Impacts of solvent electric dipole and ion valency on energy storage in ultrananoporous supercapacitor: An ising model study

Zhou, Shiqi; Zhou, Rouxi; Tian, Cheng

doi:10.1016/j.jpcs.2021.110188

Cited by 13 publications

(8 citation statements)

References 80 publications

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“…Consequently, the four-state BEG model only can describe the situations in the limit of strong adsorption of the ions and solvent (so that the pore can always be (almost) filled by particles even at zero surface charge). In another work, the present authors correct the flaw of the theory [74] by introducing the void component into the system and proposing a five-state BEG model [75]; consequently, the new theory [75] can apply to any adsorption strength of the ions and solvent.…”

Section: Introductionmentioning

confidence: 98%

“…We will use two-site charged hard sphere (HS) model for the cation and charged HS model for the anion. To deal with the increased complexities, the BEG model [69] is extended to a four-state modified BEG model, which is different from that ones in literatures [74,75] in two aspects of the transfer matrix construction and the working electrolyte considered.…”

Section: Introductionmentioning

confidence: 99%

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Ultrananoporous supercapacitor with ionic liquid comprised of two-site cation: an Ising model study (II)

Zhou¹,

Zhou²

2022

J. Phys. D: Appl. Phys.

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A four-state one-dimension discrete spin model with the nearest neighbor and partial next nearest neighbor lattice interactions is proposed for describing electrical double layer formed by ionic liquid in cylindrical pore that can accommodate only one row of particles. The model, in which cation is modelled as a dimer formed by two hard spheres: one is positively charged with diameter , while the other is neutral with diameter , and anion is modeled by charged hard sphere with diameter , is designed to investigate effects of pore diameter , ion transfer free energy, ion size and electrical valence on behaviors of specific differential capacitance and specific energy storage and its saturation value . Relevant Kramers-Wannier transfer matrix is , which gives system partition function by numerically solving maximum real root of the relevant characteristic equation. Main findings are briefly described below. (i) The ion valence has little effect on the value, but does reduce the threshold voltage strength , beyond which the energy storage reaches . However, the ion valence (whether co- or counter-ion) raises both the and values as the relevant ion size decreases enough. (ii) Decreasing of the value weakly reduces the value, but raises the peak height and the value obviously; correlation between the value and value becomes stronger with the ions getting more pore hostile. (iii) With the counter-ion or co-ion charged site size decreasing, both the value and value rise. However, the effect of the co-ion charged site size is weakened as the co-ion gets more pore hostile, and the cation neutral site size influences on the value less than the cation charged site size does. (iv) Pore friendly co-ion or pore hostile counter-ion always helps in raising the value; the two have significant synergistic effect with the co-ion pore friendliness playing more important role than the counter-ion pore hostility.

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Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Ultrananoporous supercapacitor with ionic liquid comprised of two-site cation: an Ising model study (II)

Zhou¹,

Zhou²

2022

J. Phys. D: Appl. Phys.

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“…Understanding the surface polarization effect can increase our ability to control the EDL structure and disclose work mechanisms for many practical applications, such as the design of a supercapacitor (SC) [ 25 , 26 , 27 , 28 ], modulating three-dimensional conformation of polyelectrolyte brush [ 29 ], self-assembly [ 30 , 31 ], ionic profiles [ 22 , 23 , 32 ], and surface force [ 21 , 33 , 34 , 35 , 36 , 37 , 38 , 39 ].…”

Section: Introductionmentioning

confidence: 99%

On Capacitance and Energy Storage of Supercapacitor with Dielectric Constant Discontinuity

Zhou

2022

Nanomaterials

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The classical density functional theory (CDFT) is applied to investigate influences of electrode dielectric constant on specific differential capacitance Cd and specific energy storage E of a cylindrical electrode pore electrical double layer. Throughout all calculations the electrode dielectric constant varies from 5, corresponding to a dielectric electrode, to εwr = 108 corresponding to a metal electrode. Main findings are summarized as below. (i): By using a far smaller value of the solution relative dielectric constant εr = 10, which matches with the reality of extremely narrow tube, one discloses that a rather high saturation voltage is needed to attain the saturation energy storage in the ultra-small pore. (ii): Use of a realistic low εr = 10 value brings two obvious effects. First, influence of bulk electrolyte concentration on the Cd is rather small except when the electrode potential is around the zero charge potential; influence on the E curve is almost unobservable. Second, there remain the Cd and E enhancing effects caused by counter-ion valency rise, but strength of the effects reduces greatly with dropping of the εr value; in contrast, the Cd and E reducing effects coming from the counter-ion size enhancing remain significant enough for the low εr value. (iii) A large value of electrode relative dielectric constant εrw always reduces both the capacitance and energy storage; moreover, the effect of the εrw value gets eventually unobservable for small enough pore when the εrw value is beyond the scope corresponding to dielectric electrode. It is analyzed that the above effects take their rise in the repulsion and attraction on the counter-ions and co-ions caused by the electrode bound charges and a strengthened inter-counterion electrostatic repulsion originated in the low εr value.

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“…In fact, the limitation of the narrow electrochemical window can be overcome in highly concentrated aqueous electrolytes, also known as water-in-salt (WiS) electrolytes [ 8 , 9 , 10 , 11 , 12 , 13 ], which have been shown to significantly widen the electrochemical stability window to over 3.0 V, via interface modification [ 14 , 15 ], or the development of chemically stable, high surface area carbon structures [ 16 , 17 , 18 ]. As a result, aqueous electrolytes are still popular in the study of EDLCs [ 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 ].…”

Section: Introductionmentioning

confidence: 99%

Capacitive Behavior of Aqueous Electrical Double Layer Based on Dipole Dimer Water Model

2022

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The aim of the present paper is to investigate the possibility of using the dipole dimer as water model in describing the electrical double layer capacitor capacitance behaviors. Several points are confirmed. First, the use of the dipole dimer water model enables several experimental phenomena of aqueous electrical double layer capacitance to be achievable: suppress the differential capacitance values gravely overestimated by the hard sphere water model and continuum medium water model, respectively; reproduce the negative correlation effect between the differential capacitance and temperature, insensitivity of the differential capacitance to bulk electrolyte concentration, and camel–shaped capacitance–voltage curves; and more quantitatively describe the camel peak position of the capacitance–voltage curve and its dependence on the counter-ion size. Second, we fully illustrate that the electric dipole plays an irreplaceable role in reproducing the above experimentally confirmed capacitance behaviors and the previous hard sphere water model without considering the electric dipole is simply not competent. The novelty of the paper is that it shows the potential of the dipole dimer water model in helping reproduce experimentally verified aqueous electric double layer capacitance behaviors. One can expect to realize this potential by properly selecting parameters such as the dimer site size, neutral interaction, residual dielectric constant, etc.

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Impacts of solvent electric dipole and ion valency on energy storage in ultrananoporous supercapacitor: An ising model study

Cited by 13 publications

References 80 publications

Ultrananoporous supercapacitor with ionic liquid comprised of two-site cation: an Ising model study (II)

Ultrananoporous supercapacitor with ionic liquid comprised of two-site cation: an Ising model study (II)

On Capacitance and Energy Storage of Supercapacitor with Dielectric Constant Discontinuity

Capacitive Behavior of Aqueous Electrical Double Layer Based on Dipole Dimer Water Model

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