High-Performance and Scalable Aqueous Na-Ion Batteries Comprising a Co-Prussian Blue Analogue Framework Positive Electrode and Sodium Vanadate Nanorod Negative Electrode for Solar Energy Storage

Abstract

A unique configuration of aqueous Na-ion batteries is investigated for solar energy storage, where single-wall carbon nanotube (SWCNT)-coated stainless steel (SS304), Co-Prussian blue analogue (Co-PBA/Na 2 CoFe(CN) 6 ), and sodium vanadate (NVO/NaV 3 O 8 ) nanorods are employed as a current collector, positive active material, and negative active material, respectively. The SWCNT coverage on SS radically obstructs the metallic corrosion under anodic polarization and also enhances the electrolyte stability window by preventing direct contact between the metal substrate and electrolyte. Both the positive and negative materials are structurally analyzed by Rietveld refinement of powder X-ray diffraction data. The Co-PBA framework structure demonstrates one-dimensional channels with ∼5.3 and 5.1 Å widths along [100] and [011], respectively, whereas the layered NVO depicts an interlayer spacing of ∼4.2 Å for facile Na-ion transportations. Resultantly, the high diffusion coefficients of Na-ions in Co-PBA and NVO are achieved as 1.6 × 10 −13 and 2.0 × 10 −11 cm 2 s −1 , respectively. Both Co-PBA and NVO exhibit a diffusioncontrolled Faradaic charge storage mechanism, which has been demonstrated by cyclic voltammetry. The Co-PBA provides 122 mAh g −1 specific capacity at 1C rate, which is the highest reported value in aqueous medium with low-cost current collectors. The electrochemical performance testing of NaV 3 O 8 is first described by us, explicitly for the negative electrode, and it delivers 83 mAh g −1 specific capacity at 1C. The 1.5 V silica gel-based Co-PBA//NVO full cell is fabricated with mass balancing, which shows higher cell voltage by maximizing the water splitting window. The full cell delivers a specific capacity of 141 mAh g −1 (@ 1C), an energy density of 211 Wh kg −1 (@ 250 W kg −1 ), a power density of 2466 W kg −1 (@ 94 Wh kg −1 ), and good durability (80% capacity retention @ 5C) up to 500 cycles. A 3 V/5 mAh rated prototype device is assembled, and it delivers satisfactory solar energy storage performances under 1 week of continuous operation.

Low cost & quasi solid state Na2Mn0.5Ni0.5Fe(CN)6//NaxFe2O3 hybrid Na-ion batteries for solar energy storage

“…It is mentioned in our earlier publication that PBA are known to form in different crystal structures, like monoclinic, cubic and orthorhombic phases. 36 Herein, the PXRD pattern of Mn-PBA was carefully analysed and refined with the monoclinic phase, 20 and the Rietveld refinement results are presented in Fig. 1(a) and Table S2 in the ESI †.…”

“…The Mn(NC) 6 octahedra alternate with the Fe(CN) 6 octahedra along the crystallographic a direction leading to the formation of a three-dimensional open framework structure with one-dimensional channels of Na atoms as described earlier. 36 Similarly, MnNi-PBA also crystallizes in the isostructural monoclinic phase 37 (Fig. 1(b) and Table S3,† space group: P 2 1 / n , a = 10.413(2) Å, b = 7.470(2) Å, c = 7.253(3) Å, β = 91.13(2)°) in which the Mn-site of Mn-PBA is occupied by Ni and Mn together (atomic ratio: 1 : 1).…”

“…Herein, single wall carbon nanotube (SWCNT) coated stainless steel (SS304) sheets were employed as low cost current collectors, where the SWCNT coating minimizes the corrosion and improves the electrolyte stability window. 36 In the three-electrode cell, the active material coated current collector was used as a working electrode, while a pristine current collector and Ag/AgCl served as the counter and reference electrodes, respectively. The working electrodes were prepared through slurry coating onto the current collectors by a doctor blade method (geometric area: 1 cm 2 & mass loading: 1 mg cm −2 ), where the active material slurry was prepared by homogeneous mixing of 80% active material, 10% conducting carbon black and 10% polyvinylidene fluoride (PVDF) binder in dimethyl formamide (DMF) solvent.…”

Prussian blue analogues with Na2NixCoyMnzFe(CN)6-multimetallic structures as positive and hydrogen vanadate as negative electrodes in aqueous Na-ion batteries for solar energy storage applications

“…7(c), where the energy/power densities of PBA-1//HVO are presented along with the literature data for various PBA based cells. [11][12][13][14][45][46][47][48][49][50] The PBA-1//HVO full cell demonstrates an energy density of 118 W h kg À1 (at 181 W kg À1 ) and a power density of 780 W kg À1 (at 46 W h kg À1 ).…”

An Enduring Na-Ion Solar Battery Configured with Na2Co0.5Ni0.5Fe(CN)6 Positive and NaTi2(PO4)3 Negative Electrodes in Na2SO4-SiO2 Hydrogel Electrolyte

“…Herein, the single wall carbon nanotube (SWCNT) coated stainless steel (SS304) sheet was used as current collector of working electrode, and the benefits of SWCNT coating, i.e., lowering corrosion and improved electrolyte stability, are elaborated elsewhere. 38 The three-electrode cell assembly was constructed with active material coated current collector, pristine current collector and Ag/AgCl as working, counter and reference electrodes, respectively, in 1 M Na 2 SO 4 (aq.) electrolyte.…”