Towards Solid-State Magnesium Batteries: Ligand-Assisted Superionic Conductivity

Lasse Najbjerg Skov; Jakob Grinderslev; Asger Wulff Rosenkranz; Young-Su Lee; Torben René Jensen

doi:10.1002/batt.202200163

Towards Solid-State Magnesium Batteries: Ligand-Assisted Superionic Conductivity

Lasse Najbjerg Skov, Jakob Grinderslev, Asger Wulff Rosenkranz, Young-Su Lee, Torben René Jensen^*

^*Corresponding author for this work

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaper › Journal article › Research › peer-review

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Abstract

Solid-state inorganic magnesium batteries are considered as potential high energy storage devices of the future. Here we present a series of magnesium borohydride tetrahydrofuran (THF) composites, Mg(BH ₄) ₂ ⋅ xTHF(−MgO), 0≤x≤3, as solid-state electrolytes for magnesium batteries. Three new monoclinic compounds were identified, Mg(BH ₄) ₂ ⋅ 2/3THF (Cc), α-Mg(BH ₄) ₂ ⋅ 2THF (P2 ₁/c) and β-Mg(BH ₄) ₂ ⋅ 2THF (C2), and the detailed structures of α- and β-Mg(BH ₄) ₂ ⋅ 2THF are presented. The magnesium ionic conductivity of composites formed by these compounds were several orders of magnitude higher than that of the distinct compounds, x=0, 2/3, 2, and 3. The nanocomposite stabilized by MgO nanoparticles (∼50 nm), Mg(BH ₄) ₂ ⋅ 1.5THF−MgO(75 wt%), displayed the highest Mg ²⁺ conductivity, σ(Mg ²⁺)∼10 ⁻⁴ S cm ⁻¹ at 70 °C, a high ionic transport number of t _ion=0.99, and cyclic voltammetry revealed an oxidative stability of ∼1.2 V vs. Mg/Mg ²⁺. The electrolyte was stable towards magnesium electrodes, which allowed for stable Mg plating/stripping for at least 100 cycles at 55 °C with a current density of 0.1 mA cm ⁻². Finally, a proof-of-concept rechargeable solid-state magnesium battery was assembled with a magnesium metal anode and a TiS ₂ cathode. A maximum discharge capacity of 94.2 mAh g ⁻¹ was displayed, which corresponds to y=0.2 in Mg _yTiS ₂.

Original language	English
Article number	e202200163
Journal	Batteries & Supercaps
Volume	5
Issue	9
Number of pages	9
ISSN	2566-6223
DOIs	https://doi.org/10.1002/batt.202200163
Publication status	Published - Sept 2022

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@article{4ba2169facca463b8c713d73cc2bd69e,

title = "Towards Solid-State Magnesium Batteries: Ligand-Assisted Superionic Conductivity",

abstract = "Solid-state inorganic magnesium batteries are considered as potential high energy storage devices of the future. Here we present a series of magnesium borohydride tetrahydrofuran (THF) composites, Mg(BH 4) 2 ⋅ xTHF(−MgO), 0≤x≤3, as solid-state electrolytes for magnesium batteries. Three new monoclinic compounds were identified, Mg(BH 4) 2 ⋅ 2/3THF (Cc), α-Mg(BH 4) 2 ⋅ 2THF (P2 1/c) and β-Mg(BH 4) 2 ⋅ 2THF (C2), and the detailed structures of α- and β-Mg(BH 4) 2 ⋅ 2THF are presented. The magnesium ionic conductivity of composites formed by these compounds were several orders of magnitude higher than that of the distinct compounds, x=0, 2/3, 2, and 3. The nanocomposite stabilized by MgO nanoparticles (∼50 nm), Mg(BH 4) 2 ⋅ 1.5THF−MgO(75 wt%), displayed the highest Mg 2+ conductivity, σ(Mg 2+)∼10 −4 S cm −1 at 70 °C, a high ionic transport number of t ion=0.99, and cyclic voltammetry revealed an oxidative stability of ∼1.2 V vs. Mg/Mg 2+. The electrolyte was stable towards magnesium electrodes, which allowed for stable Mg plating/stripping for at least 100 cycles at 55 °C with a current density of 0.1 mA cm −2. Finally, a proof-of-concept rechargeable solid-state magnesium battery was assembled with a magnesium metal anode and a TiS 2 cathode. A maximum discharge capacity of 94.2 mAh g −1 was displayed, which corresponds to y=0.2 in Mg yTiS 2.",

keywords = "magnesium batteries, solid electrolytes, magnesium conductors, nanocomposites",

