Highly Conductive Polymer Coated H₂Ti₁₂O₂₅ Anode Material With An In-Suit Technique And Its Electrochemical Performance

Titanium-based materials have the advantages of good cycle stability,high safety factor,and environmental friendliness compared with traditional carbon-based materials.Among them,the high-voltage anode material H₂Ti₁₂O₂₅ has gradually attracted more attention due to its high theoretical capacity and good cycle stability.However,the intrinsic low lithium ion diffusion coefficient and the conductivity for H₂Ti₁₂O₂₅,seriously restrict its practicality and commercialization.In this paper,highly conductive polymers?PANI or PEDOT?was coated on the surface of H₂Ti₁₂O₂₅,using in-situ polymerization,respectively.And the effect of PANI coating layer on the electrochemical performance of H₂Ti₁₂O₂₅5 were also analysized.1.H₂Ti₁₂O₂₅5 submicron particles were synthesized by mean of milling assisted soft-chemistry method,XRD characterization confirmed that the product was pure-phase H₂Ti₁₂O₂₅.2.PANI coated H₂Ti₁₂O₂₅5 was prepared by in-situ polymerization of polyaniline doped with a single inorganic hydrochloric acid.The discharge capacity and rate performance of H₂Ti₁₂O₂₅5 can be effectively improved by coating a polyaniline layer.When the coating content is 2 wt%?denoted as HTO/P2?,the initial discharge capacity of HTO/P2 at 1C is 253.8 mAh·g^-1,and afte 200 cycles,the capacity can still retain 151 mAhg^-1 with a capacity retention rate of 94.2%.Even at a high discharge rate of 20C,a discharge specific capacity of 76 mAhg^-1 still can be obtained.3.H₂Ti₁₂O₂₅ was also modified by PANI layer using in-situ polymerization with sulfosalicylic acid and hydrochloric acid co-dopping.Polyaniline co-doped with mixed-acid is more dispersible and more conductive.The above synthiszed sample HTO/P22 has higher discharge capacity and better rate performance,and its specific discharge capacity at 1C was up to 175.4 mAhg^-1 with a capacity retention rate of98.5%after 200 cycles.When discharged at 20C,a discharge specific capacity of 96.7mAhg^-1 can still be obtained.4.H₂Ti₁₂O₂₅ was coated by highly conductive polymer PEDOT using in-situ polymerization route.When the coating amount of PEDOT is 5 wt%?HTO/PE?,the discharge capacity and the rate performance of H₂Ti₁₂O₂₅ can be significantly improved.After cycling 200 times at 1C,the discharge specific capacity of HTO/PE was 167 mAhg^-1,whereas the 200-cycle capacity of HTO was only 109 mAhg^-1.