https://onlinelibrary.wiley.com/doi/pdf/10.1002/aenm.202002238

An Urgent Call to Spent LIB Recycling: Whys and Wherefores for Graphite Recovery

Lithium ion batteries (LIBs) are an essential energy-storage device for a majority of advanced electronics used in our everyday lives, from cell phones and laptops, to medical devices and electric vehicles. Despite their continued widespread adoption, methods to recycle and reuse end-of-life (EOL) LIB materials are still under active development. In the first part of this two-part review on LIB recycling, we review current commercial scale processes in practice for recycling or reusing EOL LIB components. Future waste projections estimate 4 million tons of cumulative EOL EV battery modules by 2030, which is above the current global recycling capacity. All of the processes in use today utilize a combination of pyrometallurgical and hydrometallurgical or mechanical and hydrometallurgical processing to recover mainly cobalt and nickel and copper, while other components are disposed as waste unless further processed. In this review, we highlight the need for recycling LIB material components based on resource availability and the current processes in practice to recover and recycle LIBs.

Recycling of End-of-Life Lithium Ion Batteries, Part I: Commercial Processes

Research for the recycling of lithium-ion batteries (LIBs) started about 15 years ago. In recent years, several processes have been realized in small-scale industrial plants in Europe, which can be classified into two major process routes. The first one combines pyrometallurgy with subsequent hydrometallurgy, while the second one combines mechanical processing, often after thermal pre-treatment, with metallurgical processing. Both process routes have a series of advantages and disadvantages with respect to legislative and health, safety and environmental requirements, possible recovery rates of the components, process robustness, and economic factors. This review critically discusses the current status of development, focusing on the metallurgical processing of LIB modules and cells. Although the main metallurgical process routes are defined, some issues remain unsolved. Most process routes achieve high yields for the valuable metals cobalt, copper, and nickel. In comparison, lithium is only recovered in few processes and with a lower yield, albeit a high economic value. The recovery of the low value components graphite, manganese, and electrolyte solvents is technically feasible but economically challenging. The handling of organic and halogenic components causes technical difficulties and high costs in all process routes. Therefore, further improvements need to be achieved to close the LIB loop before high amounts of LIB scrap return.

https://www.mdpi.com/2075-4701/10/8/1107/pdf

Industrial recycling of lithium-ion batteries: a critical review of metallurgical process routes

Transition metal impurities in carbon-based materials: Pitfalls, artifacts and deleterious effects

An innovative approach to recover anode from spent lithium-ion battery

Graphite has a stacked planar sp2-hybridized C6 ring structure, displaying a polymorphism with rhombohedral, hexagonal, and turbostratic. Based on its structure-property relationship, it affords a variety of technologically innovative applications or performances in industries, such as lithium-ion batteries, fuel cells, two dimensional graphene, water purification, electronics, fiber optics, spintronics, refractories, electrical products, electric vehicles, etc. The monetary value of graphite depends largely on carbon content and flake size. However, the physical separation of graphite from its ore body is known to be very expensive, energy intensive and time-consuming. Hence, this study extensively describes a current purification method for producing high-quality graphite material with impurities reaching about 10–100 mg/kg, attracting a lot of end users. It also describes the potential applications of graphite materials and identifies the future scope of a new market, depending on material purity. Finally, the current and future graphite-mining countries are investigated in details.

Purification, application and current market trend of natural graphite: A review

The mineralogy and petrography of natural graphite in Saba Boru of Ethiopia indicate that there exists flake graphite with a slightly oval structured fine size according to our study on thin and polished sections. Herein, for estimating the carbon content in graphite, the ASTM-C561, the test method for ash in a graphite sample, was used. For characterizing graphite, x-ray diffraction, x-ray fluorescence, inductively coupled plasma mass spectroscopy, and scanning electron microscopy were also used. Chemical analysis of ore samples determined that the average compositions are 63.35% SiO2, 15.45% Al2O3, 2.36% Fe2O3, 2.07% K2O, less than1% others, and loss-on-ignition (LOI) in the range of ~4.74%–37.42%. The total carbon content of graphitic ore ranged from 4.11% to 33.14%. Importantly, when graphite is concentrated through floatation, its average purity and recovery are 92.97% and 90.82%, respectively. Furthermore, once the graphite concentrates are treated with hydrofluoric acid, the average value attains a high grade of 96.48% C. Moreover, the average ash content is 81.93% (pre-flotation) and 3.1% (post-flotation), respectively. Finally, after beneficiation, a silica is identified as a major gangue (85.88%), usable as a raw material for other purposes such as cement. Hence, these graphite-bearing rocks seem to be worth exploring for commercialization opportunities.

Mineralogical and petrographic analysis on the flake graphite ore from Saba Boru area in Ethiopia

We investigated the effect of the acid species, the liquid-to-solid ratio, the reaction time, and temperature on the carbon content (CC) of natural crystalline flake graphite in Ethiopia. Specifically, after physical purification through a froth flotation, CC was observed to be 94.71 %. However, when the acid-alkali-acid, H2SO4/H2O2-NaOH−HCl, chemical purification process was employed in this study, CC was significantly improved to 99.68 % (or 99.72 % after additional HF leaching), based on both a loss-on-ignition test and thermogravimetric analysis. Here, the purified graphite powder exhibited a conductivity of 21.9 S/cm, placing it in the range of semiconductor materials. The hexagonal structure of graphite, when analyzed by X-ray diffraction, was independent of the purification process. However, according to the scanning electron microscopy image, the impurities in the graphite sample were removed effectively through the purification process. Finally, based on the overall material properties of this purified graphite, this natural flake graphite could be used for high tech applications such as Li-ion battery anodes.

Allah D. Jara

Papers

Purification, application and current market trend of natural graphite: A review

Mineralogical and petrographic analysis on the flake graphite ore from Saba Boru area in Ethiopia

Chemical purification processes of the natural crystalline flake graphite for Li-ion Battery anodes

A first principle study on spin-dependent transport properties of graphite nanostructures