Traditionally, there has not been a significant emphasis on recycling of spent batteries, cells, and electrical components. Although there has been some attempt to recycle lead acid batteries in the past, complex electrical components have not traditionally been recycled because of the logistics of concentrating a sufficient amount of recyclable electrical components in a single location and the hazards and potential complexity of the process technology. This is particularly the case when the electrical component to be recycled contains a material like lithium in metallic form which could be explosive.
Lithium cells, which use metallic lithium in the negative electrode, have been in practical use, have a relatively high energy density, and therefore have been used in large numbers in portable devices such as cameras and watches. Such cells containing lithium metal negative electrode or alkaline metal negative electrode are referred to as solid-state electrochemical cells. They typically contain the alkaline metal negative electrode, an ionically conducting polymeric electrolyte containing an ionizable alkaline metal salt, and a positive electrode.
The cathode is usually formed by preparing a mixture of an active material, a metal salt, a polymeric electrolyte, and a conductive filler such as carbon black, and coating this mixture on a metal foil which functions as a current collector. Electrochemical cells formed in this fashion using lithium metal as the alkali metal anode have found wide use in numerous applications requiring portable battery power, since lithium batteries formed in this manner have a high energy density. However, lithium metal is considered to be a source of safety-related problems. Metallic lithium generates hydrogen upon reaction with water and organic solvents. This poses a danger of ignition when attempting to treat them for recovery of the lithium metal.
Given the high reactivity of metallic lithium and its propensity to self-ignite on exposure to air and water, research concerning disposal of lithium cells has centered around safe methods for recovering metallic lithium from the cell. Examples of approaches for recovering metallic lithium are described in U.S. Pat. Nos. 5,352,270 and 5,491,037. In both of these patents, methods are described for recovering metallic lithium as safely as possible by opening the lithium cell in an ignition-free environment, washing the cell by submersion in water, and maintaining the cell submerged in water until the metallic lithium is converted to lithium hydroxide. Therefore, recycling of lithium cells to date has focused on methods for crushing and pulverizing the cell submerged under water and encouraging formation of lithium hydroxide as safely as possible. Components of the lithium cell which contain lithium in a non-metallic state are also addressed so that lithium salts may also be recovered along with the lithium hydroxide.
There is no mention of specific treatment for other cell components, besides the metallic lithium. For example, U.S. Pat. No. 5,491,037 describes that solid components other than metallic lithium may be simply sorted and disposed of by any variety of means including melting or pulverization. There is no description of processing of any cell components other than metallic lithium. In U.S. Pat. No. 5,352,270, likewise there is no discussion of recovery of other cell components besides the metallic lithium. In the prior art the objective has been to separate and recover lithium, with no treatment specified for other components. Therefore, what is needed is a method to recover other materials of an electrochemical cell, to foster the objective of recycling.
More specifically, prior art methods do not address recovery of active material present in the more modern generation of cells, where metallic lithium is not used as the active material. Therefore, early methods for disposal of lithium cells, which utilized lithium metal electrodes as the ion source, are not effective for recovery of the more modern intercalation active materials of present-day lithium ion cells, such as, carbon, graphite, metal oxides and lithium metal oxides. The most valuable for recovery and recycling are metal oxide and lithium metal oxide electrode active materials.