High-Rate Activation of Organic Superlithiation Anodes

Abstract

Lithium-ion batteries have achieved commercial success; however, work remains to increase the capacity and safety of both the anode and cathode electrodes. Organic anodes have the potential to replace conventional graphite anodes because they are abundant, safe, and high-capacity materials. Superlithiated organic anodes achieve capacities in excess of 1500 mA h g–1; however, the mechanism of superlithiation and how it relates to different materials is an open question. Here, we disclose a pyrene-fused azaacene polymer that undergoes superlithiation and exhibits a continuous activation process, whereby the capacity increases with the number of cycles, reaching values up to 1775 mA h g–1 (1535 mA h g–1, subtracting the carbon additive contribution). This high performance is attributed to the stability and extended conjugation afforded by the polymer design. Ex situ studies suggest cycling results in deformation of the electrode structure, from an amorphous electrode material to one with increased crystallinity and sp2 character. Importantly, this superlithiated electrode maintains the same capacity across a 10-fold increase in rate during the activation process, showing that the kinetic limitations of superlithiation can be overcome and suggesting that commercial practical superlithiation anodes are within reach.

Designing the Binder-Free Conversion-Based Manganese Oxide Nanofibers as Highly Stable and Rate-Capable Anode for Next-Generation Li-Ion Batteries

“…After 125 cycles, at the 0.1 C rate, it delivered a specific reversible capacity of 776 mA h g –1 , and after 600 cycles, a reversible specific capacity of 609 mA h g –1 was achieved at the 2 C rate with ∼98.2 and 99.3% Coulombic efficiency, respectively, which shows a facile lithium insertion/extraction. The reversible capacity of the MMO100 electrode exhibits a rising trend, which is usually observed for inorganic materials …”

“…To explain the increase in the specific capacity with cyclability, a few possible theories have been reported such as (i) the increase in the capacity partially emerges from the interfacial Li storage on the surface or voids/gaps present in the MMO nanofibers, ,− (ii) the capacity enhancement is probably ascribed to the reversible dissolution/formation of the surface polymeric layer, contributing to the extra capacity, , (iii) the improvement in the Li + diffusion kinetics caused by the partial crystallinity loss resulting in the amorphous material formation, , and (iv) the superb cyclic stability of the MMO100 electrode is ascribed to the addition of entangled and highly conductive MWCNTs in it. Here, MWCNTs help to maintain the electrical and structural integrity of the MMO100 electrode during the discharging/charging process. , Last but not least, excess capacity may be attained via Li storage in the grain boundaries of Mn-nanoparticles and Li 2 O, formed during the discharge process. , Besides, as the charge/discharge cycle proceeds, the lithium-ion transport channels extend due to the electrolyte percolation, which makes the electrode materials gradually activated …”

“…The reversible capacity of the MMO100 electrode exhibits a rising trend, which is usually observed for inorganic materials. 55 To explain the increase in the specific capacity with cyclability, a few possible theories have been reported such as (i) the increase in the capacity partially emerges from the interfacial Li storage on the surface or voids/gaps present in the MMO nanofibers, 27,55−57 (ii) the capacity enhancement is probably ascribed to the reversible dissolution/formation of the surface polymeric layer, contributing to the extra capacity, 58,59 (iii) the improvement in the Li + diffusion kinetics caused by the partial crystallinity loss resulting in the amorphous material formation, 55,60 and (iv) the superb cyclic stability of the MMO100 electrode is ascribed to the addition of entangled and highly conductive MWCNTs in it. Here, MWCNTs help to maintain the electrical and structural integrity of the MMO100 electrode during the discharging/ charging process.…”

High-performance aramid electrodes for high-rate and long cycle-life organic Li-ion batteries

“…Additionally, the overall increased capacity during the electrochemical cycling process could be ascribed by two factors, first, it was associated with the increasing Li + transport during the cycling process; second, it was connected to an activation period to fully utilize the Li-binding sites in the molecular structure of DiCN-aramids to reach fully lithiation state. 13,14,31,32,50–52…”

Aqueous zinc batteries: Design principles toward organic cathodes for grid applications

“…In our laboratory, we have used cathode formulations employing 30%–60% of additive for lithium-ion batteries ( An et al. 2020 , 2022 ; McAllister et al., 2021 ), and it is not uncommon to see formulations with up to 70% of additive in the literature. Because specific capacities are reported per mass of active material rather than total electrode mass, this reduction in effective capacity is sometimes overlooked.…”