Direct recycling of lithium-ion is a promising method for manufacturing sustainability. It is more efficient than classical methods because it recovers the functional cathode particle without decomposition into substituent elements or dissolution and precipitation of the whole particle. This case study of cathode-healing™ applied to a battery recall demonstrates an industrial model for recycling of lithium-ion, be it consumer electronic or electric vehicle (EV) batteries. The comprehensive process includes extraction of electrolyte with carbon dioxide, industrial shredding, electrode harvesting, froth flotation, cathode-healing™ and finally, building new cells with recycled cathode and anode. The final products demonstrated useful capability in the first full cells made from direct recycled cathodes and anodes from an industrial source. The lessons learned on recycling the prototypical chemistry are preliminarily applied to EV relevant chemistries.

The electric vehicle and energy storage industries will generate over one-million tons per annum of lithium-ion for recycling in the next decade. There are significant technology gaps in the recovery of lithium-ion battery materials that threaten the sustainability of these industries. Cathode healing is introduced here as a new approach to produce low cost (i.e. < $10/kg), recycled, battery grade electrode material. The soft-chemical treatment non-destructively recycles cathodes. Two examples are shown in this work: LiNi0.5Co0.2Mn0.3O2 and LiNi0.6Co 0.2Mn0.2O2 (NCM 523 and NCM 622). The cathodes were harvested from end-of-life cells and further processed with cathode-healing methods to reproduce recycled electrodes with performance equivalent to the original manufactured baseline material. The so-called healed cathodes were built into 2Ah test cells and compared side-by-side with the baseline. Healed NCM 523 performed like the baseline, recording over 2,100 charge-discharge cycles to reach 80% of original capacity. The cathode healing process was modified to fully recover end-of-life NCM 622. Powder X-ray diffraction and X-ray photoelectron spectroscopy data support the lithium capacity measurements with structural models. These analyses show that cathode healing reverses cation mixing by oxidizing nickel to reproduce well-ordered, high-capacity material. These examples show the technical feasibility and low-cost opportunity for cathode healing to enable sustainability in the electric vehicle and energy storage industries.

By 2025, the lithium-ion battery and disposal markets are forecast to reach $ 93 billion and $14 billion respectively. Logistics contribute to these costs, but processing takes its toll with energy intensive industrial smelting and/or hydrometallurgical technologies. As traction and storage cathode materials use less cobalt, these recycle technologies require centralized, large scale facilities to meet economic viability based upon the metal. Cobalt dilute or cobalt free applications may therefore require disposal fees, which is not helpful for circular economic sustainability for the advanced lithium-ion battery industry. Another technological approach is necessary to address this challenge for the industry. Direct recycling has potential for cost effective recycling of lithium-ion cathodes, which is demonstrated for NMC532 and NMC622 in this work. In the first example, NMC 532 electric vehicle grade cells were faded to 80% of their original capacity. The cells were pulverized and cathodes captured and treated and packaged. Afterwards, in a manufacturing setting, 2.2 Ah cells were built using the recycled cathode and graphite. Recycled cathode demonstrated both performance and manufacturability like new material. In side by side cycle testing, both tallied 2,500 cycles at C/10 to reach 80% of original capacity. In the second example, starting with faded cells, NMC 622 is similarly regenerated to original capacity and rate capability. Physical characterization of NMC622 before and after processing shows the treatment reverses ageing in the surface region of the electrode particles resulting in renewed performance. These examples show the ease and flexibility of hydrothermal and calcination processes to restore electrochemical performance to NMC cathode materials. A comparable industrial process is alumina production from bauxite, which has a world-wide production over 60,000 tons and demonstrates the scalability and low cost potential for direct recycling. The development of distributed direct recycling services reduces both logistical and production costs relative to the current approach. Direct recycling technologies provide a viable foundation for the future waste management services for the lithium-ion battery market. Figure 1

