Thick electrode with thickness-independent capacity enabled by assembled two-dimensional porous nanosheets

Thick electrode is essential for new-generation, high energy density batteries due to its low active/inactive-component ratio. However, current strategies using external forces for improving ion-transport in electrodes often cause low volumetric density, poor mechanical property or less mass loading. Here, high-performance thick electrodes were fabricated through layer-by-layer assembly of two-dimensional (2D), porous nanosheets. The 2D morphology and in-plane pores enable dense electrode structure but with abundant, penetrated ion-transport channels. Various cathode species (NCMs, LCO and LNMC nanosheets) were synthesized by a simple one-pot process. Typically, the mechanically robust NS-NCM electrode reveals rate and cycling performance far better than the commercial NCM counterparts. In particular, the NS-NCM electrode exhibits thickness-independent capacity and excellent volumetric capacity even when the mass loading is scaled up to 320 mg cm−2. This enables it to deliver a superb areal capacity of 45.4 mAh cm−2, surpassing all the reported cathode species and one order of magnitude higher than commercial cathodes. This strategy provides a significant stride in structural design of electrode toward higher areal and volumetric energy density.