Reduced Graphene Oxide Modulated FeSe/C Anode Materials for High-Stable and Long-Life Potassium-Ion Batteries.

Reduced graphene oxide (rGO) has been demonstrated to effectively enhance the potassium storage performance of transition metal selenides due to its robust mechanical properties and high conductivity. However, the impact of rGO on the electrode-electrolyte interface, a crucial factor in the electrochemical performance of potassium-ion batteries (PIBs), requires further exploration. In this study, we synthesized a seamless architecture of rGO on FeSe/C nanocrystals (FeSe/C@rGO). Comparative analysis between FeSe/C and FeSe/C@rGO reveals that the rGO layer exhibits robust adsorption energies towards EC and DEC, inducing the formation of organic-rich solid-electrolyte interphase (SEI) without damage to the structural integrity. Furthermore, incorporating rGO triggers K+ -ions into the double electrode layer (EDL), markedly improving the transport of K+ -ions. As a PIB anode, FeSe/C@rGO exhibits a reversible capacity of 332 mAh g-1 at 200 mA g-1 after 300 cycles, along with excellent long-term cycling stability, showcasing an ultralow decay rate of only 0.086 % per cycle after 1900 cycles at 1000 mA g-1 .

Regulating the Li+ -Solvation Structure of Ester Electrolyte for High-Energy-Density Lithium Metal Batteries.

The development of high-energy-density Li metal batteries are hindered by electrolyte consumption and uneven lithium deposition due to the unstable lithium-electrolyte interface (SEI). In this work, tetraglyme is introduced into ester electrolyte to regulate the Li+ -solvation structures for stable SEI while remaining appropriate voltage window for high-voltage cathodes. In the modified solvation structures, an enhanced lowest unoccupied molecular orbital energy level occurs, resulting in relieved electrolyte degradation. In addition, the modified solvation structures can facilitate adequate LiNO3 dissolution in the ester electrolyte (denoted as E-LiNO3 ), contributing to constant supplement of constructing highly conductive LiNx Oy -containing SEI for dendrite-free Li deposition under high capacity condition. As a result, the Li||Cu cell-based on this electrolyte exhibits high Li plating/stripping Coulombic efficiency of 98.2% over 350 cycles. Furthermore, when paired with high-voltage LiNi0.5 Co0.2 Mn0.3 O2 cathodes, the E-LiNO3 enables a stable cycling with a high-energy-density of 296 Wh kg-1 based on the full cell under realistic testing conditions (lean electrolyte of 3 g Ah-1 , limited Li excess of 2.45-fold, and high areal capacity of 4 mAh cm-2 ).

Faradaic Electrodes Open a New Era for Capacitive Deionization.

Capacitive deionization (CDI) is an emerging desalination technology for effective removal of ionic species from aqueous solutions. Compared to conventional CDI, which is based on carbon electrodes and struggles with high salinity streams due to a limited salt removal capacity by ion electrosorption and excessive co-ion expulsion, the emerging Faradaic electrodes provide unique opportunities to upgrade the CDI performance, i.e., achieving much higher salt removal capacities and energy-efficient desalination for high salinity streams, due to the Faradaic reaction for ion capture. This article presents a comprehensive overview on the current developments of Faradaic electrode materials for CDI. Here, the fundamentals of Faradaic electrode-based CDI are first introduced in detail, including novel CDI cell architectures, key CDI performance metrics, ion capture mechanisms, and the design principles of Faradaic electrode materials. Three main categories of Faradaic electrode materials are summarized and discussed regarding their crystal structure, physicochemical characteristics, and desalination performance. In particular, the ion capture mechanisms in Faradaic electrode materials are highlighted to obtain a better understanding of the CDI process. Moreover, novel tailored applications, including selective ion removal and contaminant removal, are specifically introduced. Finally, the remaining challenges and research directions are also outlined to provide guidelines for future research.