Solid-state batteries hold great promise as a next-generation battery technology for automotive applications. This technology may be able to offer future electric vehicles improvements in cell level energy and safety characteristics. A review and comparison of this new emerging technology with that of existing liquid Lithium-ion batteries will be presented.

Design of electric vehicle batteries has long been a careful balance between energy density, safety, and cost among other important considerations. In attempting to balance that “three-legged stool” of requirements, chemistry-level energy density improvements saw nickel-manganese-cobalt (NMC) chemistries increase in nickel content and overall energy density significantly over the last 10 years. Those energy density enhancements also generally provided cost benefits over the long term (nickel costs less than cobalt). Sometimes those improvements required technology enhancements at cell, module, and pack level to meet safety standards set by regulatory agencies, trade groups, or company-specific safety goals. As the 2020s continue toward 2030, nickel percentage in state-of-the-art commercial EV cells is in the 80s or possibly 90s – leaving minimal room for increase – and many EV packs are being designed around ever larger cells to further improve pack volumetric energy density. Additionally, long-awaited safety technology including solid-state electrolyte/anode has not yet seen the mass-market adoption some of us expected. At the same time, regulatory and industry standards have struggled to keep up with the rapid development of EV batteries. This presentation will review lithium-ion technology trends, including divergence of chemistry (lithium iron phosphate vs NMC), cell size and format trends (small cylindrical vs large cylindrical vs prismatic), and what the future may hold for lithium-ion in a pre-solid-state market.

Pouch Li-ion cell market is very dynamic and responsible for around 40% of Li-ion production capacity during 2022. We analyze that market base on different cell types, chemistries, advantages, and limitations. we review leading cell makers in China and out of China. Provide cells production capacity forecast and main reasons for the current market shortage.

Safety is a decisive factor when purchasing battery electric vehicles (BEVs). When the car is charging in the garage at home, it has to be just as safe as it is when being driven on the roads. The goal is 24/7 passive safety. To meet it, customer request one topic: No Propagation. In order to achieve this, AVL has developed a unique testing and simulation methodology, based on the key physical phenomena – from thermal transfer, gas flow, and the mechanical deformation of the battery house and modules, to the melting of individual components, such as bus bar insulation due to particle ejection. With this comprehensive simulation methodology, AVL has put in place all the prerequisites for OEMs to reach their no-propagation, even up to a “fail-inside“ target.

Safety events are often preceded by some weakly observable electrochemical signal indicating, for example, plated lithium or an internal short. To detect such a signal, we propose algorithms combining aging reference models and real-time measurements. Reference models indicate the expected performance and aging behavior, while real-time measurements provide corrections to the model and flag unexpected behavior. Machine learning is used both to identify models and interpret measurements.

By collecting battery data from the field and building up the battery digital twin in the cloud, the degradation of batteries can be monitored online on electrode level and the information regarding the degradation modes can be extracted from the data. Here, we present a degradation diagnosis framework for lithium-ion batteries by integrating field data, impedance-based modeling, and artificial intelligence, revolutionizing the degradation identification with accurate and robust estimation of both capacity and power fade together with degradation mode analysis.

Thermal runaway (TR) in Li-ion batteries refers to uncontrollable exothermic reactions triggered by elevated temperatures. As the temperature of the battery rises, the exothermic reactions further heat up the cell, creating a positive feedback cycle. Despite recent safety monitoring advances in battery management systems (BMS), the prevention of thermal runaway remains a challenge. The talk will provide insights into delaying/mitigating TR in large format Li-ion cells using advanced electrolyte designs.

The reactions of aluminum or other metals with electrode materials can significantly contribute to heat generation in lithium-ion during thermal runaway. Despite this, heat models rarely if ever include their contribution. The thermodynamics and chemistry of thermite reactions will be described along with estimates of their contribution to elevated temperatures during runaway.

There is no one size fits all solution or silver bullet for thermal runaway mitigation. No two thermal runaway events are the same, even for like cells, at the same state of charge, triggered with the same triggering method. Different strategies will always be required on an application-to-application basis. Here we discuss using a holistic approach to system design for the safe transportation, storage, and recycling of lithium-ion batteries. We will describe the challenges and solutions and will discuss the overall abuse test series strategies and latest results. 

VARTA’s cylindrical CoinPower cells utilize an advanced design which significantly improves performance and offers new possibilities in safety applications. Multiple cell size options and capacities are included in the VARTA portfolio, enabling a range of unique applications to benefit from these safety advances. This paper will provide details and test results illustrating the high performance, safety, and reliability of VARTA cylindrical CoinPower cells.

Our first of 4 design guidelines for achieving propagation resistance to single-cell thermal runaway (TR) events in batteries is to control the sidewall rupture risk in cylindrical cells. Our findings identified that cell features like trigger method, energy density, can wall thickness, and header burst pressure have a big influence. In addition, battery design features that impede the cell header and crimp fold from releasing and unfolding increase the risk while snuggly fitting steel and carbon fiber sleeves significantly reduce the risk. This is based on results from over 3000 cell tests.

While rare, Lithium-ion cell thermal runaway failures pose a challenge for applications ranging from consumer electronics to transportation to large-scale stationary storage applications. Fast and robust detection of failing cells is critical to improving the outcomes and preventing cascade failure within a battery system. This presentation will describe failure physics and dangers after cell venting, as well as passive and active countermeasures that can be deployed based on fast detection system that is generally agnostic to electrochemistry, cell design, and system configuration.

Two-phase battery cooling systems are expected to boost battery performance during fast charging and/or demanding drive cycles. However, implementation of such systems is complex due to system integration of thermal/mechanical and electrical subsystems. Kautex presents a fully functional 2-phase battery cooling system tailored to a Textron Off Road vehicle as a technology demonstrator.