Performance Study Of Integrated Solid-state Lithium-oxygen Battery

Solid-state Li-O₂batteries(SSLOBs)are attracting increasing attention due to the improved safety,wider electrochemical window and innate capability of suppressing Li dendrite penetration and shielding the Li metal anode from oxygen,CO₂and moisture in the air,in comparison with the conventional Li-O₂batteries using liquid organic electrolytes.However,the high impedance of the solid-solid interface between the oxygen electrode and the electrolyte in solid-state lithium-oxygen batteries has always limited the development of batteries.In this paper,an integrated structure of oxygen electrode support based on a composite polymer solid electrolyte(CPE)system is designed and prepared to reduce the interfacial impedance in a solid Li-O₂battery.This structure extends the catalyst-electrolyte-active material(O₂)three-phase interface to the overall oxygen electrode.The solid-state lithium-oxygen battery using the integrated structure exhibits larger discharge capacity,smaller energy attenuation,and smaller impedance growth.First,an integrated electrode(ICPA)was prepared using PEO(polyoxyethylene),Li salt,and LLZTO as CPE materials,and its morphology and structure were characterized.By assembling an integrated solid-state lithium-oxygen battery(ICPA battery)and carrying out the same conditions of charge and discharge and isometric cycle tests with the non-integrated ordinary solid-state lithium-oxygen battery(CPE battery).In the charge and discharge test,the initial discharge specific capacity of the CPE battery is only 1859 m Ah g^-1,and the last cycle can only provide250.6 m Ah g^-1.In contrast,the specific discharge capacity of the ICPA battery is2313.4 m Ah g^-1,and the final cycle reaches 873.2 m Ah g^-1.In the constant volume cycle test,the ICPA battery can achieve 78 cycles of charging and discharging,while the CPE battery only lasted 44 cycles.The impedance growth of CPE battery after cycling is more than twice that of ICPA battery.The results show that the use of an integrated structure reduces the interface impedance between the solid oxygen electrode and the electrolyte,and expands the three-phase reaction interface of the oxygen electrode,so the cycle performance of the battery can be significantly improved.Subsequently,PVDF-based ICPA(ICPA-V)was prepared using PVDF,Li salt,and LLZTO as CPE materials,and its morphology and structure were characterized.Assemble it into an integrated solid-state lithium-oxygen battery(ICPA-V battery)and perform performance tests with a non-integrated ordinary PVDF-based solid-state lithium-oxygen battery(CPE-V battery)under the same conditions.The discharge specific capacity of the CPE-V battery in the first cycle is1633.1 m Ah g^-1,while the ICPA-V battery can achieve 1.3 times the specific capacity of the CPE-V battery(2153.7 m Ah g^-1).The ratio of the CPE-V battery in the last cycle The capacity is 624.4 m Ah g^-1,while the ICPA-V battery is 1033.95 m Ah g^-1,and the integrated structure battery shows a slower capacity decay.In the constant volume cycle test,the CPE-V battery was cycled only 25 times,while the ICPA-V battery can be charged and discharged 70 times,more than twice that of the CPE-V battery.Moreover,the polarization impedance growth of the ICPA-V battery after cycling is also significantly smaller than that of the CPE-V battery.The results show that the integrated structure supported by the oxygen electrode helps to reduce the interface impedance of the solid-state lithium-oxygen battery,expand the three-phase reaction interface of the oxygen electrode,and realize the continuous transmission of lithium ions from the oxygen electrode to the electrolyte,thereby improving battery performance.