Solid-state rechargeable magnesium battery
Embodiments of a solid-state electrolyte comprising magnesium borohydride, polyethylene oxide, and optionally a Group IIA or transition metal oxide are disclosed. The solid-state electrolyte may be a thin film comprising a dispersion of magnesium borohydride and magnesium oxide nanoparticles in polyethylene oxide. Rechargeable magnesium batteries including the disclosed solid-state electrolyte may have a coulombic efficiency ≧95% and exhibit cycling stability for at least 50 cycles.
1. An electrolyte comprising:
an all solid-state composition comprising
Mg(BH 4 ) 2 ;
A metal oxide of MgO; and
polyethylene oxide.
2. The electrolyte of claim 1 , where the electrolyte is a solid dispersion of Mg(BH 4 ) 2 and the metal oxide in polyethylene oxide.
3. The solid-state electrolyte of claim 1 , where the solid-state electrolyte is a thin film having an average thickness from 15 μm to 400 μm.
4. The electrolyte of claim 1 , wherein the metal is a Group IIA metal, a transition metal, or a combination thereof.
5. The electrolyte of claim 1 , comprising:
3-30 wt % Mg(BH 4 ) 2 , based on a total weight of the electrolyte;
55-92 wt % polyethylene oxide, based on the total weight of the electrolyte; and
5-15 wt % metal oxide, based on the total weight of the electrolyte.
6. The electrolyte of claim 1 , comprising:
5-15 wt % Mg(BH 4 ) 2 , based on a total weight of the electrolyte;
73-88 wt % polyethylene oxide, based on the total weight of the electrolyte; and
7-12 wt % metal oxide, based on the total weight of the electrolyte.
7. The electrolyte of claim 1 , wherein the metal oxide further comprises TiO 2 , ZrO 2 , or a combination thereof.
8. The electrolyte of claim 1 , where the metal oxide comprises metal oxide nanoparticles having an average diameter ≦500 nm.
9. The electrolyte of claim 8 , where the electrolyte is a solid dispersion of Mg(BH 4 ) 2 and the metal oxide nanoparticles in polyethylene oxide.
10. The electrolyte of claim 1 , where the electrolyte consists essentially of Mg(BH 4 ) 2 , polyethylene oxide, and metal oxide.
11. The electrolyte of claim 10 , consisting essentially of:
3-30 wt % Mg(BH 4 ) 2 , based on a total weight of the electrolyte;
55-92 wt % polyethylene oxide, based on the total weight of the electrolyte; and
5-15 wt % MgO nanoparticles, based on the total weight of the electrolyte, having an average diameter ≦500 nm.
12. A rechargeable battery, comprising:
an anode comprising magnesium;
a cathode; and
the electrolyte of claim 1 .
13. The rechargeable battery of claim 12 , where the anode is magnesium metal.
14. The rechargeable battery of claim 12 , where the cathode comprises stainless steel, Mo 6 S 8 , Mg 2 Mo 6 S 8 , MoS 2 , Mo 6 S 8-y Se y where y=0, 1, or 2, Mg x S 3 O 4 where 0<x<1, MgCoSiO 4 , MgFeSiO 4 , MgMnSiO 4 , V 2 O 5 , WSe 2 , sulfur, poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl methacrylate)/graphene, MnO 2 /acetylene black, or carbyne polysulfide.
15. The rechargeable battery of claim 12 , where the anode has a capacity fade of less than 20% after 50 discharge/charge cycles.
16. The rechargeable battery of claim 12 , where the battery has a coulombic efficiency ≧95%.
17. A method for making an all solid-state magnesium electrolyte of claim 1 , comprising:
making an all solid-state magnesium electrolyte by
forming an electrolyte mixture comprising Mg(BH 4 ) 2 , polyethylene oxide, and a metal oxide a Group IIA metal, a transition metal, or a combination thereof; and
forming a thin film of the electrolyte mixture.
18. The method of claim 17 , where the thin film consists essentially of:
3-30 wt % Mg(BH 4 ) 2 , based on a total weight of the thin film;
55-92 wt % polyethylene oxide, based on the total weight of the thin film; and
5-15 wt % metal oxide, based on the total weight of the thin film.