| Lithium metal,with its extremely high capacity and ultra-low redox potential,is the preferred negative electrode for the next generation of high-energy batteries.However,conventional organic electrolytes are prone to decomposition during battery charging and discharging,and their inherent volatility and flammability are not conducive to the safe use of lithium-ion batteries.All solid-state lithium-ion batteries constructed with solid electrolytes are expected to fundamentally solve the above problems,as they have excellent mechanical strength and can effectively block lithium dendrite puncture.Currently,inorganic ceramic materials or organic polymer materials are commonly used as solid electrolytes.Compared to the former,polymers have a certain degree of flexibility and are compatible with electrode deformation during cycling,effectively reducing the"solid solid"interface resistance.However,its high crystallinity and low room temperature ion conductivity limit the application of polymer electrolytes in metal lithium batteries.Combining organic polymer electrolytes with inorganic ceramic solid electrolytes to form a composite solid electrolyte can to some extent reduce the crystallinity of the polymer,thereby improving the electrolyte conductivity,integrating the advantages of the two while avoiding their drawbacks.However,the addition of zero dimensional,one-dimensional,and two-dimensional inorganic fillers has limited contribution to improving the conductivity of composite electrolytes.Further increasing the content of inorganic fillers will lead to particle aggregation and may even lead to a decrease in ion conductivity.In addition,inorganic fillers are separated by polymers and cannot form continuous and fast ion transport channels,further limiting the improvement of the conductivity of composite solid electrolytes.Therefore,this paper prepared a 3D composite solid electrolyte with continuous ion transport channels through template method.The specific research work is as follows:（1）We prepared a 3D network structured LATP framework using NaCl as a template without the use of binders,and formed a 3D composite solid electrolyte（CSE）by adding PIL polymer to it.Porous LATP,as a rigid framework,can mechanically suppress the growth of lithium dendrites,while the 3D network structure provides a fast transport channel for Li+,forming a functionalized composite electrolyte with fast Li+transport network and high mechanical strength.The ion conductivity of CSE at room temperature is as high as 1.59×10-4S cm-1.At a current density of 0.05m A cm-2,the Li|CSE-2|Li symmetric battery can stably cycle for 600 hours,with a polarization voltage of 110 m V,has a good inhibitory effect on lithium dendrites.The assembled Li|CSE-2|LFP battery can stably cycle 150 times at a current density of 0.2 C,and its specific capacity can still be maintained at 109.9 m Ah g-1,with a capacity retention rate of 90.5%.（2）In response to the issues of low chip formation rate and difficulty in pore formation mentioned in the previous chapter,we optimized the experimental process and selected melamine sponge as support.We prepared a porous LATP framework with continuous channels using an ice template method,which was combined with PIL to obtain a 3D composite solid electrolyte（CSE）.By adjusting the content of H2O and LATP to regulate the framework of LATP,the experimental results show that when H2O:LATP=1.5:1.2,the prepared CSE has excellent room temperature ion conductivity(8.73×10-4S cm-1)and lithium ion migration number(tLi+=0.67).Thanks to the mechanical modulus of the LATP framework and the continuous Li+fast transmission channel,the assembled Li|Li symmetric battery can run smoothly for 1000 hours with an overvoltage of approximately 200 m V.When applied to LFP batteries,the first cycle discharge specific capacity reaches 141.3 m Ah g-1at a current density of 0.2 C.After 200 cycles,the discharge specific capacity still reached 107.3 m Ah g-1,with a capacity retention rate of 75.9%,demonstrating good electrochemical performance. |
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