Separation of Lithium and Cobalt from LiCoO₂: A Unique Critical Metals Recovery Process Utilizing Oxalate Chemistry

Abstract

The demand for lithium-ion batteries (LiBs) is significantly increasing leading to a shortage in supply for critical metals, such as lithium and cobalt. Recycling LiCoO 2 cathodes can provide a secondary source for these critical metals, which are necessary raw materials for the synthesis of modern LiB cathodes, such as nickel manganese cobalt oxide (NMC). In this work, an environmentally friendly, closed-loop process for recovery and separation of lithium and cobalt from LiCoO 2 cathodes has been developed using oxalate chemistry. In this paper, oxalic acid and ammonium hydrogen oxalate are utilized as digestion reagents to extract lithium into the aqueous phase (Li 2 C 2 O 4 ) and precipitate cobalt oxalate (CoC 2 O 4 •2H 2 O) in the solid phase resulting in a low-temperature, cost-effective separation of these metals. A greencolored intermediate was identified as a Co(III)-oxalate complex; this complex further reduces and precipitates as a Co(II)-oxalate complex (CoC 2 O 4 •2H 2 O). The optimum acidity for digestion and metals separation using oxalate containing acids was a pH < 2.5. The minimum amount of oxalic acid required for digestion was determined in order to develop the most economical process with more than 97 wt % Li and Co recovery. The proposed process is an energy-efficient, cost-effective, environmentally friendly process for recovering high-value, critical metals, such as lithium and cobalt from LiBs and other sources.

Extraction of aluminum and iron from bauxite: A unique closed‐loop ore refining process utilizing oxalate chemistry

“…A detailed reactor schematic can be found in our previous work. 17 The reactor temperature and agitation speed (N s ) were set at 98 C and 600 rpm, respectively, for all the experiments in this work. The temperature and agitation speed values were optimized to maximize the kinetics and avoid any diffusion limitation.…”

“…In our alternative approach for bauxite refining, oxalic acid (H C 2 O 4 ) utilize the chelation property along with the acidity to extract metals from the metal oxides. Previously, H 2 C 2 O 4 has been used to extract metals from various sources ranging from spent lithium-ion battery cathodes [17][18][19] to ores such as laterite 20 and scheelite. 21,22 Corbin et al developed two environmentally-friendly closed-loop processes for extraction of Fe and Ti from ilmenite using ammonium hydrogen oxalate (NH 4 HC 2 O 4 ) 23 and trimethylammonium hydrogen oxalate ((NH[CH 3 ] 3 )HC 2 O 4 ).…”

“…However, the H 2 C 2 O 4 and K 2 C 2 O 4 are more expensive than inorganic acids such as H 2 SO 4 and HNO 3 . 17 To offset the cost of oxalate-based acids and make this process economical, an ion-exchange resin and a pH-based separation have been developed to recover the oxalate-based acids in their original form. To the best of our knowledge, this is the first study on extraction of metals from bauxite using oxalic acid and its derivatives.…”

Extraction of Aluminum and Iron from Bauxite: A Unique Closed-Loop Ore Refining Process Utilizing Oxalate Chemistry

“…) utilize the chelation property along with the acidity to extract metals from the metal oxides. Previously, H 2 C 2 O 4 has been used to extract metals from various sources ranging from spent lithium-ion battery cathodes [17][18] to ores such as laterite 19 and scheelite. [20][21] Corbin et al developed two environmentally-friendly closed loop processes for extraction of Fe and Ti from ilmenite using ammonium hydrogen oxalate (NH 4 HC 2 O 4 ) 22 and trimethylammonium hydrogen oxalate ((NH(CH 3 ) 3 )HC 2 O 4 ).…”

“…In this study, a standard bauxite material from the Australian Darling range (NIST SRM600) has been used to investigate the feasibility of a closed-loop Al and Fe recovery process using H 17 To offset the cost of oxalate-based acids and make this process economical, an ion-exchange resin and a pH-based separation have been developed to recover the oxalate-based acids in their original form. To the best of our knowledge, this is the first study on extraction of metals from bauxite using oxalic acid and its derivatives.…”