By taking tetragonal tungsten bronze(TTB)phase Nb_(18)W_(16)O_(93)as an example,an improved solid-state sintering method at lower temperature of 1000℃for 36 h was proposed via applying nanoscale raw materials.XRD,SEM...By taking tetragonal tungsten bronze(TTB)phase Nb_(18)W_(16)O_(93)as an example,an improved solid-state sintering method at lower temperature of 1000℃for 36 h was proposed via applying nanoscale raw materials.XRD,SEM and XPS confirm that the expected sample was produced.GITT results show that the lithium-ion diffusion coefficient of Nb_(18)W_(16)O_(93)(10−12 cm^(2)/s)is higher than that of the conventional titanium-based anode,ensuring a relatively superior electrochemical performance.The lithium-ion diffusion mechanism was thoroughly revealed by using density functional theory simulation.There are three diffusion paths in TTB phase,among which the interlayer diffusion with the smallest diffusion barrier(0.46 eV)has more advantages than other typical anodes(such as graphite,0.56 eV).The relatively smaller lithium-ion diffusion barrier makes TTB phase Nb_(18)W_(16)O_(93)become a potential highspecific-power anode material.展开更多
Single crystal LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)is currently widely used due to the outstanding cycle stability and safety.However,its sensitivity to the environment and the high residual alkali makes the electrochemica...Single crystal LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)is currently widely used due to the outstanding cycle stability and safety.However,its sensitivity to the environment and the high residual alkali makes the electrochemical performance and processing property severely degraded after long-term storage,especially for the Ni-rich single crystal material.Therefore,it is highly urgent to develop a cost-effective strategy for the revival of degraded Ni-rich cathode materials.Here,a low-carbon strategy is proposed to revive the degraded single crystal LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)(SCNCM622)through water washing.The solid-liquid reaction mechanism of SCNCM622 and water was revealed and the strong dependence of the recovery effect on the washing time was clarified.Under optimized conditions,the sample with a washing time of 24 h shows 31.2%reduction in viscosity,18.4%improvement in discharge capacity,15.3%enhancement in cycle life,and excellent rate performance compared to the blank sample.Therefore,this strategy can achieve higher utilization of single crystal Ni-based cathode materials with a lower cost.展开更多
基金the Key R&D Program of Shaanxi Province,China(No.2019ZDLGY04-05)the Natural Science Foundation of Shaanxi Province,China(No.2019JLZ-01)+1 种基金the Fundamental Research Funds for the Central Universities of China(Nos.19GH020302,3102019JC005,3102021ZD0401,3102021TS0406)the Science,Technology,and Innovation Commission of Shenzhen Municipality,China(No.JCYJ20180508151856806).
文摘By taking tetragonal tungsten bronze(TTB)phase Nb_(18)W_(16)O_(93)as an example,an improved solid-state sintering method at lower temperature of 1000℃for 36 h was proposed via applying nanoscale raw materials.XRD,SEM and XPS confirm that the expected sample was produced.GITT results show that the lithium-ion diffusion coefficient of Nb_(18)W_(16)O_(93)(10−12 cm^(2)/s)is higher than that of the conventional titanium-based anode,ensuring a relatively superior electrochemical performance.The lithium-ion diffusion mechanism was thoroughly revealed by using density functional theory simulation.There are three diffusion paths in TTB phase,among which the interlayer diffusion with the smallest diffusion barrier(0.46 eV)has more advantages than other typical anodes(such as graphite,0.56 eV).The relatively smaller lithium-ion diffusion barrier makes TTB phase Nb_(18)W_(16)O_(93)become a potential highspecific-power anode material.
基金financially supported by the Science,Technology,and Innovation Commission of Shenzhen Municipality(No.JCYJ20180508151856806)the National Natural Science Foundation of China(No.51974256)+3 种基金the Outstanding Young Scholars of Shaanxi(No.2019JC-12)the Key R&D Program of Shanxi(No.2019ZDLGY04-05)the National Natural Science Foundation of Shaanxi(Nos.2019JLZ-01,2019JLM-29)the Fundamental Research Funds for the Central Universities(Nos.19GH020302,3102019JC005)。
文摘Single crystal LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)is currently widely used due to the outstanding cycle stability and safety.However,its sensitivity to the environment and the high residual alkali makes the electrochemical performance and processing property severely degraded after long-term storage,especially for the Ni-rich single crystal material.Therefore,it is highly urgent to develop a cost-effective strategy for the revival of degraded Ni-rich cathode materials.Here,a low-carbon strategy is proposed to revive the degraded single crystal LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)(SCNCM622)through water washing.The solid-liquid reaction mechanism of SCNCM622 and water was revealed and the strong dependence of the recovery effect on the washing time was clarified.Under optimized conditions,the sample with a washing time of 24 h shows 31.2%reduction in viscosity,18.4%improvement in discharge capacity,15.3%enhancement in cycle life,and excellent rate performance compared to the blank sample.Therefore,this strategy can achieve higher utilization of single crystal Ni-based cathode materials with a lower cost.
