Engineering the formulation of non-aqueous liquid electrolytes is a viable strategy to produce high-energy lithium metal batteries. However, when the lithium metal anode is combined with a Ni-rich layered cathode, the (electro)chemical stability of both electrodes could be compromised. To circumvent this issue, we report a combination of aluminum ethoxide (0.4 wt.%) and fluoroethylene carbonate (5 vol.%) as additives in a conventional LiPF6-containing carbonate-based electrolyte solution. This electrolyte formulation enables the formation of mechanically robust and ionically conductive interphases on both electrodes’ surfaces. In particular, the alumina formed at the interphases prevents the formation of dendritic structures on the lithium metal anode and mitigate the stress-induced cracking and phase transformation in the Ni-rich layered cathode. By coupling a thin (i.e., about 40 μm) lithium metal anode with a high-loading (i.e., 21.5 mg cm−2) LiNi0.8Co0.1Mn0.1O2-based cathode in coin cell configuration and lean electrolyte conditions, the engineered electrolyte allows a specific discharge capacity retention of 80.3% after 130 cycles at 60 mA g−1 and 30 °C which results in calculated specific cell energy of about 350 Wh kg−1.
Characteristics like air-stability and high carrier mobility make non-van-der-Waals layered Bi2O2Se a good prospect for planar integrated nanosystems. However, experimental investigation about its analogue Bi2O2Te is rather rare due to difficulty in synthesis. Herein, a low-pressure CVD process is proposed that is adjusted to the rigorous growth condition required, with large-scale Bi2O2Te ultrathin film obtained. Magneto-transport behavior reveals a very large anisotropic nonsaturating low-temperature magnetoresistance (∼1133% under 9 T magnetic field). Despite the contradiction between high conductivity and ferroelectricity in principle (mobile electrons screen electrostatic forces between ions), the high-conductive Bi2O2Te film here is revealed experimentally as another intrinsic ferroelectric with the polarization switchable by external electric field (predicted in Nano Lett. 2017, 17, 6309). These results prove that Bi2O2Te possesses a very narrow bandgap (∼0.15 eV), high conductivity, large magnetoresistance, and room-temperature ferroelectricity, displaying great potential as a high-performance nanoelectronic two-dimensional semiconductor and, in advanced functional devices, working in the mid-infrared region.
In nature, the human body is a perfect self-organizing and self-repairing system, with the skin protecting the internal organs and tissues from external damages. In this work, inspired by the human skin, we design a metal electrode skin (MES) to protect the metal interface. MES can increase the flatness of electrode and uniform the electric field distribution, inhibiting the growth of dendrites. In detail, an artificial film made of fluorinated graphene oxide serves as the first protection layer. At molecular level, fluorine is released and in-situ formed a robust SEI as the second protection “skin” for metal anode. As a result, Cu@MES | | K asymmetric cell is able to achieve an unprecedented cycle life (over 1600 cycles). More impressively, the full cell of K@MES | | Prussian blue exhibits a long cycle lifespan over 5000 cycles. This work illustrates a mechanism for metal electrode protection and provides a strategy for the applying bionics in batteries.
Aqueous sodium-ion batteries (AIBs) are promising candidates for large-scale energy storage due to their safe operational properties and low cost. However, AIBs have low specific energy (i.e., <80 Wh kg−1) and limited lifespans (e.g., hundreds of cycles). Mn-Fe Prussian blue analogues are considered ideal positive electrode materials for AIBs, but they show rapid capacity decay due to Jahn-Teller distortions. To circumvent these issues, here, we propose a cation-trapping method that involves the introduction of sodium ferrocyanide (Na4Fe(CN)6) as a supporting salt in a highly concentrated NaClO4-based aqueous electrolyte solution to fill the surface Mn vacancies formed in Fe-substituted Prussian blue Na1.58Fe0.07Mn0.97Fe(CN)6 · 2.65H2O (NaFeMnF) positive electrode materials during cycling. When the engineered aqueous electrolyte solution and the NaFeMnF-based positive electrode are tested in combination with a 3, 4, 9, 10-perylenetetracarboxylic diimide-based negative electrode in a coin cell configuration, a specific energy of 94 Wh kg–1 at 0.5 A g−1 (specific energy based on the active material mass of both electrodes) and a specific discharge capacity retention of 73.4% after 15000 cycles at 2 A g−1 are achieved.
Ca‐metal batteries, one of the promising advanced energy storage devices, have received significant development in the last few years. However, challenges still exist in efficient and cost‐effective Ca‐metal utilization, fast Ca‐ion transport and diffusion, and high energy density and stable‐cycling Ca‐storage. Herein, by cross‐checking most relevant literature reported previously, an intuitive depiction for state‐of‐the‐art Ca‐metal batteries, including collectors, electrolytes, and cathode materials, is presented from a voltage‐capacity‐efficiency's view, which facilitates reasonable comparisons from related fields. The performance of most cathode materials and calcium‐metal electrodes in various electrolytes reported previously is comprehensively reviewed, as well as interphases and collectors. The strong and weak points of various electrolytes are discussed, and relevant challenges are pointed out. Recent breakthroughs in electrolyte and interphase engineering are emphasized. Finally, potential development directions for Ca‐metal and electrolytes, as well as some future prospects for cathode materials, are rationally predicted.
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