A Pyrite Iron Disulfide Cathode with a Copper Current Collector for High‐Energy Reversible Magnesium‐Ion Storage

Abstract

Owing to its low cost, high theoretical capacity, and environmentally friendly characteristics, pyrite FeS2 demonstrates promise as a cathode material for high‐energy metal‐anode‐based rechargeable batteries. When it is used in a rechargeable magnesium battery (RMB), the electrode couple exhibits an extremely low theoretical volume change upon full discharge. However, its electrochemical Mg‐ion storage is considerably hindered by slow reaction kinetics. In this study, a high‐performance FeS2 cathode for RMBs using a copper current collector is reported, which is involved in cathode reactions via a reversible redox process between copper and cuprous sulfide. This phase transformation with the formation of copper nanowires during discharge activates the redox reactions of FeS2 via a two‐step and four‐electron Mg‐ion transfer that dominates the cathode reactions. As a result, the as‐prepared FeS2 nanomaterial cathode delivers a significantly enhanced reversible capacity of 679 mAh g−1 at 50 mA g−1. The corresponding energy density of 714 Wh kg−1 is superior to those of all previously reported metal chalcogenide cathodes in RMBs or hybrid batteries using a Mg metal anode. Notably, the as‐assembled FeS2–Mg battery can operate over 1000 cycles with a good capacity retention at 400 mA g−1.

A Se-Doped S@CMK3 Composite as a High-Performance Cathode for Magnesium–Sulfur Batteries with Mg2+/Li+ Hybrid Electrolytes

“…Cu is widely used in Mg–S batteries in the form of current collector or interlayer. , Because of the chemical interaction between Cu and S, the shuttle effect could be inhibited effectively . It is reported that the Cu current collector could be involved in the electrochemical reactions, enabling the transition of active materials and realizing the stability of the battery system . In this work, the effect of current collectors is investigated.…”

“…46 It is reported that the Cu current collector could be involved in the electrochemical reactions, enabling the transition of active materials and realizing the stability of the battery system. 47 In this work, the effect of current collectors is investigated. When employing aluminum foil-coated carbon as the current collector, the S 0.96 Se 0.04 @CMK3 cathode delivers low capacity and poor cycling performance in Figure S8 and the overcharging results from the severe shuttle effect.…”

TiVCTx MXene/Chalcogenide Heterostructure‐Based High‐Performance Magnesium‐Ion Battery as Flexible Integrated Units

“…As activation progresses, the electrolyte slowly penetrates the cathode and the wettability gradually increases, thus more cathode materials participate in the oxidation reaction. [7,24,25] The discharge capacity in the first cycle was ≈167 mAh g −1 , and did not show a voltage plateau. The voltage polarization was large in the first few cycles but decreased as the cycles increased.…”

“…S and Se, which possess multiple oxidation states, show weak Coulomb attraction to Mg by forming Mg-S or Mg-Se bonds that promote rapid magnesium ion reaction kinetics. [6] Therefore, transition metal chalcogenides such as CuS, [5] FeS 2 , [7] VS 2 , [8] NiCo 2 Se 4 , [9] and Ni 3 Se 4 [10] are considered promising as MIB hosts and are appropriate cathode materials for magnesium ion storage. Further investigation of high-performance cathode materials based on optimal structural design is an effective strategy in developing rechargeable magnesium batteries (RMBs).…”

Rational Design Strategy of Novel Energy Storage Systems: Toward High‐Performance Rechargeable Magnesium Batteries

“…[139] By controlling the intercalation chemistry using the Mg 2+ /Li + hybrid ion electrolyte, the battery exhibited a discharge capacity of 105 mAh g −1 at 10C and ultrafast diffusion kinetics with a high capacity retention of 93.6% at 20C and 87.5% at 30C. After the successful employment of Mo 6 S 8 cathode, transition metal dichalcogenides (TMDs) such as MoS 2 , [140] TiS 2 , [141] and FeS 2 [58] were also tried for MLHIBs with higher capacities (170-250 mAh g −1 ).…”