Sodium-ion battery (SIB) is a promising option for bridging the intermittent renewable energy to modern power grid due to the substantially lower cost compared to its lithium cousin. Early SIBs inherited traditional organic electrolyte and membrane designs from lithium-ion industry and had very poor cycle life due to severe side reactions at electrodes and electrolyte degradation. Recent development of highly concentrated electrolytes (HCE) has enabled high voltage cathode and Na metal anode with good cyclability and hence leads to competitive performance against some LIB chemistries. The ion transport of HCE, however, is often compromised due to its intrinsic pr when used with traditional polypropylene/polyethylene separators. These drawbacks make it challenging to achieve high power performance without sacrificing safety, energy density and cycle life. Separately, most polymer electrolytes that exhibit decent ion transport properties are electrochemically stable only in a narrow voltage window and suffer interfacial degradation over long-term operation. Therefore, an advanced membrane technology that can improve the Na+ transport, stabilize the electrode interphase and utilize the potential of HCE to the fullest is indispensable to for the success of high voltage SIBs. Storagenergy Technologies, Inc. (Storagenergy) will develop an innovative gradient polymer/ceramic single-ion conducting membrane (GSICM) for high voltage sodium-ion batteries using HCE. The proposed technology will enable selective Na+-ion transport with a transference number close to unity, while preserving a comparable ionic conductivity to liquid electrolyte. The proposed membrane will utilize our proprietary polymer electrolytes and 3D sodium super ionic conductor (NASICON) network that provide both good interfacial contact with electrode materials and exceptional single-ion conducting characteristic. The gradient distribution of two types of polymer layers, cathodic and anodic, enables oxidation and reduction stability against high voltage cathode and Na metal anode, respectively. The reduction of greenhouse emissions through the adoption of alternative energy sources require large-scale distributed energy storage to counter their intermittent nature. Our membrane design will facilitate the deployment of low-cost sodium-ion batteries for grid-scale energy storage systems. The successful development of this membrane technology will enable a new family of American batteries for both commercial and defense sectors. This technology will revolutionize other energy related fields, e.g. electric transport by enabling widespread adoption of renewable energy sources through low cost and high reliability. The insights gained in this project will also benefit the development of emerging battery chemistries using unconventional electrolytes, including potassium, zinc and aluminum batteries.
