Li-Based Electrochemical Memory Achieving Stable Analog Weight Modulation via Interface Engineering

Analog electrochemical memories provide ionic control of conductance for neuromorphic computing, but reliable retention of programmed states remains a critical challenge. Here we report a three-terminal Li-based electrochemical random-access memory (Li-ECRAM) consisting of a LiCoO2 channel, a mechanically buffered and moisture protective SiOx ion reservoir and a LiPON interlayer. The device supports 64 distinguishable conductance states and maintains representative programmed states over 103 s at temperatures up to 80 °C and 80% relative humidity. First-principles-informed thermodynamic analysis indicates that LiPON adjusts the interface band alignment and the interfacial electrostatic potential. This interface potential redistribution suppresses lithium migration and parasitic electronic transport, stabilizing the lithium-vacancy profile in LiCoO2. The Li-ECRAM exhibits paired pulse facilitation, excitatory and inhibitory postsynaptic currents, and long-term potentiation and depression with nonlinearity factors of αP = 0.501and αD = 0.826, while keeping cycle-to-cycle variation below 0.4% and device-to-device variation at 0.52%. When the measured conductance updates are mapped into a YOLOv5 fire detection network, the system reaches a mean average precision of 76.7%, or 91.1% of the software performance. These results identify LiPON/SiOx synergistic channel-reservoir interface regulation as a route to environmentally stable Li-ECRAM synapses.