Mussel-Inspired Polydopamine Coating for Enhanced Thermal Stability and Rate Performance of Graphite Anodes in Li-Ion Batteries

Despite two decades of commercial history, it remains very difficult to simultaneously achieve both high rate capability and thermal stability in the graphite anodes of Li-ion batteries because the stable solid electrolyte interphase (SEI) layer, which is essential for thermal stability, impedes facile Li⁺ ion transport at the interface. Here, we resolve this longstanding challenge using a mussel-inspired polydopamine (PD) coating via a simple immersion process. The nanometer-thick PD coating layer allows the formation of an SEI layer on the coating surface without perturbing the intrinsic properties of the SEI layer of the graphite anodes. PD-coated graphite exhibits far better performances in cycling test at 60 °C and storage test at 90 °C than bare graphite. The PD-coated graphite also displays superior rate capability during both lithiation and delithiation. As evidenced by surface free energy analysis, the enhanced performance of the PD-coated graphite can be ascribed to the Lewis basicity of the PD, which scavenges harmful hydrofluoric acid and forms an intermediate triple-body complex among a Li⁺ ion, solvent molecules, and the PD’s basic site. The usefulness of the proposed PD coating can be expanded to various electrodes in rechargeable batteries that suffer from poor thermal stability and interfacial kinetics

Succinonitrile as a Corrosion Inhibitor of Copper Current Collectors for Overdischarge Protection of Lithium Ion Batteries

Succinonitrile (SN) is investigated as an electrolyte additive for copper corrosion inhibition to provide overdischarge (OD) protection to lithium ion batteries (LIBs). The anodic Cu corrosion, occurring above 3.5 V (vs Li/Li⁺) in conventional LIB electrolytes, is suppressed until a voltage of 4.5 V is reached in the presence of SN. The corrosion inhibition by SN is ascribed to the formation of an SN-induced passive layer, which spontaneously develops on the copper surface during the first anodic scan. The passive layer is composed mainly of Cu­(SN)₂PF₆ units, which is evidenced by Raman spectroscopy and electrochemical quartz crystal microbalance measurements. The effects of the SN additive on OD protection are confirmed by using 750 mAh pouch-type full cells of LiCoO₂ and graphite with lithium metal as a reference electrode. Addition of SN completely prevents corrosion of the copper current collector in the full cell configuration, thereby tuning the LIB chemistry to be inherently immune to the OD abuses

New Macrobicyclic Chelator for the Development of Ultrastable ⁶⁴Cu-Radiolabeled Bioconjugate

Ethylene cross-bridged cyclam with two acetate pendant arms, ECB-TE2A, is known to form the most kinetically stable ⁶⁴Cu complexes. However, its usefulness as a bifunctional chelator is limited because of its harsh radiolabeling conditions. Herein, we report new cross-bridged cyclam chelator for the development of ultrastable ⁶⁴Cu-radiolabeled bioconjugates. Propylene cross-bridged TE2A (PCB-TE2A) was successfully synthesized in an efficient way. The Cu­(II) complex of PCB-TE2A exhibited much higher kinetic stability than ECB-TE2A in acid decomplexation studies, and also showed high resistance to reduction-mediated demetalation. Furthermore, the quantitative radiolabeling of PCB-TE2A with ⁶⁴Cu was achieved under milder conditions compared to ECB-TE2A. Biodistribution studies strongly indicate that the ⁶⁴Cu complexes of PCB-TE2A cleared out rapidly from the body with minimum decomplexation

Unraveling the Magnesium-Ion Intercalation Mechanism in Vanadium Pentoxide in a Wet Organic Electrolyte by Structural Determination

Magnesium batteries have received attention as a type of post-lithium-ion battery because of their potential advantages in cost and capacity. Among the host candidates for magnesium batteries, orthorhombic α-V₂O₅ is one of the most studied materials, and it shows a reversible magnesium intercalation with a high capacity especially in a <i>wet</i> organic electrolyte. Studies by several groups during the last two decades have demonstrated that water plays some important roles in getting higher capacity. Very recently, proton intercalation was evidenced mainly using nuclear resonance spectroscopy. Nonetheless, the chemical species inserted into the host structure during the reduction reaction are still unclear (i.e., Mg­(H₂O)_<i>n</i>²⁺, Mg­(solvent, H₂O)_<i>n</i>²⁺, H⁺, H₃O⁺, H₂O, or any combination of these). To characterize the intercalated phase, the crystal structure of the magnesium-inserted phase of α-V₂O₅, electrochemically reduced in 0.5 M Mg­(ClO₄)₂ + 2.0 M H₂O in acetonitrile, was solved for the first time by the ab initio method using powder synchrotron X-ray diffraction data. The structure was tripled along the <i>b</i>-axis from that of the pristine V₂O₅ structure. No appreciable densities of elements were observed other than vanadium and oxygen atoms in the electron density maps, suggesting that the inserted species have very low occupancies in the three large cavity sites of the structure. Examination of the interatomic distances around the cavity sites suggested that H₂O, H₃O⁺, or solvated magnesium ions are too big for the cavities, leading us to confirm that the intercalated species are single Mg²⁺ ions or protons. The general formula of magnesium-inserted V₂O₅ is Mg_0.17H_<i>x</i>V₂O₅, (0.66 ≤ <i>x</i> ≤ 1.16). Finally, density functional theory calculations were carried out to locate the most plausible atomic sites of the magnesium and protons, enabling us to complete the structure modeling. This work provides an explicit answer to the question about Mg intercalation into α-V₂O₅

