Design Principles of Quinone Redox Systems for Advanced Sulfide Solid-State Organic Lithium Metal Batteries.

The emergence of solid-state battery technology presents a potential solution to the dissolution challenges of high-capacity small molecule quinone redox systems. Nonetheless, the successful integration of argyrodite-type Li6PS5Cl, the most promising solid-state electrolyte system, and quinone redox systems remains elusive due to their inherent reactivity. Here, a library of quinone derivatives is selected as model electrode materials to ascertain the critical descriptors governing the (electro)chemical compatibility and subsequently the performances of Li6PS5Cl-based solid-state organic lithium metal batteries (LMBs). Compatibility is attained if the lowest unoccupied molecular orbital level of the quinone derivative is sufficiently higher than the highest occupied molecular orbital level of Li6PS5Cl. The energy difference is demonstrated to be critical in ensuring chemical compatibility during composite electrode preparation and enable high-efficiency operation of solid-state organic LMBs. Considering these findings, a general principle is proposed for the selection of quinone derivatives to be integrated with Li6PS5Cl, and two solid-state organic LMBs, based on 2,5-diamino-1,4-benzoquinone and 2,3,5,6-tetraamino-1,4-benzoquinone, are successfully developed and tested for the first time. Validating critical factors for the design of organic battery electrode materials is expected to pave the way for advancing the development of high-efficiency and long cycle life solid-state organic batteries based on sulfides electrolytes.

Controlling Charge Transport in 2D Conductive MOFs─The Role of Nitrogen-Rich Ligands and Chemical Functionality.

Two-dimensional electrically conducting metal-organic frameworks (2D-e-MOFs) have emerged as a class of highly promising functional materials for a wide range of applications. However, despite the significant recent advances in 2D-e-MOFs, developing systems that can be postsynthetically chemically functionalized, while also allowing fine-tuning of the transport properties, remains challenging. Herein, we report two isostructural 2D-e-MOFs: Ni3(HITAT)2 and Ni3(HITBim)2 based on two new 3-fold symmetric ligands: 2,3,7,8,12,13-hexaaminotriazatruxene (HATAT) and 2,3,8,9,14,15-hexaaminotribenzimidazole (HATBim), respectively, with reactive sites for postfunctionalization. Ni3(HITAT)2 and Ni3(HITBim)2 exhibit temperature-activated charge transport, with bulk conductivity values of 44 and 0.5 mS cm-1, respectively. Density functional theory analysis attributes the difference to disparities in the electron density distribution within the parent ligands: nitrogen-rich HATBim exhibits localized electron density and a notably lower lowest unoccupied molecular orbital (LUMO) energy relative to HATAT. Precise amounts of methanesulfonyl groups are covalently bonded to the N-H indole moiety within the Ni3(HITAT)2 framework, modulating the electrical conductivity by a factor of ∼20. These results provide a blueprint for the design of porous functional materials with tunable chemical functionality and electrical response.

Fluorine-free organic electrolytes for the stable electrodeposition of neodymium metal.

Electrowinning is regarded as a clean process to recover neodymium metal from secondary sources such as spent Nd-Fe-B permanent magnets, but the current methods are severely limited by a high energy consumption (molten salts), or by the high costs and environmental impact of the electrolyte components (ionic liquids). Therefore, there is a demand for more sustainable electrowinning methods for the recovery of neodymium metal. Inspired by our own previous work and the work of others, we developed new fluorine-free organic electrolytes that enable the electrodeposition of neodymium metal at room temperature. The electrolytes consist of solvated neodymium borohydride, Nd(BH4)3, dissolved in the ether solvents tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-MeTHF), 1,2-dimethoxyethane (DME) and diethylene glycol dimethyl ether (diglyme, G2), and these complexes can be prepared entirely from non-fluorinated precursors such as neodymium(III) chloride (NdCl3) and sodium borohydride (NaBH4). In contrast to our previous bis(trifluoromethylsulfonyl)imide-containing electrolytes, electrodeposition of neodymium proceeds over time without significant loss of current density, indicating a higher stability against unwanted side-reactions that lead to passivation of the deposit on the electrode. Characterization of the deposits by scanning electron microscopy (SEM), energy-dispersive X-ray fluorescence (EDX), and X-ray photoelectron spectroscopy (XPS) unambiguously indicated the presence of neodymium metal.

Modulating the Interlayer Spacing and Na+/Vacancy Disordering of P2-Na0.67MnO2 for Fast Diffusion and High-Rate Sodium Storage.

Modulating the interlayer spacing and Na+/vacancy disordering can significantly affect the electrochemical behavior of P2-type cathode materials. In this work, we prepare a series of P2-Na0.67MnO2 cathodes (Na0.67Ni0.2- xMn0.8Mg xO2) with varying doping amounts of Mg and Ni to realize the maximization of the interlayer spacing within the experimental range and optimize the Na+/vacancy ordering. Consequently, the as-prepared Na0.67Ni0.1Mn0.8Mg0.1O2 illustrates an excellent rate performance of 193 mA h g-1 discharge capacity at 0.1 C (1 C = 180 mA g-1), and even at a high rate of 8 C, the battery can deliver a capacity of 70 mA h g-1. The kinetics analysis indicates the raising of Na+ mobility, which could due to the reduced Na+/vacancy ordering and the enhanced Na interlayer spacing. The codoping of Ni and Mg also enhances the stability of the layered structure, leading to improved cycling performance of 74.7% capacity retention after 100 cycles.

Achieving High-Energy Full-Cell Lithium-Storage Performance by Coupling High-Capacity V2O3 with Low-Potential Ni2P Anode.

To optimize the potential window and maximize the utilization of the capacity of both negative and positive electrodes, rational design of electrode materials are critically important in full-cell construction of rechargeable batteries. In this work, we propose and fabricate a carbon-confined V2O3/Ni2P/C composite structure for excellent performance lithium ion batteries by taking advantage of the high capacity of V2O3 and low potential of Ni2P. The full cell constructed with V2O3/Ni2P/C as anode and commercial LiMn2O4 as cathode offers a record high energy density of 361.5 Wh kg-1 and excellent cycle stability, outperforming the state-of-the-art work reported in literature.