High volumetric capacity nanoparticle electrodes enabled by nanofluidic fillers

• A conductive nanofluidic filler with nanoconfined interlayer solvent facilitates the ion transport in dense electrode. • The nanofiller-enhanced dense nanoparticle electrode delivers superior areal capacity and volumetric capacity. • The self-shearing property of nanofluidic filler introduces a facile approach to densify nanoparticles by compaction. Nanosized materials are widely applied in lithium-ion battery to improving power/energy performances. However, the low packing density of nanoparticles limits the volumetric capacity of electrodes. Calendering nanoparticle electrodes leads to pore destruction, electrolyte blocking and poor ion transport. This work reports unimpeded ion transport in ultracompact nanoparticle electrodes by nanofluidic additives that provide rapid ion pathways without loss of electrode density. Sub-micron commercial LiFePO 4 particles, as a model cathode material, are deployed to fabricate the nanofluidic-enhanced dense electrodes that show excellent volumetric capacities in liquid and gel polymer electrolytes, which surpass state-of-the-art LiFePO 4 electrodes. This extraordinary performance (303.6 mAh cm −3 and 1026.2 Wh L –1 at 0.06 C) correlates with the conductive nanofluidic network through which lithium ions can move around swiftly. This nanofluidic strategy can be extended to other electroactive nanoparticles in the design of high-capacity compact batteries. Nanomaterials are in favor to improving the capability of lithium-ion batteries. However, their low tapping density restricts the volumetric performance. Herein, we introduce a new electrode compaction strategy via dry densification. With nanofluidic Li + conductive network, the densified electrode performs remarkable volumetric performance in liquid and gel electrolytes. Our results point out a promising nanoparticle densification strategy for battery electrodes.