Aqueous electrochemical preparation of insertion compounds and use in non-aqueous rechargeable batteries

Claim 1

A method for preparing insertion compounds which are unstable in pure water wherein an amount of an alkali metal or an alkaline earth metal is inserted into a first insertion compound thereby forming a second insertion compound which is unstable in pure water, comprising: a) preparing in an electrochemical cell having a working electrode collector, a counter electrode, and a basic aqueous electrolyte, the electrolyte comprising a salt of said alkali metal or alkaline earth metal dissolved in water wherein the dissolved alkali metal or alkaline earth metal is at a starting concentration and the electrolyte is at a starting pH; b) electrically contacting said first insertion compound to the working electrode collector thereby forming a working electrode; c) charging said cell such that electrons and ions of said alkali metal or alkaline earth metal are supplied to the working electrode thereby inserting an amount of the alkali metal or alkaline earth metal in the first insertion compound and thereby forming the second insertion compound which is less stable in pure water than said first insertion compound, such that degradation of said second insertion compound will occur upon exposure to pure water; d) maintaining the concentration of the dissolved alkali metal or alkaline earth metal in the electrolyte between the starting concentration and a final concentration; the final concentration being greater than zero, and such that the second insertion compound is stable in the electrolyte; e) maintaining the pH of the electrolyte between the starting pH and a final pH; the final pH being a value such that the concentration of H + in the electrolyte is at least an order of magnitude less than said final concentration, whereby the electrolyte provides greater stability than that provided by pure water, and such that the second insertion compound is stable in the electrolyte; and f) isolating the second insertion compound from the electrolyte after insertion of the amount of the alkali metal or alkaline earth metal in the first insertion compound to form the second insertion compound is complete.

Claim 2

A method for preparing insertion compounds which are unstable in pure water wherein an amount of an alkali metal or an alkaline earth metal is inserted into a first insertion compound thereby forming a second insertion compound which is unstable in pure water, comprising: a) preparing in an electrochemical cell having a working electrode collector, a counter electrode, and a basic aqueous electrolyte, the electrolyte comprising a salt of said alkali metal or alkaline earth metal dissolved in water wherein the dissolved alkali metal or alkaline earth metal is at a starting concentration and the electrolyte is at a starting pH; b) electrically contacting said first insertion compound to the working electrode collector thereby forming a working electrode; c) charging said cell such that electrons and ions of said alkali metal or alkaline earth metal are supplied to the working electrode thereby inserting an amount of the alkali metal or alkaline earth metal in the first insertion compound and thereby forming the second insertion compound which is less stable in pure water than said first insertion compound, such that degradation of said second insertion compound will occur upon exposure to pure water; d) maintaining the concentration of the dissolved alkali metal or alkaline earth metal in the electrolyte between the starting concentration and a final concentration; the final concentration being greater than zero, and such that the second insertion compound is stable in the electrolyte; e) maintaining the pH of the electrolyte between the starting pH and a final pH; the final pH being a value such that the concentration of H + in the electrolyte is at least an order of magnitude less than said final concentration, whereby the electrolyte provides greater stability than that provided by pure water, and such that the second insertion compound is stable in the electrolyte; and f) isolating the second insertion compound from the electrolyte after insertion of the amount of the alkali metal or alkaline earth metal in the first insertion compound to form the second insertion compound is complete.