Abstract

The innovation of electrode structures has been lagging far behind that of materials, hampering the industrialization process of high performance batteries. Especially for thick electrodes with high active materials loadings, it’s inadequate to achieve satisfactory performance, especially working at higher current densities, due to the restricted ion transport rate across the electrodes with traditional densely packed structure [1]. To solve the above issue, a vertically aligned laminate porous structure is designed and fabricated for the first time [2]. It seems to cut the thick electrode into thousands of slices vertically arranging like a maze in the X-Y plane, leaving thousands of straight slits (working as ions transport channels) in the Z axis direction. As a result, the electrolyte composition in the slits keeps similar to that on the surface of the electrodes, ascribe to the really large mass effective diffusivity in these slits with lowest tortuosity. Then the real ions transport resistance only exists in the slices, which is much smaller than traditional thick electrodes. The as proposed maze-like electrode structure (MLPE) is realized by a scalable freeze casting process. Electrodes with such novel structure have shortened ion diffusion channels to rapidly supply electrolyte for reaction and significantly increase active materials loading. The capacity at 2C of Li-S is increased by 50% compared to electrodes directly drying (447mAh g-1). In addition, electrodes with 8 mg cm−2 sulfur can also be easily prepared and show excellent cycling stable at 0.1C (initial discharge capacity: 949 mAh g-1, capacity retention: 98.2%). What’s more, capacities of 89 and 115 mAh g-1 at 10C have achieved for LiFePO4 (LFP) and NaTi2(PO4)3 (NTP) electrodes, respectively, which is over 70% and 130% compared to their contrast with active substances loading of 8.8 and 5.5 mg cm−2. Fig. a) Schematic illustration of MLPE. b) Schematic illustration of ion transport in the MLPE. c) Rate performance of MLPE-S. d) Cycle performance of MLPE-S. e) Rate performance of MLPE-LFP. f) Rate performance of MLPE-NTP.

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