We developed two-step solution-phase reactions to form hybrid materials of Mn3O4 nanoparticles on reduced graphene oxide (RGO) sheets for lithium ion battery applications. Mn3O4 nanoparticles grown selectively on RGO sheets over free particle growth in solution allowed for the electrically insulating Mn3O4 nanoparticles wired up to a current collector through the underlying conducting graphene network. The Mn3O4 nanoparticles formed on RGO show a high specific capacity up to ~900mAh/g near its theoretical capacity with good rate capability and cycling stability, owing to the intimate interactions between the graphene substrates and the Mn3O4 nanoparticles grown atop. The Mn3O4/RGO hybrid could be a promising candidate material for high-capacity, low-cost, and environmentally friendly anode for lithium ion batteries. Our growth-on-graphene approach should offer a new technique for design and synthesis of battery electrodes based on highly insulating materials.

Mn3O4-Graphene Hybrid as a High Capacity Anode Material for Lithium Ion Batteries

Although current high-energy-density lithium-ion batteries (LIBs) have taken over the commercial rechargeable battery market, increasing concerns about limited lithium resources, high cost, and insecurity of organic electrolyte scale-up limit their further development. Rechargeable aqueous zinc-ion batteries (ZIBs), an alternative battery chemistry, have paved the way not only for realizing environmentally benign and safe energy storage devices but also for reducing the manufacturing costs of next-generation batteries. This Review underscores recent advances in aqueous ZIBs; these include the design of a highly reversible Zn anode, optimization of the electrolyte, and a wide range of cathode materials and their energy storage mechanisms. We also present recent advanced techniques that aim at overcoming the current issues in aqueous ZIB systems. This Review on the future perspectives and research directions will provide a guide for future aqueous ZIB study.

Recent Advances in Aqueous Zinc-Ion Batteries

Zinc-ion batteries built on water-based electrolytes featuring compelling price-points, competitive performance, and enhanced safety represent advanced energy storage chemistry as a promising alternative to current lithium-ion battery systems. Attempts to develop rechargeable aqueous zinc-ion batteries (ZIBs) can be traced to as early as the 1980s; however, since 2015, the research activity in this field has surged throughout the world. Despite the achievements made in exploring electrode materials so far, significant challenges remain at the material level and even on the whole aqueous ZIBs system, leading to the failure of ZIBs to meet commercial requirements. This review aims to discuss how to pave the way for developing aqueous ZIBs. The current research efforts related to aqueous ZIBs electrode materials and electrolytes are summarized, including an analysis of the problems encountered in both cathode/anode materials and electrolyte optimization. Some concerns and feasible solutions for achieving practical aqueous ZIBs are discussed in detail. We would like to point out that merely improving the electrode materials is not enough; synergistic optimization strategies toward the whole battery system are also deeply needed. Finally, some perspectives are provided on the subsequent optimization design for further research efforts in the aqueous ZIB field.

Issues and opportunities facing aqueous zinc-ion batteries

https://www.cell.com/joule/pdf/S2542-4351(20)30094-5.pdf

Scientific Challenges for the Implementation of Zn-Ion Batteries

Safety concerns about organic media-based batteries are the key public arguments against their widespread usage. Aqueous batteries (ABs), based on water which is environmentally benign, provide a promising alternative for safe, cost-effective, and scalable energy storage, with high power density and tolerance against mishandling. Research interests and achievements in ABs have surged globally in the past 5 years. However, their large-scale application is plagued by the limited output voltage and inadequate energy density. We present the challenges in AB fundamental research, focusing on the design of advanced materials and practical applications of whole devices. Potential interactions of the challenges in different AB systems are established. A critical appraisal of recent advances in ABs is presented for addressing the key issues, with special emphasis on the connection between advanced materials and emerging electrochemistry. Last, we provide a roadmap starting with material design and ending with the commercialization of next-generation reliable ABs.

/pdf/roadmap-for-advanced-aqueous-batteries-from-design-of-1xqgvunnyt.pdf

Roadmap for advanced aqueous batteries: From design of materials to applications.

The ever-increasing demand for storing renewable energy sources calls for novel battery technologies that are of sustainably low levelized energy cost. Research into battery chemistry has evolved to a stage where a plethora of choices based on earth-abundant elements can be compared during their development. One of the emerging candidates is the nonaqueous potassium-ion battery. K-ion’s unique properties as a charge carrier have aroused intense interest in exploring high-performing cathode and anode materials for this battery. Rapid progress has been made, where leading candidates of electrodes have been proposed, i.e., hard carbon as anode and Prussian white analogues as cathode. In this new battery technology’s infancy, it is our opinion that the focus should be given to potentially scalable, inexpensive electrode materials and the understanding of their cycle-life-property correlations. It may be the ultralong cycle life that differentiates potassium-ion batteries from sodium-ion batteries in the futur...

Emerging Non-Aqueous Potassium-Ion Batteries: Challenges and Opportunities

A ZnCl2 water-in-salt electrolyte for a reversible Zn metal anode.

Dual-ion batteries are known for anion storage in the cathode coupled to cation incorporation in the anode. We flip the sequence of the anion/cation-storage chemistries of the anode and the cathode...

Reverse Dual-Ion Battery via a ZnCl2 Water-in-Salt Electrolyte.

Concentrated potassium acetate as a water-in-salt electrolyte provides a wide potential window from −1.7 to 1.5 V vs Ag/AgClKCl sat.. It facilitates the reversible operation of KTi2(PO4)3, an anode of potassium-ion batteries, that otherwise only functions in nonaqueous electrolytes.

Daniel P. Leonard

Papers

Emerging Non-Aqueous Potassium-Ion Batteries: Challenges and Opportunities

A ZnCl2 water-in-salt electrolyte for a reversible Zn metal anode.

Reverse Dual-Ion Battery via a ZnCl2 Water-in-Salt Electrolyte.

Water-in-Salt Electrolyte for Potassium-Ion Batteries

ZnCl2 “Water‐in‐Salt” Electrolyte Transforms the Performance of Vanadium Oxide as a Zn Battery Cathode