In a lithium ion battery, one or more chelating agents may be attached to a microporous polymer separator for placement between a negative electrode and a positive electrode or to a polymer binder material used to construct the negative electrode, the positive electrode, or both. The chelating agents may comprise, for example, at least one of a crown ether, a crown ether, a podand, a lariat ether, a calixarene, a calixcrown, or mixtures thereof. The chelating agents can help improve the useful life of the lithium ion battery by complexing with unwanted metal cations that may become present in the battery's electrolyte solution while, at the same time, not significantly interfering with the movement of lithium ions between the negative and positive electrodes.