Delocalized Lithium Ion Flux by Solid-State Electrolyte Composites Coupled with 3D Porous Nanostructures for Highly Stable Lithium Metal Batteries

This work investigates the root cause of failure withthe ultimateanode, Li metal, when employing conventional/composite separatorsand/or porous anodes. Then a feasible route of utilizing Li metalis presented. Our operando and microscopy studies have unveiled thatLi(+) flux passing through the conventional separator isnot uniform, resulting in preferential Li plating/stripping. Porousanodes alone are subject to clogging with moderate- or high-loadingcathodes. Here we discovered it is necessary to seek synergy fromour separator and anode pair to deliver delocalized Li+ to the anode and then uniformly plate Li metal over the large surfaceareas of the porous anode. Our polymer composite separator containinga solid-state electrolyte (SE) can provide numerous Li+ passages through the percolated SE and pore networks. Our finiteelement analysis and comparative tests disclosed the synergy betweenthe homogeneous Li+ flux and current density reductionon the anode. Our composite separators have induced compact and uniformLi plating with robust inorganic-rich solid electrolyte interphaselayers. The porous anode decreased the nucleation overpotential andinterfacial contact impedance during Li plating. Full cell tests withLiFePO(4) and Li[Ni0.8Mn0.1Co0.1]O-2 (NMC811) exhibited remarkable cycling behaviors: & SIM;80%capacity retention at the 750th and 235th cycle, respectively. A high-loadingNMC811 (4 mAh cm(-2)) full cell displayed maximumcell-level energy densities of 334 Wh kg(-1) and 783Wh L-1. This work proposes a solution for raisingenergy density by adopting Li metal, which could be a viable optionconsidering only incremental advancement in conventional cathodeslately.