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Silicon and polyanionic chemistries and architectures of Li-ion cell for high energy battery

Periodic Reporting for period 2 - SPICY (Silicon and polyanionic chemistries and architectures of Li-ion cell for high energy battery)

Okres sprawozdawczy: 2016-11-01 do 2018-07-31

SPICY is a collaborative research project to develop a new generation of Li-ion batteries meeting the expectations of electrical vehicle end-users, including performances, safety, cost, recyclability and lifetime.
Batteries can fulfil the need for a constant, efficient, clean, safe and renewable power supply for vehicles. Battery storage systems have been recognized by all stakeholders as a key enabling technology to optimize energy recovery and energy management of the whole vehicle with an appropriate level of safety while respecting the environment. Worldwide, the most significant technological challenges currently facing electric vehicles are the cost and performance of their components, particularly the battery. The development of new chemistries and cell architectures for Li-ion battery is the only way to increase cell capacity and possible energy density which could lead to greater electric vehicle autonomy.
Large automotive batteries will be implemented “locally – worldwide” due to cost associated to ship them. This means that our technology has great chance to stay in European manufacturing facilities over long term, ensuring sustainable employment and economic opportunities.
In this context, SPICY is considering the development of new chemistry materials, cell architectures and packaging with the support of understanding and modelling activities have been investigated. 3 optimized generations have been developed, assembled in 17Ah cell according to Plug-in Hybrid Electric Vehicle design, deeply tests and analysed by modelling or by Life Cycle and Cost Analysis. Finally, the recycling rate has been estimated.
Based on the polyanionic chemistry, a Plug-in Hybrid Electrical Vehicles (PHEV) application has been defined. This application has served as background to define specifications at cell and material level.
Various LiFexMn1-xPO4 materials have been synthesized by solution route but did not reach the objectives. Thus, solid state route has been used and reach 100% of the objective. Phosphorous coating do not show improvement. High voltage electrolytes based on sulfolane and adiponitrile have been tested and full graphite/NMC Li-ion cell has been operated at 4.5V with very long cycle life but low power capabilities.
A new graphite material has been selected which is going over the specifications. Regarding the electrolyte, original approach has shown that imide sacrificial salt could significantly reduce the first irreversible capacity. Formation step has been investigated by a cross-check of very powerful characterizations.
Concerning silicon material synthesis, the 2 reactors of synthesis have been updated based on flow modelling. It opens the way now of efficient material as Si-Ge alloy with a carbon shell with first results very promising. Also the capabilities of the induction plasma technology have been demonstrated to produce silicon nanoparticles as battery grade.
Aqueous process has been demonstrated for cathode coating with an electrode of 600 m length and a very low coating loading was achieved for a silicon based anode. 4 km of electrodes have been delivered during the project.
10 cells designed were manufactured with a total of 225 cells or 10 kWh of energy. For every cell series, a deviation between 2 and 5% was observed, allowing suitable evaluation of the optimized material integrated or the different cell architectures. 4 different cell architectures have been assembled for the reference generation. The comparison was particularly unique as all electrodes, electrolyte, separator and formation protocol are the same.
A modular lightweight and robust plastic composite packaging was developed in association to a power connector allowing rotation between 2 packaging. Connectors have shown no supplemental resistance and strong durability. Lead frame in the packaging were very efficient to collect the current but induced slight deformation of the packaging.
Management of the tests done by 5 partners was a huge work to validate protocols of each partner as data recovery in the way to have an exploitation. However strong collaboration between partners led to carrying out of test plan without major issue. Test protocols were developed to have input for modelling. In the aim of standardization, a common workshop was organized between the GV-1-2014 projects leading to a white paper on a joint standardization effort. This workshop has led to a considerable cooperation afterwards to create a website for battery standards, including a standards survey, tables on test methods and related literature, and to create a white paper on battery cell test methods.
Modelling has demonstrated that LiFe0.45Mn0.55PO4 material should improve the energy density of 23% at cell level. Optimized cell designs for every generations have been obtained by modelling for 3 C-rate discharge. It shows that areal capacity between 2.5 and 3.0 mAh/cm² is optimum for this C-rate associated with a porosity of around 35% at the anode and the cathode.
A combined approach for LCC and LCA has been developed for the first time in the form of an excel model. This model will help the user to determine the price per kWh as well as the environmental impact of different cell architectures in different regions of the European Union for different scenario of production rate. When aiming to improve the environmental impact of batteries, it is thus seems more relevant to focus on improving energy content, rather than selecting the materials that have the lowest environmental impact per unit of weight. Increasing the production rate results in a major reduction in the cell costs due to concept of economies of scale.
Recycling study has shown that recovered material can achieve 60% technically and economically for the hard cylindrical cell.
At the end of the project, more than 30 presentations were done in conference, 20 papers were published with peer-review process, 2 patents were deposited and a joint workshop was organized in collaboration with the 3 projects on the same call during the Transport Research Arena in Vienna with 2 booths.
The works of SPICY project, from components development to cell evaluation, modelling or recycling, were done based in the framework of the end-users specifications. Partners evolving in SPICY project are so completely in link with industrial concerns. The around fifteen PhD students and post-docs evolving in SPICY project will be also particularly well formed personnel to go with the launching of new production in Europe. The works done have also generating innovation in terms of knowledge, components or understanding which will also be part of the stronger position from European industry.
Simulations models and tools address shortcomings of today’s Li-ion battery technologies. Fast calculation time model developed in SPICY will be able to define the optimum cell design based on application and active material electrochemical behavior with fast answer. They will support development of optimized Li-ion cells resulting in cells with higher performance and shorter time to market. Tests protocols were developed to have all the inputs to do modelling. This test methods were proposed for standardization and a website was created for battery standards, including a standards survey, tables on test methods and related literature.