Striving to Disclose the Electrochemical Processes of Organic Batteries

Abstract

Organic/polymeric materials are promising as electrode materials for batteries because of their advantages of flexibility, high specific capacity due to the possible multielectron transfer, low cost from green natural resources, and weak intermolecular interactions that enable the storage of low-cost large-sized or multivalent metal ions. However, the development of organic electrode materials (OEMs) and organic batteries and the understanding of the electrochemical process face great challenges in the characterization of polymers and the charge storage mechanisms: (1) the charged and/or discharged states of OEMs are often air unstable, which makes the ex situ characterizations susceptible to the interference of air. (2) OEMs, particularly polymeric materials, are designed to be insoluble to deliver high cyclability, which makes it difficult for them to be separated from the electrode. (3) Possible multielectron transfer makes it difficult to determine whether the proposed charge storage mechanism or the experiment results are wrong when the actual capacity mismatches with the theoretical capacity based on the proposed mechanisms. (4) It is difficult to achieve single crystals of polymers, and hence, it seems impossible to know the actual locations of the stored ions in the polymers. (5) The typical methods for characterization of insoluble polymers are only qualitative, and it is challenging to quantify the amount of stored ions. (6) Even for most in situ characterizations, they can only give the tendency of qualitative structural evolution.