Study On Preparation And Lithium Storage Properties Of M₃O₄?M=Fe?Co? With Flexible Base

Due to their deformable,stretchable mechanical stability and high energy density,flexible lithium-ion battery has become a hot spot about energy storage research.However,in the current research of flexible lithium-ion battery,there are still three main problems: 1)the design and manufacturing of flexible electrode;2)the stability performance under dynamic electrochemical reaction;3)high energy density and power density and other issues.To solve the above problems,the foam nickel and the graphene was used as flexible substrate and the graphene also used as active material,and then the transition metal oxides with excellent morphological structure were prepaered and combined with the flexible substrate to form the compsite flexible anode materials for lithium ion battery.The mechanical properties and the electrochemical proprieties of the flexible negative electrode were imporved.1)Fe₃O₄@C composites were prepared by calcination method after hydrothermal method,then the flexible foam nickel-based three-dimensional petal Fe₃O₄@C composites was successfully prepared.The relationship between the formation mechanism of the precursor and the deposition time of the precursor was investigated.The results showed that the precursor was deposited first and then undergone a classical two-step nucleation and growth mechanism.The three-dimensional petal Fe₃O₄@C flexible composites sample showed a first discharge capacity up to 1163.17 mAh·g-1 with the initial coulombic efficiency was 86.21% at 0.3C in the range of 0.02-3.0 V.During 50 cycles,the coulombic efficiency retention was above 98%,and the capacity was maintained at 863.99 mAh·g-1 after 50 cycles,which showed good electrochemical performance.2)The graphene oxide and graphene oxide films were prepared by classical chemical stripping Hummer method and the as-prepared graphene films were characterized.3)The preparation of flexible radical Fe₃O₄/rGO composite material by hydrothermal method was carried out.The first discharge capacity of the flexible Fe₃O₄/rGO composite was 891.76 mAh·g-1,the specific capacity of the charge is 733.76 mAh·g-1,the first coulombic efficiency is 81.79%.During 100 cycles,the coulombic efficiency retention was above 97%,the retention capacity was still maintained 508.96 mAh·g-1 after 100 cycles,showing better electrochemical performance.4)The hydrothermal method was used to prepare the flexible Co₃O₄/rGO composites.The constant current was charged at 0.5 A·g-1 between 0.01-3.0 V.Under constant 0.5 A·g-1 charge and discharge,its initial specific capacity is 1045 mAh·g-1.After that,its stability was basically good.