Cation-Driven Valence Change Mechanism in 2D AgCrS₂ for Ultralow-Power and Reliable Memristors

Memristive devices are promising building blocks for next-generation memory and neuromorphic circuits in artificial intelligence. Among them, filamentary memristors offer great potential for high-performance and densely integrated systems. However, achieving both low-power operation and long-term cycling stability remains a key challenge. Here, we present a 2D AgCrS₂ volatile memristor that operates via a novel cation-driven valence change mechanism (CVCM). Unlike traditional filament-based conduction, this mechanism enables Ag⁺-driven switching without metal filament growth. The threshold switching process is governed by the reversible intercalation of highly mobile Ag⁺ ions into tetrahedral vacancies between CrS₂ layers, forming and rupturing the highly conductive Ag₂CrS₂ pathway and thus delivering an on/off ratio exceeding 10⁵ at 0.1 V. The AgCrS₂ memristor enables a reduced threshold voltage of 0.2 V and an ultralow power consumption down to 200 pW when the compliance current is further reduced to the nA level. Additionally, the absence of elemental Ag metallization in the switching layer prevents structural degradation, enabling stable operation for over 3 × 10⁵ switching cycles. These findings establish CVCM as a promising way for developing energy-efficient and reliable memristive technologies.