Highly Efficient Sodium Storage in Iron Oxide Nanotube Arrays Enabled by Built‐In Electric Field

Abstract

High‐power sodium–ion batteries capable of charging and discharging rapidly and durably are eagerly demanded to replace current lithium–ion batteries. However, poor activity and instable cycling of common sodium anode materials represent a huge barrier for practical deployment. A smart design of ordered nanotube arrays of iron oxide (Fe2O3) is presented as efficient sodium anode, simply enabled by surface sulfurization. The resulted heterostructure of oxide and sulfide spontaneously develops a built‐in electric field, which reduces the activation energy and accelerates charge transport significantly. Benefiting from the synergy of ordered architecture and built‐in electric field, such arrays exhibit a large reversible capacity, a superior rate capability, and a high retention of 91% up to 200 cycles at a high rate of 5 A g−1, outperforming most reported iron oxide electrodes. Furthermore, full cells based on the Fe2O3 array anode and the Na0.67(Mn0.67Ni0.23Mg0.1)O2 cathode deliver a specific energy of 142 Wh kg−1 at a power density of 330 W kg−1 (based on both active electrodes), demonstrating a great potential in practical application. This material design may open a new door in engineering efficient anode based on earth‐abundant materials.

Photocatalysis‐Assisted Co3O4/g‐C3N4 p–n Junction All‐Solid‐State Supercapacitors: A Bridge between Energy Storage and Photocatalysis

“…Inspired by polarized photocatalytic materials, [25,26] constructing built-in electric field for accelerated charge separation is a new strategy to enhance the energy storage capability of electrode materials, [27] which has been mainly applied for promoting lithium, sodium, and aluminum ion storage, [28][29][30] for example, Li et al used the built-in electric field of sulfurized Fe 2 O 3 anode to reduce the activation energy and significantly improve the charge transfer kinetics in sodium batteries. [31] Given the p-type semiconductor feature of Co 3 O 4 , construction of p-n junction between Co 3 O 4 and g-C 3 N 4 may be an ideal solution to enhance the energy density of supercapacitor devices. In particular, p-n junction-based PIEC behavior and the fabrication of heterostructure-based PIEC device has not been realized so far.…”

Co‐Construction of Sulfur Vacancies and Heterojunctions in Tungsten Disulfide to Induce Fast Electronic/Ionic Diffusion Kinetics for Sodium‐Ion Batteries

“…[20] Guo et al [21] designed SnS/SnO 2 heterostructures with internal electric fields that shows an enhanced charge-transfer capability. Li et al [22] prepared an ordered nanotube arrays of Fe 2 O 3 simply enabled by surface sulfurization. The heterostructure of oxide and sulfide could spontaneously develop a built-in electric field, which significantly reduces the activation energy and accelerates charge transport.…”

Progress and Prospects of Transition Metal Sulfides for Sodium Storage

“…Moreover, the built-in electric field with an n → p direction could facilitate sodium ions in the heterostructure leading to a fast ion transport kinetics. The built-in electric field and matched energy band of the heterostructures provide the multi-component metal sulfides with better electronic conductivity and faster ion diffusion [59][60][61]. Constructing heterostructures with various transition metal sulfides can enhance the electrochemical activity and sodium storage performance [33].…”

“…is considered as one of the most promising cathode materials for SIFCs because of its superior electrochemical performance and good safety features resulting from the stable structure, high working voltage and good thermal stability [119]. Lin et al constructed h Digital photo of the SICF lighting a LED plate [59] a flexible pouch-type full cell by using as-prepared freestanding Co 9 S 8 @C/3DNCF anode and NVP/C cathode [87]. Figure 14b shows a high ICE of 90.2% and an outstanding capacity of 377.4 mAh g −1 of the SIFC at 0.5 A g −1 .…”