Preparation And Properties Of Li₄Ti₅O₁₂ Ceramic Target Materials

With the size of electronic products began to miniaturized and light weight,all-solid-state thin-film batteries have been widely studied and applied.As a key component of the all-solid-state thin-film lithium-ion battery,The spinel type lithium titanate material is a new type of lithium ion battery anode material,which has the advantages of no volume change during lithium deintercalation,good cycle performance,long cycle life and low voltage plateau structure stability,which is widely concern and research.However,the poor electrical conductivity of lithium titanate electrode(electron conductivity is only 10^-9 S/cm),the lack of large rate charge and discharge capability severely limit its application in lithium ion batteries.Doping modification is an effective method to improve the conductive properties of lithium titanate thin films.One of the key points is to introduce uniform heterogeneous atoms during the preparation of ceramic targets without affecting the coating performance of the target.This is an important prerequisite for the doping of lithium titanate ceramics,and it is also a difficult problem in this area that has not yet been resolved.In this paper,lithium titanate ceramic targets were sintered by wet milling,dry pressing and sintering under normal pressure.The target materials were modified by Li₂CO₃ and Mg?OH?₂.The effects of different sintering temperature,holding time,doping ions and doping amount of ionic substances on the properties of lithium titanate ceramic target were studied.The experiment main contents and conclusions are as follow:1.When the Li₄Ti₅O₁₂ ceramic target is sintered,the properties of the target are increased with the increase of temperature.It is obtained by XRD analysis that when the temperature exceeds 930?,lithium poor lithium phase Li₂Ti₃O₇ is generated due to lithium loss caused by lithium loss.Through the basic research of target can be concluded,when sintering temperature is 930?and holding time,can get the best performance,single phase Li₄Ti₅O₁₂ceramic target,the shrinkage rate is 18.2%,the relative density is 88.1%,the bending strength is 73.79 MPa,Vivtorinox hardness is 309.83 HV₅₀.2.It can be seen from the phase diagram that the corresponding lithium-rich phase and lithium-poor phase are generated in either an excess of lithium source or a small amount of lithium source,The Li₂CO₃ doping is used as a lithium source to supplement the loss of Li due to high temperature during sintering of ceramic targets due to the easy loss of Li during high temperature sintering.Through the research on the properties of Li₂CO₃ doped Li₄Ti₅O₁₂ceramic target after sintering,the results showed that the best Li₄Ti₅O₁₂ ceramic target was obtained when the content of Li₂CO₃ was 3 wt.%and the holding time was 5 h at 950?,the shrinkage rate was 19.0%,the density was 93.1%,the bending strength was 80.03 MPa,and the vickers hardness was 322.22 HV₅₀.Due to the replenishment of the lithium source,the lithium-poor phase Li₂Ti₃O₇ does not appear in the ceramic target at this time.3.When Mg?OH?₂ is added as magnesium source,the analysis of Mg?OH?₂ doped Li₄Ti₅O₁₂ceramic target can be seen that the optimum doping amount of Mg?OH?₂ is 4 wt.%.Through the discussion on sintering temperature and holding time obtained at the highest sintering temperature of 950?for 5h has the best performance of Mg?OH?₂ doped Li₄Ti₅O₁₂ ceramic target,the shrinkage rate is 20.0%,the density is 96.0%,the flexural strength is 83.19 MPa,the hardness of Vivtorinox 364.26 HV₅₀₀.After XPS analysis,the relative atomic content of four elements of Li,Mg,Ti and O were 10.9%,4.8%,24.0%and 60.3%.4.Ceramic targets with excellent properties were prepared by powder metallurgy sintering.The ceramic target was coated by pulsed laser deposition?PLD?,and the obtained films were annealed in the sintering furnace.The XRD analysis showed that the amorphous film was obtained by the coating experiment,and the growth state of the film was good by SEM analysis.It is further indicated that the ceramic targets prepared by sintering in this paper can meet the demand of the coating process.