Thermal Gradient Effects on Active Material Loss in Prismatic Formats
Internal thermal gradients accelerate prismatic cell active material loss by driving localized current crowding, high-temperature SEI growth, and particle cracking.
Prismatic Formats
Meaning
Rigid rectangular metal enclosures house flattened or stacked electrode assemblies to provide structural protection and high spatial packing efficiency. Rigid aluminum or steel outer cans contain internal pressure while offering large flat surface areas for thermal management contact. Adopting prismatic formats enables modular energy storage configurations with minimal void spaces inside battery pack enclosures.
Internal pressure build can cause casing swelling if wall thickness is insufficient or vent pressures are miscalibrated.
Volumetric Efficiency
Rectangular packaging minimizes empty space between adjacent cells when assembled into rectangular modules. Flat outer walls stack neatly against adjacent surfaces, achieving high packaging factors inside module frames. Elimination of cylindrical gaps increases total energy density per unit volume.
Module designs capitalize on flat faces for mechanical clamping and structural support.
Thermal Management
Flat surface geometry provides large contact areas for liquid cooling plates and thermal interface materials. Heat generated in internal electrode stacks transfers through flat side walls to external cooling channels. Uniform cooling across flat surfaces reduces internal thermal gradients compared to cylindrical cells.
Cooling plate integration is simplified by straight linear contact faces.
Structural Integrity
Outer metal casings withstand internal gas pressures generated during normal cell aging and light abuse. Mechanical rigidity protects delicate electrode stacks from external impact and vibration forces. Wall thickness must balance mechanical strength requirements against cell weight penalties.
Integrated burst discs provide controlled pressure relief under severe thermal events.