Abstract
Electrochemical reduction of CO
2
to multi-carbon fuels and chemical feedstocks is an appealing approach to mitigate excessive CO
2
emissions. However, the reported catalysts always show ...either a low Faradaic efficiency of the C
2+
product or poor long-term stability. Herein, we report a facile and scalable anodic corrosion method to synthesize oxygen-rich ultrathin CuO nanoplate arrays, which form Cu/Cu
2
O heterogeneous interfaces through self-evolution during electrocatalysis. The catalyst exhibits a high C
2
H
4
Faradaic efficiency of 84.5%, stable electrolysis for ~55 h in a flow cell using a neutral KCl electrolyte, and a full-cell ethylene energy efficiency of 27.6% at 200 mA cm
−2
in a membrane electrode assembly electrolyzer. Mechanism analyses reveal that the stable nanostructures, stable Cu/Cu
2
O interfaces, and enhanced adsorption of the *OCCOH intermediate preserve selective and prolonged C
2
H
4
production. The robust and scalable produced catalyst coupled with mild electrolytic conditions facilitates the practical application of electrochemical CO
2
reduction.
MXene has been found as a good host for lithium (Li) metal anodes because of its high specific surface area, lithiophilicity, good stability with lithium, and the in situ formed LiF protective layer. ...However, the formation of Li dendrites and dead Li is inevitable during long‐term cycle due to the lack of protection at the Li/electrolyte interface. Herein, a stable artificial solid electrolyte interface (SEI) is constructed on the MXene surface by using insulating g‐C3N4 layer to regulate homogeneous Li plating/stripping. The 2D/2D MXene/g‐C3N4 composite nanosheets can not only guarantee sufficient lithiophilic sites, but also protect the Li metal from continuous corrosion by electrolytes. Thus, the Ti3C2Tx/g‐C3N4 electrode enables conformal Li deposition, enhanced average Coulombic efficiency (CE) of 98.4%, and longer cycle lifespan over 400 cycles with an areal capacity of 1.0 mAh cm−2 at 0.5 mA cm−2. Full cells paired with LiFePO4 (LFP) cathode also achieve enhanced rate capacity and cycling stability with higher capacity retention of 85.5% after 320 cycles at 0.5C. The advantages of the 2D/2D lithiophilic layer/artificial SEI layer heterostructures provide important insights into the design strategies for high‐performance and stable Li metal batteries.
A stable artificial solid electrolyte interface is constructed on the MXene surface by using insulating g‐C3N4 layer to regulate homogeneous Li plating/stripping. The amorphous g‐C3N4 enables highly uniform artificial SEI and MXene provides sufficient lithiophilic sites for Li nucleation. The obtained Ti3C2Tx/g‐C3N4 composite electrode enables conformal Li deposition, enhanced average Coulombic efficiency, and longer cycle lifespan.
Abstract
Single-atom catalysts provide efficiently utilized active sites to improve catalytic activities while improving the stability and enhancing the activities to the level of their bulk metallic ...counterparts are grand challenges. Herein, we demonstrate a family of single-atom catalysts with different interaction types by confining metal single atoms into the van der Waals gap of two-dimensional SnS
2
. The relatively weak bonding between the noble metal single atoms and the host endows the single atoms with more intrinsic catalytic activity compared to the ones with strong chemical bonding, while the protection offered by the layered material leads to ultrahigh stability compared to the physically adsorbed single-atom catalysts on the surface. Specifically, the trace Pt-intercalated SnS
2
catalyst has superior long-term durability and comparable performance to that of commercial 10 wt% Pt/C catalyst in hydrogen evolution reaction. This work opens an avenue to explore high-performance intercalated single-atom electrocatalysts within various two-dimensional materials.
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•The enhanced Li+ transport is obtained in AAO-20 nanochannels through the pore sizes effects on transference number and ionic conductivity, preventing rapid Li+ depletion near the ...deposition substrate potentially.•Smaller Li nucleation overpotential and larger exchange current density in AAO-20 can directly reveal the enhanced kinetics at deposition interface, which is derived from the improved Li+ transport in nanochannels, leading to a superior Li deposition.•Stable Li deposition behavior in AAO-20 can achieve excellent cycling performances in different cells.
The high theoretical capacity of lithium (Li) has sparkled its intensive research as the anode for Li batteries. However, the dendritic growth due to the uneven Li deposition causes premature cell failure and dramatically restricts the application of Li anode. Herein, inspired by the pore sizes effects of anodized aluminum oxide (AAO) membranes on Li+ transport performance, 20 nm aperture membrane (AAO-20) with enhanced Li+ transport can achieve higher Li+ concentration near the deposition substrate, possibly preventing rapid Li+ depletion compared to other aperture sizes. Subsequently, smaller Li nucleation overpotential and larger exchange current density in AAO-20 reveal the enhanced kinetics at deposition interface, which is derived from the enhanced Li+ transport in nanochannels, leading to a superior Li deposition. With AAO-20 which can stabilize Li anode, Li-Cu, Li-Li, and Li-LiFePO4 cells demonstrate high Coulombic efficiency, superior cycling stability, and excellent capacity retention, respectively. Such findings can be helpful for the development of high-energy Li metal batteries.
