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.