Research On Composite Electrolyte Based On Porous LATP Tandm Framework And Its Performance Of Solid Lithium Metal Battery

Solid-state lithium metal battery（SSLMBs）is expected to solve the issues of inferior safety and poor energy density of conventional lithium-ion battery,which is the focus of current research.Li_1.3Al_0.3Ti_1.7（PO₄）₃（LATP）has been widely concerned by researchers for its ideal ionic migration ability,excellent water-oxygen stability and high oxidation voltage.However,rigid LATP has huge interfacial impedance with electrodes,and the compatibility with Li anode is poor,thus Ti⁴⁺from LATP can be reduced to Ti³⁺.In order to solve the problem of LATP in application,a composite solid electrolyte（CSE）based on porous 3D LATP tandem framework was designed in this paper:3D porous LATP framework and commercial cellulose membrane TF4030 were used to construct a porous LATP tandem framework.And then 1,3-dioxane（DOL）was used as precursor,CSE based on LATP tandem framework was constructed by in-situ polymerization through osmosis.On this basis,integrated SSLMBs,and study its performance.Specific work contents are as follows:（1）The flexible porous LATP tandem framework was prepared by solution pouring method,then,the flexible CSE was obtained by permeation and in-situ polymerization of DOL.The in-situ polymerization strategy and the introduction of TF4030 can effectively reduce the interface impedance and improve the interface stability.The interface impedance of the Li/Li symmetric battery is only 141.6Ω,and the Li/Li symmetrical battery can cycle for more than 1200 h under the low polarization voltage at 0.1 m A cm^-2,60℃.This CSE provides a variety of continuous ion migration networks and thus has a high ion conductivity of 3.25×10^-4S cm^-1（60℃）.In addition,CSE also possesses an outstanding oxidation voltage of 5.05 V and a high Li⁺migration number of 0.67.Excellent interfacial stability and electrochemical performance enable the corresponding Li Fe PO4/Li battery to have excellent rate and cycling performance:An initial specific capacity of 163.3 m Ah g^-1is provided at 0.5 C and 60℃,and the capacity retention ratio is 89.7%after120 cycles.（2）A porous 3D LATP framework was prepared by NH₄HCO₃template method.LATP nanoparticles are closely connected by sintering at high temperature,which could provide a faster Li⁺migration network.Porous 3D LATP framework and TF4030 constitute rigid LATP tandem framework.CSE based on rigid LATP tandem framework is obtained by double permeation and in-situ polymerization strategies,in which the porous 3D LATP framework provides high ionic conductivity(1.16×10^-4S cm^-1,25℃),wide electrochemical window（5.48 V）and high Li⁺migration number（0.70）for the CSE,TF4030 enhances the interface stability of CES,thus,its Li/Li symmetrical battery can cycle stably for more than 2000 h at 20-30℃and0.1 m A cm^-2,and its Li Fe PO₄/Li battery can achieve an initial specific capacity of 140.8 m Ah g^-1at 0.5 C,and the capacity retention ratio is 72.2%after 400 cycles.