Search

The Zn-air battery is a promising next-generation battery because of the higher energy density and safety compared with the Li-ion battery. However, the Zn-air battery suffers from huge energy loss and poor cycling performance, which are due to the sluggish kinetics of oxygen reduction/evolution reactions (ORR/OER) and the instability of bifunctional catalysts. The state-of-the-art bifunctional catalyst is the composite of Pt and Ir/Ru oxides, which is hindered by the scarce resource and high cost. Therefore, developing low-cost and high-efficient bifunctional non-noble metal-based catalysts is essential to the deployment of Zn-air batteries. Herein, we report a dual-nitrogen-source mediated pyrolysis route to rationally design and synthesize the hybrid Co/Co–N–C bifunctional catalyst. The tailored catalyst consisting of carbon confined Co nanoparticles and atomically dispersed Co–N–C moiety is identified. Remarkably, the dual-nitrogen-source derived Co/Co–N–C catalyst demonstrates excellent electrochemical performances with a half-wave potential of 0.882 V for ORR and a potential of 1.640 V at 10 mA cm−2 for OER; reasonably, the bifunctionality of Co/Co–N–C, which is supported by the excellent self-breathing Zn-air battery performance (the maximum energy density of 897.1 Wh kg Zn −1; no obvious degradation within 167h cycling). The abundant Co-Nx sites and metallic Co nanoparticles synergistically boost the ORR and OER. Image 1 • A dual-nitrogen-source method is proposed to synthesize porous Co-based catalysts. • The dual nitrogen sources play different roles in morphology and structure control. • The hybrid carbon-confined Co nanoparticles and Co-N x sites are well tailored. • The good bifunctionality is due to the hybrid active site configuration. • Excellent performance and lifetime are obtained in a Zn-air battery. [ABSTRACT FROM AUTHOR]

The electrochemical characterization of new electrode materials in the lithium battery field is commonly conducted using a simplified two-electrode configuration, known as the "half-cell" concept. However, this approach often overlooks the critical error related to the polarizability of the lithium electrode, especially when the working electrode has a high areal capacity and the half-cell undergoes long-term cycling. In our work, we propose a simple way to improve the properties of the Li electrode, which is using a superstoichiometric Li 1+x Al surface enrichment of the metallic lithium foil in situ by direct contact with aluminum foil, serving as a counter/reference electrode. The method eliminates the inhomogeneity of the lithium surface and creates a buffer zone between the highly active lithium electrode and liquid organic electrolytes. The high lithium content in the surface alloy allows the electrode to behave like a lithium electrode while providing low polarization and maintaining a stable potential throughout the long duration of cycling. By implementing this method, we improve the charge/discharge characteristics of high-capacity electrodes and obtain more accurate evaluations of their electrochemical performance. [Display omitted] • A new counter/reference electrode——Li@Li 1+x Al electrode. • The Li@Li 1+x Al electrode exhibits an equilibrium potential of Li one. • The Li@Li 1+x Al electrode is more stable than Li electrode in coin-type half-cell. [ABSTRACT FROM AUTHOR]

Abstract Ionically conductive polymer electrolytes represent a class of safe and environment-friendly electrolytes for next-generation alkali metal batteries. Understanding the interplay between composition-driven interfacial processes and battery performance can fundamentally inform the design of polymer electrolytes for practical applications. In this study, we fabricate lithium metal batteries based on transparent free-standing ionic liquid gel polymer electrolytes (ILGPEs) and LiFePO 4 cathodes. We develop the ILGPEs using a composite of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), N-methyl-N-propylpiperidinium bis(trifluoromethanesulfonyl)imide (PP13TFSI), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). A thorough compositional optimization shows that the lithium ion conductivity of the ILGPE increases with the increase of PP13TFSI and LiTFSI, reaching maxima of 1.3 mS cm−1 at 23 °C and 5.82 mS cm−1 at 80 °C when the ILGPE contains 60 wt% PP13TFSI and 20 wt% LiTFSI. The optimized ILGPE exhibits excellent interfacial stability against the lithium metal, as signified by the stable interfacial resistance upon long-term storage. The LiFePO 4 |ILGPE|Li cells can deliver superior battery performance with a practical capacity approaching 89.5% of the theoretical capacity and capacity retention of 95.0% after 200 cycles. The formation of the electrode–electrolyte interphases takes place primarily during the initial cycles, which likely accounts for the activation period observed in LiFePO 4 |ILGPE|Li cells. Graphical abstract Image 1 Highlights • Ionic liquid gel polymer electrolytes with high ionic conductivity were prepared. • The compatibility of ILGPE-Li metal was studied under practical conditions. • Solid-state LFP cells showed remarkable discharge capacity and cycle life at RT. • The interfacial chemistry of cells was investigated as a function of cycle number. [ABSTRACT FROM AUTHOR]

A new method to determine the heating power of ternary cylindrical lithium ion batteries with highly repeatable thermal runaway test characteristics is proposed based on statistical principles. By selecting the key parameters for the process of heating-triggered thermal runaway of a lithium ion battery, such as the heating time and thermal runaway temperature, the standard deviation coefficients in multiple tests are used as the basis for evaluating the repeatability and determining the heating power of the highly repeatable thermal runaway test results. A systematic experimental study of four typical ternary cylindrical lithium ion batteries is carried out and a method for calculating the heating power based on the rated energy and weight of the battery is proposed. The results show that this method could effectively ensure the repeatability of the thermal runaway test for cylindrical batteries. The method is simple, original and innovative for the selection of the thermal runaway heating power of ternary cylindrical lithium ion batteries. The results also serve as a reference to select the heating power for other types of lithium ion batteries. Image 1 • A method is given to determine the optimum heating power to trigger thermal runaway. • Heating time and temperature were used to judge the repeatability of the method. • The heating power was calculated using the rated energy and weight of the battery. • The formula was validated using NCM/C cylindrical lithium-ion batteries. [ABSTRACT FROM AUTHOR]