Electrolyte additives for electrochemical cells

Abstract

A system and method for a liquid electrolyte for use in a secondary electrochemical cell having at least one electrode comprising a TMCCC material, the liquid electrolyte enabling extended lifetime while allowing high rate discharge to very high depths of discharge. The addition of dinitriles to the liquid electrolyte of electrochemical cells in which energy storage is achieved by ion intercalation in transition metal cyanide coordination compounds (TMCCCs) has the advantage of extending device lifetime by inhibiting common chemical and electrochemical degradation mechanisms.

Claims

1. It is an electrochemical cell, Electrolytes, The negative electrode is electrically connected to the electrolyte, The electrolyte comprises a positive electrode that is electrically in contact with the electrolyte, The negative electrode comprises a first cyanide transition metal coordination compound material, and the positive electrode comprises a second cyanide transition metal coordination compound material different from the first cyanide transition metal coordination compound material. The electrolyte comprises a mononitrile solvent, one or more alkali metal salts in a solution of the mononitrile solvent, and an additive disposed in the mononitrile solvent. The mononitrile contains acetonitrile, and An electrochemical cell comprising the aforementioned additive a dinitrile material.

2. Each of the cyanide transition metal coordination compound materials has composition A ｘ P ｙ [R(CN)] （６） ] ｚ n(H ２ The electrochemical cell according to claim 1, comprising O), A comprising an alkali metal cation, P comprising a transition metal cation, R comprising a transition metal cation, and 0 ≤ x ≤ 2, y = 1, 0.75 ≤ z ≤ 1, and 0 ≤ n ≤ 6.

3. The electrochemical cell according to claim 2, wherein P of the positive electrode comprises at least one of manganese and iron, and R of the positive electrode comprises iron.

4. The electrochemical cell according to claim 1, wherein the dinitrile material includes a linear dinitrile material.

5. The electrochemical cell according to claim 4, wherein the linear dinitrile material comprises succinonitrile.

6. The electrochemical cell according to claim 1, wherein the ratio N of the mononitrile solvent to the additive is 70:30 < N < 99:1 by weight.

7. The electrochemical cell according to claim 2, wherein P of the negative electrode comprises at least one of manganese and iron, and R of the negative electrode comprises manganese.

8. The electrochemical cell according to claim 2, wherein R of the negative electrode contains manganese.

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