Green and facile method for the recovery of spent Lithium Nickel Manganese Cobalt Oxide (NMC) based Lithium ion batteries

Highlights

• Green technique for the management of spent Lithium Nickel Manganese Cobalt Oxide (NMC) based Lithium ion batteries.

• Proposes novel use of Citrus Juice (CJ) as reagent and solvent.

• CJ was fond green reagent for binder removal from Lithium ion batteries.

• Leaching efficiency of CJ was found in between 94% and 100%.

• Role of various counterions and flavonoids was justified in leaching.

Abstract

The research reports a novel green method to use citrus fruits for the management of spent NMC based lithium ion batteries (LIBs). Citrus fruit juice (CJ) can provide an excellent chemical combination to remove the binder and support the leaching with efficiency in between 94% to 100%. CJ have many advantages in LIBs recycling as an economic and green method due to rich in many organic acids like citric and malic acid as complexing agents with ascorbic acid and citrus flavonoids, for the reduction of many heavy metals. Application of CJ can avoid the use of N-Methylpyrrolidine, γ-Butyrolactone, dimethylformamide, and dimethyl sulfoxide like toxic solvents commonly used for peeling off Al/Cu. Furthermore, counterions (like Na⁺, Mg⁺, Ca²⁺) present in CJ was responsible for the improvement in the leaching efficiency of organic acids. A mechanistic pattern of the overall reaction was also proposed and duly supported by various spectroscopic techniques. Binder removal experiment was supported by analytical techniques like XRD, XRF, IR, and FE-SEM, while the metal concentration was monitored by using ICP-MS analysis.

Introduction

Technological advancement has greatly increasing the demand for newer lithium ion batteries due to the more use of advanced energy storage devices like electric vehicles, consumer electronics, renewable energy storage, back-up power, medical devices, etc. It was reported that in the year 2006 rechargeable (secondary) batteries covered 11% of the total global battery business and it was growing at the rate of 6% annually (Battery Statistics, 2015). India is the world’s second-largest cellular phone user with over 930.20 million subscribers (547.70 million urban and 382.50 million rural) as on November 2014 (TRAI, 2014).

The removal of the binder is an essential step towards the recovery of metals from spent lithium ion batteries. It can be removed either by the high temperature treatment (Guo et al., 2016) or by using solvents like N-methyl pyrrolidone (NMP), γ-Butyrolactone, dimethylformamide, and dimethyl sulfoxide (Li et al., 2013, Li et al., 2010a). High-temperature treatment process required temperature 500–700 °C and has many issues related to toxic emission and material management (Wang et al., 2016), whereas solvents based techniques have the limitation in terms of toxicity and post management (Chen and Zhou, 2014). So some alternative technique is the need of the hour.

The existing methods for metal recovery from LIB recycling involved: (i) aqueous stream based limited recycling using the liquid stream mixed with soda ash with the hammer mill and shaker table (Meshram et al., 2015a); (ii) supercritical CO₂ based recycling of cathode and anode (Bertuol et al., 2016) (iii) pyro and hydrometallurgical processes (Chen et al., 2015a, Pant and Singh, 2014). There was also some limitation over pyro-metallurgical processes towards the recovery of lithium and aluminium and further treatment is needed for the recovery of Li (Hanisch et al., 2015).

The use of strong acids can provide good results in metal leaching but harmful emission like Cl₂, SO_x and NO_x makes its limitation to be a popular technique, also the post management of acids is a complex issue (Zhang et al., 2013). Organic acid has the potential to avoid these adverse environmental impacts. Pure citric, oxalic malic, aspartic, ascorbic, tartaric and iminodiacetic acids (Sun and Qiu, 2012, Li et al., 2013, Nayaka et al., 2016a) can be used as the leaching agent for LIB recycling with incomplete leaching. Use of pure organic acid cannot provide efficient leaching and for improvement H₂O₂ (1–6 vol.%) be used as a reducing agent (Li et al., 2010b).

To avoids the use of H₂O₂ like toxicant methods can be modified by using mixture of acids (Table 1) out of which one acid is used as a complexing agent and another as a reducing agent (Li et al., 2012, Nayaka et al., 2016b). Citric and malic acid with a different combination of ascorbic acid/ H₂O₂ give nearly 100% leaching of Li (Nayaka et al., 2015, Li et al., 2013). Cobalt gives average leaching in between 60% and 97% and best results are with the combination of malic acid and ascorbic acid (Nayaka et al., 2016a).

To develop more environmentally benign process, i.e. avoid the use of H₂O₂ and mineral acid like toxicant; in an affordable cost we are proposing the use of CJ as a green solvent. Waste resultant from LIBs can cause an inescapable risk for the environment and public health (Pant et al., 2012), while on the other hand it have the harm to improper dispose to the metal resources like Li, Co, Ni and Mn. In year 2005 cobalt in LIB waste was found 12,000 tonnes and respective to this the approximate amount for Li, Mn and Ni contents were 5723, 35,312 and 21,970, respectively (Dewulf et al., 2010). A proper management strategic can reduce the risk of the release of toxic organic compound and also mitigate the risk of resource depletion. The use of CJ for the recovery of metals from waste LIB can make the process safe for the environment with an effective recovery. CJ is a source of mixed organic acid with flavonoids as complexing and reducing agent with different counterions for efficient leaching and binder removal. This study will devote to discover a green recovery of Li, Co, Ni and Mn from LIB using CJ as the innovative waste management.