author = "Skov, {Lasse Najbjerg} and Jakob Grinderslev and Rosenkranz, {Asger Wulff} and Young-Su Lee and Jensen, {Torben Ren{\'e}}",

year = "2022",

month = sep,

doi = "10.1002/batt.202200163",

language = "English",

volume = "5",

journal = "Batteries & Supercaps",

issn = "2566-6223",

publisher = "John Wiley & Sons Ltd",

number = "9",

}

TY - JOUR

T1 - Towards Solid-State Magnesium Batteries

T2 - Ligand-Assisted Superionic Conductivity

AU - Skov, Lasse Najbjerg

AU - Grinderslev, Jakob

AU - Rosenkranz, Asger Wulff

AU - Lee, Young-Su

AU - Jensen, Torben René

PY - 2022/9

Y1 - 2022/9

N2 - Solid-state inorganic magnesium batteries are considered as potential high energy storage devices of the future. Here we present a series of magnesium borohydride tetrahydrofuran (THF) composites, Mg(BH 4) 2 ⋅ xTHF(−MgO), 0≤x≤3, as solid-state electrolytes for magnesium batteries. Three new monoclinic compounds were identified, Mg(BH 4) 2 ⋅ 2/3THF (Cc), α-Mg(BH 4) 2 ⋅ 2THF (P2 1/c) and β-Mg(BH 4) 2 ⋅ 2THF (C2), and the detailed structures of α- and β-Mg(BH 4) 2 ⋅ 2THF are presented. The magnesium ionic conductivity of composites formed by these compounds were several orders of magnitude higher than that of the distinct compounds, x=0, 2/3, 2, and 3. The nanocomposite stabilized by MgO nanoparticles (∼50 nm), Mg(BH 4) 2 ⋅ 1.5THF−MgO(75 wt%), displayed the highest Mg 2+ conductivity, σ(Mg 2+)∼10 −4 S cm −1 at 70 °C, a high ionic transport number of t ion=0.99, and cyclic voltammetry revealed an oxidative stability of ∼1.2 V vs. Mg/Mg 2+. The electrolyte was stable towards magnesium electrodes, which allowed for stable Mg plating/stripping for at least 100 cycles at 55 °C with a current density of 0.1 mA cm −2. Finally, a proof-of-concept rechargeable solid-state magnesium battery was assembled with a magnesium metal anode and a TiS 2 cathode. A maximum discharge capacity of 94.2 mAh g −1 was displayed, which corresponds to y=0.2 in Mg yTiS 2.

AB - Solid-state inorganic magnesium batteries are considered as potential high energy storage devices of the future. Here we present a series of magnesium borohydride tetrahydrofuran (THF) composites, Mg(BH 4) 2 ⋅ xTHF(−MgO), 0≤x≤3, as solid-state electrolytes for magnesium batteries. Three new monoclinic compounds were identified, Mg(BH 4) 2 ⋅ 2/3THF (Cc), α-Mg(BH 4) 2 ⋅ 2THF (P2 1/c) and β-Mg(BH 4) 2 ⋅ 2THF (C2), and the detailed structures of α- and β-Mg(BH 4) 2 ⋅ 2THF are presented. The magnesium ionic conductivity of composites formed by these compounds were several orders of magnitude higher than that of the distinct compounds, x=0, 2/3, 2, and 3. The nanocomposite stabilized by MgO nanoparticles (∼50 nm), Mg(BH 4) 2 ⋅ 1.5THF−MgO(75 wt%), displayed the highest Mg 2+ conductivity, σ(Mg 2+)∼10 −4 S cm −1 at 70 °C, a high ionic transport number of t ion=0.99, and cyclic voltammetry revealed an oxidative stability of ∼1.2 V vs. Mg/Mg 2+. The electrolyte was stable towards magnesium electrodes, which allowed for stable Mg plating/stripping for at least 100 cycles at 55 °C with a current density of 0.1 mA cm −2. Finally, a proof-of-concept rechargeable solid-state magnesium battery was assembled with a magnesium metal anode and a TiS 2 cathode. A maximum discharge capacity of 94.2 mAh g −1 was displayed, which corresponds to y=0.2 in Mg yTiS 2.

KW - magnesium batteries

KW - solid electrolytes

KW - magnesium conductors

KW - nanocomposites

U2 - 10.1002/batt.202200163

DO - 10.1002/batt.202200163

M3 - Journal article

SN - 2566-6223

VL - 5

JO - Batteries & Supercaps

JF - Batteries & Supercaps

IS - 9

M1 - e202200163

ER -

Towards Solid-State Magnesium Batteries: Ligand-Assisted Superionic Conductivity

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