Research On High Mass Loading Ultra-thick Porous Lithium-ion Battery Electrode Fabricated Via Low Temperature Direct Writing Technology

High mass loading ultra-thick porous lithium-ion battery electrodes are fabricated via low temperature direct writing,which avoids the contradiction between the energy density and power density of the traditionally manufactured two-dimensional lithium-ion batteries.Low temperature direct writing combined with vacuum freeze-drying can easily produce ultra-thick porous electrodes with high surface specific capacity.In this paper,we studied the configuration of electrode slurry that customized for low temperature direct writing process,the setting of printing process parameters and the morphological characterization of printed electrodes.Adding coagulant 1,4-dioxane to the formula of traditional lithium-ion electrode slurry to improve the molding performance of the slurry at low temperature.The rheological properties of different slurry ratios were configured and characterized,and the solid content and rheological properties of the slurry were taken into consideration.The final slurry ratio used as a lithium ion negative electrode slurry was Li₄Ti₅O₁₂（LTO）:acetylene black:CMC:deionized water:1,4-dioxane=15 g:1.875 g:1.875g:20 m L:20 m L.Tested better printing parameter groups:molding room temperature=-7°C,initial extrusion pressure=9N,extrusion speed v_j=0.001mm/s,scanning speed v_xy=4mm/s,layering height h_s=0.06mm.Anode slurry was used to print 6 layers,12 layers,and 18 layers of electrodes,and the morphology of electrodes was characterized.The heights of the electrodes were 200μm（6-layer）,450μm（12-layer）,and 820μm（18-layer）.The porosity of6 and 12 layers was 72%and the porosity of 18 layers was 65%.All the electrodes produced the porous structure inside.This paper also studied the comparison between low temperature direct writing and other processes,and the electrochemical performance of 6-,12-,18-layer electrodes.Compared with the single-layer electrode line manufactured by 3D printing in room temperature,the low temperature direct writing own the narrower width and better surface quality,and its packaged battery has better performance at high charge and discharge rate than 3D printing in room temperature and traditional coated electrodes.Next,selected copper foam as the current collector to produce 6-,12-and 18-layer LTO electrodes,their specific capacities stabilized at146m Ah/g,143m Ah/g,and 138m Ah/g respectively after 100 cycles@0.5C.It is worth noting that the specific capacity of the 18-layer high mass loading porous LTO electrode exceeds115m Ah/g@2C,and its surface specific capacity reaches an astonishing～4.8m Ah/cm²@0.2C.In summary,high-capacity porous electrodes fabricated via low temperature direct writing get excellent electrochemical performance at low and medium charge and discharge rates,and its high area-specific capacity makes the lithium-ion battery structure more compact.