Trends in Hydrogen, Lithium and Oxygen-Based Electrochemical RAM: Materials, Mechanisms, and Applications

Abstract

Electrochemical Random-Access Memory (ECRAM) has emerged as a compelling class of nonvolatile memory devices capable of analog conductance modulation, making them promising candidates for neuromorphic computing. ECRAMs operate via reversible ion migration and electrochemical redox reactions within solid-state materials, enabling fine-tuned, energy-efficient, and biologically inspired signal processing. While various reviews have addressed neuromorphic hardware broadly, this work focuses specifically on the materials-centric mechanisms and challenges of ECRAM systems. We categorize and analyze ECRAMs based on the dominant mobile ion species; hydrogen (H⁺), lithium (Li⁺), and oxygen (O²⁻) and discuss their operation principles, material platforms, ion transport behaviors, and structure–function relationships. We highlight recent advances in channel and electrolyte design, in situ characterization techniques, and performance optimization strategies for each system. This review also outlines current limitations in achieving ideal device characteristics (e.g., linearity, retention, symmetry), and concludes by identifying critical research directions for achieving reliable, scalable, and application-specific ECRAM technologies.