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Storage performance of Mg²⁺ substituted NaMnPO₄ with an olivine structure.

ABSTRACT: Sodium manganese phospho-olivine, NaMnPO₄, is considered to be a higher-voltage alternative to the presently used iron-based electrode material, NaFePO₄, for sodium ion batteries. Irrespective of this advantage, the electrochemical performance of NaMnPO₄ is still far from what is desired. Herein we provide the first report on the storage performance of NaMnPO₄ having a structure modified by Mg²⁺ substitution. The Mg-substituted phospho-olivines are prepared on the basis of ionic exchange reactions involving the participation of Mg-substituted KMnPO₄·H₂O dittmarites as structural template. Furthermore, the phosphate particles were covered with a thin layer (up to 5 nm) of activated carbon through ball-milling. The storage performance of phospho-olivines is analyzed in sodium and lithium half-ion cells, as well as in full-ion cells versus bio-mass derived activated carbon and spinel Li₄Ti₅O₁₂ as anodes. The compatibility of phospho-olivines with electrolytes is assessed by utilization of several types of lithium and sodium carbonate-based solutions. In sodium half-cell, the Mg-substituted phosphate displays a multi-phase mechanism of Na⁺ intercalation in case when NaTFSI-based electrolyte is used. In lithium half-cell, the high specific capacity and rate capability is achieved for phospho-olivine cycled in LiPF₆-based electrolyte. This is a consequence of the occurrence of dual Li⁺,Na⁺ intercalation, which encompass nano-sized domains. The utilization of the Mg-substituted phospho-olivine in the full ion cell is demonstrated.

SUBMITTER: Boyadzhieva T

PROVIDER: S-EPMC9055941 | biostudies-literature | 2020 Aug

REPOSITORIES: biostudies-literature

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Storage performance of Mg2+ substituted NaMnPO4 with an olivine structure.

Boyadzhieva Tanya T Koleva Violeta V Kukeva Rosica R Nihtianova Diana D Harizanova Sonya S Stoyanova Radostina R

RSC advances 20200806 49

Sodium manganese phospho-olivine, NaMnPO4, is considered to be a higher-voltage alternative to the presently used iron-based electrode material, NaFePO4, for sodium ion batteries. Irrespective of this advantage, the electrochemical performance of NaMnPO4 is still far from what is desired. Herein we provide the first report on the storage performance of NaMnPO4 having a structure modified by Mg2+ substitution. The Mg-substituted phospho-olivi ...[more]

PMID: 35521091

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Project description:Cardiac small conductance Ca2+-activated K+ (SK) channels are activated solely by Ca2+, but the SK current (ISK) is inwardly rectified. However, the impact of inward rectification in shaping action potentials (APs) in ventricular cardiomyocytes under β-adrenergic stimulation or in disease states remains undefined. Two processes underlie this inward rectification: an intrinsic rectification caused by an electrostatic energy barrier from positively charged amino acids at the inner pore and a voltage-dependent Ca2+/Mg2+ block. Thus, Ca2+ has a biphasic effect on ISK, activating at low [Ca2+] yet inhibiting ISK at high [Ca2+]. We examined the effect of ISK rectification on APs in rat cardiomyocytes by simultaneously recording whole-cell apamin-sensitive currents and Ca2+ transients during an AP waveform and developed a computer model of SK channels with rectification features. The typical profile of ISK during AP clamp included an initial peak (mean 1.6 pA/pF) followed by decay to the point that submembrane [Ca2+] reached ∼10 μM. During the rest of the AP stimulus, ISK either plateaued or gradually increased as the cell repolarized and submembrane [Ca2+] decreased further. We used a six-state gating model combined with intrinsic and Ca2+/Mg2+-dependent rectification to simulate ISK and investigated the relative contributions of each type of rectification to AP shape. This SK channel model replicates key features of ISK recording during AP clamp showing that intrinsic rectification limits ISK at high Vm during the early and plateau phase of APs. Furthermore, the initial rise of Ca2+ transients activates, but higher [Ca2+] blocks SK channels, yielding a transient outward-like ISK trajectory. During the decay phase of Ca2+, the Ca2+-dependent block is released, causing ISK to rise again and contribute to repolarization. Therefore, ISK is an important repolarizing current, and the rectification characteristics of an SK channel determine its impact on early, plateau, and repolarization phases of APs.

Dataset Information

Storage performance of Mg²⁺ substituted NaMnPO₄ with an olivine structure.

Publications

Storage performance of Mg<sup>2+</sup> substituted NaMnPO<sub>4</sub> with an olivine structure.

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