This paper describes performance capabilities of nickel-rich LiNixMnyCozO2 lithium-ion chemistries after Direct Recycling, which is a method to reinstate structure/property relationships in worn/failed electrodes. It includes comparative analyses of treated NMCs (T-NMCs) and pristine NMCs after Direct Recycling. The vertical integration of Direct Recycling into battery manufacturing will significantly reduce material costs and address long term economic sustainability for the battery industry. Current lithium-ion cathode production exceeds $2B. Market projections indicate this will top $7.3B by 2025 [1]. Recycling does not significantly contribute to cathode production; but a modest use of 5% recycled cathode by 2025 has a potential value in excess of $370M. Challenges for lithium-ion recycling include: (1) Fees for end-of-life recycling or disposition. (2) Loss of critical material in low recycling yields. (3) Low grade material from recycling. Hydrometallurgic or pyrometallurgic refining technologies are the main approaches for recycling; these aim for cobalt and nickel recovery. The energy investment in original manufacturing of cathode structures is lost with these processes. On the other hand, Direct Recycling offers a feasible way to conserve that energy-input independently of cobalt/nickel content [2-3]. Other workers have developed Direct Recycling using painstaking stoichiometric methods to reinstate lithium-metal-oxide ratios [4]. OnTo’s processes refurbish the cathode materials, using simple methods without extensive elemental analyses; examples include reintroduction of lithium into spent electrode materials taught in US patents referenced below [5-6]. These methods also remove trace metals from >75ppm to 12ppm. Such high purity has the potential to improve performance of reclaimed material over original (i.e. longer cycle life). Direct Recycled, EV grade NMC electrodes (R-NMC) demonstrate 2,500 cycles, low self-discharge and performance equal to original NMC; with a cost of 1/3rd of the original manufacture. Processing spent batteries includes production of shredder residue (sometime referred to as black-mass in the recycling industry). Separation of solid oxide electrode materials from binders, carbon black and graphite is a feature that is a simultaneous part of Direct Recycling. Aqueous methods can be used in these process. One challenge is the dissolution of metals from the oxide particles. This paper demonstrates the control/minimization of dissolution while improving the lithium capacity in the (used) lattice system. This paper outlines Direct Recycle feasibility on a suite of lithium-ion chemistries including nickel rich NMC, spinel lithium manganese oxide (LMO) mixed with NMC, lithium-iron phosphate (LFP), and lithium cobalt oxide (LCO) from early prototypical formulations to the modern, high capacity versions. This work investigates Direct Recycling on NMC and T-NMCs. New samples of each electrode were allowed to stand in air to degrade capacity. As a result of Direct Recycle processing, the specific capacity of T-NMC rebounded from 140 to 175mAh/g; while similarly processed uncoated NMC rebounded from 90 to 140 mAh/g. These processes are designed to address failure mechanisms exhibited during life cycling and storage of NMC chemistries, such as the Ni2+ accumulation in the surface regions of electrodes. One feature is they oxidize surface nickel ions as shown in the comparison (below) of used and treated electrode particles with XPS. Specifically, the Ni 3p signal diminishes indicating the drop in concentration of Ni2+ at the particle surface after processing. References Pillot, C. Proceedings of The International Battery Seminar and Exhibit IBSE 2015 Ft. Lauderdale, FL March 16, 2015. Dunn, J.B.; Gaines, L. ; Sullivan, J.; Wang, M.Q. Environ. Sci. Technol. “Impact of recycling on cradle-to-gate energy consumption and greenhouse gas emissions of automotive lithium-ion batteries” 46 (22), 12704-12710, (2012) Gaines, L. Sloop, S.; “EV Battery Recycling Technology: Challenges and Opportunities” IBSE 2016 Ft. Lauderdale, FL, March 21, 2016. Mathew, S.; Menon, K.; Scordilis-Kelly, C.; Saidi M.Y. “Method for Recovering Particulate Material from Electrical Components” U. S. Patent # 6,150,050. Sloop, S. “Reintroduction of lithium into recycled battery materials” U. S. Patent # 8,846,225. Sloop, S. “Reintroduction of lithium into recycled battery materials” U.S. Patent # 9,287,552 Keywords: lithium-ion manufacture; recycle; critical materials; direct recycling; atomic layer deposition; failure modes. Figure 1

Des modes de realisation de l’invention concernent le recyclage de piles alcalines. Un mode de realisation concerne un procede de recyclage d’une pile a electrolyte de base, consistant a rompre cette pile dans des conditions anaerobies et a faire couler a l’interieur de la pile du dioxyde de carbone dans une chambre anaerobie.

