Periodic Reporting for period 2 - ASTRABAT (All Solid-sTate Reliable BATtery for 2025)
Reporting period: 2021-07-01 to 2022-06-30
The work performed in ASTRABAT wishes to find optimal solid-state cell materials, components and architecture that could well suited to the demands of the electric vehicle market and identification of process for manufacturing in mass production.
Five ambitious objectives were defined:
1. Development of materials for a solid hybrid electrolyte and electrodes enabling high energy, high voltage and reliable all-solid state Li-ion cells. The use of fluorinated polymer electrolyte is considered as catholyte, and an inorganic-organic hybrid polymers known as ORMOCER® is developed as anolyte. Additionally, ionic liquids as plasticizer and inorganic conductive ceramic Li7La3Zr2O12 (LLZO) are also considered in the electrolyte formulation.
Electrode materials considered at the cathode is a NMC-based material (NMC 622 and NMC 811) and,
new nanostructured composite Silicium based material –C at the anode side allowing achieving high energy density. To achieve this objective of high energy cell density, adaptation of interface material is done. Series of Li-salt will be synthesised to optimise the ionic conductivity in polymers electrolyte.
2. Development of a cell considering processing techniques compatible in a large scale manufacturing For this purpose, we will develop the formulation of electrodes and electrolyte considering the case of electrode-electrolyte architecture based on the use of classical process of electrode coating (tape casting) with polymer electrolyte and/or conductive ionic ceramic electrolyte (LLZO) infiltrated inside electrode material. This ionic network structure of electrode is random and not optimised. Process manufacturing will, as well, consider dry process such as hot rolling process to reduce the porosity and avoid the use of solvent. A 10 Ah cell will be developed and assessed for performance test and safety certification.
3. Considering next generation of all solid state battery, we target to develop eco-designed P-Type (power) and E-Type (energy) of all-solid state battery in pre-prototype. Two type of electrode structure will be considered. The first electrode structure is based on the use of nano-wire or nano-rods of LLZO to favour the ionic conduction inside the electrode. First of all, synthesis of nao-rod of LLZO will be done, then formulation of electrode material or electrolyte membrane. Secondly, we plan to develop an organised electrode structure with ionic and electronic network based on modelling and using 3D-printing process.
4. All these cells development must support the definition of an efficient cell architecture to comply with improved safety demands. More precisely, temperature of thermal runaway (>150°C) and no flammable electrolyte, no leakage, no gas formation during cycling will be assessed.
5. The eco-design of the new cells developed through a life cycle assessment as well as recycling tests.
Five ambitious objectives were defined:
1. Development of materials for a solid hybrid electrolyte and electrodes enabling high energy, high voltage and reliable all-solid state Li-ion cells. The use of fluorinated polymer electrolyte is considered as catholyte, and an inorganic-organic hybrid polymers known as ORMOCER® is developed as anolyte. Additionally, ionic liquids as plasticizer and inorganic conductive ceramic Li7La3Zr2O12 (LLZO) are also considered in the electrolyte formulation.
Electrode materials considered at the cathode is a NMC-based material (NMC 622 and NMC 811) and,
new nanostructured composite Silicium based material –C at the anode side allowing achieving high energy density. To achieve this objective of high energy cell density, adaptation of interface material is done. Series of Li-salt will be synthesised to optimise the ionic conductivity in polymers electrolyte.
2. Development of a cell considering processing techniques compatible in a large scale manufacturing For this purpose, we will develop the formulation of electrodes and electrolyte considering the case of electrode-electrolyte architecture based on the use of classical process of electrode coating (tape casting) with polymer electrolyte and/or conductive ionic ceramic electrolyte (LLZO) infiltrated inside electrode material. This ionic network structure of electrode is random and not optimised. Process manufacturing will, as well, consider dry process such as hot rolling process to reduce the porosity and avoid the use of solvent. A 10 Ah cell will be developed and assessed for performance test and safety certification.
3. Considering next generation of all solid state battery, we target to develop eco-designed P-Type (power) and E-Type (energy) of all-solid state battery in pre-prototype. Two type of electrode structure will be considered. The first electrode structure is based on the use of nano-wire or nano-rods of LLZO to favour the ionic conduction inside the electrode. First of all, synthesis of nao-rod of LLZO will be done, then formulation of electrode material or electrolyte membrane. Secondly, we plan to develop an organised electrode structure with ionic and electronic network based on modelling and using 3D-printing process.
4. All these cells development must support the definition of an efficient cell architecture to comply with improved safety demands. More precisely, temperature of thermal runaway (>150°C) and no flammable electrolyte, no leakage, no gas formation during cycling will be assessed.
5. The eco-design of the new cells developed through a life cycle assessment as well as recycling tests.
The technical activities of the project were mainly done addressing material and cell specifications, materials development and characterisation allowing to formulate and develop model of electrodes and electrolyte materials.
For the catholyte development, two main strategies were employed to improve the material properties to match the key performances indices of the project: a blending approach and the use of additives beyond the plasticizer (Ionic liquid) and the LLZO ceramic particles. A focus on the LLZO synthesis and process of functionalisation of it to preserve it from CO2 attacks and enhance the Li+ transport was also carried out.
For the development of electrode materials involving tape casting, two different electrode preparation routes were tested and evaluated – the classical slurry route followed by infiltration of the electrolyte components and an electrode slurry route where the electrolyte is included in the slurry itself. Understanding the properties of the various electrolyte formulations will permit better comprehend effects that arise when the anode electrolyte and cathode electrolyte interface is formed in the full cells. ABased on the process route, it was decided that the LLZO (preferably surface-modified for better transport with the polymer phase) will be added only in the electrolyte layer to improve the conductivity.
