deficiency. The exclusive research and industrial focus on the development of new energy sources cannot meet the current energy demands. The main reason is lack of efficient storage of the collected energy. Because the consumption rate of generated energy usually cannot be synchronized with the rate of generation. Fortunately, this problem has received attention from researchers and engineers around the world. Electrochemical energy storage devices (EESDs) [1,2] are competitive candidates for energy storage. Lithiumion batteries (LIBs), [3][4][5][6][7][8][9][10][11] electron double layer capacitors (EDLCs) as well as pseudocapacitors (PCs), [12][13][14][15][16][17] lithium-sulfur (Li-S) batteries, [18][19][20][21][22] lithium-air (Li-air) or lithium-oxygen (Li-O 2 ) batteries, [23][24][25][26][27][28][29] sodium-ion batteries, [30][31][32][33] magnesium-ion batteries, [34] lithium solid state batteries, [35] among others are currently popular EESDs. Among those devices, lithium-ion batteries are of great interest. Since being initially commercialized by Sony, Inc. in 1990, [36] for more than a quarter of a century, the lithium-ion battery has become a popular, portable, and rechargeable second battery used in various applications such as personal electronic devices, [37] electric vehicles, [38] hybrid electric vehicles, [39] and smart grids. [40] To date, it is still needed to further improve the electrochemical performance of lithium-ion batteries. The fabrication of novel and reliable electrode materials is critical for further development of better lithium-ion batteries.A lithium-ion battery cell usually includes components of a solid-state positive electrode (cathode), a solid-state negative electrode (anode), some lithium-ion included liquidstate electrolyte (can be either non-aqueous or aqueous [41] ), a polymeric separator, and a pair of the current collectors with encapsulated cases. [3] If an external voltage applied to both electrodes, lithium ions are deintercalated from cathode to anode through the electrolyte, so called the charging process; when there is an external loading applied to both electrodes, lithium ions are intercalated into unlithiated cathode from lithiated anode through the electrolyte again, i.e., the discharging process. [3,39,42] The discharging procedure of a LIB cell is shown in Figure 1. [39] The role of the porous separator is to prevent the short circuit inside a cell. As the most significant components of one lithium-ion battery cell, the properties of both cathode and anode materials determine the electrochemical energy storage ability of the cell. Therefore, the selection of Vanadium pentoxide (V 2 O 5 ) has played important roles in lithium-ion batteries due to its unique crystalline structure. To assist researchers understanding the roles this material plays, a comprehensive and critical review is conducted based on about 250 publications. Here, we report basics and applications of micro-and nano-materials of V 2 O 5 and V 2 O 5 -based composites. The comparative and stati...

A one-step microwave-assisted method is used for the synthesis of small gold nanoclusters, Au(16)NCs@BSA, which are used as a fluorescence enhanced sensor for detection of silver(I) ions with high selectivity and sensitivity.

The demand for high energy‐density, mass‐producible cathode materials has spurred the exploration of new material structures and compositions. Lithium‐excess, cation‐disordered rocksalt (DRX) materials are a new class of transition metal oxides that display high capacity and environmental friendly composition. These materials achieve their high capacities partially through oxygen redox, which leads to oxygen loss and detrimental reactivity with the electrolyte. It has previously been shown that oxygen loss can be suppressed by partial substitution of the lattice oxygen for fluorine, but the explicit mechanism behind this effect remains unknown. In this work, differential electrochemical mass spectrometry (DEMS) and titration mass spectrometry are used to quantify the primary electrochemical reactions occurring during the first cycle in DRX materials. Comparing a DRX oxide and a DRX oxyfluoride, it is shown that fluorination limits oxygen redox and suppresses oxygen loss. Additionally, DEMS is coupled with fluoride‐scavenging to demonstrate that small amounts of fluorine dissolve from DRX oxyfluorides during the first cycle. Finally, these techniques are extended over the first several cycles, demonstrating that CO2 evolution persists and fluoride dissolution continues to a diminishing extent during the first few cycles. These findings motivate surface modifications to control interfacial reactivity and improve long‐term cycling.

Fragrant nitrogen‐doped carbon dots of gram scale can be prepared from commercial bee pollens by a hydrothermal process. These carbon dots of 1–2 nm in size show promising applications in cellular imaging and catalysis/photocatalysis.

We report a new strategy for the gram-scale synthesis of highly blue fluorescent nitrogen and sulfur embedded organic dots through one-pot hydrothermal condensation of citric acid (CA) with cysteamine (Cys) at 200 °C. Under such circumstance, the dehydration between CA and Cys produces a molecular fluorophore, which self-assembles to amorphous dots through hydrophobic interaction and π–π stacking. In aqueous solution, the dots exhibit a very high fluorescent quantum yield that is above those of most photoluminescent carbon dots to date, since the fluorophore is not carbonized. The intense fluorescence emission is achieved by establishing an efficient push–pull fluorophore system, as revealed by first-principles simulations. In the solid phase, the fluorescence of the dots is severely attenuated. More importantly, unlike excitation-independent emission displayed in solution, the fluorescence of the organic dots in the aggregated solid state is dependent on excitation wavelength, which is quite a rare and unique phenomenon. Finally, this new kind of organic dots has shown diverse applications in sensing and imaging.