“…[63] The coating amount, particularly the carbonization temperature, is crucial to the features of the carbon layer. Using a relatively high carbonaceous precursor concentration and with the temperature controlled at 750 °C, "carbon glue" (CG) was generated on the Fe 3 O 4 NAs surface, [64] as illustrated in Figure 5b. The resulting carbon infiltrated the interspacing of individual NRs, forming a 3D continuous glue-like architecture tightly immobilizing the NAs, giving rise to excellent cycling life (≈99% capacity retention after 1000 cycles).…”

“…Benefiting from the interface optimization, the Cu@Si@Al 2 O 3 NAs retained a high capacity of 1560 mA h g −1 after 100 cycles. In another example, [64] Copyright 2018, Wiley-VCH. c,d) TEM image of the Fe 3 O 4 @TiO 2 hybrid NR arrays.…”

Recent advances in materials and device technologies for aqueous hybrid supercapacitors

“…The rate performance of iron oxide anodes in alkaline electrolyte was also affected by the formation of iron hydroxide passivation layer. To address the abovementioned problems, our group has made continuous efforts to modify the surface of iron oxides with carbon or oxide layer, for the purpose of restricting the variation in inner volume, which can enhance the electronic conductivity or alleviate hydrogen evolution [104][105][106]. In detail, a "carbon shell protection" solution and an interesting "carbon glue" penetration strategy (Fig.…”