Polymer–ceramic composite electrolytes are emerging as a promising solution to deliver high ionic conductivity, optimal mechanical properties, and good safety for developing high‐performance ...all‐solid‐state rechargeable batteries. Composite electrolytes have been prepared with cubic‐phase Li7La3Zr2O12 (LLZO) garnet and polyethylene oxide (PEO) and employed in symmetric lithium battery cells. By combining selective isotope labeling and high‐resolution solid‐state Li NMR, we are able to track Li ion pathways within LLZO‐PEO composite electrolytes by monitoring the replacement of 7Li in the composite electrolyte by 6Li from the 6Li metal electrodes during battery cycling. We have provided the first experimental evidence to show that Li ions favor the pathway through the LLZO ceramic phase instead of the PEO‐LLZO interface or PEO. This approach can be widely applied to study ion pathways in ionic conductors and to provide useful insights for developing composite materials for energy storage and harvesting.
Where do they go? The first experimental evidence was obtained for lithium ions diffusing through composite ceramic electrolytes (LLZO and PEO) in an all‐solid‐state battery. Lithium ion diffusion was determined using 6,7Li NMR and isotope exchange, and indicated that Li ions mainly pass through the LLZO ceramic phase instead of the LLZO‐PEO interface or the PEO phase.
Li+‐conducting oxides are considered better ceramic fillers than Li+‐insulating oxides for improving Li+ conductivity in composite polymer electrolytes owing to their ability to conduct Li+ through ...the ceramic oxide as well as across the oxide/polymer interface. Here we use two Li+‐insulating oxides (fluorite Gd0.1Ce0.9O1.95 and perovskite La0.8Sr0.2Ga0.8Mg0.2O2.55) with a high concentration of oxygen vacancies to demonstrate two oxide/poly(ethylene oxide) (PEO)‐based polymer composite electrolytes, each with a Li+ conductivity above 10−4 S cm−1 at 30 °C. Li solid‐state NMR results show an increase in Li+ ions (>10 %) occupying the more mobile A2 environment in the composite electrolytes. This increase in A2‐site occupancy originates from the strong interaction between the O2− of Li‐salt anion and the surface oxygen vacancies of each oxide and contributes to the more facile Li+ transport. All‐solid‐state Li‐metal cells with these composite electrolytes demonstrate a small interfacial resistance with good cycling performance at 35 °C.
The strong interaction between the surface oxygen vacancies of GDC/LSGM and the TFSI− anions in the composite polymer electrolyte changes Li+ distribution in two local environments, and the population increase of mobile Li+ ions in A2 significantly enhances the Li+ conductivity of the composite electrolyte.
Composite electrolytes are widely studied for their potential in realizing improved ionic conductivity and electrochemical stability. Understanding the complex mechanisms of ion transport within ...composites is critical for effectively designing high-performance solid electrolytes. This study examines the compositional dependence of the three determining factors for ionic conductivity, including ion mobility, ion transport pathways, and active ion concentration. The results show that with increase in the fraction of ceramic Li7La3Zr2O12 (LLZO) phase in the LLZO–poly(ethylene oxide) composites, ion mobility decreases, ion transport pathways transit from polymer to ceramic routes, and the active ion concentration increases. These changes in ion mobility, transport pathways, and concentration collectively explain the observed trend of ionic conductivity in composite electrolytes. Liquid additives alter ion transport pathways and increase ion mobility, thus enhancing ionic conductivity significantly. It is also found that a higher content of LLZO leads to improved electrochemical stability of composite electrolytes. This study provides insight into the recurring observations of compositional dependence of ionic conductivity in current composite electrolytes and pinpoints the intrinsic limitations of composite electrolytes in achieving fast ion conduction.
While sodium-ion batteries (SIBs) hold great promise for large-scale electric energy storage and low speed electric vehicles, the poor capacity retention of the cathode is one of the bottlenecks in ...the development of SIBs. Following a strategy of using lithium doping in the transition-metal layer to stabilize the desodiated structure, we have designed and successfully synthesized a novel layered oxide cathode P2–Na0.66Li0.18Fe0.12Mn0.7O2, which demonstrated a high capacity of 190 mAh g–1 and a remarkably high capacity retention of ∼87% after 80 cycles within a wide voltage range of 1.5–4.5 V. The outstanding stability is attributed to the reversible migration of lithium during cycling and the elimination of the detrimental P2–O2 phase transition, revealed by ex situ and in situ X-ray diffraction and solid-state nuclear magnetic resonance spectroscopy.
Over the past 3 years, glucose oxidase (GOx) has aroused great research interest in the context of cancer treatment due to its inherent biocompatibility and biodegradability, and its unique catalytic ...properties against β‐d‐glucose. GOx can effectively catalyze the oxidation of glucose into gluconic acid and hydrogen peroxide. This process depletes oxygen levels, resulting in elevated acidity, hypoxia, and oxidative stress in the tumor microenvironment. All of these changes can be readily harnessed to develop a multimodal synergistic cancer therapy by combining GOx with other therapeutic approaches. Herein, the representative studies of GOx‐instructed multimodal synergistic cancer therapy are introduced, and their synergistic mechanisms are discussed systematically. The current challenges and future prospects to advance the development of GOx‐based nanomedicines in this cutting‐edge research area are highlighted.
The rapid developments in GOx‐instructed multimodal synergistic cancer therapy and their synergistic mechanisms are systematically discussed; the current challenges and future prospects are also highlighted to expedite the development of GOx‐based nanomedicines.
