Mass Balancing of Hybrid Ion Capacitor Electrodes: A Simple and Generalized Semiempirical Approach

Abstract

Hybrid ion capacitors (HICs) are emerging as promising energy-storage devices exhibiting the advantages of both batteries and supercapacitors. However, the difference in the electrodes' specific capacities and rate capabilities makes it extremely challenging to achieve optimum mass balancing for a full-cell HIC device. Here, we demonstrate a method to predict well-performing mass ratios of electrodes for a Na-HIC by analyzing the capacities of anodes and cathodes as a function of the actual current densities experienced by the individual electrodes. We employ a simple design tool, a "Ragone Plot Simulator", to predict specific energy and specific power on Ragone plots and study the performance trend of devices with varying electrode mass ratios. The validation of the proposed method is done based on the experimental data obtained from several hybrid ion capacitor devices reported in the literature, which closely matches with the simulated Ragone plots. Further, we exemplify the validity of our calculations by comparing the simulated Ragone plot with that of a Na-HIC fabricated using in-house-made carbon. This unique approach presents a simple, generalized, yet never reported, method, which could be employed as a design tool to guide the selection of optimized HIC devices for the intended applications.

Open or Closed? Elucidating the Correlation between Micropore Nature and Sodium Storage Mechanisms in Hard Carbon

“…In light of research, they offer high specific capacity, cycling stability, sufficiently low operating voltages, and possess expanded interlayers (d ranging from 3.7 to 4 Å). [1][2][3][4][5] The widely accepted structure of HCs has been the 'house of cards' model suggested by Dahn and Stevens in 2000, wherein they propound that the turbostratic/pseudo graphitic domains are randomly distributed (randomness at a relatively large scale) with graphene sheets, inducing shortrange ordering unlike that in graphite. [6] For the same objective, the precursor is expected to have a highly branched and crosslinked matrix that can avert long-range ordered graphitization even at high carbonization temperatures.…”

“…Hard carbons (HC) are well‐considered and investigated as sodium‐ion battery (SIB) anodes due to their economic feasibility, environmental friendliness, and easily available bioresources. In light of research, they offer high specific capacity, cycling stability, sufficiently low operating voltages, and possess expanded interlayers ( d ranging from 3.7 to 4 Å) [1–5] . The widely accepted structure of HCs has been the ′house of cards′ model suggested by Dahn and Stevens in 2000, wherein they propound that the turbostratic/pseudo graphitic domains are randomly distributed (randomness at a relatively large scale) with graphene sheets, inducing short‐range ordering unlike that in graphite [6] .…”

Intertwined CNT Assemblies as an All-Around Current Collector for Volume-Efficient Lithium-Ion Hybrid Capacitors

“…The volumetric power and energy densities of the AC–CNT/LIG–CNT LIHCs calculated from GCD measurements are plotted in a Ragone plot for comparison with those of previously reported carbon material-based LIHCs (Figure C). − Notably, all the energy and power values are normalized by the summed volumes of the anodes and cathodes, which include all volumes of active materials, conducting agents, binders, and current collectors (the detailed calculation process is described in Supporting Information). − The AC–CNT and LIG–CNT LIHCs deliver a maximum energy density of 122 Wh L –1 (at a power density of 612 W L –1 ) and a maximum power density of 8792 W L –1 (at an energy density of 77 Wh L –1 ), respectively. The performance of CNT-based LIHCs exceeds that of previously reported studies.…”

Upcycling of Spent LiCoO2 Cathode to Lithium Dual‐Ion Battery Anode

“…Additionally, the influence of the mass of the anode and cathode on the device is estimated by varying the mass loading of the electrode. [ 72 ] The Ragone plot and capacity versus current density for full‐cells with three different mass loadings is presented in Figure 5e and its inset. Since the mass ratio of the electrode materials is a crucial factor, an initial assessment of the effect of mass loading on the rate capability was estimated.…”