A Sodiophilic Amyloid Fibril Modified Separator for Dendrite-Free Sodium-Metal Batteries

Sodium (Na) batteries are being considered as prospective candidates for the next generation of secondary batteries in contrast to lithium-based batteries, due to their high raw-material abundance, low cost, and sustainability. However, the unfavorable growth of Na-metal deposition and severe interfacial reactions have prevented their large-scale applications. Here, a vacuum filtration strategy, through amyloid-fibril-modified glass-fiber separators, is proposed to address these issues. The modified symmetric cell can be cycled for 1800 h, surpassing the performance of previously reported Na-based electrodes under an ester-based electrolyte. Moreover, the Na/Na3V2(PO4)(3) full cell with a sodiophilic amyloid-fibril-modified separator exhibits a capacity retention of 87.13% even after 1000 cycles. Both the experimental and the theoretical results show that the sodiophilic amyloid fibril homogenizes the electric field and Na-ion concentration, fundamentally inhibiting dendrite formation. Simultaneously, the glutamine amino acids in the amyloid fibril have the highest adsorption energy for Na, resulting in the formation of a stable Na3N- and NaNxOy-rich solid-electrolyte-interface film on the anode during cycling. This work provides not only a possible pathway to solve the dendrite problem in metal batteries using environmentally friendly biomacromolecular materials, but also a new direction for expanding biomaterial applications. A novel composite separator is fabricated through the vacuum filtration technique, which incorporates a unique amyloid fibril onto a glass-fiber separator. The composite separator demonstrates remarkable efficacy in suppressing the growth of sodium dendrites due to the formation of a stable solid-electrolyte-interphase film enriched with nitride, which showcases its potential as a promising solution in sodium-battery technology.image