Cathode Design for Aqueous Rechargeable Multivalent Ion Batteries: Challenges and Opportunities

Abstract

With the rapid growth in energy consumption, renewable energy is a promising solution. However, renewable energy (e.g., wind, solar, and tidal) is discontinuous and irregular by nature, which poses new challenges to the new generation of large‐scale energy storage devices. Rechargeable batteries using aqueous electrolyte and multivalent ion charge are considered more suitable candidates compared to lithium‐ion and lead‐acid batteries, owing to their low cost, ease of manufacture, good safety, and environmentally benign characteristics. However, some substantial challenges hinder the development of aqueous rechargeable multivalent ion batteries (AMVIBs), including the narrow stable electrochemical window of water (≈1.23 V), sluggish ion diffusion kinetics, and stability issues of electrode materials. To address these challenges, a range of encouraging strategies has been developed in recent years, in the aspects of electrolyte optimization, material structure engineering and theoretical investigations. To inspire new research directions, this review focuses on the latest advances in cathode materials for aqueous batteries based on the multivalent ions (Zn2+, Mg2+, Ca2+, Al3+), their common challenges, and promising strategies for improvement. In addition, further suggestions for development directions and a comparison of the different AMVIBs are covered.

Recent Advances in Transition Metal Dichalcogenide Cathode Materials for Aqueous Rechargeable Multivalent Metal-Ion Batteries

“…The energy storage mechanism of MIBs is similar to that of ZIBs: intercalation and conversion processes. Although the ionic radius (0.72Å) and hydrated ionic radius of Mg 2+ (4.28 Å) are similar to those of Li + (ionic radius of 0.76 Å and hydrated ionic radius of 4.3 Å of Li + ), most cathode materials for LIBs are not favorable for MIBs owing to the high charge density of Mg 2+ [86]. Cathode materials for MIBs should exhibit high reversible capacities under adequate operating voltages.…”

MXene/Carbon Nanotube Hybrids: Synthesis, Structures, Properties, and Applications

“…Figure 13b, a stable reversible capacity of Ti 3 C 2 T x /CNT/P anode (> 2000 mAh g À 1 at 130 mA g À 1 ) was observed after the formation of a solid electrolyte interphase (SEI) layer on the electrode surface. [176] Additionally, Ti 3 C 2 T x /CNT could also be used as a host framework in the cathode for ZIBs (a type of multivalent metalion battery), [177] in which the active cathode material (MnO x ) was deposited on the surface of Ti 3 C 2 T x while CNTs acted as a robust scaffold providing conductive pathways in the intertwining structure. [178] As a result, the 3D interpenetrating network effectively improved the rate capability from around 0 (for pure MnO 2 cathode) to 50 mAh g À 1 (for hybrid cathode) at a high current density (5 A g À 1 ) with no capacity drop observed after 400 cycles (Figure 13c).…”

Al-doped α-MnO2 coated by lignin for high-performance rechargeable aqueous zinc-ion batteries

“…[28][29][30] Thus far, some mitigation strategies focusing on the optimization of crystal structure of MnO 2 have been proposed. [31][32][33][34][35] For example, Cao's group prepared a-MnO 2 /graphite nanosheet hybrids via ball milling method. The chemical bonding between MnO 2 and graphite nanosheets strengthened the internal stability and interfacial adhesion and enhanced wettability and conductivity, thereby promoting charge transfer rate.…”