A nonvolatile memory device with very low power consumption based on the switching of a standard electrode potential

Abstract

We prepared a nonvolatile memory device that could be reversibly switched between a high and a low open-circuit voltage (Voc) regime. The device is composed of a solid electrolyte Li3PO4 film sandwiched between metal Li and Au electrodes: a Li/Li3PO4/Au heterostructure, which was fabricated at room temperature on a glass substrate. The bistable states at Voc ∼ 0.7 and ∼0.3 V could be reversibly switched by applying an external voltage of 2.0 and 0.18 V, respectively. The formation and deformation of an ultrathin Au–Li alloy at the Li3PO4/Au electrode interface were the origin of the reversible switching.

First-principles study of Li-ion distribution atγ−Li3PO4/metal interfaces

“…In the experiment, the LVS and HVS appear after the 0.2 and 2.0 V voltage applications, respectively, where the only LVS shows the interface resistance [5]. When the 2.0 V is applied, Li-ions transfer inside the electrolyte from Au electrode side toward Li electrode side, which results in the Li-poor condition near the Au electrode.…”

“…However, the current flow from Au to Li electrodes around 0.5 V suggests the movement of the accumulated Li-ion at the Au electrode toward the Li electrode. The current impedance measurement at the two voltage states reveals that the Nyquist plots of the HVS and LVS have one and two semicircles, respectively [5]. The one semicircle seen in both states originates from the resistance in Li 3 PO 4 .…”

“…Experiments also reported that the novel memory devices with 4 mm 2 surface area consumes ca. 3 × 10 −5 C during the voltage switching (LVS to HVS, vice versa) [5]. Using the experimental surface area and ca.…”

“…The current-voltage characteristics obtained by the cyclic voltammetry measurement in the Au/Li 3 PO 4 /Li stacked system show two remarkable peaks [5,6]. The peak at 0.2 V corresponds to the current from Li to Au electrodes, suggesting the Li-ion migration toward the Au electrode.…”

“…Recently, the Au/Li 3 PO 4 /Li stacked system, which has a similar geometry to ASSLIBs, has been found to exhibit two different internal voltage states, viz., high voltage state (∼0.7 V versus Li + /Li; HVS) and low voltage state (∼0.3 V versus Li + /Li; LVS) [5]. The transition from LVS to HVS (HVS to LVS) occurs by applying 2.0 V (0.2 V) to the Au electrode.…”