(211e) Recovery of Metals from Cathode of Lithium-Ion Batteries: A Closed-Loop Approach Using Oxalate Chemistry

Lithium-ion batteries (LIBs) power the lives of millions of people each day. Their usage has expanded from cellphones and laptops to powering hybrid and electric cars, homes, and even the electrical grid. However, after reaching the end of their life cycles, LIBs must be recycled and present new challenges for the battery industry. The ability to separate and recover valuable metals from these batteries is required to provide sustainable reuse. In this work, we introduce a novel chemistry to extract valuable metals from lithium cobalt oxide (the most common cathode material) using different derivatives of oxalic acid. Oxalic acid has the unique property of separating lithium and cobalt directly by precipitating cobalt oxalate during the digestion. In traditional approaches using sulfuric acid and nitric acid with a strong reducing agent like H₂O₂, both lithium and cobalt completely dissolve into the solution. The metal separation from leachate requires another precipitation step which adds to the overall cost of the process. Also, the emission of harmful pollutants such as SO_X and NO_X pose a significant environmental challenge. All of these issues can be eliminated using oxalic acid and its derivatives for this process. In this work, we have demonstrated metal extraction using oxalic acid and ammonium hydrogen oxalate to efficiently recover lithium and cobalt from lithium cobalt oxide. Cobalt directly precipitates out as cobalt oxalate which can be converted to cobalt oxide by appropriate thermal treatment whereas lithium can be precipitated out in the form of carbonate or phosphate. Remaining oxalate in the filtrate after lithium precipitation can be recycled and used for extraction again which provides a closed-loop process. The possibility of reusing the filtrate provides an economic advantage to the oxalate chemistry. This presentation will describe the experimental details of the process which includes digestion, separation and precipitation.