Study On The Preparation And Modification Of LiNi_1/3Co_1/3Mn_1/3O₂ With Spent Zn-Mn Batteries As Manganese Source

The spent Zn-Mn batteries hurt the environment a lot in term of the heavy mental content and toxic chemicals when abandoned casually.So the recovery and utilization of waste zinc manganese batteries has been widely studied.But it was difficult to form economies of scale because of high cost-recovering and low value added.Lithium-ion battery has been developed rapidly because of high efficiency and environmentally.The LiNi_1/3Co_1/3Mn_1/3O₂ powders act as a promising cathode material for lithium ion batteries because of its so many superior properties,such as high specific capacity,low cost and safety.However,bare LiNi_1/3Co_1/3Mn_1/3O₂powders have poor cycling performance when charged and discharged.In this study,MnCO₃ product has been recycled from spent Zn-Mn batteries and it was selected as manganese source to synthesize LiNi_1/3Co_1/3Mn_1/3O₂ by co-precipitation method and Sol-Gel method.The MnCO₃ was leached by HNO₃ and H₂O₂.Then the pH was adjusted by NaOH in order to remove the Fe³⁺in the solution.Next,the MnCO₃ would be precipated after adding some Na₂CO₃.Finally,the MnCO₃ was obtained by filtration.The optimal concentration of nitric acid was 3.65 mol·L^-1.The recovery of manganese carbonate reached the maximum,and the amount of manganese carbonate recovery did not change obviously with the increase of nitric acid concentration.LiNi_1/3Co_1/3Mn_1/3O₂ was synthesized by co-precipitation method using MnCO₃as raw materials with NaOH+NH₃·H₂O as precipitator,powders precipated at pH=11has better performance than the others.LiNi_1/3Co_1/3Mn_1/3O₂ surface modification has enhanced the cycling performance obviously,but the performance faded with the increase of the amount of coating.0.5wt%SiO₂-coated LiNi_1/3Co_1/3Mn_1/3O₂ has showed the best electrochemical performance of all,and its specific capacity has enhanced 26.6 mAh·g^-1 after 100 cycles compared with that of the bare LiNi_1/3Co_1/3Mn_1/3O₂ after 100 cycles.LiNi_1/3Co_1/3Mn_1/3O₂ was synthesized by Sol-Gel method using C₆H₈O₇·H₂O as chelating agent.The bare LiNi_1/3Co_1/3Mn_1/3O₂ showed a relative poor electrochemical performance.0.5wt%Al₂O₃-coated treatment was carried out,which resulted in a significant enhancement of the electrochemical properties.The specific capacity of0.5wt%Al₂O₃-coated LiNi_1/3Co_1/3Mn_1/3O₂ was 117.3 mAh?g^-1 after 100 cycles,and the capacity retention was 77.12%.The specific capacity of bare LiNi_1/3Co_1/3Mn_1/3O₂was only 72 mAh?g^-1 after 100 cycles,and the capacity retention was only 45.56%.