Stable bismuth-antimony alloy cathode with a conversion-dissolution/deposition mechanism for high-performance zinc batteries

Although a large number of intercalation cathode materials for aqueous Zn batteries have been reported, limited intercalation capacity precludes achieving a higher energy density. Here we develop a high-performance aqueous Zn battery based on BiSb alloy (Bi0.5Sb0.5) using a high-concentrated strong-basic polyelectrolyte. We demonstrate that a conversion-dissolution/deposition electrochemical mechanism (BiSb <-> Bi + SbO2- <-> Bi + SbO3- <-> Bi2O3) through in situ X-ray diffraction (XRD), Raman, and ex-situ X-ray photoelectron spectrometry (XPS) characterizations with the help of density functional theory calculations. The BiSb cathode delivers large capacity of 512 mAh g(-1) at 0.3 Ag-1 and superior rate capability of 90 mAh g(-1) even at 20 Ag-1 , and long-term cyclability with capacity retentions of 184 mAh g(-1) after 600 cycles at 0.5 Ag-1 and 130 mAh g(-1) after 1300 cycles at 1 Ag-1. Remarkably, even at temperatures as low as -10 and -20 degrees C, capacities of 210 and 197 mAh g(-1) are reserved at 1 Ag-1 , respectively. Moreover, the prepared pouch Zn//BiSb battery delivers a high energy density of 303 Wh kg(BiSb)(-1) at 0.3 Ag-1. When coupled with a high concentration polyelectrolyte, the Zn/BiSb battery exhibits an excellent performance over a wide temperature range (-40 to 40 degrees C). Our research reveals the metal cathode is promising for Zn batteries to achieve a high performance with the unique mechanism and alloys can be an effective approach to stabilize metal electrodes for cycling.

Automated summary

A high-performance aqueous Zn battery using BiSb alloy cathode with a unique electrochemical mechanism has been developed, exhibiting large capacity, superior rate capability, and long-term cyclability. The research demonstrates the promising potential of metal cathodes and alloys for achieving high performance in Zn batteries.