Considering next generation of all solid state battery, the main focus was the development of the initial inks for 3D printing. This included reducing the size of the solid materials to a size that would enable successful printing without clogging of the print head. The right combination of solvents had to be determined to make a stable ink.
For multi-scale characterisation and modelling, the consortium has been working on examining and visualizing various parameters within the cell components and then using these parameters to model the behaviours of the components to determine the optimal cell architectures. One aspect that has been addressed is the ionic conductivity of the hybrid LLZO-polymer electrolyte and ionic transfer between these two phases. Specially, a TOF-SIMS method has been developed using 6Li/7Li to visualize the transport during cycling.The multiscale modelling has permit to identify electrode-electrolyte architecture allowing reducing lithium plating without affecting to much the internal resistance of the cell. This architecture will be considered for the advanced printing process .
To mitigate this risk, partner in charge of the development of the ORMOCER® has started to test alternative materials that could be polymerized in an acceptable time for industrial development (2-6 hours). New initiators have been tested and seem promising for the electrode formulation. During this second period, the synthesis of the 4 new Li-salts discussed in the project (LiTDI, LiPDI, LiPCP, LiHCAP) and of 15 ionic liquids for the use of these new Li-salts.
The functionalization of LLZO has been also investigated in cold-pressed LLZO pellets for 3 functionalization. One functionalization has been identified to improve the conductivity by 2 order in comparison to the none-functionalized LLZO.
The synthesis of nanofiber LLZO has also progressed with a yield achieved up to 16% and study of 2 new methods of synthesis.
First membrane of NEOFLON VT475 and LLZO have been formulated and tested with success.
cell assembly was manufactured and tested at Fraunhofer-ISC on small size. These first tests have allowed validating the protocol of assembly, and over 100 cycles has been recorded under C/5 rate at 60°C showing a strong capacity fading. Test with lithium metal electrode as negative has also been validated at 20°C under more than 100 cycles at C/5 with stable capacity of 100 mAh/g.
For the manufacturing of GEN#2D cell, the Ben 10, YUNASKO, and CEA (Ben 1) who has a larger pilot equipment will manufacture a roll of porous Si-electrode where the last step of ORMOCER ® coating will be performed on it by a tape casting step. Similarly, the positive electrode should be considered.
For the catholyte development, two main strategies were employed to improve the material properties to match the key performances indices of the project: a blending approach and the use of additives beyond the plasticizer (Ionic liquid) and the LLZO ceramic particles. A focus on the LLZO synthesis and process of functionalisation of it to preserve it from CO2 attacks and enhance the Li+ transport was also carried out.
For the development of electrode materials involving tape casting, two different electrode preparation routes were tested and evaluated – the classical slurry route followed by infiltration of the electrolyte components and an electrode slurry route where the electrolyte is included in the slurry itself. Understanding the properties of the various electrolyte formulations will permit better comprehend effects that arise when the anode electrolyte and cathode electrolyte interface is formed in the full cells. ABased on the process route, it was decided that the LLZO (preferably surface-modified for better transport with the polymer phase) will be added only in the electrolyte layer to improve the conductivity.
Considering next generation of all solid state battery, the main focus was the development of the initial inks for 3D printing. This included reducing the size of the solid materials to a size that would enable successful printing without clogging of the print head. The right combination of solvents had to be determined to make a stable ink.
For multi-scale characterisation and modelling, the consortium has been working on examining and visualizing various parameters within the cell components and then using these parameters to model the behaviours of the components to determine the optimal cell architectures. One aspect that has been addressed is the ionic conductivity of the hybrid LLZO-polymer electrolyte and ionic transfer between these two phases. Specially, a TOF-SIMS method has been developed using 6Li/7Li to visualize the transport during cycling.The multiscale modelling has permit to identify electrode-electrolyte architecture allowing reducing lithium plating without affecting to much the internal resistance of the cell. This architecture will be considered for the advanced printing process .
To mitigate this risk, partner in charge of the development of the ORMOCER® has started to test alternative materials that could be polymerized in an acceptable time for industrial development (2-6 hours). New initiators have been tested and seem promising for the electrode formulation. During this second period, the synthesis of the 4 new Li-salts discussed in the project (LiTDI, LiPDI, LiPCP, LiHCAP) and of 15 ionic liquids for the use of these new Li-salts.
The functionalization of LLZO has been also investigated in cold-pressed LLZO pellets for 3 functionalization. One functionalization has been identified to improve the conductivity by 2 order in comparison to the none-functionalized LLZO.
The synthesis of nanofiber LLZO has also progressed with a yield achieved up to 16% and study of 2 new methods of synthesis.
First membrane of NEOFLON VT475 and LLZO have been formulated and tested with success.
cell assembly was manufactured and tested at Fraunhofer-ISC on small size. These first tests have allowed validating the protocol of assembly, and over 100 cycles has been recorded under C/5 rate at 60°C showing a strong capacity fading. Test with lithium metal electrode as negative has also been validated at 20°C under more than 100 cycles at C/5 with stable capacity of 100 mAh/g.
For the manufacturing of GEN#2D cell, the Ben 10, YUNASKO, and CEA (Ben 1) who has a larger pilot equipment will manufacture a roll of porous Si-electrode where the last step of ORMOCER ® coating will be performed on it by a tape casting step. Similarly, the positive electrode should be considered.
The first result in electrolyte material conductivity for the fluorocarbon polymer with plasticizer allows to be closed to the KPI-2, ionic conductivity with 1.1*10-3 S.cm-1 at 60°C and 3.45*10-4 S.cm-1 at 20°C. [KPI-2: 0.4 *10-3 S.cm-1].