LIFE+ GLEE Project
Solvay is committed to develop an innovative water-based production technology that will eliminate the toxic solvent NMP, reduce manufacturing costs, and improve performance and life of Li-Ion batteries.
Introduction to the LIFE+ GLEE Project
The Solvay LIFE+ GLEE Project is aimed at developing and demonstrating a sustainable technology for the manufacturing of Li-Ion batteries. The project is supported by the European Commission via funding from the LIFE financial instrument of the European Community.
This project aims to eliminate NMP, a toxic solvent historically used in the rechargeable Li-Ion battery manufacturing process, thanks to an alternative technology using water-based green binders which, in addition to not carrying toxic risks, also reduces the manufacturing costs associated with the NMP solvent recovery and re-purification processes
The objective is to prove that these new Li-Ion batteries, created using the innovative Electroless Cathode Coating Technology (ECCT) and sustainable manufacturing, will outperform conventional Li-Ion batteries. The effectiveness of this alternative process, in particular for electric vehicles, is realized within a pilot Li-Ion battery materials’ plant in the Solvay Specialty Polymers R&I Center of Bollate, Milan (Italy). The pilot plant produces Cathode Active Materials (CAM) under real industrial conditions that are available for evaluation by battery makers and research organizations. It is currently operative.
The Li-Ion Battery Marketplace
There are two main factors behind the enormous success of commercialization of lithium batteries. One is related to the continuous evolution of mobile electronic systems such as cellular phones, laptops and tablets, which requires new types of high power and high energy-density batteries. Then the continuous demand of energy and the increasing pollution due to the growing CO2 content in the atmosphere requires the use of clean energy sources at a much higher level than today. The dream of a consistent replacement of combustion-engine cars with electric or hybrid vehicles relies anyway on the availability of suitable storage systems.
The rechargeable lithium-ion battery is the most suitable energy storage system for these purposes, because it has several advantages over other competing rechargeable battery systems. In practice, it is much smaller and lighter than other technologies as Nickel Cadmium (Ni-Cd) and Nickel metal hydride (Ni-MH) rechargeable batteries, and it also offers excellent energy density, which can be traded for high power.
This explains why lithium batteries receive most attention at both fundamental and applied levels.
In the current production, NMP solvent is used in cathode electrode manufacturing. NMP is toxic and of high concern for human health. The European Union's REACH regulation encourages progressive substitution of NMP in all applications.
Steering Committee: The LIFE+ GLEE Project is supervised by a high level Steering Committee composed by 4 Senior Managers of both Solvay Specialty Polymers and Solvay Corporate
Project Manager: Maurizio Biso (Lithium-Ion Batteries Researcher) is the LIFE+ GLEE project manager. The LIFE+ GLEE project belongs to the worldwide Solvay Open Innovation organization with the target of keeping perfect balance between technical results and dissemination and collaboration actions.
Process Development: The coordinator of the New Technology Development Lab and the inventor of the GLEE technology represent together with their team the core competencies of the LIFE+ GLEE. Following an Open Innovation approach, the Team is working in close contact with the Politecnico of Milano to bring additional scientific insight in the LIFE+ GLEE technology.
Technology: Three experienced engineers are assigned to the project in order to scale-up the technology from lab- to industrial-scale conditions. Under their responsibility there will also be the planning of a number of sustainability measures to minimize the project carbon footprint and overall environmental impact of the initiative.
Testing & Quality: This team will contribute to test the output of the pilot plant and interact with external labs to have independent validation. In addition, this group will be in charge of liaising the LIFE+ GLEE project with the many European projects and initiatives on Lithium ion batteries.
Engineering & Infrastructure: Several professionals worked at different levels to the building of the new and customized GLEE pilot plant.
Monitoring: A special committee will be assigned to assess the environmental impact and carbon footprint of the project.
Communication: The project has the objective of communicating in a comprehensive way with a very wide range of stakeholders. The Marketing and Communication Team works very closely with the LIFE+ GLEE Team in order to ensure visibility and support all GLEE activities.
Public Relations: Special attention is and will be given in the links and involvement of the project’s Stakeholders during the whole project’s duration.
The Innovative Idea
High-performance, high-capacity Cathode Active battery Materials (CAM), including Nickel Cobalt Aluminum (NCA), Lithium Iron Phosphate (LFP), Cobalt-based lithium-ion (LCO) and Nickel Cobalt Manganese (NCM), are a critical core component of Li-Ion batteries. That’s why the rush in the industry to develop the next generation’s Li-Ion batteries, with even higher power and more energy densities, has normally focused on the investigation of new and higher performing CAM. These developments, however, are impeded by the sensitivity of CAM to moisture and their inability to resist harsh environments.
The technology at the basis of the LIFE+ GLEE project addresses and brilliantly solves this issue by providing an easy way to coat the active material with a protection layer.
The immediate advantage of the protected CAM is to allow the usage of water-based formulations in the production process of Cathode slurry. In addition, during battery operation, the protection coating enhances CAM resistance toward the electrolyte.
The Technological Challenge
Problem: Water-borne cathode electrodes cannot be manufactured due to low stability of active materials when in contact with water.
Solution: Protective coating on active material surface prevents interaction with water and maintains good battery performance.
