An artificial interphase enables reversible magnesium chemistry in carbonate electrolytes

Abstract

Magnesium-based batteries possess potential advantages over their lithium counterparts. However, reversible Mg chemistry requires a thermodynamically stable electrolyte at low potential, which is usually achieved with corrosive components and at the expense of stability against oxidation. In lithium-ion batteries the conflict between the cathodic and anodic stabilities of the electrolytes is resolved by forming an anode interphase that shields the electrolyte from being reduced. This strategy cannot be applied to Mg batteries because divalent Mg cannot penetrate such interphases. Here, we engineer an artificial Mg-conductive interphase on the Mg anode surface, which successfully decouples the anodic and cathodic requirements for electrolytes and demonstrate highly reversible Mg chemistry in oxidation-resistant electrolytes. The artificial interphase enables the reversible cycling of a Mg/VO full-cell in the water-containing, carbonate-based electrolyte. This approach provides a new avenue not only for Mg but also for other multivalent-cation batteries facing the same problems, taking a step towards their use in energy-storage applications.

Mg Cathode Materials and Electrolytes for Rechargeable Mg Batteries: A Review

“…Another surface modification method showed that by engineering a conductive layer on the Mg anode, a Mg cell can be constructed with a V 2 O 5 cathode and Mg[NTf 2 ] 2 electrolyte, even in the presence of H 2 O. This work has addressed the H 2 O passivating issue while maintaining the charge shielding effect of H 2 O with respect to Mg 2+ that is significant on the cathode . In other work, Chen et al.…”

“…Various modification methods to Mg anodes have been developed to diminish the influence of the passivation layer at the Mg electrode interface . It has been demonstrated that after surface treatment with Ti[NTf 2 ] 2 Cl 2 , the Mg anode was compatible with Mg[TFSI] 2 /DME/G2 based electrolytes.…”

Halide‐Based Materials and Chemistry for Rechargeable Batteries

“…When this electrolyte was used in the Mg/V 2 O 5 electrode system, a very low discharge capacity was achieved as a result of the high interfacial resistance at the Mg anode . One approach to achieve the efficient use of carbonate solvents was developed by Son et al., who engineered an artificial Mg 2+ ‐conductive interphase that consisted of the thermally cyclized polyacrylonitrile and Mg triflate (Mg(CF 3 SO 3 ) 2 ) on the Mg anode surface. The as‐prepared electronic‐insulating interphase with a thickness of about 100 nm can prevent the electrochemical reduction of the electrolytes, shows good compatibility with water, and allows Mg 2+ transfer (ionic conductivity: 1.19×10 −6 S cm −1 ).…”

Electrolytes for Batteries with Earth‐Abundant Metal Anodes

“…[47] As an analoguet ot he lithium-sulfur battery,m agnesiumsulfur battery was also proposed to achieveahigher full-cell energy density.T he magnesium-sulfur system can theoretically achieve ac apacity of 957 mA h À1 g À1 with ac ell voltage of 1.77 V. One of the most seriousp roblemst hat remainf or the magnesium-sulfur system is the electrolyte. [52] In their report, the overpotential of bare magnesium metal rapidly increased in 0.5 m MgTFSI/acrylonitrile (AN) electrolyte, whereas coated magnesium remained stable for over 1000 cycles. Muldoone tal.…”