DMSO–Li₂O₂ Interface in the Rechargeable Li–O₂ Battery Cathode: Theoretical and Experimental Perspectives on Stability

Abstract

One of the greatest obstacles for the realization of the nonaqueous Li-O2 battery is finding a solvent that is chemically and electrochemically stable under cell operating conditions. Dimethyl sulfoxide (DMSO) is an attractive candidate for rechargeable Li-O2 battery studies; however, there is still significant controversy regarding its stability on the Li-O2 cathode surface. We performed multiple experiments (in situ XPS, FTIR, Raman, and XRD) which assess the stability of the DMSO-Li2O2 interface and report perspectives on previously published studies. Our electrochemical experiments show long-term stable cycling of a DMSO-based operating Li-O2 cell with a platinum@carbon nanotube core-shell cathode fabricated via atomic layer deposition, specifically with >45 cycles of 40 h of discharge per cycle. This work is complemented by density functional theory calculations of DMSO degradation pathways on Li2O2. Both experimental and theoretical evidence strongly suggests that DMSO is chemically and electrochemically stable on the surface of Li2O2 under the reported operating conditions.

Raman Spectroscopy in Lithium–Oxygen Battery Systems

“…LiOH, DMSO 2 and Li 2 SO 4 have also been proposed as products of superoxide attack on DMSO with support from FTIR and Raman spectroscopy (only LiOH for the latter) . A new report, however, suggests DMSO decomposition is unlikely in practical Li–O 2 cells . Despite the lack of clarity, we must accept that DMSO is not as stable an electrolyte solvent as once thought.…”

High‐Capacity and Long‐Cycle Lifetime Li−CO2/O2 Battery Based on Dandelion‐like NiCo2O4 Hollow Microspheres

“…With the rapidly increasing demand for new energy storage systems in recent years, Li−O 2 batteries have become a research focus due to their higher theoretical specific energy than state‐of‐the‐art Li‐ion batteries . However, many challenges remain to be solved, including their high polarization, poor cyclability and low rate capability.…”

“…With the rapidly increasing demand for new energy storage systems in recent years, LiÀ O 2 batteries have become a research focus due to their higher theoretical specific energy than stateof-the-art Li-ion batteries. [1][2][3][4][5] However, many challenges remain to be solved, including their high polarization, poor cyclability and low rate capability. The crucial barrier is the inhibition of O 2 * À , which causes inevitable decomposition of the electrolyte, oxidation of the carbon cathode and formation of byproducts such as Li 2 CO 3 , LiOH, Li acetate, etc.…”

Influence of Binders and Solvents on Stability of Ru/RuOx Nanoparticles on ITO Nanocrystals as Li–O2 Battery Cathodes

“…DMSO allowed prolonged cell cycling when paired with carbon‐free cathodes, but side‐products, mainly LiOH, were detected in some experiments with carbon‐based cathodes . The debate surrounding DMSO also includes comprehensive experimental and theoretical investigations that revealed the very good stability of DMSO on the Li 2 O 2 surface in the presence of platinum@carbon nanotube core–shell cathodes . Recently, however, researchers have achieved remarkable reductions in charging overpotential through the stable and reversible formation of a LiOH phase preferentially or through the use of redox mediators in the electrolytes, and these results point to alternative battery chemistries based on reversible, thermodynamically stable and electrochemically stable LiOH and LiO 2 phases instead of Li 2 O 2 .…”