Synthesis Of Polyaniline And Its Application In Cathode Materials For Lithium Ion Batteries

As one of the most promising conductive polymers,polyaniline?PANI?has the advantages of environmental friendliness,low cost,high theoretical specific capacity,reversible redox,etc.It can act as both conductive agent and active substance in lithium ion battery cathode material.It has broad prospects for development.However,pure PANI tends to agglomerate,and its comprehensive performance often cannot be fully exerted.In order to give full play to the performance of PANI materials,PANI with different states was prepared by adsorption double oxidant method,and the relationship between the state and performance of PANI was explored.Then different states of PANI and LiFePO₄materials were composited to obtain LiFePO₄/PANI composites.LiNi_0.5Co_0.2Mn_0.3O₂ was modified with different states of PANI to obtain LiNi_0.5Co_0.2Mn_0.3O₂/PANI composite materials.The impact of PANI on the performance of traditional lithium cathode materials and the performance of PANI were explored.Firstly,four different states of PANI were prepared by the adsorption double oxidant method.They were polyaniline doped with hydrochloric acid?y-PANI?,polyaniline?PANI?in the intrinsic state,polyaniline?r-PANI?in the reduced state,and perchloric acid-doped polyaniline?d-PANI?.The physical and electrochemical performance analysis showed that r-PANI has a large specific surface area,the structure is the most regular,with the maximum discharge capacity of 124 mAh/g?0.1 C?.The doped d-PANI has good electrical conductivity and cycle performance,and the electrical conductivity is 7.5 S/cm.Under 0.1 C conditions,the cycle is 50times,the capacity retention rate is 96.2%.Then,different states of polyaniline?PANI,r-PANI and d-PANI?were composited with LiFePO₄ materials in different proportions?5%,10%,15%?to obtain a series of LiFePO₄/PANI composites.Physical and chemical properties analysis showed that the addition of PANI did not change the structure of LiFePO₄,and the state of PANI itself did not change.Among them,LiFePO₄/r-PANI composites have the best performance.The rod like r-PANI forms a stable spatial network structure around LiFePO₄.The charge discharge capacity of LiFePO₄/r-PANI composites is higher than that of pure LiFePO₄ material.The LiFePO₄/r-PANI composites can give a specific capacity of nearly 150 mAh/g?0.2 C?at the content of 5%,10%.After 100 cycles,the capacity retention rate was 96%,and 98 mAh/g capacity was still released at 5 C.Different states of polyaniline?PANI,r-PANI and d-PANI?were compounded with LiNi_0.5Co_0.2Mn_0.3O₂ material in different proportions?3%,6%,9%?to obtain a series of LiNi_0.5Co_0.2Mn_0.3O₂/PANI composites.Physical and chemical properties showed that the addition of PANI did not change the structure of LiNi_0.5Co_0.2Mn_0.3O₂,and the state of PANI itself did not change.With the increase of PANI content,the specific capacity of LiNi_0.5Co_0.2Mn_0.3O₂/PANI composites decreased slightly,but its cycle performance and rate performance was obviously better than that of pure LiNi_0.5Co_0.2Mn_0.3O₂.In all composites,the LiNi_0.5Co_0.2Mn_0.3O₂/r-PANI has the best morphology,the cycle performance and rate performance was better than other composites.Finally,the market prospects and the economic cost of the PANI were investigated.Compared with other cathode materials,the PANI and PANI/lithium cathode composite materials has low cost,simple process,low pollution to the environment,etc.The application of PANI in lithium ion batteries has a broad prospect.