Exploiting High‐Performance Anode through Tuning the Character of Chemical Bonds for Li‐Ion Batteries and Capacitors

Abstract

determine the working voltage and energy density of batteries. While a high capacity is desired in both electrodes, a high potential in cathode and a low potential in anode are needed for a wide working voltage of batteries within the safe operating range of electrolyte. [14][15][16] Similar to cathodes, anodes work through three mechanisms: intercalation, conversion, and alloying, [17] thus, it is not surprised that transition metal oxides and complex oxides, metals and lithiation compounds have been studied intensively over the past years. [17][18][19][20][21] For example, intercalation compounds, such as Li 4 Ti 5 O 12 , can insert and extract Li ion from the crystal lattices reversibly with a small strain offering a highly stable cyclability and an ideal potential plateau, [22] but deliver a relatively low specific capacity of 175 mA h g −1 . [23,24] Metals and metalloids including Sn, Zn, Pb, Bi, Se, and Si are based on alloying mechanism to store charges and ions, offering exceedingly high specific storage capacity but accompanied with drastic volume change during lithiation/delithiation leading to inferior cyclability. [25][26][27][28][29] Transition metal oxides, such as MnO, FeO, CoO, NiO, and CuO, store charges through reversible conversion reactions, in which metal oxides decompose to metal and Li 2 O and display a high specific capacity. However, such metal oxides also suffer from poor cycling stability. [19,[30][31][32][33] Transition metal nitrides and fluorides have also been studied and demonstrated the capability of reversible conversion reactions but also suffer from the similarly inferior cyclability. [34][35][36] To circumvent the challenges in conversion materials, design and fabrication of various nano and microstructures, or doping with heteroatoms have been investigated with some noticeable improvement. [37][38][39][40] Exploring new materials with desired properties based on some fundamental considerations is another effective approach. For example, tuning the covalent-ionic bond characters between ion components can effectively alter the electrochemical potential of electrode materials. [41] The present investigation has explored a new anode material, manganese carbodiimide (MnNCN) with excellent lithium storage properties. Figure 1a is the schematic illustrating the crystal structure of MnNCN that consists of alternating layers of Mn 2+ cations and NCN 2− anions (the pseudo-sulfide anions) along the trigonal axis, and the anions are strictly linearly oriented perpendicular to the layers. Each divalent Mn ion is coordinated by six nitrogen atoms and the A high-performance anode material, MnNCN, is synthesized through a facile and low-cost method. The relationship between electrochemical properties and chemical composition is explored on the scientific considerations that can provide an insight on designing expected materials. MnNCN with the long bonding length of 2.262 Å in MnN and weak electronegativity of 3.04 Pauling units in N leads to a lower charge/discharge potential than th...

Synthesis and Characterisation of the Nitridocuprate(I) Nitride Carbodiimide (Sr6N)[CuN2][CN2]2

“…For M = Hg two modifications, one cyanamide and one carbodiimide, are known , . Interestingly, some of these compounds show potential applications as negative electrode materials for lithium and sodium ion batteries, corrosion protective layers, photovoltaic devices, fluorescent light sources, and light‐emitting diodes , . Due to the carbodiimide anion being a pseudo‐chalcogenide anion, it can act as a bridging ligand to allow effective magnetic super exchange between bridged paramagnetic cations, as seen for Cr 2 [CN 2 ] 3 and M [CN 2 ] ( M = Mn – Cu), which are isostructural to their respective oxide variants, exhibit similar magnetic ordering and also have the same colours .…”

Dual‐Doped Hematite Nanorod Arrays on Carbon Cloth as a Robust and Flexible Sodium Anode

“…As presented in Figure a, a kinetic model is established to explain the improved reactivity by nitrogen doping. The introduction of nitrogen changes the chemical bonding character, which can be evaluated based on the following Equation where X a and X b are the electronegativity value of the anion (3.44 for O and 3.04 for N) and cation (1.83 for Fe), respectively (Figure 4b). As nitrogen has a lower Pauling electronegativity than oxygen element, the covalent character of FeN (69.3%) is augmented compared with that of FeO (52.3%).…”

High‐Performance Asymmetric Li‐Ion Pseudocapacitors Based on Pyroprotein Nanowebs

“…Cocoons from B. mori silkworms (Uljin Farm, South Korea) were boiled for 25 min in an aqueous solution containing 0.02 M Na 2 CO 3 (99 %; OCI Co., South Korea) and rinsed thoroughly with deionized water to extract the glue‐like sericins and other impurities (i. e., a degumming process) . After drying at room temperature for 3 d, the resulting fibrous silk fibers (silk fibroin) were dissolved in an aqueous solution of 9.3 M LiBr (99 %; Sigma‐Aldrich, St. Louis, MO, USA) at 60 °C for 6 h. The silk fibroin solution was dialyzed in water using a Slide‐a‐Lyzer dialysis cassette (MWCO 3500; Pierce) for 2 d. The final concentration of the silk fibroin in the aqueous solution was approximately 8 wt %.…”