Monodispersed hollow spindle-like nanosphere (HS-NS) and tetrapod nanorod (TP-NR) MnS nanocrystals are obtained via a facile template-free hydrothermal process. The MnS nanocrystals are used as supercapacitor materials and they exhibit high performances. The TP-NR nanocrystals show a higher specific capacitance of 704.5 F g⁻¹ compared to the HS-NS nanocrystals, and both show higher values compared to manganese oxide.

Spin polarization has been recently recognized as a critical factor that affects the catalytic behavior of electrocatalysts. Half metals, with an exotic quantum state of 100% spin-polarized conduction electrons, and the spin associated atomic magnetization could show great potential in catalyst applications, however the corresponding research is insufficient. In this work, a prototype study of (Co and/or Fe)–N_x (x = 1–6) embedded configurations (FeCoN_x–gra) is conducted within density functional theory (DFT) via spin-polarized calculation. The results indicate that an itinerant ferromagnetic half metal can be recognized as a promising candidate for a bifunctional electrocatalyst for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Specifically, the ferromagnetically coupled spin-polarized electrons in a half metal tend to attract oxygen molecules so as to stimulate ORR, while the formation of the O–O bond in OER requires spin conservation. The delocalized spin character (metallic spin of a half metal) guarantees the moderate binding strength of main reaction intermediates, i.e., *O₂, *O, *OH, and *OOH, which can be measured by the atomic spin moment in the reaction center (0.4–1.5 μ_B for Fe in this study). This study identifies a new specific link between the electron structure and catalytic activities which has predictive power for catalyst design.

Using lithium as the anode material to achieve high energy density lithium-ion/metal batteries is the ultimate goal of energy storage technology. A recent development of solid state electrolytes (SSEs) with high ionic conductivity holds great promise for enabling the practical applications of solid state lithium metal batteries (SSLMBs), as the high mechanical strength of SSEs can be harnessed to suppress dendrite growth. However, the application of SSLMBs is hampered by the new multifold problems from the solid–solid contact to dendrites to deleterious interfacial reactions between lithium and the SSEs. In this burgeoning field of SSLMBs, it is imperative to understand the fundamental science of these emerging problems at a very basic level before the application of SSLMBs can be realized. These problems are inter-related and they arise from the intrinsic physical, chemical, and electro-chemo-mechanical properties of lithium. We start this review by providing a brief account of the history of lithium, and how it has evolved from the anode of primary lithium metal batteries to that of liquid electrolyte based rechargeable batteries and to that of SSE based SSLMBs. We then summarize the literature about the mechanical properties of bulk lithium, lithium pillars and lithium whiskers. We analyze from an electro-chemo-mechanical perspective how lithium dendrites penetrate through SSEs and cause short circuits in SSLMBs. We identify possible strategies to mitigate lithium dendrite propagation through SSEs, and summarize our understanding of the lithium reaction with various interfaces, such as Li/Li₇La₃Zr₂O₁₂, Li/polyethylene oxide, Li/Na-superionic conductor, and Li/sulfide, with the ultimate goal of developing strategies to mitigate detrimental interfacial reactions and maintain sustainable stable interfaces. We review briefly characterization tools to address the challenging issues in SSLMBs. We conclude by pointing out the outstanding issues in SSLMBs.

All-solid-state high-performance asymmetric supercapacitors (ASCs) are fabricated using γ-MnS as positive electrode and porous eggplant derived activated carbon (EDAC) as negative electrode with saturated potassium hydroxide agar gel as the solid electrolyte. The laminar wurtzite nanostructure of γ-MnS facilitates the insertion of hydroxyl ions into the interlayer space and the manganese sulfide nanowire offers electronic transportation channels. The size-uniform porous nanostructure of EDAC provides a continuous electron pathway as well as facilitates short ionic transportation pathways. Due to these special nanostructures of both the MnS and the EDAC, they exhibited a specific capacitance of 573.9 and 396 F g⁻¹ at 0.5 A g⁻¹, respectively. The optimized MnS//EDAC asymmetric supercapacitor shows a superior performance with specific capacitance of 110.4 F g⁻¹ and 89.87% capacitance retention after 5000 cycles, a high energy density of 37.6 Wh kg⁻¹ at a power density of 181.2 W kg⁻¹ and remains 24.9 Wh kg⁻¹ even at 5976 W kg⁻¹. Impressively, such two assembled all-solid-state cells in series can light up a red LED indicator for 15 minutes after fully charged. These impressive results make these pollution-free materials promising for practical applications in solid aqueous electrolyte-based ASCs.