In battery electric vehicles (BEVs), the battery becomes a key component, however, will impact vehicle weight and cost. The compromise between battery performance, crash properties, cost, and platform integration constraints are crucial to determine the success of BEVs. This set of priorities leads to various battery housing design and material choices to meet regulatory and profitability targets, while still focusing on providing an attractive vehicle to final customers.
Choosing a Battery Technology Leads to Compromises in Technology:
- Battery integration into the vehicle depends on the type of vehicle platform (i.e., dedicated, versatile, or skateboard), and, more specifically, if the battery will be a structural element or not
- Manufacturing capabilities and costs are also key OEM considerations in battery design decisions
- Battery cell form directly influences the battery energy density, overall volume and design of the housing, and impacts thermal management
- Battery chemistry determines the energy density, reliability, costs, and sets several other technical requirements for housing design and thermal management
- The vehicle segment strongly influences the battery size and cost targets, leading lower segments to consider steel for the battery housing while higher segments and performance-oriented models are likely to select aluminum for lightweighting purposes
All these parameters can be combined in multiple trade-offs, leading to a large diversity of solutions.
OEM Decision-Making Follows a Ranking in the Set of Priorities
- Mandatory requirements: As electric vehicle models tend to be sold globally, regulations from all three major automotive markets (China, Europe, and North America) are being applied by OEMs from all continents
- Critical requirements: Machineability, processability and serviceability of the housing parts; thermal management system to optimize temperature and energy efficiency; vehicle integration costs that impact vehicle design at a larger scale (suspension, linkages, running gears, etc.); NVH management for durability, handling and comfort are considered critical to electric vehicles
- Second-tier priorities: Priorities can vary from one OEM to another, particularly with respect to range improvement, manufacturing capabilities and costs, and supplier diversity
Depending on priorities in the decision-making process, OEMs will set technical requirements that are communicated to battery cell manufacturers, material and part suppliers, battery packagers, and BMS suppliers – all resulting in the final design of the battery housing.
Major Regulations Define Overall Safety Through Four Main Test Categories
Regulations are focused on containing the consequences from runaway cells, road hazards and aging to keep vehicle occupants safe.
- Crashworthiness sets the crushing capabilities of the housing, along with mechanical shocks (decelerations) and internal integrity
- Fire mitigation and thermal management requirements are tested through fire exposure, thermal shock, and overheating
- Charge/discharge must be proven for a battery to be considered safe, with requirements including overcharge, over-discharge, and short circuit
- Automotive grade of batteries and housings and must resist long-term vibrations, without any failures, cracks, or excessive fatigue to achieve current automotive standards
As battery technology evolves and experience with EV safety grows, regulations are expected to consider longer time resistance for fire mitigation.
Impact on Lightweighting and Material Choices:
- While in its infancy, no standardization has yet occurred; however, regulations are currently being proposed and implemented and vehicle volumes are increasing
- Premium automakers tend to utilize aluminum for battery housings in order to reduce weight creep and secure performance, range, and handling
- Volume brands are typically more material-agnostic, and tend to select materials based on costs, manufacturing capabilities, and platform strategies
- In the medium term, OEM strategies should result in a reduction in the diversity of battery design and material choices
- With the solid-state battery technology expected to arise before 2030, and progressively replace current li-ion technology, battery designs will become more compact, with a reduced need for skateboard platforms, as well as lower thermal management and fire mitigation requirements – a reset of material choice decisions is expected
The automotive industry is still in the early years of electrification and various approaches are under development. The rise of a limited number of best-compromise designs – proven safe, performant, and cost-effective – will come with experience as the number of automotive applications increase.
Based on your technological expertise, geographical coverage, value chain positioning, and growth ambitions, DuckerFrontier can help you achieve your goals with fact-based market analyses and market projections relying on direct OEM and supplier inputs on strategies, specifically for battery housing design and material choices.
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