Organic–Rare Earth Hybrid Anode with Superior Cyclability for Lithium Ion Battery

Abstract

new applications. Much effort is concentrated on design and synthesis of novel electrodes that possess high theoretical capacity, proper potential, and excellent structural stability during long-term cycling. [2] Considering the sustainable development, organic redox compounds with structural diversity should be ideal electrode materials. However, organic compounds frequently suffer from intractable technical challenges: [3] a) limited electroactive sites for Li-ions insertion/ desertion cause low specific capacity; b) lithiated products are soluble in electrolytes, leading to rapid capacity fading; c) agglomerates of organic molecules cause sluggish electrochemical kinetics. To increase Li-ions storage sites, introducing redox functional groups to organic compound represents one efficient approach to improve theoretical capacity. [4] For classical dicarboxylic compounds as anode materials, [5] they reversibly transfer two electrons during electrochemical processes. In other words, they reversibly intercalate two extra lithium ions in organic compounds during discharge process. In previous studies, we have demonstrated that when four sulfur atoms are introduced to a single carboxylate scaffold, electron delocalization and electrical conductivity were remarkably improved. Accordingly, ion storage sites are significantly increased to six, [6] resulting in an exceptional theoretical capacity.Although the problem of organic compound dissolution has been largely addressed by polymerization, [7] this approach relies on the development of multicomponent polymeric reactions of small molecules. As for polymer battery, recent reports are mainly focused on the field of π-conjugated polymer electrodes such as polythiophene, [8] polypyrrole, [9] polyphenylene, [10] and polyacetylene. [11] Clearly, these polymers have no distinct redox sites. As a result, their low doping-degrees lead to decreased theoretical capacities. Furthermore, most of the organic polymers display the morphology of agglomerates, which is not conducive to the thermodynamics and kinetics of their electrode reactions. Fortunately, incorporating nanostructured conductors (e.g., carbon and metal oxides) to form composites has been demonstrated as one effective strategy for preventing active material dissolution. [12] For instance, Zhang et al. found that the carbon layer can improve electrical conductivity and the tangled CNT network can maintain the integrity of composite electrodes (Si@C-CNTs). [13] Chen et al. used nanostructured magnesium nickel oxide (Mg 0.6 Ni 0.4 O) to prepare the Organic compounds with electroactive sites are considered as a new generation of green electrode materials for lithium ion batteries. However, exploring effective approaches to design high-capacity molecules and suppressing their solubilization remain big challenges. Herein, a functional anode architecture is first designed by using chemical bonds between organic compound and rare earth hollow structure, which enables active materials to be efficiently utilized, accelerate...

Organic Negative Electrode Materials for Metal‐Ion and Molecular‐Ion Batteries: Progress and Challenges from a Molecular Engineering Perspective

“…Zhao et al [215] reported another molecular modification dwelling on substitution of oxygens in dicarboxylate scaffolds with sulfur atoms to form thiocarboxylate compounds as an alternative negative electrode materials for sodium batteries (Figure 7c). [215][216][217] The authors proposed three different chemistries: sodium dithioterephthalate (denoted as Na 2 -DTT), sodium tetrathioterephthalate (denoted as Na 2 -TTT), and sodium 4,4'-biphenyltetrathiodicarboxylate (denoted as Na 2 -BTTC). Contrary to conjugated dicarboxylates derivatives, which have a typical aspect of white powders (empirically attributed to poor electronic conductivity), the thiocarboxylate samples present darker coloring, an indication of intrinsic electrical conductivity.…”

Carbon skeleton materials derived from rare earth phthalocyanines (MPcs) (M = Yb, La) used as high performance anode materials for lithium-ion batteries

“…Furthermore, hard carbon can also avoid the disadvantage of the high reactivity of graphitized carbon, which provides a new idea for modified graphite anode materials. Wang 27 and co-workers prepared CeO 2 @carbon hollow spheres by mild hydro-thermal reactions. The capacity retention of the hybrid material is enhanced by 27.0% after 120 cycles, and the CeO 2 @Carbon electrode still shows a reversible specific capacity of 119 mA h g −1 after 120 cycles at a current density of 200 mA.…”

Room-Temperature Synthesis of Sub-2 nm Ultrasmall Platinum–Rare-Earth Metal Nanoalloys for Hydrogen Evolution Reaction

“…Recent studies have suggested that in energy conversion and storage aspects, catalysts alloying with rare-earth (RE) elements significantly influence their performance. − Due to their unique electronic configurations, the rare-earth elements play an important role in tuning their functional properties from the perspective of electronic and catalytic activities. − In view of the superior electrocatalytic activity of platinum in HER, the electrocatalytic performance can be enhanced by doping rare-earth elements into metallic platinum. The lanthanide series have similar atomic radii and electronic structure properties, so we can deduce that if platinum can form an alloy with one of the rare-earth elements (e.g., lanthanum), the other rare-earth elements can also form stable alloy phases as a result .…”