Oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) involve proton coupled electron transfer reaction (PCET), resulting in sluggish redox kinetics. At present, the development of high-efficiency bifunctional oxygen electrocatalysts is still a puzzling challenge. Herein, we propose a scalable strategy for embedding and beading ZIF-derived hollow Co–Nx nanocube cage dispersion implanted with porous carbonized nanofibers (EH/PCNFs and BH/PCNFs) through electrospinning and annealing. The cobalt species prevent themselves from agglomerating during the annealing process through the “fence” effect of the non-volatile Zn species, thereby synergizing with ligand volatilization to facilitate the formation of Co–Nx nanocube cages. Benefiting from the ultralong interconnected multi-layered carbon nanofiber matrix, the hollow Co–Nx nanocube cages can change the charge density and electron distribution of the carbon nanofiber matrix, endowing the carbonized nanofiber carrier with special surface polarization and accelerating the electrocatalytic kinetics. Remarkably, the integrated Li–O2 batteries (LOBs) based on BH/PCNFs and EH/PCNFs electrodes exhibit significantly decreased charge/discharge polarization (0.79 V) and a long-term cyclability (147 cycles) under a cut off capacity of 500 mA h g−1 at 200 mA g−1. This work might be beneficial for the practically viable design and manufacture of dual-function oxygen electrocatalysts.
All-solid-state Li batteries (ASSLBs) with solid-state electrolytes (SSEs) are exciting candidates for next-generation energy storage and receive considerable attention owing to their reliability. Halide SSEs are promising candidates due to their excellent stability against 4 V-class layered cathodes. Compared with Li 3 InCl 6 or Li 3 ScCl 6 , the low ionic conductivity of Li 2 ZrCl 6 (LZC) is a challenge despite its low raw-material cost. Herein, we report a family of Li-Richened chloride, Li 2+2 x Zr 1– x M x Cl 6 , which can be used in high-performance ASSLBs owing to its high ionic conductivity (up to 0.62 mS cm −1 ). The theoretical (ab initio molecular dynamics simulations) and experimental results prove that the strategy of aliovalent substitution with divalent metals to obtain Li-Richened LZC is effective in improving Li + conductivity in SSEs. By combining Li 2.1 Zr 0.95 Mg 0.05 Cl 6 (Mg5-LZC) with a Li–In anode and a LiCoO 2 cathode, a room-temperature ASSLBs with excellent long-term cycling stability (88% capacity retention at 0.3C for 100 cycles) and high-rate capability (121 mA h g −1 at 1C) is reported. This exploratory work sheds light on improving the Li + conductivity of low-cost LZC-family SSEs for constructing high performance ASSLBs.
Polymer electrolytes (PEs) synthesized from an in situ polymerization strategy are considered as promising candidates to improve interfacial compatibility. However, most in situ formed PEs still suffer from problems such as low lithium-ion transference number (tLi+) and insufficient ionic conductivity at room temperature (RT). Herein, a series of copolymer electrolytes (CPEs) consisting of 1,3-dioxolane (DOL) and 1,3,5-trioxane (TXE) monomers are synthesized. Due to the additive of succinonitrile (SN), and the promoted dissociation of lithium salt, the obtained polymer electrolyte (SN-CPE) exhibits an excellent ionic conductivity (4.06 × 10−4 S cm−1) and a high lithium-ion transference number (tLi+ = 0.881) at RT, as well as a high voltage oxidation window of 5.1 V. Thanks to the in situ formed intimate contacted electrode/electrolyte interface, the symmetric Li/Li cell can achieve long-term cycling stability over 1500 h without a short circuit. A LiF-rich organic–inorganic composite layer is formed on both the solid electrolyte interphase (SEI) and cathode electrolyte interphase (CEI) as demonstrated by XPS, TEM, and SEM analyses. Thereafter, the LiFePO4/Li cell has a high capacity retention of 84.1% after 900 cycles at RT, and it can still work effectively at high temperatures (e.g. 80 °C). Furthermore, SN-CPE exhibits excellent electrochemical performance and safety in the LiCoO2/Li cell and LiFePO4/graphite pouch cell, which again supports the promising application of SN-CPE.
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