Supercapacitor Degradation: Understanding Mechanisms of Cycling‐Induced Deterioration and Failure of a Pseudocapacitor

Abstract

Owing to a reputation for long lifetimes and excellent cycle stability, degradation in supercapacitors has largely been overlooked. In this work, we demonstrate that significant degradation in some commercial supercapacitors can in fact occur early in their life, leading to a rapid loss in capacitance, especially when utilized in full voltage range, high charge‐discharge frequency applications. By using a commercial 300 F lithium‐ion pseudocapacitor rated for 100,000 charge/discharge cycles as an example system, it is shown that a ∼96 % loss in capacitance over the first ∼2000 cycles is caused by significant structural and chemical change in the cathode active material (LiMn2O4, LMO). Multi‐scale in‐situ and ex‐situ characterization, using a combination of X‐ray computed tomography, Raman spectroscopy and X‐ray photoelectron spectroscopy, shows that while minimal material loss (∼5.5 %), attributed to the dissolution of Mn2+, is observed, the primary mode of degradation is due to manganese charge disproportionation (Mn3+→Mn4++Mn2+) and its physical consequences (i. e. microstrain formation, particle fragmentation, loss of conductivity etc.). In contrast to prior understanding of LMO material degradation in battery systems, negligible contributions from cubic‐to‐tetragonal phase transitions are observed. Hence, as supercapacitors are becoming more widely utilized in real‐world applications, this work demonstrates that it is vital to understand the mechanisms by which this family of devices change during their lifetimes, not just for lithium‐ion pseudocapacitors, but for a wide range of commercial chemistries.

Effect of graphite concentration on the electrochemical performance of a novel α-MnO2-expanded graphite-PVDF composite cathode material based on FTO substrate

“…Aggregation, volume expansion of the electrode material during repeated charge-discharge operations, and degradation of redox-active materials are some of the causes of the low retention rate. Furthermore, the surface Mn-ion reduction has been connected to a two-step oxidation-reduction mechanism including OH oxidation in the electrolyte [71,72]. A material with low retention may deteriorate more quickly, reducing its commercial viability and necessitating frequent replacements or maintenance.…”

Applicability of the MoS2–aSiC Heterostructure for Durable Supercapacitance and NO2 Gas Sensing in a Harsh Environment

“…have been widely used in various electronic devices. However, they suffer from significant performance degradation over time and device failure in harsh environments. − Therefore, it is greatly required that these materials be processed to work efficiently under broader environmental conditions.…”

MnO2/PANI/SWCNT Nanokompozit Süperkapasitör Elektrot Geliştirilmesi ve Elektrokimyasal Performansının İncelenmesi

“…There are several critical differences between pseudocapacitors and other supercapacitors. Pseudocapacitors rely on faradaic reactions, while other supercapacitors, such as electrostatic double-layer capacitors, primarily depend on the physical separation of charges at the electrodeelectrolyte interface (Mazloomian et al, 2023). Pseudocapacitors provide increased energy storage capabilities owing to the faradaic reactions involved.…”