The purpose of this paper is to report on the reactivity of PF5 and EC/linear carbonates to understand the thermal and electrochemical decomposition reactions of LiPF6 in carbonate solvents and how these reactions lead to the formation of products that impact the performance of lithium-ion batteries. The behavior of other salts such as LiBF4 and LiTFSI are also examined. Solid LiPF6 is in equilibrium with solid LiF and PF5 gas. In the bulk electrolyte, the equilibrium can move toward products as PF5 reacts with the solvents. The Lewis acid property of the PF5 induces a ring-opening polymerization of the EC that is present in the electrolyte and can lead to PEO-like polymers. The polymerization is endothermic until 170°C and is driven by CO2 evolution. Above this temperature the polymerization becomes exothermic and leads to a violent decomposition. The PEO-like polymers also react with the PF5 to yield further products that may be soluble in the electrolyte or participate in solid electrolyte interphase (SEI) formation in real cells. GPC analysis of the heated electrolytes indicates the presence of material with Mw up to 5000. More details on the polymerization reactions and further reactions with PF5 are reported. Transesterification and polymer products are observed in the electrolytes of cycled and aged Li-ion cells. Formation of polymer materials which are further cross-linked by reaction with acidic species leads to degradation of the transport properties of the electrolyte in the composite electrodes with the accompanying loss of power and energy density. Generation of CO2 in lithium-ion cells leads to saturation of the electrolyte and cessation of the polymerization reaction. However, CO2 is easily reduced at the anode to oxalate, carbonate and CO. The carbonate contributes to the SEI layer while the oxalate is sufficiently soluble to reach the cathode to be re-oxidized to CO2 thus resulting in a shuttle mechanism that explains reversible self-discharge. Irreversible reduction of CO2 to carbonate and CO partially accounts for irreversible self-discharge.

The behavior of polymer electrolytes in lithium batteries is reviewed in the context of molecular scale models as well as on the system scale. It is shown how the molecular structure of the electrolyte strongly influences ion transport through the polymer as well as across the interfaces and determines the values of a number of parameters needed for system models that can predict the performance of the battery (e.g. κ, D, t0+ and i0). The interaction of the electrolyte with the electrodes not only leads to transfer of the lithium ion across the interface but also to side reactions that profoundly influence the calendar and life cycle of the battery. Typically these electrochemically induced side reactions generate the SEI layer, but inherent instability of the bulk electrolyte may also play a role in the formation of surface layers. These various reactions can lead to changes in the mechanical properties of the separator and electrode structure that promote life-limiting phenomena such as dendrite growth, passivation and morphology changes. The rheological model of Eisenberg is drawn upon to show how the interactions of the electrolyte with surfaces can lead to distinct changes in mechanical and transport properties that may limit the battery performance and lead to diminished performance with time. The molecular level models may be combined with the rheological models to provide workable models of the interfaces and bulk electrolyte dynamics that in turn can be used to provide a more accurate level of performance prediction from the system models. This connects molecular structure with battery performance and guides the design and synthesis of new and better materials.

Poly (ethylene oxide) (PEO) and poly [oxymethylene-oligo (oxyethylene)] (PEM) disks are cross-linked by exposure to 254 nm radiation. The rate of formation of cross-links is greatly enhanced by the presence of benzophenone, and an average cross-link density of up to 6 mol % of ethoxy units can be obtained after several hours of irradiation. The highly cross-linked polymers are insoluble in water or organic solvents and show improved physical properties for handling and the formation of free-standing films. Scanning calorimetry and polymer swelling are employed to characterize the polymers, and impedance measurements are reported for sodium salt complexes prepared from the cross-linked polymers. Dynamic modulus measurements show that, upon irradiation, PEO and PEM become cross-linked, elastomeric solids. (C) 1994 John Wiley and Sons, Inc.