Protecting a water-sensitive material with a coating is not a difficult task. The unique challenge of shielding cathode materials is preserving the essential process of intercalation and deintercalation of Li-Ions within their structure to retain the full functionality in Li-Ion battery operation. To that purpose, the LIFE+ GLEE technology developed a coating that is permeable to Li-Ions and is also impermeable to water and other aggressive media. This innovation is achieved by close control of coating deposition and layer thickness.
The LIFE+ GLEE Protection Process of CAM
Powders of active materials are coated using an electroless deposition process.
This is composed of three steps:
- Activation: the surface of the particles need to be activated. This is done by the adsorption of a catalyst; the powders are dispersed in an aqueous solution containing, for instance, Palladium ions. Clusters of Pd atoms will be created after adsorption on the surface of the particles, and they will act as active sites where the reduction of metal ions will take place during the deposition process. This preparatory action is fundamental to achieve an efficient deposition in the following step.
- Deposition of protection layer. The protective layer is plated by a controlled chemical reduction of metal ions, dispersed in an aqueous solution, on the surface of the powders. The activated particles from previous are immersed in the deposition bath. The aqueous solution into which powders are dispersed contains metal ions and a reducing agent. The latter is able to provide the electrons needed to complete the metal ion-reduction process. The progressive reduction of metal ions will create a continuous layer on the surface of the dispersed particles.
- Final coating formation with subsequent annealing. In order to allow their use in manufacturing electrodes for Li-ion batteries, at the end of the process powders have to be dried. Once the deposition process is completed, the particles are separated from the plating bath and dried at high temperature in contact with air.
Now the powders are protected and ready to be used in manufacturing a Li-ion battery.
What is Electroless?
- Metallization process based on autocatalytic metal ion reduction
- Can coat conductive and non-conductive substrates
- Produces conformal coatings
- Substrate can be of any geometry and shape
The electroless deposition (ELD) is an electrochemical plating technique that allows the reduction of metal ions from an aqueous solution, without the need of an external power source. ELD is also known as autocatalytic deposition, since the reduced metal acts as catalyst for the reduction of metal ions dispersed in the plating solution.
The most important components of an aqueous ELD plating bath are the salt of the metal to be deposited (source of metal ions) and the reducing agent (source of electrons). The redox reaction that is established in the system is composed by the oxidation of the reducing agent, that generates electrons necessary for the reduction of metal ions dispersed in the plating bath.
Among the metals that can be deposited using this technique there are gold, silver, copper, nickel. Substrates made of glass, metals, polymers and oxides can be coated using ELD, with few limitations on its geometry, since deposition takes place wherever the plating solution is wetting the substrate.
Lithium ion Batteries Configuration
In the classical configuration a Li-Ion battery is made of a cathode, an anode and a separator which divides the two.
The battery operating mechanism consists in the cyclic migration of lithium ions among the two electrodes (cathode and anode).
CAMs are coated with a binder, usually Polyvinylidene Fluoride (PVDF), and a conductive additive (CA), generally carbon black or graphite to improve the electrical conductivity of the electrode, on thin metal foils that act as current collectors (typically Al and Cu).
Lithium ions move in the electrolyte interacting with cathodes and anodes: active materials have to intercalate and de-intercalate lithium ions in their molecular structure or have to react reversibly with lithium ions.
Located inside the battery, the electrolyte is typically a liquid with dissolved salts which increases the ionic conductivity. The electrolyte needs to have a good ionic conductivity but no electrical conductivity because this could cause an internal short circuit.
In a standard battery, a separator is used to physically separate the anode and cathode in the electrolyte solution to prevent an internal short circuit. However, the separator is permeable to the electrolyte in order to maintain the desired level of ionic conductivity.
Carbon-based materials (conductive additives) are used to improve the electrode’s electrical conductivity and create a continuous network of filling the pores between the CAM particles.
The function of the polymeric binder in the electrode is to link together the different components in order to create a mechanically and chemically stable network.
The most widely used binder for cathodes is PVDF. It is a high performance partially-fluorinated polymer with excellent thermal, chemical and electrical stabilities.
This polymer grants good electrochemical performance and excellent adhesion among the materials which forms the electrode and the current collector.
The demonstration process will use a single multi-purpose off-the-shelf automated apparatus. The pilot plant shall be scaled to produce approximately 1kg of CAM per batch and to operate at standard capacity of one batch per day. This is roughly enough material for 50 small phone batteries per day at standard operating capacity. This volume, approximately 200 times smaller than a modest battery production facility, will be produced using real equipment and processes and will be scalable to hundreds of times the size by replicating the process with larger equipment and/or multiple lines.
The Plant Design
The LIFE+ GLEE pilot plant is located in the Solvay Specialty Polymers HQ of Bollate (Milan), one of the most advanced research & innovation centers in the Solvay group. The site, which hosts more than 300 employees, includes laboratories specialized in the development of innovative solutions for sustainable technologies in the photovoltaic, Li-Ion battery and hydrogen markets. The GLEE plant covers an area of nearly 300sqm and includes two cisterns which contain the solution needed by the process, a reactor where the chemical reaction occurs, and a filter which divides the powder from the liquid phase, allowing for treatment in the drier at the end of the process. All this equipment is protected by the Glove Box, a structure which prevents the operators’ contact with any of the agents used during the process. The whole plant is monitored by an automated system which simplifies the activities while granting improved safety.