High-Entropy Spinel Oxide Ferrites for Battery Applications.

Four different high-entropy spinel oxide ferrite (HESO) electrode materials containing 5-6 distinct metals were synthesized by a simple, rapid combustion synthesis process and evaluated as conversion anode materials in lithium half-cells. All showed markedly superior electrochemical performance compared to conventional spinel ferrites such as Fe3O4 and MgFe2O4, having capacities that could be maintained above 600 mAh g-1 for 150 cycles, in most cases. X-ray absorption spectroscopy (XAS) results on pristine, discharged, and charged electrodes show that Fe, Co, Ni, and Cu are reduced to the elemental state during the first discharge (lithiation), while Mn is only slightly reduced. Upon recharge (delithiation), Fe is reoxidized to an average oxidation state of about 2.6+, while Co, Ni, and Cu are not reoxidized. The ability of Fe to be oxidized past 2+ accounts for the high capacities observed in these materials, while the presence of metallic elements after the initial lithiation provides an electronically conductive network that aids in charge transfer.

SiSe2 for Superior Sulfide Solid Electrolytes and Li-Ion Batteries.

Among the various existing layered compounds, silicon diselenide (SiSe2) possesses diverse chemical and physical properties, owing to its large interlayer spacing and interesting atomic arrangements. Despite the unique properties of layered SiSe2, it has not yet been used in energy applications. Herein, we introduce the synthesis of layered SiSe2 through a facile solid-state synthetic route and demonstrate its versatility as a sulfide solid electrolyte (SE) additive for all-solid-state batteries (ASSBs) and as an anode material for Li-ion batteries (LIBs). Li-argyrodites with various compositions substituted with SiSe2 are synthesized and evaluated as sulfide SEs for ASSBs. SiSe2-substituted Li-argyrodites exhibit high ionic conductivities, low activation energies, and high air stabilities. In addition, when using a sulfide SE, the ASSB full cell exhibits a high discharge/charge capacity of 202/169 mAh g-1 with a high initial Coulombic efficiency (ICE) of 83.7% and stable capacity retention at 1C after 100 cycles. Furthermore, the Li-storage properties of SiSe2 as an anode material for LIBs are evaluated, and its Li-pathway mechanism is explored by using various cutting-edge ex situ analytical tools. Moreover, the SiSe2 nanocomposite anode exhibits a high Li- insertion/extraction capacity of 950/775 mAh g-1, a high ICE of 81.6%, a fast rate capability, and stable capacity retention after 300 cycles. Accordingly, layered SiSe2 and its versatile applications as a sulfide SE additive for ASSBs and an anode material for LIBs are promising candidates in energy storage applications as well as myriad other applications.

Li-Compound Anodes: A Classification for High-Performance Li-Ion Battery Anodes.

Four main anode types are generally considered as typical anodes for Li-ion batteries (LIBs): Li-metal, carbon-based, alloy-based, and oxide-based anodes. Although they exhibit satisfactory electrochemical performance as LIB anodes, they cannot simultaneously satisfy all key requirements for LIB anodes: high reversible capacity, high initial Coulombic efficiency (ICE), long cycle life, fast rate capability, structural stability, and no safety concerns. Here, we suggest Li-compound anodes as a promising class of high-performance LIB anodes. Three binary (LiSn, Li2Sb, and LiBi) and three ternary (Li2ZnSb, Li5GeP3, and Li5SnP3) Li compounds were introduced as Li-compound anodes. LiSn and Li5SnP3 were selected and further modified into their nanocomposites by solid-state synthetic routes using carbon sources for high-performance LIB anodes. The Li-compound nanocomposite anodes exhibited excellent performance and simultaneously fulfilled all the key requirements for high-performance LIB anodes. Therefore, Li-compound anodes are expected to be a promising and innovative category of high-performance LIB anodes.

Self-Healing Graphene-Templated Platinum-Nickel Oxide Heterostructures for Overall Water Splitting.

Electrocatalysts with dramatically enhanced water splitting efficiency, derived from controlled structures, phase transitions, functional activation, etc., have been developed recently. Herein, we report an in situ observation of graphene-based self-healing, in which this functional activation is induced by a redox reaction. Specifically, graphene on stainless steel (SUS) switches between graphene (C-C) and graphene oxide (C-O) coordination via an electrical redox reaction to activate water splitting. A heterostructure comprising Pt-NiO thin films on single-layer graphene directly grown on a SUS substrate (Pt-NiO/Gr-SUS) was also synthesized by electrodeposition. Pt-NiO/Gr-SUS exhibited water splitting activity with low Pt loading (<1 wt %). The findings provide valuable insight for designing robust electrodes based on reversible redox-induced self-healable graphene to develop more efficient catalysts.

Zinc Phosphides as Outstanding Sodium-Ion Battery Anodes.

To design a high-performance sodium-ion battery anode, binary zinc phosphides (ZnP2 and Zn3P2) were synthesized by a facile solid-state heat treatment process, and their Na storage characteristics were evaluated. The Na reactivity of ZnP2 was better than that of Zn3P2. Therefore, a C-modified ZnP2-based composite (ZnP2-C) was fabricated to achieve better electrochemical performance. To investigate the electrochemical reaction mechanism of ZnP2-C during sodiation/desodiation, various ex situ analytical techniques were employed. During sodiation, ZnP2 in the composite was transformed into NaZn13 and Na3P phases, exhibiting a one-step conversion reaction. Conversely, Zn and P in NaZn13 and Na3P, respectively, were fully recombined to the original ZnP2 phase during desodiation. Owing to the one-step conversion/recombination of ZnP2 in the composite during cycling, the ZnP2-C showed high electrochemical performance with a highly reversible capacity of 883 mA h g-1 after 130 cycles with no capacity deterioration and a fast C-rate capability of 500 mA h g-1 at 1 C and 350 mA h g-1 at 3 C.

Emergency management training in Korea: combining and balancing supply- and demand-centered paradigms.

This article aims to encourage NEMA (or newly named as MPSS) to combine its supply-centered paradigm with a newly proposed "demand-centered paradigm" in the Korean field of emergency management training (EMT). Based on qualitative content analysis, this paper defined the current field of EMT to be a supply-centered paradigm via three components: locations, courses, and participants. This paradigm focuses on EMT provision as supplied and dictated by the national government. On the other hand, a demand-centered model is about looking into stakeholders' actual needs for EMT. In this regard, alternatives with reference to the demand-centered paradigm via the same three components were discussed and considered. The key tenet is that having revealed that NEMA has unequivocally focused on the results side or effectiveness of EMT via a supply-centered paradigm, Korea should address and consider the same three components, this time by fusing and incorporating a fair process of EMT by enlisting active roles from the local community, academic scholars, and civilian training attendees in a demand-centered paradigm.