Towards a Pseudocapacitive Battery: Benchmarking the Capabilities of Quantized Capacitance for Energy Storage

Benchmarking the ragone behaviour and power performance trends of pseudocapacitive batteries

“…The goal of this paper is to assess the power performance capabilities of systems utilizing quantized capacitance as an energy storage mechanism. This builds directly on the earlier findings in [26], wherein the potentially high energy density of such pseudocapacitive batteries were extensively explored and found to be plausible extendable to ⩾100 Wh l −1 . Our aim in this work is to assess whether realistically achievable diffusion constants can simultaneously deliver a targeted power performance of ∼ 10 4 W l −1 in figure 1(a).…”

“…This allows ET redox peaks to overlap and can theoretically provide a ideal near-rectangular voltammetry profile [27]. Quantized capacitance theories based on the Gerischer-Hopfield formalism have been extensively discussed in previous publications [26,27]. We shall not overview this formalism in detail here [37][38][39][40], but simply state that the effect of quantized capacitance (when U is sufficiently small) is to provide a continuum of redox levels with an energetic density of states (DOS) per electron-volt (eV) that can be reasonably approximated in volumetric units as where V d is the applied potential window, being split equally across both terminals, at which the maximum target concentration of electrons, ρ e,max , is stored [26] (see figures 1(b) and 2).…”

“…Recently, it was proposed that one may dramatically enhance the energy density of supercapacitors through the use of quantized capacitance in the form of device that was termed a 'pseudocapacitive battery' (see the bronze region in figure 1(a)) [26,27]. Such a pseudocapacitive battery consists of an electrolytic media sandwiched between two oppositely charged metal current collectors, where the surface is modified with a volume of deposited nanoparticles as illustrated in figure 1(b)-it is essentially a multiple redox-level variation on a redox-polymer battery [26]. During the charging process, a potential bias on the electrode causes electron tunnelling and diffusion into the nanoparticles (through Faradaic means) to achieve energy storage via quantized capacitance.…”

“…First in section 3.1, we assess the performance properties in the regime where electron diffusion dominates (i.e. electron transfer (ET) between redox species in figure 1(b) [26]). Subsequently, in section 3.2, we examine the performance in the regime where electron and ion diffusion constants are matched in an optimized manner, both under the condition of monolithically applied coatings and when conductive pathways are introduced to accelerate electron transport.…”

Nanoquantization Fills Gap in Battery Technology

“…Typically, improving one of these properties degrades the other. Now Kirk Bevan at McGill University, Canada, and his colleagues propose a device called a pseudocapacitive battery that uses a phenomenon called quantized capacitance to provide both a high energy density and a high power density [1]. The team says that many energy-storage applications could benefit from such a device.…”