Self‐Discharge in Batteries Based on Lignin and Water‐in‐Polymer Salt Electrolyte

Abstract

Lignin, the most abundant biopolymer on earth, has been explored as an electroactive material in battery applications. One essential feature for such lignin‐based batteries to reach successful usage and implementation, e.g., large‐scale stationary grid applications, is to have slow self‐discharge characteristics on top of the essential safety and life‐cycle properties. Water‐in‐polymer salt electrolytes (WIPSEs) have been demonstrated as an attractive route to solve this issue; however, little has been done to understand the fundamentals of actual self‐discharge mechanisms. Herein, the impact of some critical chemical and physical parameters (pH, dissolved oxygen, viscosity, and cutoff potential) on self‐discharge of batteries based on WIPSE and lignin has been investigated. The pH range is crucial as there is an interplay between long‐term stability and high energy density. Indeed, lignin derivatives typically store relatively more charge in acidic media but later promote corrosion affecting device stability. A robust and high‐performing organic battery, incorporating potassium polyacrylate as WIPSE, is demonstrated, which expresses good self‐discharge behavior for a broad range of pH and with little impact on the atmosphere used for manufacturing. It is believed that the investigation will provide critical insights to the research community to promote the advancement of printed large‐scale energy storage devices.