Electrolytes for Batteries with Earth‐Abundant Metal Anodes

Abstract

Earth-abundant metal anodes have become one of the hottest topics in recent years. As alternatives to lithium metals, earth-abundant metal anodes have significantly lower cost and higher energy density, but with unprecedented problems that cannot be solved by simply referring to experiences with lithium-metal anodes. The electrolytes for these anodes greatly influence the overall performance, such as Coulombic efficiency, stability, and even the availability to become an anode. In this Minireview, some excellent state-of-art works on the electrolytes of energy-storage systems with sodium-, potassium-, magnesium-, calcium-, and aluminum-metal anodes are concisely summarized. The performance of these systems is highlighted by the rational design of the electrolyte and electrolyte/electrode interface.

Recent Progress in the Electrolytes of Aqueous Zinc‐Ion Batteries

“…In addition, ac onversion reactionm echanism is also observed in the Zn/MnO 2 system with ZnSO 4 electrolyte. In this system, H + reactedw ith the a-MnO 2 to form MnOOH, whilet he OH-could react with the ZnSO 4 electrolyte to from Zn 4 SO 4 (OH) 6 ·x H 2 O. [13] As discussed above,t he electrolyte also plays as ignificant role in the electrochemical mechanismso fZ IBs.…”

“…Besides, in aqueous solution,Z n 2 + ions could be solvated to form Zn-(H 2 O) 6 2 + due to the enough H 2 Om olecules being available. And then, ad eprotonation process would occur and generate an acidic solutionw ith as eries of deprotonated monomeric species (e.g.,Z n-(H 2 O) 6 2 + ,Z n(OH) 2 or even ZnO). The general deprotonation process could be formulized as follows [Eq.…”

“…The formation of inactive Zn(OH) 2 or ZnO by-productsw ill degradet he electrochemical performance of aqueous ZIBs with conventionals alt-in-water electrolytes. To overcome this drawback, the novel highly concentrated electrolyte, knowna s water-in-salt electrolyte, and which consists of 20 m LiTFSI and 1 m Zn(TFSI) 2 (where TFSI À is considered as bis(trifluoromethanesulfonyl)imide), was developed.I ns uch ah ighly concentrated electrolyte, the Zn 2 + has au nique solvation-sheath structure that could significantly form close ion pairs (Zn-TFSI) + rather than Zn-(H 2 O) 6 + with the surrounding of the abundant anions( Figure 4d). [16c] Such water-in-salt electrolyte not only displays nearly 100 %C oulombic efficiency withoutt he growth of dendrites during Zn plating/strippingp rocess, but also suppresses the consumption of water in the open atmosphere.…”

“…[5] Furthermore, the selection of electrolytes is vitally important for the accurate evaluation of electrode materials and the achievement of superior electrochemical performance. [6] The common aqueous electrolytes of ZIBs are ZnSO 4 and Zn(CF 3 SO 3 ) 2 solutions, due to their excellent stabilitya nd compatibility with the electrodes. [3b, 7] Nevertheless, rechargeable ZIBs based on these aqueous electrolytes often suffer from poor Coulombic Efficiency (CE) and rapid capacity fading due to the dissolution of cathodem aterials in the electrolytes, and the irreversible side reactions on both cathodes and anodes.…”

Rechargeable Magnesium–Sulfur Battery Technology: State of the Art and Key Challenges

“…The general requirements for a suitable electrolyte include high ionic conductivity, good electrochemical and chemical stability toward the electrodes, good thermal stability and sufficiently low toxicity and flammability . In addition, an appropriate electrolyte system should allow for a reversible Mg deposition and dissolution and also provide a wide voltage window . Therefore, the design of novel electrolyte systems that are fully compatible with Mg–S batteries and the underlying chemistry is of great importance.…”