Report

Teaser, summary, work performed and final results

Periodic Reporting for period 3 - eCAIMAN (Electrolyte, Cathode and Anode Improvements for Market-near Next-generation Lithium Ion Batteries)

Teaser

The great success achieved by lithium-ion battery (LIB) technology is due to its high power and energy densities.The LIB market is expected to grow significantly based on the increasing momentum of electric mobility. Significant LIB performance and cost improvements are also...

Summary

The great success achieved by lithium-ion battery (LIB) technology is due to its high power and energy densities.The LIB market is expected to grow significantly based on the increasing momentum of electric mobility. Significant LIB performance and cost improvements are also expected over the coming decade. Prices for complete automotive LIB packs are expected to drop significantly until 2025, while cycle life could increase significantly at the same time, potentially making plug-in hybrids and electric vehicles cost-competitive with traditional internal combustion engine vehicles on a TCO basis.

To further increase the energy density of a LIB, both cathode and anode materials with higher specific capacities and cathode materials with a higher voltage plateau are required. The majority of research efforts are focused on improvements of a positive electrode active material in LIB since materials – and specifically cathodes – play a critical role in battery performance and cost, and will affect the cost of LIBs in the future. eCAIMAN focuses on lithium nickel manganese oxide (LNMO), a high-voltage spinel that can be used as a cathode active material. Overall, the performance of the high-voltage spinel cathode is influenced by a variety of factors that depend on how it is synthesized and processed. LNMO as a material of the future is garnering interest for commercialization among major materials manufacturers, not least because it is completely free of Cobalt, an element that is extracted under problematic environmental and social conditions and whose supply is characterized by a high market concentration under the control of a few suppliers globally.

eCAIMAN addresses the Topic GV1-2014, Next generation of competitive lithium-ion batteries to meet customer expectations. The activities of eCAIMAN are tailored to the challenges addressed by the call topic:
Development of new materials, facilities, and technologies; scale-up for manufacturing in Europe; reduced cost; safety aspects; durability; recyclability; impact of hybridization.
The overall objective of eCAIMAN is to bring European expertise together to develop a battery cell that can be produced in Europe and meet the following demands:
Energy density of Lithium-ion batteries (LIB) of ~270 Wh/kg; cost 200 €/kWh. This will be achieved by i) industrializing a 5V high-voltage spinel cathode material ii) industrializing a high-capacity composite anode material iii) industrializing a stable high-voltage electrolyte iv) producing Technical Readiness Level (TRL) 6 large scale automotive cells applying above materials and technology. The project will also: i) investigate the integration in light, passenger, and heavy-duty vehicles ii) validate safety and reliability of the cells ii) support the development processes with advanced multiphysical modelling. In addition, the following “soft goals” are to be achieved: i) contribute to establishing a complete battery value chain in Europe ii) bringing European battery production to the level of global innovation leaders iii) provide inputs to update current regulations and standards for high voltage batteries, aiming for international standardization iv) raise market share of (PH)EVs through better and cheaper cells.
The overall importance to society in improved LIB lies in the fact that with adequate performance and acceptable cost, LIB can help the transition from combustion-engine-based transportation to electric-motor based transport. This shift can make a major contribution towards reduction of global greenhouse gas emissions from transport.

Work performed

A significant focus of the eCAIMAN project is on the development of active materials for an automotive cell, i.e. active materials for cathode and anode, and a corresponding compatible electrolyte. Extensive cell engineering to harmonize compatibility of the developed active materials with the needed inactive materials in the cell, such as separators, binders, current collectors, etc., is also undertaken.

For the cathode, eCAIMAN worked with LNMO (LiNi0.5Mn1.5O4). Different synthesis approaches to producing the spinel were pursued in parallel by three partners in the consortium. Structural modifications to the spinel, such as doping and substitution strategies, were also investigated to optimize the performance of the synthesized LNMOs. Finally, surface treatments of the spinel were applied to reduce undesirable reactions between the active material and the electrolyte. The most promising LNMOs were selected and subjected to performance testing, and finally the best-performing, an Al-doped and an Fe-doped LNMO, were scaled up to pilot scale (~1kg each). Since the module demonstrator in the project requires a larger number of cells, commercial LNMO was purchased and the parameters for cell harmonization were determined. One hundred pouch cells were produced with the commercial LNMO for use in the demonstrator modules.

For the anode, two generations of modified synthetic carbons as active material were developed. The second generation was selected for further use in the cells developed in the project. An investigation on partial replacement of carbon by tin dioxide (SnO2) was undertaken utilizing different techniques. SnO2 particles -pure and doped- were synthesized. The possibility of enhancing SnO2 performance via a surface modification leading to better SEI properties was also explored (SnO2+g-C3N4).

For the electrolyte, a reference generation was used as a baseline. The initial gas formation and attendant cell swelling could be overcome with the next iteration of the electrolyte, “eCAIMAN1”. This led to significantly reduced swelling as compared to the baseline electrolyte, and enabled the assembly of a set of cells with commercial LNMO cathode, graphite anode and eCAIMAN1 electrolyte developed in the project.

To investigate the integration of the cells into two-wheelers, cars and trucks, the technical requirements of the three vehicle OEMs participating in the project were harmonized. This enabled the design of a flexible module that is suitable for all three vehicle classes. The battery management system was updated to enable operation with high-voltage cells.

The developed cells were subjected to out-of-operation/abuse testing to determine their safety, and the power electronics (BMS) were examined from a safety perspective as well.

In cooperation with two other projects funded under the same call (SPICY and FIVEVB), eCAIMAN issued a white paper with harmonized recommendations on cell testing for this new generation of high energy/high voltage cells. The findings are intended for uptake by standardization bodies, and this is promoted by the members of the project consortia active in these bodies.

Final results

Progess beyond state of the art:

* A working 5V 10Ah, cobalt-free pouch cell with LNMO cathode and graphite anode at TRL6. No commercial cells with LNMO cathode were available at time of writing.
* For the first time, a full coin cell with LNMO as cathode and SnO2 as anode was assembled. SnO2 with surface modifications was shown to work at rates of upto 20C.
* A module uniting the end user requirements of three OEMs and offering passive as well as active cooling has been prototyped. The BMS is updated for operation with 5V cells.
* Testing standards for high energy/high voltage cells have been updated collaboratively between eCAIMAN, SPICY and FIVEVB in a white paper.

Website & more info

More info: http://www.ecaiman.eu.