Solid polymer electrolytes (SPEs) are seen as the key component in the development of solid-state lithium batteries (SSLBs) by virtue of their good processability and flexibility. However, poor ...mechanical strength, low room-temperature lithium-ion (Li-ion) conductivity and unsatisfactory interfacial compatibility with electrodes limit their practical application. In this work, a composite electrolyte consisting of polyvinylidene fluoride and polyvinylidene carbonate with a Li6.4La3Zr1.4Ta0.6O12(LLZTO) active filler (PFPC: LLZTO-SPE) is reported to achieve excellent ionic conductivity (4.25 × 10−4 S cm−1 at 30 °C), a wide electrochemical window (>4.6 V), a high Li-ion transference number (tLi+ = 0.49) and good interfacial compatibility with the electrode. Incorporating LLZTO as an active filler not only increases the ionic conductivity of the electrolyte, but also homogenizes Li-ion flux and stabilizes the electrode/electrolyte interface, thereby preventing lithium dendrites from piercing the electrolyte. As a result, Li/Li symmetrical cells using PFPC: LLZTO-SPEs deliver more than 800 h of cyclability at 0.1 mA cm−2 and a high critical current density (CCD) of 2.6 mA cm−2. The assembled Li/PFPC: LLZTO/LFP SSLBs achieve 87% capacity retention after 150 cycles at 0.2 C and 89% capacity retention for 100 cycles at 0.5 C. This work inspires new insights into designing high-performance SPEs.
Solid‐state lithium batteries (SSLBs) have received considerable attention due to their advantages in thermal stability, energy density, and safety. Solid electrolyte (SE) is a key component in ...developing high‐performance SSLBs. An in‐depth understanding of the intrinsic bulk and interfacial properties is imperative to achieve SEs with competitive performance. This review first introduces the traditional electrochemical approaches to evaluating the fundamental parameters of SEs, including the ionic and electronic conductivities, activation barrier, electrochemical stability, and diffusion coefficient. After that, the characterization techniques to evaluate the structural and chemical stability of SEs are reviewed. Further, emerging interdisciplinary visualization techniques for SEs and interfaces are highlighted, including synchrotron X‐ray tomography, ultrasonic scanning imaging, time‐of‐flight secondary‐ion mass spectrometry, and three‐dimensional stress mapping, which improve the understanding of electrochemical performance and failure mechanisms. In addition, the application of machine learning to accelerate the screening and development of novel SEs is introduced. This review article aims to provide an overview of advanced characterization from a broad physical chemistry view, inspiring innovative and interdisciplinary studies in solid‐state batteries.
The evaluation of solid electrolytes (SEs) is essential for the development of solid‐state lithium batteries. This review introduces the conventional electrochemical approaches to evaluating the fundamental parameters of SEs. Furthermore, emerging structural characterizations and interdisciplinary techniques for SEs and interfaces are highlighted, including synchrotron X‐ray tomography, ultrasonic scanning imaging, time‐of‐flight secondary‐ion mass spectrometry, three‐dimensional stress mapping, and machine learning.
Interfacial chemistry between lithium metal anodes and electrolytes plays a vital role in regulating the Li plating/stripping behavior and improving the cycling performance of Li metal batteries. ...Constructing a stable solid electrolyte interphase (SEI) on Li metal anodes is now understood to be a requirement for progress in achieving feasible Li‐metal batteries. Recently, the application of novel analytical tools has led to a clearer understanding of composition and the fine structure of the SEI. This further promoted the development of interface engineering for stable Li metal anodes. In this review, the SEI formation mechanism, conceptual models, and the nature of the SEI are briefly summarized. Recent progress in probing the atomic structure of the SEI and elucidating the fundamental effect of interfacial stability on battery performance are emphasized. Multiple factors including current density, mechanical strength, operating temperature, and structure/composition homogeneity that affect the interfacial properties are comprehensively discussed. Moreover, strategies for designing stable Li‐metal/electrolyte interfaces are also reviewed. Finally, new insights and future directions associated with Li‐metal anode interfaces are proposed to inspire more revolutionary solutions toward commercialization of Li metal batteries.
The interfacial chemistry between Lithium metal anodes and electrolytes is vital in regulating Li plating/stripping behavior and improving the cycling performance of Li metal batteries. Key achievements in formation mechanisms, conceptual models, and structural characteristics of solid electrolyte interphases utilizing advanced analytical tools are summarized. Factors affecting interfacial stability and corresponding strategies for stabilizing anode/electrolyte interface are also presented.
Solid polymer electrolytes (SPEs) hold a great promise in the application of solid‐state lithium batteries, but suffer from poor mechanical properties and uncontrolled electrode/electrolyte ...interfacial reaction, which restrict their overall electrochemical performance. Herein, the design of 2D fluorinated graphene‐reinforced PVDF‐HFP‐LiTFSI (FPH‐Li) polymer electrolytes to address these challenges is reported. Uniformly dispersed fluorinated graphene induces a unique grain refinement effect, which effectively improves the mechanical properties without excessively increasing the thickness of the polymer electrolyte. Significant reduction in polymer grain size enhances interfacial lithium ion (Li‐ion) transport and homogenizes Li‐ion flux, thereby improving Li‐ion conductivity and promoting uniform Li plating/stripping. Furthermore, extensive characterizations show that fluorinated graphene is involved in the construction of a stable artificial interface, which effectively prevents the side reactions between the lithium metal anode and solvated molecules. As a result, the use of thin FPH‐Li polymer electrolytes (thickness of ≈45 µm) enables long‐term Li plating/stripping with a small overpotential in Li/Li symmetrical cells and stable cycling of Li/LiNi0.6Co0.2Mn0.2O2 full cells with a high average Coulombic efficiency of 99.5% at 1.0 C. This work verifies the effectiveness of 2D materials in improving the comprehensive properties of polymer electrolytes and promotes the applications of SPEs in high‐performance solid‐state lithium batteries.
2D fluorinated graphene is found to induce a unique grain refinement effect, which can improve the mechanical properties, increase the Li‐ion conductivity, and regulate the interfacial stability of the poly(vinylidene fluoride‐co‐hexafluoropropylene)‐based polymer electrolytes. The use of fluorinated graphene‐reinforced polymer electrolytes enables stable cycling of both symmetric cells and full cells at room temperature.
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