Electrochemical cell with TMCCC electrodes in an acetonitrile solvent including a dinitrile additive
A system and method for a liquid electrolyte used in secondary electrochemical cells having at least one electrode including a TMCCC material, the liquid electrolyte enabling an increased lifetime while allowing for fast discharge to extremely high depth of discharge. The addition of dinitriles to liquid electrolytes in electrochemical cells in which energy storage is achieved by ion intercalation in transition metal cyanide coordination compounds (TMCCC) has the advantage of increasing device lifetime by inhibiting common chemical and electrochemical degradation mechanisms.
1. An electrochemical cell, comprising:
an electrolyte;
an anode electrode in electrical communication with said electrolyte; and
a cathode electrode in electrical communication with said electrolyte;
wherein said cathode electrode includes a first transition metal cyanide coordination compound material; and
wherein said electrolyte includes an organic solvent, a salt in solution with said solvent, and an additive disposed within said solvent;
wherein said organic solvent includes a mononitrile solvent;
wherein said salt includes an alkali cation and a polyatomic anion including fluoride; and
wherein said additive includes a dinitrile material.
2. The electrochemical cell of claim 1 wherein each said transition metal cyanide coordination compound material includes a composition A x P y [R(CN) (6) ] z n(H 2 O), wherein A includes an alkali metal cation, wherein a P includes a transition metal cation, wherein R includes a transition metal cation, and wherein 0≤x≤2, y=1, 0.75≤z≤1, and 0≤n≤6.
3. The electrochemical cell of claim 2 wherein P of said cathode electrode includes at least one of manganese and iron; and wherein R of said cathode electrode includes at least one of manganese and iron.
4. The electrochemical cell of claim 1 in which said dinitrile material includes a linear dinitrile material.
5. The electrochemical cell of claim 4 in which said linear dinitrile material includes succinonitrile.
6. The electrochemical cell of claim 4 in which said linear dinitrile material includes adiponitrile.
7. The electrochemical cell of claim 1 having a weight ratio N of said solvent to said additive wherein 70:30<N<99:1.
8. The electrochemical cell of claim 2 wherein A includes one or more of Li, Na, K, Rb, and Cs cations.
9. The electrochemical cell of claim 1 in which said polyatomic anion includes a fluoridated sulfonimide.