Conjugated Cobalt Polyphthalocyanine as the Elastic and Reprocessable Catalyst for Flexible Li–CO₂ Batteries

Abstract

on the redox chemistry of CO 2 , ideally following the equation 4Li + 3CO 2 ↔ 2Li 2 CO 3 + C with a theoretical energy density of 1876 Wh kg −1 . Li-CO 2 batteries represent a novel approach for the utilization of atmospheric CO 2 , and may potentially find applications where the CO 2 concentration is high, for example, in submarines or on Mars.Despite their great potential, many challenges would have to be overcome before Li-CO 2 batteries become a practical reality. The most serious one is the reversible electrochemical decomposition of Li 2 CO 3 at charge. It has been widely recognized from earlier Li-O 2 researches that the accumulation of Li 2 CO 3 on cathode from the parasitic reaction between CO 2 and Li 2 O 2 would passivate the electrode surface and gradually degrade the battery performance. [19][20][21][22] A high voltage (sometimes > 4.3 V versus Li/Li + ) is often required in order to decompose Li 2 CO 3 . Under such anodic potential, the electrolyte oxidation becomes significant. This problem escalates when it comes to Li-CO 2 batteries. We are in urgent need of efficient and robust cathode catalysts to facilitate the reversible Li 2 CO 3 formation and decomposition, promote the energy efficiency and enhance the cycle life. [14,15] Carbonaceous materials including pristine or doped graphene and carbon nanotubes were the first type of catalysts investigated for the Li-CO 2 application. [17,23,24] Despite the relative abundance and low cost, they generally fell short of expectations in terms of activity and stability. The charging overpotential was often observed to quickly rise with cycling. Very recently, Ru nanoparticles were revealed to promote Li 2 CO 3 decomposition: they lowered the charge voltage to 3.9 V and enabled an impressive cycle life. [16] Nevertheless, the high cost of Ru would obviously prohibit its large-scale application. It is therefore imperative to develop high-performance nonprecious metal-based cathode catalysts for Li-CO 2 batteries.One possible strategy is to search within the existing pool of catalyst materials for CO 2 reduction reaction (CO 2 RR) in aqueous solution. Even though the reaction pathways of CO 2 reduction in aqueous and aprotic media differ substantially, we believe that the knowledge accumulated on aqueous CO 2 RR can be used to inspire the Li-CO 2 research. Transition metal porphyrins and phthalocyanines have long been known for their CO 2 RR activities. [25,26] However, they are not naturally suited as the cathode catalyst of Li-CO 2 batteries owing to their Li-CO 2 batteries represent an attractive solution for electrochemical energy storage by utilizing atmospheric CO 2 as the energy carrier. However, their practical viability critically depends on the development of efficient and low-cost cathode catalysts for the reversible formation and decomposition of Li 2 CO 3 . Here, the great potential of a structurally engineered polymer is demonstrated as the cathode catalyst for rechargeable Li-CO 2 batteries. Conjugated cobalt polyphthalocyanine is prepared vi...

Conjugated Microporous Polymers with Bipolar and Double Redox‐Active Centers for High‐Performance Dual‐Ion, Organic Symmetric Battery

“…[15,16] Interestingly, Pcs have high structural variability including not only the central cavity with four nitrogenlinked isoindole units to bind various metal ions, but also the controllable peripheral active functional group to enable them to be molecular building blocks of the polymer skeletons. [17][18][19][20] In addition, Pcs exhibit good electronic carrier ability and fast redox kinetics due to their large delocalized π conjugated macrocyclic and also have highly stable CN bonds that are beneficial to facilitate fast redox kinetics and high reversible capacity, Redox-active conjugated microporous polymers (RCMPs) have received remarkable interest in electrochemical energy-storage systems in view of their porous structure and tunable redox nature. This work presents an effective strategy to construct RCMPs with bipolar and double redox-active centers by integrating copper (II) tetraaminephthalocyanine (CuTAPc) and 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA) units into the RCMPs (CuPcNA-CMP).…”

Tuning electronic and composition effects in ruthenium-copper alloy nanoparticles anchored on carbon nanofibers for rechargeable Li-CO2 batteries

“…Electrocatalysts utilized to facilitate the kinetics of discharge and charge processes in Li-CO2 batteries have been extensively studied [18], such as carbon nanomaterials [19,20], transition metals [12,15,[21][22][23][24], metal oxides [25,26], metal carbides [27,28] and redox mediator [29]. Zhang and co-workers introduced carbon nanotubes as cathode catalyst in rechargeable Li-CO2 batteries [30], which showed a discharge capacity of 5786 mAh g -1 and cycling performance of 20 cycles at current density of 100 mA g -1 .…”

High‐Performance Li–O2 Batteries Based on All‐Graphene Backbone

“…In the rate test, the Li@GA||NCO@rGA cell delivered an impressive total capacity of 12 mAh cm −2 at the current density of 0.1 mA cm −2 and 2.2 mAh cm −2 at 1 mA cm −2 . It is worth to note that most previous studies on Li–O 2 batteries involving current collectors and binders typically used a low catalyst loading and a small operating current normalized to the catalyst mass, [ 22 ] whereas in this work, all current densities are calculated based on the nominal area of the self‐standing electrode. Thus, problems caused by parasitic side reactions and inefficient Li stripping/plating during repeated cycling would be more prominent, not to mention the less‐ideal ohmic contact.…”