Recent Progress on Organic Electrodes Materials for Rechargeable Batteries and Supercapacitors

Abstract

Rechargeable batteries are essential elements for many applications, ranging from portable use up to electric vehicles. Among them, lithium-ion batteries have taken an increasing importance in the day life. However, they suffer of several limitations: safety concerns and risks of thermal runaway, cost, and high carbon footprint, starting with the extraction of the transition metals in ores with low metal content. These limitations were the motivation for an intensive research to replace the inorganic electrodes by organic electrodes. Subsequently, the disadvantages that are mentioned above are overcome, but are replaced by new ones, including the solubility of the organic molecules in the electrolytes and lower operational voltage. However, recent progress has been made. The lower voltage, even though it is partly compensated by a larger capacity density, may preclude the use of organic electrodes for electric vehicles, but the very long cycling lives and the fast kinetics reached recently suggest their use in grid storage and regulation, and possibly in hybrid electric vehicles (HEVs). The purpose of this work is to review the different results and strategies that are currently being used to obtain organic electrodes that make them competitive with lithium-ion batteries for such applications.

Phosphaviologen‐Based Pyrene‐Carbon Nanotube Composites for Stable Battery Electrodes

“…Cyclic voltammetry on PY 2 PV shows two reversible reductions occurring at −0.1 V and −0.5 V vs. Ag/Ag + with the position and shape of these peaks showing little dependency on scan rate, behavior typical of fast and reversible redox kinetics. This corresponds to charging/ discharging reactions that happen at 3.2–2.8 V vs. Li/Li + , a relatively high voltage for organic materials . The PY 2 PV :SWCNT composite shows the same electrochemical behavior, indicating that pyrene interactions with SWCNTs do not impact the favorable electrochemical properties of PY 2 PV (Figure ).…”

“…It is in this context that electrode materials based on carbon, nitrogen, oxygen, sulfur, and phosphorus are increasingly being evaluated as alternatives for use in Li‐ion batteries . Electrodes made from abundant elements, or elements which are consumed in the biomass cycle, make recycling or disposal more environmentally friendly .…”

“…While organic electrodes are potentially advantageous, there are issues that plague their performance and prevent their widespread adoption in commercial batteries. These issues include lower cycle stability due to degradation or dissolution upon repeated oxidation or reduction, self‐discharge due to organic small molecules solubilizing in the electrolyte, the lower conductivity of organic materials lowering discharge rates, and low voltages due to the difficulty in finding carbon‐based materials with a high reduction potential relative to lithium …”

“…It is in this context that electrode materials based on carbon, nitrogen, oxygen, sulfur, and phosphorus are increasingly being evaluated as alternatives for use in Li-ion batteries. [7][8][9] Electrodes made from abundant elements, or elements which are consumed in the biomass cycle, make recycling or disposal more environmentally friendly. [1,2] In addition, organic materials are held together with weaker noncovalent interactions and van der Waals forces, thus they do not generate significant heat or degrade upon swelling and higher charge/discharge rates can be safely achieved.…”

“…These issues include lower cycle stability due to degradation or dissolution upon repeated oxidation or reduction, self-discharge due to organic small molecules solubilizing in the electrolyte, the lower conductivity of organic materials lowering discharge rates, and low voltages due to the difficulty in finding carbon-based materials with a high reduction potential relative to lithium. [7][8][9]14,15] These issues can be mitigated to some extent by judicious optimization, as molecular structures can be optimized to improve operating voltage and redox stability. [16,17] Electrode dissolution can be reduced by choosing appropriate solvents, electrolytes, and electrode binders, while conductive additives improve the conductivity of organic electrodes.…”