Recycling Cobalt From Discarded Lithium-ion And Research Of Lithium-rich Anode Materials

With the development of portable energy storage and new energy vehicles,the recycling and performance improvement of lithium ion batteries are becoming more and more focus.In this paper,cobalt is recovered by wet method.Nickel-cobalt-manganese ternary lithium-rich anode materials were synthesized by co-precipitation method using recovered cobalt materials,and their surfaces were coated by MOF materials with porous structure to obtain anode materials and better electrochemical properties.What's more,nano-level active materials were synthesized by hydro-thermal method,and the morphology and structure were improved with active agents.Which possess complete crystal structure and high capacity.Firstly,in this paper,the precursor of Mn_0.54Ni_0.13Co_0.13?OH?₂ was prepared by co-precipitation method.And then it was mechanically mixed with lithium hydroxide and sintered to synthesis lithium-rich anode materials.The crystal structure and surface morphology were analyzed by X-ray diffraction?XRD?and scanning electron microscopy?SEM?,and electrochemical performance tested by current charge-discharge,cyclic volt-ampere?CV?and alternating current impedance?EIS?.Finally conclusion that is the precursor prepared at pH=11,sintering temperature is850?,which has good electrochemical performance,at 0.1C?1C=250 mAh/g?ratio,the discharge capacity is 268 mAh/g.And has a relatively good cycle performance,capacity retention is 186 mAh/g after 50 times cycle.Co-precipitation method has good industrial application,but circulation performance and large current discharge capacity is poor.In order to improve this disadvantage,using ternary anode material,whose first discharge is capacity 217 mAh/g,after 50 cycles,capacity retention is 153mAh/g,is coated by MOF synthesized by hydro-thermal method.Composite materials has better surface coating effect by BET and energy spectrum test show that when the surface coating amount is 10%.The initial discharge capacity was 241mAh/g,at the rate of 0.1C,after 50 cycles,the capacity was maintained at 197mAh/g,and the capacity retention rate was 81.7%.Most importantly,at the rate of 1C,capacity retention is 167mAh/g after 50 cycles.Its cycle performance,capacity retention rate of larger current were significantly improved.A series of lithium-rich anode materials were synthesized by hydro-thermal one-step method,and then sintered.The materials were obtained with good crystal and layer structure and uniform particles by XRD and SEM tests.According to the electrochemical performance test,the initial discharge capacity of ternary anode material synthesized at the reaction time of 36h,is 325mAh/g at the rate of 0.1C.After 100 cycles,the capacity was maintained at 297mAh/g and the capacity retention rate was 91.4%.But the performance of large current discharge is poor.And the positive electrode material obtained by adding ethylene glycol in the hydro-thermal reaction solvent has a capacity of 617mAh/g for the first discharge,but the capacity retention rate is poor.The capacity is maintained at 412mAh/g after 20 cycles,and the capacity drops rapidly after 20 cycles.ICP test shows that the higher capacity of ternary materials synthesized by hydro-thermal method is related to the increase of nickel content.