Sustainable and Convenient Recovery of Valuable Metals from Spent Li-Ion Batteries by a One-Pot Extraction Process

Abstract

Spent Li-ion battery (LIB) recovery has become the hot research area due to its surge in quantity and release of heavy metals and toxic substances harmful to the environment. Green and efficient recovery methods are of great significance for the recovery of valuable metals. Herein, an oxalic acid-based deep eutectic solvent (DES) with the weak acidic character and reducibility of oxalic acid was designed for the recovery of valuable metals from spent LIBs via a sustainable and convenient process. Nearly 96.1% of Li and 96.3% of Co can be extracted from lithium cobalt oxide at 120 °C. The DES can extract valuable metals from cathode materials and separate metal ions by itself after extraction without destroying its own structure in a one-pot extraction process. The composition and the structure of DES have been maximum retained and could be intact recycled for another recovery process. After five cycles, the Li and Co extraction efficiencies were maintained above 92.9 and 74.5%, respectively. This work provides a sustainable one-pot recovery process with inexpensive and simple operations for valuable metal recovery from spent LIBs.

Separation of nickel from cobalt and manganese in lithium ion batteries using deep eutectic solvents

“…30 The recovery of lithium from LiCoO 2 in OxA : ChCl has been demonstrated by Lu et al by cooling of the leachate to form LiHC 2 O 4 and CoC 2 O 4 . 42 The solubilities of LiHC 2 O 4 and CoC 2 O 4 in water are 80 g L −1 and 0.037 g L −1 respectively, allowing for efficient separation when washed with water. 65,66 LiHC 2 O 4 •4H 2 O was then recovered by recrystallisation.…”

“…It was also proposed that this behaviour could also be applied to the leaching of the active materials from end-of-life LIB cathodes and recovery as useful chemical precursors that can be returned to the supply chain. In addition, OxA has been employed in many recycling processes as both a leaching and precipitating agent, 41,42 as the oxalate end-product can easily be transformed into an oxide upon heating at 950 °C. 43 Therefore, in the present work, a protocol for the separation and recovery of the critical elements manganese, cobalt and nickel from LiNMC using a DES formed from a 1 : 1 molar ratio of OxA : ChCl is developed.…”

Status and advances of deep eutectic solvents for metal separation and recovery

“…, by chemical reactions) of DESs. 154,161–163 This issue along with the relatively complex procedures of the precipitation processes may hinder the industrialization of the DES-based metal recovery process. Regarding this, more sustainable and convenient DES-based metal extraction processes integrated with precipitation were developed in recent studies.…”

“…This is because integrating DES extraction with the precipitation process cannot avoid a series of physical and chemical procedures, including dilution, pH adjustment, redox reactions, as well as successive addition of various precipitants, which would change the composition (e.g., by diluting and coprecipitating the main components) or even destroy the structure (e.g., by chemical reactions) of DESs. 154,[161][162][163] This issue along with the relatively complex procedures of the precipitation processes may hinder the industrialization of the DES-based metal recovery process. Regarding this, more sustainable and convenient DES-based metal extraction processes integrated with precipitation were developed in recent studies.…”

“…Lu et al (2021) proposed a convenient one-pot extraction process using a ChCl :oxalic acid DES (1 : 1) to extract both Li and Co from LiCoO 2 at 90 °C for 2 h with extraction efficiencies of around 80–90%. 163 Notably, the separation of Li and Co from the DES liquid phase in the form of oxalate precipitates could be attained only upon cooling down the Li and Co-loaded DES leachate without the addition of any precipitant. The Li and Co products were further separated as LiHC 2 O 4 ·4H 2 O and CoC 2 O 4 ·2H 2 O with high purity of 99% and 98%, respectively, by repeating water washing according to the difference in their solubility.…”