Two-dimensional boron nitride as a sulfur fixer for high performance rechargeable aluminum-sulfur batteries

Kaiqiang Zhang,Tae Hyung Lee,Joo Hwan Cha,Mohammadreza Shokouhimehr,Ji-Won Choi,Ho Won Jang,Rajender S Varma

doi:10.1038/s41598-019-50080-9

Abstract

Aluminum-ion batteries (AIBs) are regarded as promising candidates for post-lithium-ion batteries due to their lack of flammability and electrochemical performance comparable to other metal-ion batteries. The lack of suitable cathode materials, however, has hindered the development of high-performing AIBs. Sulfur is a cost-efficient material, having distinguished electrochemical properties, and is considered an attractive cathode material for AIBs. Several pioneering reports have shown that aluminum-sulfur batteries (ASBs) exhibit superior electrochemical capacity over other cathode materials for AIBs. However, a rapid decay in the capacity is a huge barrier for their practical applications. Here, we have demonstrated systematically for the first time that the two-dimensional layered materials (e.g. MoS2, WS2, and BN) can serve as fixers of S and sulfide compounds during repeated charge/discharge processes; BN/S/C displays the highest capacity of 532 mAh g−1 (at a current density of 100 mA g−1) compared with the current state-of-the-art cathode material for AIBs. Further, we could improve the life-span of ASBs to an unprecedented 300 cycles with a high Coulombic efficiency of 94.3%; discharge plateaus at ~1.15 V vs. AlCl4−/Al was clearly observed during repeated charge/discharge cycling. We believe that this work opens up a new method for achieving high-performing ASBs.

Highlights

Aluminum-ion batteries (AIBs) are considered one of the best potential alternatives to lithium-ion batteries, due in part to Al being one of the most common elements in the Earth’s crust, together with its high safety and a higher reduction potential (−1.76 V versus a standard hydrogen electrode)[1]
The representative sulfur decorated boron nitride (BN) is inserted as a cathode of an aluminum-sulfur batteries (ASBs)
We demonstrate three types of emerging layered materials (MoS2, WS2, and BN, Supplementary Fig. S1) as hosts to fix sulfur-active materials

Summary

Introduction

Aluminum-ion batteries (AIBs) are considered one of the best potential alternatives to lithium-ion batteries, due in part to Al being one of the most common elements in the Earth’s crust, together with its high safety (can be directly inserted as an anode) and a higher reduction potential (−1.76 V versus a standard hydrogen electrode)[1]. The active sites on surfaces of two-dimensional materials may adsorb elemental sulfur and polysulfide compounds to preserve the electrochemical capacities of ASBs and improve the life-span by addressing polysulfide dissolution. This strategy apparently benefits from the synergetic effect between WS2 nanosheets and carbon nanotube/reduced graphene oxide scaffold networks and the three dimensional ordered porous structures[39] Motivated by these advanced results, we demonstrate here the effect of both S-containing (MoS2 and WS2) and S-free (BN) layered materials on preserving electrochemical capacities during repeated charge/discharge cycling of ASBs. The incorporation of ball-milled BN/S/C, MoS2/S/C, and WS2/S/C as cathode materials, respectively, demonstrates a long-term stability and the highest capacity of BN/S/C among the reported cathode materials for AIBs

Methods

Results

Conclusion