Unexpected Effect of Electrode Architecture on High-Performance Lithium-Sulfur Batteries

Insights into the solvation chemistry in liquid electrolytes for lithium-based rechargeable batteries

Lithium-based rechargeable batteries have dominated the energy storage field and attracted considerable research interest due to their excellent electrochemical performance. As indispensable and ubiquitous components, electrolytes play a pivotal role in not only transporting lithium ions, but also expanding the electrochemical stable potential window, suppressing the side reactions, and manipulating the redox mechanism, all of which are closely associated with the behavior of solvation chemistry in electrolytes. Thus, comprehensively understanding the solvation chemistry in electrolytes is of significant importance. Here we critically reviewed the development of electrolytes in various lithium-based rechargeable batteries including lithium-metal batteries (LMBs), nonaqueous lithium-ion batteries (LIBs), lithium-sulfur batteries (LSBs), lithium-oxygen batteries (LOBs), and aqueous lithium-ion batteries (ALIBs), and emphasized the effects of interactions between cations, anions, and solvents on solvation chemistry, and functions of solvation chemistry in different types of electrolytes (strong solvating electrolytes, moderate solvating electrolytes, and weak solvating electrolytes) on the electrochemical performance and redox mechanism in the abovementioned rechargeable batteries. Specifically, the significant effects of solvation chemistry on the stability of electrode-electrolyte interphases, suppression of lithium dendrites in LMBs, inhibition of the co-intercalation of solvents in LIBs, improvement of anodic stability at high cut-off voltages in LMBs, LIBs and ALIBs, regulation of redox pathways in LSBs and LOBs, and inhibition of hydrogen/oxygen evolution reactions in LOBs are thoroughly summarized. Finally, the review concludes with a prospective outlook, where practical issues of electrolytes, advanced in situ/operando techniques to illustrate the mechanism of solvation chemistry, and advanced theoretical calculation and simulation techniques such as "material knowledge informed machine learning" and "artificial intelligence (AI) + big data" driven strategies for high-performance electrolytes have been proposed.

Interface Engineering between the Metal-Organic Framework Nanocrystal and Graphene toward Ultrahigh Potassium-Ion Storage Performance

The potassium-ion battery (PIB) has been recognized as a promising low-cost and high-energy battery; however, it suffers from a relatively low capacity and inferior cycling performance compared with current electrode materials. Herein, we report an effective interface engineering strategy to prepare metal-organic framework (MOF) nanocrystals tightly encapsulated by reduced graphene oxide (rGO) via strong chemical interaction as a free-standing anode for PIB. Based on experimental analysis and theoretical calculations, we systematically investigated the effect of the chemical-bonded interface between MOF nanocrystals and conductive rGO and revealed that the strong chemical interface can substantially enhance the adsorption energy and ion transport kinetics of the potassium ion within the MOF nanocrystals compared to the physical mixture of MOF and rGO with almost the same microscopic morphologies. As a result, such an MOF-rGO hybrid with strong interfacial chemical couplings delivered an ultrahigh reversible capacity of 422 mAh g^-1 at 0.1 A g^-1, superior rate performance (202 mAh g^-1 at 5 A g^-1), and outstanding long-term cycling performance (an ultralow decay rate of 0.013% per cycle after 2000 cycles at 2 A g^-1), which are not only significantly better than those of the physical mixture of MOF/rGO but also among the best for anodes for PIB reported thus far.

Two-Dimensional MoS2 for Li-S Batteries: Structural Design and Electronic Modulation

Two-dimensional molybdenum disulfide (MoS₂ ) nanosheets attract great interest for applications in lithium-sulfur (Li-S) batteries, due to their unique physical and chemical properties, which originate from diverse chemical compositions and unique electronic structures. In recent years, many efforts have been devoted to employing MoS₂ as a polysulfide immobilizer and catalyst, functional separator, and Li-metal protection for Li-S batteries through structural design and electronic modulation. A fundamental understanding of the interplay between structural features, electronic properties, and advanced electrochemical performance is crucial for providing valuable insights for the development of Li-S batteries. In this regard, recent advances in Li-S batteries with 2D MoS₂ materials are summarized from the perspective of structural design and electronic modulation. Finally, future prospects and remaining challenges of MoS₂ for Li-S batteries are highlighted.