New Bifunctional Chelator for ⁶⁴Cu-Immuno-Positron Emission Tomography

A new tetraazamacrocyclic bifunctional chelator, TE2A-Bn-NCS, was synthesized in high overall yield from cyclam. An extra functional group (NCS) was introduced to the <i>N</i>-atom of TE2A for specific conjugation with antibody. The Cu complex of TE2A-Bn-NCS showed high kinetic stability in acidic decomplexation and cyclic voltammetry studies. X-ray structure determination of the Cu-TE2A-Bn-NH₂ complex confirmed octahedral geometry, in which copper atom is strongly coordinated by four macrocyclic nitrogens in equatorial positions and two carboxylate oxygen atoms occupy the elongated axial positions. Trastuzumab was conjugated with TE2A-Bn-NCS and then radiolabeled with ⁶⁴Cu quantitatively at room temperature within 10 min. Biodistribution studies showed that the ⁶⁴Cu-labeled TE2A-Bn-NCS-trastuzumab conjugates maintain high stability in physiological conditions, and NIH3T6.7 tumors were clearly visualized up to 3 days by ⁶⁴Cu-immuno-positron emission tomography imaging in animal models

Non-Grignard and Lewis Acid-Free Sulfone Electrolytes for Rechargeable Magnesium Batteries

A major challenge for developing rechargeable Mg-ion batteries (MIB) is the lack of suitable electrolytes. We report herein dialkyl sulfones as non-Grignard and Lewis acid-free MIB electrolytes. In particular, a dipropyl sulfone (DPSO)/tetrahydrofuran (THF) (1/1, v/v) solution with MgCl₂ salt exhibits high ionic conductivity (1.1 mS cm^–1 at 30 °C), Mg cycling efficiency (>90%), and anodic stability (ca. 3.0 V vs Mg). As evidenced by single crystal X-ray diffraction analysis, a novel [Mg­(DPSO)₆]²⁺ cation complex balanced by two [MgCl₃(THF)]⁻ anions is identified in the DPSO/THF solution. The DPSO/THF electrolyte also enables excellent cycle performance (>300 cycles) of a Chevrel phase Mo₆S₈ cathode and displays a decent compatibility with an organic cathode (3,4,9,10-perylenetetracarboxylic dianhydride, PTCDA). Along with the superior electrochemical properties of the DPSO/THF electrolyte, its innate chemical stability and eco-friendly nature make it a promising MIB electrolyte

Fire-Inhibiting Nonflammable Gel Polymer Electrolyte for Lithium-Ion Batteries

Herein, we present a gel polymer electrolyte (GPE) improving nonflammability of lithium-ion batteries (LIBs) by blocking radical-initiated chain reactions which cause thermal runaway and finally fire issues. The polymer that makes up the nonflammable GPE was (1) soluble in carbonate electrolytes, (2) cross-linkable in the presence of a popularly used lithium salt such as LiPF6, (3) gelated only with 2 wt % in electrolytes, and (4) radical-scavenging by its functional side chains. Electrolytes having the polymer were thermally gelated within battery cells after the cells were assembled by a conventional way. LIB cells with the GPE were durable against external thermal and mechanical shocks without sacrificing cell performances. The high transference number of lithium ions and liquid-equivalent ionic conductivity of the GPE at only 2% solid content having a stable solid-electrolyte interphase layer formed even improved cell performances at normal operation conditions

Fire-Inhibiting Nonflammable Gel Polymer Electrolyte for Lithium-Ion Batteries

Herein, we present a gel polymer electrolyte (GPE) improving nonflammability of lithium-ion batteries (LIBs) by blocking radical-initiated chain reactions which cause thermal runaway and finally fire issues. The polymer that makes up the nonflammable GPE was (1) soluble in carbonate electrolytes, (2) cross-linkable in the presence of a popularly used lithium salt such as LiPF6, (3) gelated only with 2 wt % in electrolytes, and (4) radical-scavenging by its functional side chains. Electrolytes having the polymer were thermally gelated within battery cells after the cells were assembled by a conventional way. LIB cells with the GPE were durable against external thermal and mechanical shocks without sacrificing cell performances. The high transference number of lithium ions and liquid-equivalent ionic conductivity of the GPE at only 2% solid content having a stable solid-electrolyte interphase layer formed even improved cell performances at normal operation conditions

Fire-Inhibiting Nonflammable Gel Polymer Electrolyte for Lithium-Ion Batteries

Herein, we present a gel polymer electrolyte (GPE) improving nonflammability of lithium-ion batteries (LIBs) by blocking radical-initiated chain reactions which cause thermal runaway and finally fire issues. The polymer that makes up the nonflammable GPE was (1) soluble in carbonate electrolytes, (2) cross-linkable in the presence of a popularly used lithium salt such as LiPF6, (3) gelated only with 2 wt % in electrolytes, and (4) radical-scavenging by its functional side chains. Electrolytes having the polymer were thermally gelated within battery cells after the cells were assembled by a conventional way. LIB cells with the GPE were durable against external thermal and mechanical shocks without sacrificing cell performances. The high transference number of lithium ions and liquid-equivalent ionic conductivity of the GPE at only 2% solid content having a stable solid-electrolyte interphase layer formed even improved cell performances at normal operation conditions

Phosphonate Pendant Armed Propylene Cross-Bridged Cyclam: Synthesis and Evaluation as a Chelator for Cu-64

A propylene cross-bridged macrocyclic chelator with two phosphonate pendant arms (PCB-TE2P) was synthesized from cyclam. Various properties of the synthesized chelator, including Cu-complexation, Cu-complex stability, ⁶⁴Cu-radiolabeling, and in vivo behavior, were studied and compared with those of a previously reported propylene cross-bridged chelator (PCB-TE2A)