Although solid-state lithium (Li)-metal batteries promise both high energy density and safety, existing solid ion conductors fail to satisfy the rigorous requirements of battery operations. Inorganic ...ion conductors allow fast ion transport, but their rigid and brittle nature prevents good interfacial contact with electrodes. Conversely, polymer ion conductors that are Li-metal-stable usually provide better interfacial compatibility and mechanical tolerance, but typically suffer from inferior ionic conductivity owing to the coupling of the ion transport with the motion of the polymer chains
. Here we report a general strategy for achieving high-performance solid polymer ion conductors by engineering of molecular channels. Through the coordination of copper ions (Cu
) with one-dimensional cellulose nanofibrils, we show that the opening of molecular channels within the normally ion-insulating cellulose enables rapid transport of Li
ions along the polymer chains. In addition to high Li
conductivity (1.5 × 10
siemens per centimetre at room temperature along the molecular chain direction), the Cu
-coordinated cellulose ion conductor also exhibits a high transference number (0.78, compared with 0.2-0.5 in other polymers
) and a wide window of electrochemical stability (0-4.5 volts) that can accommodate both the Li-metal anode and high-voltage cathodes. This one-dimensional ion conductor also allows ion percolation in thick LiFePO
solid-state cathodes for application in batteries with a high energy density. Furthermore, we have verified the universality of this molecular-channel engineering approach with other polymers and cations, achieving similarly high conductivities, with implications that could go beyond safe, high-performance solid-state batteries.
The large-voltage hysteresis remains one of the biggest barriers to optimizing Li/Na-ion cathodes using lattice anionic redox reaction, despite their very high energy density and relative low cost. ...Very recently, a layered sodium cathode Na2Mn3O7 (or Na4/7Mn6/7□1/7O2, □ is vacancy) was reported to have reversible lattice oxygen redox with much suppressed voltage hysteresis. However, the structural and electronic structural origin of this small-voltage hysteresis has not been well understood. In this article, through systematic studies using ex situ/in situ electron paramagnetic resonance and X-ray diffraction, we demonstrate that the exceptional small-voltage hysteresis (<50 mV) between charge and discharge curves is rooted in the well-maintained oxygen stacking sequence in the absence of irreversible gliding of oxygen layers and cation migration from the transition-metal layers. In addition, we further identify that the 4.2 V charge/discharge plateau is associated with a zero-strain (de)intercalation process of Na+ ions from distorted octahedral sites, while the 4.5 V plateau is linked to a reversible shrink/expansion process of the manganese-site vacancy during (de)intercalation of Na+ ions at distorted prismatic sites. It is expected that these findings will inspire further exploration of new cathode materials that can achieve both high energy density and efficiency by using lattice anionic redox.
To enhance Li+ transport in all‐solid‐state batteries (ASSBs), harnessing localized nanoscale disorder can be instrumental, especially in sulfide‐based solid electrolytes (SEs). In this ...investigation, the transformation of the model SE, Li3PS4, is delved into via the introduction of LiBr. 31P nuclear magnetic resonance (NMR)unveils the emergence of a glassy PS43− network interspersed with Br−. 6Li NMR corroborates swift Li+ migration between PS43− and Br−, with increased Li+ mobility indicated by NMR relaxation measurements. A more than fourfold enhancement in ionic conductivity is observed upon LiBr incorporation into Li3PS4. Moreover, a notable decrease in activation energy underscores the pivotal role of Br− incorporation within the anionic lattice, effectively reducing the energy barrier for ion conduction and transitioning Li+ transport dimensionality from 2D to 3D. The compatibility of Li3PS4 with Li metal is improved through LiBr incorporation, alongside an increase in critical current density from 0.34 to 0.50 mA cm−2, while preserving the electrochemical stability window. ASSBs with 3Li3PS4:LiBr as the SE showcase robust high‐rate and long‐term cycling performance. These findings collectively indicate the potential of lithium halide incorporation as a promising avenue to enhance the ionic conductivity and stability of SEs.
Incorporation of Br‐ into the β‐Li3PS4 anion sublattice creates local disorder and diversifies coordinating partners of Li+, yielding fast‐ion transport with lowered activation energy barriers and improved compatibility with Li metal anodes. This approach holds promise for enhancing the ion conduction and stability of sulfide‐based solid electrolytes for all‐solid‐state batteries.
Solid‐oxide Li+ electrolytes of a rechargeable cell are generally sensitive to moisture in the air as H+ exchanges for the mobile Li+ of the electrolyte and forms insulating surface phases at the ...electrolyte interfaces and in the grain boundaries of a polycrystalline membrane. These surface phases dominate the total interfacial resistance of a conventional rechargeable cell with a solid–electrolyte separator. We report a new perovskite Li+ solid electrolyte, Li0.38Sr0.44Ta0.7Hf0.3O2.95F0.05, with a lithium‐ion conductivity of σLi=4.8×10−4 S cm−1 at 25 °C that does not react with water having 3≤pH≤14. The solid electrolyte with a thin Li+‐conducting polymer on its surface to prevent reduction of Ta5+ is wet by metallic lithium and provides low‐impedance dendrite‐free plating/stripping of a lithium anode. It is also stable upon contact with a composite polymer cathode. With this solid electrolyte, we demonstrate excellent cycling performance of an all‐solid‐state Li/LiFePO4 cell, a Li‐S cell with a polymer‐gel cathode, and a supercapacitor.
A perovskite that is stable in water with 3≤pH≤14 shows small interfacial resistance and excellent cycling performance in an all‐solid‐state Li/LiFePO4 cell, a Li‐S cell, and a supercapacitor.
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