Few‐Atomic‐Layered Co‐Doped BiOBr Nanosheet: Free‐Standing Anode with Ultrahigh Mass Loading for “Rocking Chair” Zinc‐Ion Battery

Abstract

Insertion host materials are considered as a candidate to replace metallic Zn anode. However, the high mass loading anode with good electrochemical performances is reported rarely. Herein, a few‐atomic‐layered Co‐doped BiOBr nanosheet (Co‐UTBiOBr) is prepared via one‐step hydrothermal method and a free‐standing flexible electrode consisting of Co‐UTBiOBr and CNTs is designed. Ultrathin nanosheet (3 atomic layers) and CNTs accelerate Zn2+ and electron transfer respectively. The Co‐doping is conducive to the reduced Zn2+ diffusion barrier, the improved volume expansion after Zn2+ intercalation, and the enhanced electronic conductivity of BiOBr, verified by experimental and theoretical studies. An insertion‐conversion mechanism is proposed according to ex situ characterizations. Benefiting from many advantages, Co‐UTBiOBr displays a high capacity of 150 mAh g−1 at 0.1 A g−1 and a long‐term cyclic life with ≈100% capacity attention over 3000 cycles at 1 A g−1. Remarkably, excellent electrochemical performances are maintained even at an ultrahigh mass loading of 15 mg cm−2. Co‐UTBiOBr//MnO2 “rocking chair” zinc‐ion battery exhibits a stable capacity of ≈130 mAh g−1 at 0.2 A g−1 during cyclic test and its flexible quasi‐solid‐state battery shows outstanding stability under various bending states. This work provides a new idea for designing high mass loading anode.

Challenges and Strategies in the Development of Zinc‐Ion Batteries

“…Long et al developed the use of a three-atomic layer thick Co-doped BrOBr nanosheet (Co-UTBiOBr) with carbon nanotubes as a free-standing flexible electrode. [127] While improving the electrical conductivity of the active material and lowering the diffusion barrier of Zn 2+ , it was also able to prevent the formation of dendrites. Thus, for a Co-UTBiOBr//MnO 2 battery, a stable capacity of ≈130 mA h g −1 at 0.2 A g −1 was reported.…”

Boosting the Proton Intercalation via Crystal Plane Optimization of TiS2 for Cycling‐Stable Aqueous Zn‐Ion Batteries

“…[12] Layered materials are suitable for Zn 2+ storage due to their larger interlayer spacing, formed by stacking 2D layers together through weak van der Waals interactions. Several nonzinc metal anode layered materials have already been explored for aqueous zincion batteries, such as Ti-based materials (TiS 2 , [13][14][15] TiSe 2 [16] ), Mo-based materials (MoO 2 , [17] 𝛼-MoO 3 , [18] h-MoO 3 [19] ), W-based materials (WO 3 [20,21] ) and Bibased materials (BiOCl, [22] BiOBr, [23] Bi 2 O 2 CO 3 [24] ), demonstrating significant application potential in AZIBs. However, the development of an "intercalation-type" anode in aqueous zinc ion batteries is still in its early stages and faces two major obstacles.…”

Reliable lateral Zn deposition along (002) plane by oxidized PAN separator for zinc-ion batteries

“…At present, the most commonly used separator in the Zn battery is glass ber (GF) lter paper. [27][28][29][30] However, due to the shortcomings of GF separator, such as large and uneven pores, low mechanical strength and fragility, Zn dendrites are particularly easy to grow freely, puncturing the separator and resulting in short circuit. [31][32][33] Therefore, a dual function separator which is capable to regulate Zn deposition along (002) plane and separates anode and cathode could provide a durable dendrite suppression effect AZIBs.…”