Preparation And Performance Research Of PAN/UIO-66-based Composite Solid-state Electrolyte

Lithium metal batteries are expected to become a new generation of high energy density energy storage devices due to their high theoretical capacity and energy density,but excessive Li dendrite growth and formation of dead lithium tend to short circuit inside the battery,causing thermal runaway,even fire and explosion.The development of electrolytes with high safety and high ionic conductivity is expected to achieve safer,high-performance lithium metal batteries.Previous studies have shown that inorganic or organic solid-state electrolytes can effectively inhibit the growth of Li dendrites,but low ion transport efficiency and high interfacial impedance within the electrolyte limit the practical application of solid-state lithium metal batteries.In this paper,organic and inorganic electrolyte materials are structurally designed to construct ion transport channels and prepare electrolyte materials with excellent overall performance.Firstly,we use PAN material with excellent mechanical properties as polymer matrix,constructs self-supporting fiber structure,uses UIO-66 for regulating ion transport,selects[EMIM][TFSI],which is chemically stable,non-volatile and non-flammable,as the main ion transport medium,and prepares ion transport materials based on synchronous electrospinning and electrostatic spraying method.PUIE-3 achieves a high ionic conductivity of1.08 m S cm^-1 at room temperature and a low ion migration activation energy（Ea～0.15 e V）due to its coherent 3D ion transport channels,while exhibiting an electrochemical window above 5.5 V.By virtue of the size limiting effect of UIO-66 and the Lewis acid-base effect of the active site,PUIE-3 also exhibits a high lithium ion migration number of 0.52.In-situ observation of the lithium cathode and Li plating/stripping tests show that PUIE-3 exhibits significant inhibition of Li dendrites.Li Fe PO₄|PUIE-3|Li cells exhibit high initial discharge specific capacity(154 m Ah g^-1 at 0.1 C),substantial cycling capacity retention（85%after 100 cycles at 0.2 C）and multiplicative performance.NCM|PUIE-3|Li cells also exhibit excellent cycling stability and reversible multiplier performance.Secondly,the continuous distribution of LLZAO in PAN fibers was achieved by using PDA-coated LLZAO to complement the ion transport pathways and construct an electrolyte with multiple 3D ion transport channels（PLUIE）with an enhanced room temperature ionic conductivity of 1.25 m S cm^-1.PLUIE also exhibited a high lithium ion mobility number（0.49）and a wide electrochemical window（5.5 V）.In the Li plating/stripping test,the stable voltage profile demonstrates the inhibition of Li dendrite growth by PLUIE.Li Fe PO₄||Li cells assembled by PLUIE exhibit high initial discharge specific capacity(152.1 m Ah g^-1)and near 100%Coulomb efficiency in the cycling test at 0.2 C.Li Fe PO₄|PLUIE|Li also showed stable reversibility in the rate performance test.NCM|PLUIE|Li cell also exhibited high initial discharge specific capacity(157.9 m Ah g^-1 at 0.2 C),capacity retention（96.8%after 60cycles）and excellent multiplier performance in the test.