Researchers at the University of Science and Technology Beijing, with colleagues at Beijing Institute of Technology, have demonstrated the potential of rechargeable tellurium (Te) nanowire positive electrodes to construct ultrahigh-capacity rechargeable tellurium-aluminum batteries (TABs).

In an open-access paper in the RSC journal Energy & Environmental Science, they report that the Te nanowires deliver an ultrahigh discharge capacity of ~1026 mA h g^-1 (with a specific current of 0.5 A g^-1) along with an initial 1.4 V discharge voltage—competitive to the record-setting energy density of documented aluminum-ion batteries (AIBs).

Electrochemical performance of TABs. (a) Cycling voltammetry profiles of various positive electrodes as marked. (b) The corresponding charge/discharge curves at 0.5 A g^-1 as marked. (c) The specific discharge capabilities of Type III TAB at various current densities as marked. (d) Cycling performance of the three types of TABs at specific current of 1 A g^-1. (e) Self-discharge behavior Cycling performance of Type III TAB at specific current of 2.0 A g^-1. (f) State-of-the-art diagram of showing the capacity versus voltage for the documented AIB systems. Note that the specific capacities are from TeNWs in each type via deducting the contribution of rGO and SWCNTs. Zhang et al.

Aluminum ion batteries (AIBs) have drawn significant attention for their favorable energy-to-price ratios and high energy density of aluminum and safe feature. However, there are still great challenges to meet the requirement of an appropriate rechargeable electrochemical system for next-generation energy storage. Among these bottlenecks, positive electrode materials with ultra-high specific capacity beyond graphitic materials are highly pursued, while either high electrical conductivity, sufficient voltage discharge plateau or stable cycling performance is a remaining issue in the most promising chalcogen or chalcogenide-based AIB positive electrode materials.

For substantially addressing these unexpected challenges, in this contribution, we developed a novel cell configuration to construct ultrahigh-capacity tellurium-aluminum batteries (TABs), where a reduced graphene oxide support and a functionalized carbon nanotube modified membrane were collectively employed to essentially promote the stable high-specific capacity. To prove such concept, the evolution mechanism of tellurium was fundamentally studied, which confirms the effectiveness of cell configuration for avoiding capacity loss from soluble tellurium chloroaluminate compounds upon both chemical dissolution and electrochemical conversion processes.

The understanding of the mechanism and cell configuration not only allows for fabricating stable non-graphitic TABs, but provides a versatile strategy for boosting developing advanced electrochemical storage devices using chalcogen or chalcogenide materials.

—Zhang et al.

Because of abundant natural resources, the higher energy density of aluminum (gravimetric: 2980 mA h g⁻¹, volumetric: 8063 mA h cm⁻³) and the elimination of unexpected safety risks, AIBs based on ionic liquid electrolytes are being considered as promising prototypes of safe energy storage devices beyond lithium-ion batteries.

However, the well-documented AIB positive electrode materials—including graphitic materials, oxides, sulfides, selenides, and sulfur—are still insufficient to deliver desirable energy density.

Cathodes from chalcogens (sulfur and selenium) have been shown to present more promising specific capacities (sulfur positive electrode: >1000 mA h g^-1) than chalcogenides (sulfides and selenides specifically), with the electrochemical mechanisms of redox reactions.

However S-Al and Se-Al batteries generally exhibit poor rechargeable performance because of the intrinsic electrically insulating feature of sulfur because of the intrinsic electrically insulating feature of sulfur and selenium.

To address this, the researchers used Te nanowires (TeNWs) as the cathode material to illustrate a novel prototype of Te-Al batteries (TABs) with ultra-high capacities. Te is intrinsically more electrically conductive among chalcogen (electrical conductivity: ~2 × 10^-4 S m⁻¹) and holds ultrahigh theoretical specific capacity (∼1260.27 mA h g^-1 and discharge voltage plateau at ∼1.5 V).

Resources

• Xuefeng Zhang, Shuqiang Jiao, Jiguo Tu, Weili Song, Xiang Xiao, Shijie Li, Mingyong Wang, Haiping Lei, Donghua Tian, Hao-Sen Chen and Daining Fang (2019) “Rechargeable Ultrahigh-capacity Tellurium-Aluminum Batteries” Energy & Environmental Science doi: 10.1039/C9EE00862D