Although sulfur(s) has been extensively studied as a positive electrode for batteries, it can be used as a low-potential negative electrode by altering the charge carrier in the electrolyte.
Here it is, Qiao Shizhang's team at the University of AdelaideA highly reversible S-anode is reported that completely converts from S80 to S2- in a static aqueous S-i2 cell by using Na+ as a charge carrier. The negative electrode has -0Low potential of 5 V (relative to standard hydrogen electrodes) and close to theoretical capacity of 1404 mA h g-1. Importantly, it shows significant advantages over zinc anodes, which are widely used in aqueous media, by avoiding dendrite formation and H2 release. To suppress the "shuttle effect" faced by the S and I2 electrodes, this work proposes a scalable sulfonated polysulfone (SPSF) membrane that is superior to commercial Nafion™ in terms of cost and environmental friendliness. Due to its ultra-high selectivity for polysulfide iodide, SPSF cells exhibit excellent cycling stability. Even at 100% depth of discharge (DOD), the battery exhibited up to 500 after 87 cyclesThe capacity retention rate of 6% is better than the capacity of 3 under the same conditions1% ZN-i2 battery.
Figure 1Electrochemical and practical challenges of sulfur(s) anodes, as well as the synthesis and characterization of membranes
In conclusion, the work proposes S as a promising anode material and demonstrates its potential in S-i2 cells by designing an SPSF membrane that effectively reduces polysulfide iodide crossovers. The discharged capacity of the assembled battery is 1404 mA h g-1, which is close to theory and better than N117 and GF, which are manifested as 724 and 127 mA h g-1, respectively. The effectiveness of SPSF membranes in inhibition of polysulfides and polyiodides was confirmed by UV-visible in situ during electrode operation.
It is worth noting that SPSF-based batteries are available even at a record 8 C (134 A g-1) with a capacity retention rate of 99 per cycle95%。The pouch battery with a large mass load of 37 mg cm-2 has high stability, with a capacity retention rate of 84 for 200 cycles9%。More importantly, the superiority of the S anode over the Zn anode is emphasized. The in-situ dems confirmed that the S negative electrode exhibited a significantly higher reduction potential than the HER, while galvanizing was prone to induce unwanted gas release. Compared to the metal zinc anode, the S anode has 100% utilization rate and cycle stability, which contributes to high energy density output.
Figure 2Battery performance
high-reversibility sulfur anode for advanced aqueous battery,advanced materials2023 doi: 10.1002/adma.202309038