Pseudocapacitive Charge Storage in Thick Composite MoS₂ Nanocrystal‐Based Electrodes

Abstract

A synthesis methodology is demonstrated to produce MoS2 nanoparticles with an expanded atomic lamellar structure that are ideal for Faradaic‐based capacitive charge storage. While much of the work on MoS2 focuses on the high capacity conversion reaction, that process is prone to poor reversibility. The pseudocapacitive intercalation‐based charge storage reaction of MoS2 is investigated, which is extremely fast and highly reversible. A major challenge in the field of pseudocapacitive‐based energy storage is the development of thick electrodes from nanostructured materials that can sustain the fast inherent kinetics of the active nanocrystalline material. Here a composite electrode comprised of a poly(acrylic acid) binder, carbon fibers, and carbon black additives is utilized. These electrodes deliver a specific capacity of 90 mAh g−1 in less than 20 s and can be cycled 3000 times while retaining over 80% of the original capacity. Quantitative kinetic analysis indicates that over 80% of the charge storage in these MoS2 nanocrystals is pseudocapacitive. Asymmetric full cell devices utilizing a MoS2 nanocrystal‐based electrode and an activated carbon electrode achieve a maximum power density of 5.3 kW kg−1 (with 6 Wh kg−1 energy density) and a maximum energy density of 37 Wh kg−1 (with 74 W kg−1power density).

Exploiting Lithium–Ether Co‐Intercalation in Graphite for High‐Power Lithium‐Ion Batteries

“…To our surprise, a significant pseudocapacitive nature was revealed for the [lithium-ether] + complex intercalation, in contrast to the charge storage behavior of conventional lithium ion intercalation, which is mostly diffusion controlled. Also, similar observations have been reported in such as mesoporous MoS 2 , [52] MoO 3−x , [53] MoS 2 nanocrystal, [54] nanosized-MoO 2 , [55] and TiS 2 nanocrystals, [56] which were ascribed to the intercalation pseudocapacitance resulting from the suppressing intercalation-induced phase transitions. [52][53][54][55][56] Considering the apparent first-order phase transition of the [lithium-ether] + complex in the bulk graphite, as evidenced in the ex situ XRD patterns in Figure 1d, the precise origin of this behavior has not yet been clearly understood.…”

“…[50] We calculated the b values of every peak in the [lithium-ether] + complex intercalation by plotting log (scan rate) versus log (peak current), as shown in Figure 5g. [52][53][54][55][56] Considering the apparent first-order phase transition of the [lithium-ether] + complex in the bulk graphite, as evidenced in the ex situ XRD patterns in Figure 1d, the precise origin of this behavior has not yet been clearly understood. [51] The b values of the peaks were estimated to be 0.99, 0.87, 0.61, and 0.58, respectively, indicating a mixed pseudocapacitive and diffusion reaction, or previously reported partial intercalation pseudocapacitance, during the electrochemical response.…”

Bi‐Metal (Zn, Mn) Metal–Organic Framework–Derived ZnMnO3 Micro‐Sheets Wrapped Uniformly with Polypyrrole Conductive Network toward High‐Performance Li‐Ion Batteries

“…In the present case, i p is indeed proportional to ν 1/2 , as plotted in Figure b. From the slope of the linear fit, the D values can be calculated as high as ≈4.34 × 10 −9 and ≈3.21 × 10 −8 cm 2 s −1 for the anode (Peak a ) and cathode (Peak c ) processes, which higher than other reported anodes, for which the unique hierarchical porous MSs with the conductive PPY coating may be reasonably account.…”

Rational Design of Nickel Hydroxide‐Based Nanocrystals on Graphene for Ultrafast Energy Storage

“…[8][9][10][11][12][13] For example, nickel hydroxides (Ni(OH) 2 ) have been successfully used in rechargeable alkaline batteries (due to their low-cost and high capacity) [5,14] and in hybrid supercapacitors (due to high rate capability). [16][17][18][19][20] Moreover, hybrid supercapacitors can achieve much higher power density than rechargeable batteries. [16][17][18][19][20] Moreover, hybrid supercapacitors can achieve much higher power density than rechargeable batteries.…”