While most electric vehicle owners perceive their EV batteries as power sources and energy storage units, these seemingly humble components are a testament to incredible technological advancements. Evolving from fueling simple devices like flashlights, electric vehicle batteries now power entire cars, marking a significant journey.
In this exploration, we delve into the intricate world of EV batteries, focusing on the fundamental building blocks—EV battery cells.
Composition of EV Batteries: At the core of EV batteries lies the EV battery cell, consisting of six key components crafted from base and precious metals. These elements enable the battery to function as both a power provider and an energy storage unit. The major components include:
- Anode: Graphite
- Cathode: Aluminum, nickel, manganese, cobalt, iron, lithium
- Separator: Micro-porous polymer (polyolefin)
- Electrolyte: Lithium hexafluorophosphate
- Current collectors: Aluminum, copper
- Casing: Aluminum, steel
Hierarchy of EV Battery Design: Key Elements: Every EV battery boasts a unique design hierarchy, comprising essential elements:
- Individual EV battery cell: The smallest packaged form, containing Lithium-ion cells.
- Modules: Cells connected in parallel or series within a housing.
- Battery pack: The final deployable form, integrating multiple modules to meet specific EV requirements.
Formats of EV Battery Cells: EV battery cells are available in three formats:
- Cylindrical cells: Characterized by a symmetrical shape, providing efficient packing and cost-effectiveness.
- Prismatic cells: Larger than cylindrical cells, enclosed in a robust casing, offering enhanced power and energy storage but with higher manufacturing costs.
- Pouch cells: Distinctive for their pouch-like design, contained in laminated foil or soft plastic casing, providing higher packaging efficiency but with lower mechanical resistance.
Common Cell Chemistries in EV Batteries: Various cell chemistries contribute to the composition of EV batteries, each identified by the metals and elements present. Common chemistries include:
- Lithium-ion: Popular for cost-efficiency and superior energy storage, with variants like lithium nickel cobalt aluminum oxide and lithium iron phosphate.
- Nickel Manganese Cobalt: Known for balanced power delivery and energy storage, found in Chevy Volts.
- Nickel Metal Hydride: Used in early hybrid cars like the Prius and still present in some hybrid EVs.
- Lithium Sulfur: Found in EV buses for large energy storage but requires preheating.
- Lead Acid: Utilized in low-performance EVs like golf carts due to low maintenance.
EV Battery Safety Measures: As electric vehicle batteries contain volatile and flammable electrolytes, safety measures are paramount. Compliance tests, including vibration, thermal and mechanical shock, and overcharging tests, ensure safety from corrosion, fire, and explosions. Every EV battery incorporates a Battery Management System (BMS) and Battery Thermal Management System (BTMS) to monitor and control temperature during charging and discharging.
Recycling EV Batteries: To address the inevitable end of an EV battery’s lifespan, recycling measures are crucial. Sustainable EV batteries aim to use recyclable materials. Destructive dismantling processes, such as smelting, direct recovery, and intermediate processes, recover valuable materials like lithium, cobalt, nickel, and aluminum for reuse in new batteries or other applications.
In an era of evolving electric vehicle battery technology, manufacturers strive for enhanced driving range and lifecycle, paralleled by ongoing research on recycling processes. The goal is to not only improve the batteries’ environmental impact but also promote responsible disposal or reuse, minimizing adverse effects on the ecosystem and human health.”