Abstract: The invention features the use of redox reagents, dissolved in non-aqueous electrolytes, to provide overcharge protection for cells having alkali metal negative electrodes (anodes). In particular, the invention features the use of organometallic compounds, known as metallocenes, as redox shuttle reagents to provide overcharge protection. Specific examples of this invention are bis(cyclopentadienyl)iron, known as ferrocene; bis(n-butyl-cyclopentadienyl)iron, known as butylferrocene; bis(cyclopentadienyl)nickel, known as nickelocene; and bis(cyclopentadienyl)cobalt, known as cobaltocene. An example of a rechargeable battery in which these redox reagents are used as an Li negative electrode and a TiS.sub.2 positive electrode.