Magnesium electrochemical cells

1. An electrochemical cell comprising:

a cathode comprising at least 80 wt % of an early transition metal fluoro-bronze comprising MoO 2.8 F 0.2 and having a layered structure;

an anode comprising magnesium; and

an electrolyte;

wherein:

the early transition metal fluoro-bronze is configured for intercalation of magnesium ions.

2. The electrochemical cell of claim 1 , wherein the cathode further comprises a current collector.

3. The electrochemical cell of claim 1 , wherein the cathode further comprises a binder.

4. The electrochemical cell of claim 1 , wherein the binder comprises poly-vinylidene fluoride (PVdF), poly(vinylidene fluoride-co-hexafluoropropene) (PVdF-HFP) or polytetrafluoroethylene (PTFE).

5. The electrochemical cell of claim 1 , wherein the anode further comprises a current collector.

6. The electrochemical cell of claim 1 , wherein the electrolyte comprises an aprotic solvent and a salt.

7. The electrochemical cell of claim 6 , wherein the aprotic solvent comprises tetrahydrofuran, 2-methyl tetrahydrofuran, dimethoxyethane, glyme, monoglyme, dimethyl glycol, ethylene glycol dimethyl ether, diethyl ether, ethyl glyme, diglyme, proglyme, ethyl diglyme, triglyme, butyl diglyme, tetraglyme, polyglyme, higlyme, or propylene carbonate.

8. The electrochemical cell of claim 6 , wherein the salt is a magnesium salt.

9. The electrochemical cell of claim 8 , wherein the magnesium salt is Mg[B(C 2 O 4 ) 2 ] 2 ; Mg[BF 2 (C 2 O 4 )] 2 ; Mg(ClO 4 ) 2 , Mg(BF 4 ) 2 ; Mg(PF 6 ) 2 ; Mg(AsF 6 ) 2 ; Mg(SbF 6 ) 2 ; MgBr 2 ; Mg(CF 3 SO 3 ) 2 ; Mg(CF 3 SO 2 ) 2 ; Mg(C(CF 3 SO 2 ) 3 ) 2 ; Mg(B(C 6 F 5 ) 4 ) 2 ; Mg(B(C 6 H 5 ) 4 ) 2 ; Mg(N(SO 2 CF 3 ) 2 ) 2 ; Mg(N(SO 2 CF 2 CF 3 ) 2 ) 2 ; Mg(N(SO 2 C 2 F 5 ) 2 ) 2 ; Mg(BF 3 C 2 F 5 ) 2 ; or Mg(PF 3 (CF 2 CF 3 ) 3 ) 2 .