A novel method for preparing Ta-doped Ti02 via using Ta2 05 as the doping source is proposed. The preparation process combines the hydrothernlal fluorination of Ta2O5 and the subsequent formation of Ta-doped TiO2 sol....A novel method for preparing Ta-doped Ti02 via using Ta2 05 as the doping source is proposed. The preparation process combines the hydrothernlal fluorination of Ta2O5 and the subsequent formation of Ta-doped TiO2 sol. The results show that the doped sample annealed at 393 K generates an unstable intermediate NH4 TiOF3, which converts into anatase TiO2 with the increase of temperature. After annealing at ≥673K, the Ta-doped TiO2 nanocrystals with the grain size 〈20nm are obtained. Both the XRD and TG-DSC results confirm that Ta doping prevents the anatase-rutile crystal transition of TiO2. The band gap values of the doped samples, as obtained by UV-vis diffuse reflectance spectra, are smaller than that of pure anatase TiO2. The first-principle pseudopotential method calculations indicate that Ta5＋ lies in the TiO2 lattice at the interstitial position.展开更多
Ni-rich layered oxide with Ni molar content larger than 90%was regarded as an extremely promising candidate for cathode material applied in lithium-ion batteries owing to the significant discharging capacity and low c...Ni-rich layered oxide with Ni molar content larger than 90%was regarded as an extremely promising candidate for cathode material applied in lithium-ion batteries owing to the significant discharging capacity and low cost.Nevertheless,rigorous cycling attenuation resulted from the crystal structure collapse and unstable particles interface deeply restrained the commercial application.In the work,LiNi_(0.90)Co_(0.05)Mn_(0.05)O_(2) was modified by Ta5+doping and Li_(2)MnO_(3) covering,which was aimed to enhance the structure stability,defend the electrolyte attacking and promote Li+migration during cycling.The material characterization demonstrated the cathodes after Ta5+doping delivered the larger cell lattice parameters and higher cation ordering,which was helpful to improve the rate property and discharge capacity at low temperature.The Li_(2)MnO_(3) layer was tightly adhered on the outside of LiNi_(0.90)Co_(0.05)Mn_(0.05)O_(2),which could effectively relieve the electrolyte attacking and sustain the particle morphology integrity.As a result,2 wt%Li_(2)MnO_(3) coated Li(Ni_(0.90)Co_(0.05)Mn_(0.05))_(0.98)Ta_(0.02)O_(2) exhibited the outstanding discharge capacity of 150.2 mAh g^(−1) at 10.0 large current density and 140.6 mAh g^(−1) at−30℃ as well as the remarkable capacity retention of 93.1%after 300 cycles.Meanwhile,the pouch full batteries obtained by 2 wt%Li_(2)MnO_(3) coated Li(Ni_(0.90)Co_(0.05)Mn_(0.05))_(0.98)Ta_(0.02)O_(2) also showed the more stable storage capability,cyclic property in comparison with bare LiNi_(0.90)Co_(0.05)Mn_(0.05)O_(2).展开更多
基金Supported by the Fundamental Research Funds for the Central Universities under Grant No 2012QNA03
文摘A novel method for preparing Ta-doped Ti02 via using Ta2 05 as the doping source is proposed. The preparation process combines the hydrothernlal fluorination of Ta2O5 and the subsequent formation of Ta-doped TiO2 sol. The results show that the doped sample annealed at 393 K generates an unstable intermediate NH4 TiOF3, which converts into anatase TiO2 with the increase of temperature. After annealing at ≥673K, the Ta-doped TiO2 nanocrystals with the grain size 〈20nm are obtained. Both the XRD and TG-DSC results confirm that Ta doping prevents the anatase-rutile crystal transition of TiO2. The band gap values of the doped samples, as obtained by UV-vis diffuse reflectance spectra, are smaller than that of pure anatase TiO2. The first-principle pseudopotential method calculations indicate that Ta5＋ lies in the TiO2 lattice at the interstitial position.
基金supported by the Natural Science Research Projects of Colleges and Universities in Jiangsu Province (grant No.24KJA430012)the Open Project Program of Key Laboratories of Fine Chemicals and Surfactants in Sichuan Provincial Universities (grant No.SCFY2203).
文摘Ni-rich layered oxide with Ni molar content larger than 90%was regarded as an extremely promising candidate for cathode material applied in lithium-ion batteries owing to the significant discharging capacity and low cost.Nevertheless,rigorous cycling attenuation resulted from the crystal structure collapse and unstable particles interface deeply restrained the commercial application.In the work,LiNi_(0.90)Co_(0.05)Mn_(0.05)O_(2) was modified by Ta5+doping and Li_(2)MnO_(3) covering,which was aimed to enhance the structure stability,defend the electrolyte attacking and promote Li+migration during cycling.The material characterization demonstrated the cathodes after Ta5+doping delivered the larger cell lattice parameters and higher cation ordering,which was helpful to improve the rate property and discharge capacity at low temperature.The Li_(2)MnO_(3) layer was tightly adhered on the outside of LiNi_(0.90)Co_(0.05)Mn_(0.05)O_(2),which could effectively relieve the electrolyte attacking and sustain the particle morphology integrity.As a result,2 wt%Li_(2)MnO_(3) coated Li(Ni_(0.90)Co_(0.05)Mn_(0.05))_(0.98)Ta_(0.02)O_(2) exhibited the outstanding discharge capacity of 150.2 mAh g^(−1) at 10.0 large current density and 140.6 mAh g^(−1) at−30℃ as well as the remarkable capacity retention of 93.1%after 300 cycles.Meanwhile,the pouch full batteries obtained by 2 wt%Li_(2)MnO_(3) coated Li(Ni_(0.90)Co_(0.05)Mn_(0.05))_(0.98)Ta_(0.02)O_(2) also showed the more stable storage capability,cyclic property in comparison with bare LiNi_(0.90)Co_(0.05)Mn_(0.05)O_(2).
