Choice of Binder on Conversion Type CuO Nanoparticles toward Building High Energy Li‐Ion Capacitors: An Approach Beyond Intercalation

Abstract

lithium-ion capacitors (LICs), seek much attention due to their eccentric behavior. Slow charge kinetics of batteries and low energy density of capacitors lead people to think of LIC. The LIC is the hybridization of high-power capacitors and highenergy batteries. [2,3] It generally comprises battery-type anode materials (with faradaic reaction) and activated carbon (AC) cathode (with the non-faradaic process), which brings a synergistic effect helping to advance along the diagonal of the Ragone plot. High power than LIBs and high energy than electrostatic double-layer capacitors (EDLCs) make it unique among other energy storage devices. Hence, applying LIC in public transport such as electric buses and trains has increased because of its ability to use the regeneration braking energy. [4,5] The anode determines the overall performance of LIC, so researchers are focusing on these negative electrodes. Many studies have reported insertion type anodes [6,7] (Li 4 Ti 5 O 12 , graphite, etc.), but the low energy density is the major limitation. [6] People now are more fascinated by conversion/alloying type materials (primarily metal oxides) because of their high theoretical capacity. [8][9][10][11][12][13][14][15] Nevertheless, volume variation and thereby cycling instability are the significant drawbacks of such anode. So, people attempt various composites to tackle these issues where intercalation and conversion/ alloying reactions occur simultaneously. [16][17][18] The research attempts and reports on bare CuO as active anode material for LIC are not reported yet to the best of our knowledge. Hence, in this study, we chose CuO as anode for LIC assembly by considering its high theoretical capacity (674 mAh g −1 ), chemical stability, abundance, and low cost. Further, due to the enormous demand for batteries, the number of spent LIBs is also increasing. Improper disposal of batteries may lead to air and water pollution. So, it became necessary to recycle the spent LIBs for environmental safety. [19][20][21] Hence, we used recovered CuO (r-CuO) as anode and the AC as the cathode in which faradaic reaction occurs in the former and non-faradaic reaction in the latter. We optimized the temperature and dwelling time of the r-CuO synthesis procedure and obtained the best electrochemical performance at 500 °C and 2 h of dwelling time. We also compared the electrochemical performance of r-Li/CuO In this work, the assembly of lithium-ion capacitor (LIC) is described by pairing conversion typeCuO nanoparticles recovered from the Cu current collector of spent lithium-ion batteries (r-CuO) as battery type electrode and activated carbon (AC) as the capacitor type electrode. The Li-storage property of r-CuO is studied in the presence of two binders (polyvinylidene fluoride, PVDF and carboxymethylcellulose, CMC) and found the aptness of CMC in comparison with PVDF. Accordingly, the Li/r-CuO half-cells with CMC binder exhibits better electrochemical performance such that even after 150 chargedischarge cycles, the cells could retain a...

Review of the Mechanistic and Structural Assessment of Binders in Electrodes for Lithium-Ion Batteries

“…Figure 7: (a-c) Field-emission scanning electron microscope (FE-SEM) images of r-CuO at different magnifications,(d, e) TEM images at two magnifications, (f) HR-TEM image, (g) SAED pattern, (h) HAADF image, and (i, j) EDS elemental mapping[107].…”

Defect Engineered Dendritic Fibrous Nanosilica as Prospective Alloy Anode for the Fabrication of High-Energy Li-Ion Capacitors with Ultralong Durability

“…Nevertheless, the low theoretical capacity and lower energy density pull back its further exploration for next-generation applications. Researchers are more fascinated to explore the utilization of conversion − and alloying type ,− anodes as they have 3 to 4 times higher theoretical capacity, moderate operational potential, and better safety characteristics than insertion anodes.…”