High-stability double-layer polymer-inorganic composite electrolyte fabricated through ultraviolet curing process for solid-state lithium metal batteries

Electrolyte interface resistance and low ionic conductivity are essential issues for commercializing solid-state lithium metal batteries(SSLMBs).This work details the fabrication of a double-layer solid composite electrolyte(DLSCE)for SSLMBs.The composite comprises poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP)and poly(methyl methacrylate)(PMMA)combined with 10 wt.%of Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)(LLZTO),synthesized through an ultraviolet curing process.The ionic conductivity of the DLSCE(2.6×10^(-4) S·cm^(-1))at room temperature is the high lithium-ion transference number(0.57),and the tensile strength is 17.8 MPa.When this DLSCE was assembled,the resulted LFP/DLSCE/Li battery exhibited excellent rate performance,with the discharge specific capacities of 162.4,146.9,93.6,and 64.0 mA·h·g^(-1) at 0.1,0.2,0.5,and 1 C,respectively.Furthermore,the DLScE demonstrates remarkable stability with lithium metal batteries,facilitating the stable operation of a Li/Li symmetric battery for over 200 h at both 0.1 and 0.2 mA-cm^(-2).Notably,the formation of lithium dendrites is also effectively inhibited during cycling.This work provides a novel design strategy and preparation method for solid composite electrolytes.

Acceleration of bidirectional sulfur conversion kinetics and inhibition of lithium dendrites growth via a“ligand-induced”transformation strategy

The introduction of materials with dual-functionalities,i.e.,the catalytic(adsorption)features to inhibit shuttle effects at the cathode side,and the capability to facilitate homogenous Li-ion fluxes at the anode side,is a promising strategy to realize high performance lithium-sulfur batteries(LSBs).Herein,a facile and rational organic“ligand-induced”(trimesic acid(TMA))transformation tactic is proposed,which achieves the regulation of electronic performance and d-band center of bimetallic oxides(NiFe_(2)O_(4))to promote bidirectional sulfur conversion kinetics and stabilize the Li plating/striping during the charge/discharge process.The battery assembled with NiFe_(2)O_(4)-TMA modified separator exhibits a remarkable initial specific capacity of 1476.6 mAh·g^(-1)at 0.1 C,outstanding rate properties(661.1 mAh·g^(-1)at 8.0 C),and excellent cycling ability.The“ligand-induced”transformation tactic proposed in this work will open a whole new possibility for tuning the electronic structure and d-band center to enhance the performance of LSBs.

Mechanism of vertical crack formation in Yb_(2)SiO_(5) coatings deposited via plasma spray-physical vapor deposition

Plasma spray-physical vapor deposition(i.e.,PS-PVD)is a promising method for obtaining advanced environmental barrier coatings(EBCs).The EBCs must meet some requirements in the application,in which the thermal cycle performance affects the service lifetime.The preparation of artificial vertical cracks in Yb_(2)SiO_(5) coatings is an effective approach for meeting the requirements above because vertical cracks provide a strain tolerance.To clarify the formation mechanism of vertical cracks during the PSPVD,the effects of coating thickness and substrate temperature on the formation of vertical cracks were investigated.In addition,the interactions of spray powder and plasma flame during coating deposition were also characterized by optical spectroscopy.It is indicated that vertical cracks are formed due to a thermal expansion mismatch between Yb_(2)SiO_(5) and mullite coating,transient cooling after deposition and the nucleation of evaporated Yb_(2)SiO_(5) as well.

Structural evolution of plasma sprayed amorphous Li_(4)Ti_(5)O_(12) electrode and ceramic/polymer composite electrolyte during electrochemical cycle of quasi-solid-state lithium battery

A quasi-solid-state lithium battery is assembled by plasma sprayed amorphous Li_(4)Ti_(5)O_(12) to provide the outstanding electrochemical stability and better normal interface contact.Scanning Electron Microscope(SEM),Scanning Transmission Electron Microscopy(STEM),Transmission Electron Microscopy(TEM),and Energy Dispersive Spectrometer(EDS)were used to analyze the structural evolution and performance of plasma sprayed amorphous LTO electrode and ceramic/polymer composite electrolyte before and after electrochemical experiments.By comparing the electrochemical performance of the amorphous LTO electrode and the traditional LTO electrode,the electrochemical behavior of different electrodes is studied.The results show that plasma spraying can prepare an amorphous LTO electrode coating of about 8μm.After 200 electrochemical cycles,the structure of the electrode evolved,and the inside of the electrode fractured and cracks expanded,because of recrystallization at the interface between the rich fluorine compounds and the amorphous LTO electrode.Similarly,the ceramic/polymer composite electrolyte has undergone structural evolution after 200 test cycles.The electrochemical cycle results show that the cycle stability,capacity retention rate,coulomb efficiency,and internal impedance of amorphous LTO electrode are better than traditional LTO electrode.This innovative and facile quasi-solid-state strategy is aimed to promote the intrinsic safety and stability of working lithium battery,shedding light on the development of next-generation high-performance solid-state lithium batteries.