Lil.03Co0.10MnL90FxO4-x （z=0, 0.05, 0.10, 0.15 and 0.20） cathode materials were synthesized by solid-state reaction using Mn203, Li2CO3, C0203 and LiF as raw materials. The chemical compositions of Lil.03COo.lMnl.9F...Lil.03Co0.10MnL90FxO4-x （z=0, 0.05, 0.10, 0.15 and 0.20） cathode materials were synthesized by solid-state reaction using Mn203, Li2CO3, C0203 and LiF as raw materials. The chemical compositions of Lil.03COo.lMnl.9FzO4-z were examined by inductively coupled plasma （ICP） and potentiometric analysis, the effects of F-substitution contents on structure, morphology and electrochemical performance of spinel Lil.03Coo.loMnl.9004 were studied by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and electrochemical measurements. It is found that the Lix.03 Co0.10Mnl.9oFzOa_z samples display a single phase of cubic spinel structure. The lattice parameters increase with the increase of F content when z〈_0.10. However, the lattice parameters begin to decrease when F content continues to increase. The results show that an appropriate amount ofF substitution for O element with Li＋, Co3＋ improves discharge capacity and structure stability of the materials. The Lil.03Co0.10Mnl.90FoAsO3.s5 sample shows an initial discharge capacity of 111.0 mA.h/g and has capacity retention of 97.0% after 30 cycles at 0.2C.展开更多
O3-type Na NiO_(2)-based cathode materials undergo irreversible phase transition and serious capacity decay at high voltage above 4.0 V in sodium-ion batteries. To address these challenges, effects of Fsubstitution on...O3-type Na NiO_(2)-based cathode materials undergo irreversible phase transition and serious capacity decay at high voltage above 4.0 V in sodium-ion batteries. To address these challenges, effects of Fsubstitution on the structure and electrochemical performance of Na Ni_(0.4)Mn_(0.25)Ti_(0.3)Co_(0.05)O_(2) are investigated in this article. The F-substitution leads to expanding of interlayer, which can enhance the mobility of Na+. NaNi_(0.4)Mn_(0.25)Ti_(0.3)Co_(0.05)O_(1.92)F_(0.08)(NMTC-F_(0.08)) with the optimal F-substitution degree exhibits much improved rate capability and cyclic stability. It delivers reversible capacities of 177 and 97 m Ah g^(-1) at 0.05 and 5 C within 2.0–4.4 V, respectively. Galvanostatic intermittent titration technique verifies faster kinetics of Na+diffusion in NMTC-F_(0.08). And in-situ XRD investigation reveals the phase evolution of NMTC-F_(0.08), indicating enhanced structural stability results from F-substitution. This study may shed light on the development of high performance cathode materials for sodium-ion storage at high voltage.展开更多
基金Project(2011GZ0131) supported by the Sichuan Province Key Technology Support Program,China
文摘Lil.03Co0.10MnL90FxO4-x （z=0, 0.05, 0.10, 0.15 and 0.20） cathode materials were synthesized by solid-state reaction using Mn203, Li2CO3, C0203 and LiF as raw materials. The chemical compositions of Lil.03COo.lMnl.9FzO4-z were examined by inductively coupled plasma （ICP） and potentiometric analysis, the effects of F-substitution contents on structure, morphology and electrochemical performance of spinel Lil.03Coo.loMnl.9004 were studied by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and electrochemical measurements. It is found that the Lix.03 Co0.10Mnl.9oFzOa_z samples display a single phase of cubic spinel structure. The lattice parameters increase with the increase of F content when z〈_0.10. However, the lattice parameters begin to decrease when F content continues to increase. The results show that an appropriate amount ofF substitution for O element with Li＋, Co3＋ improves discharge capacity and structure stability of the materials. The Lil.03Co0.10Mnl.90FoAsO3.s5 sample shows an initial discharge capacity of 111.0 mA.h/g and has capacity retention of 97.0% after 30 cycles at 0.2C.
基金financial support from the Foundation for Innovative Research Groups of the National Natural Science Foundation of China (No. NSFC51621001)the Guangdong Special Support Program (2017TQ04N224)+1 种基金the Guangdong Natural Science Funds for Distinguished Young Scholar (Grant No. 2017B030306004)the Guangdong Province Universities and Colleges Pearl River Scholar Funded Scheme。
文摘O3-type Na NiO_(2)-based cathode materials undergo irreversible phase transition and serious capacity decay at high voltage above 4.0 V in sodium-ion batteries. To address these challenges, effects of Fsubstitution on the structure and electrochemical performance of Na Ni_(0.4)Mn_(0.25)Ti_(0.3)Co_(0.05)O_(2) are investigated in this article. The F-substitution leads to expanding of interlayer, which can enhance the mobility of Na+. NaNi_(0.4)Mn_(0.25)Ti_(0.3)Co_(0.05)O_(1.92)F_(0.08)(NMTC-F_(0.08)) with the optimal F-substitution degree exhibits much improved rate capability and cyclic stability. It delivers reversible capacities of 177 and 97 m Ah g^(-1) at 0.05 and 5 C within 2.0–4.4 V, respectively. Galvanostatic intermittent titration technique verifies faster kinetics of Na+diffusion in NMTC-F_(0.08). And in-situ XRD investigation reveals the phase evolution of NMTC-F_(0.08), indicating enhanced structural stability results from F-substitution. This study may shed light on the development of high performance cathode materials for sodium-ion storage at high voltage.
