Photo-assisted Charge/discharge Li-organic Battery with a Charge-separated and Redox-active C60@Porous Organic Cage Cathode

Photo-assisted Li-organic batteries provide an attractive approach for solar energy conversion and storage, while the challenge lies in the design of high-efficiency organic cathodes. Herein, a charge-separated and redox-active C60@porous...

Rational Design of Stable Four-Electron-Accepting Carbonyl-N-methylpyridinium Species for High-Performance Lithium-Ion Batteries

Development of novel organics that exhibit multiple and stable redox states, limited solubility and improved conductivity is a highly rewarding direction for improving the performance of lithium-ion batteries (LIBs). As biologically derived organic molecules, carbonylpyridinium compounds have desirable and tunable redox properties, making them suitable candidates for battery applications. In this work, we report a structural evolution of carbonylpyridinium-based redox-active organics, from 2-electron accepting BMP to 4-electron accepting small, conjugated molecules (1, 2), and then to the corresponding conjugated polymers (CP1, CP2). Through suppression of dissolution and increasing electrochemical conductivity, the LIBs performance can be gradually enhanced. At a relatively high current of 0.5 A g-1, high specific capacities for 1 (100 mAh g-1), 2 (260 mAh g-1), CP1 (360 mAh g-1) and CP2 (540 mAh g-1) can be reached after 240 cycles. Particularly, the rate performance and cycling stability of CP2 surpasses many reported commercial inorganic and organic electrode materials. This work provides a promising new carbonylpyridinium-based building block featured with multiple redox centers, on the way to high performance Li-organic batteries.

Electrochemical Mechanism of Al Metal–Organic Battery Based on Phenanthrenequinone

Al metal-organic batteries are a perspective high-energy battery technology based on abundant materials. However, the practical energy density of Al metal-organic batteries is strongly dependent on its electrochemical mechanism. Energy density is mostly governed by the nature of the aluminium complex ion and utilization of redox activity of the organic group. Although organic cathodes have been used before, detailed study of the electrochemical mechanism is typically not the primary focus. In the present work, electrochemical mechanism of Al metal-phenanthrenequinone battery is investigated with a range of different analytical techniques. Firstly, its capacity retention is optimized through the preparation of insoluble cross-coupled polymer, which exemplifies extremely low capacity fade and long-term cycling stability. Ex situ and operando ATR-IR confirm that reduction of phenanthrenequinone group proceeds through the two-electron reduction of carbonyl groups, which was previously believed to exchange only one-electron, severely limiting cathode capacity. Nature of aluminium complex ion interacting with organic cathode is determined through multiprong approach using SEM-EDS, XPS, and solid-state NMR, which all point to the dominant contribution of AlCl2+ cation. Upon full capacity utilization, Al metal-polyphenanthrenequinone battery utilizing AlCl2+ offers an energy density of more than 200 Wh/kg making it a viable solution for stationary electrical energy storage.