Comparison Of Structural Differences And Applications Between Soft-Pack Batteries And Aluminum Case Batteries

In the new energy vehicle and energy storage industries, the material and structure of the battery casing directly impact product performance, safety, and lifespan. Currently, the mainstream battery cell structures are represented by soft-pack batteries (LiFePO4 soft pack cells) and aluminum case batteries (automotive battery aluminum cases and lithium battery aluminum cases).

 

Each has its own unique packaging, energy density, mechanical strength, and assembly design, driving the technological development of different types of battery aluminum cases, power battery shells, and prismatic cell aluminum battery cases.

 

 

 

 

The difference between the two can be understood using a visual metaphor:

 

An aluminum case battery is like a can of cola, with a hard metal casing (aluminum battery casing). Its fixed shape and high strength provide resistance to external pressure and mechanical shock, making it a typical structural battery cell packaging format.

 

Soft-pack batteries are more like a bag of jelly, with a flexible, multi-layer aluminum-plastic composite film (rechargeable aluminum shell) on the outside. While flexible and lightweight, they are more sensitive to external forces and require more sophisticated protective designs.

 

This metaphor fully illustrates the fundamental differences between the two battery cells in terms of material structure and mechanical protection strategies.

 

 

In terms of energy density per unit weight, soft-pack batteries generally outperform aluminum-shell batteries. Due to the extremely thin and lightweight aluminum-plastic film, soft-pack batteries can pack more active material per unit mass, resulting in higher energy density. They are suitable for weight-sensitive and space-constrained applications, such as high-end consumer electronics and some high-end electric vehicles.

 

In contrast, the metal shell of aluminum-shell batteries (Battery Aluminum Cases/Aluminum Cases for New Energy Cars) is heavier, but its rigid structure serves as a load-bearing component for the module, increasing volumetric energy density during system integration. This design is widely used in New Energy Aluminum Battery Cases and Battery Packs with Aluminum Housing, providing additional support for the vehicle structure.

 

 

Safety is a core characteristic of battery design.

 

Aluminum-cased batteries (EV Car Battery Shell / Lithium-ion Battery Aluminum Shell) offer significant advantages in mechanical strength, effectively protecting against puncture, crushing, and impact. However, if internal thermal runaway causes a sudden increase in pressure, the rigid shell can increase the risk of explosion if the pressure relief system (such as the Power Battery Cover Plate) fails to respond promptly.

 

Soft-pack batteries offer a different safety approach. Their aluminum-plastic film packaging naturally bulges or even cracks when internal gas expands, releasing energy through "self-pressure relief" and reducing the risk of explosion. While mechanical strength is lower, their pressure relief properties provide a more flexible and protective feature for overall safety.

 

 

In modular battery systems, structural design directly determines vehicle layout and assembly efficiency.

 

Aluminum battery cases (Square Aluminum Shell / Prismatic Cell Aluminum Battery Cases) feature a regular shape and are easily stackable, making them ideal for square modules or blade-style layouts. They are the mainstream form factor for aluminum battery cases in new energy vehicles. Their aluminum alloy casings (such as the Deep Drawn Aluminum Battery Housing) offer excellent dimensional stability and heat dissipation.

 

Soft-pack batteries stand out for their exceptional flexibility. They can be designed to vary thicknesses, proportions, and even custom shapes to suit the vehicle chassis, providing greater space utilization for CTP (Cell to Pack) and CTC (Cell to Chassis) technologies. However, their "soft structure" also incurs additional fixing and support costs, requiring reinforcement with end plates, brackets, and module frames.

 

 

Aluminum battery cases (Battery Shell / Aluminum Battery Cases) have a long history of development, with highly mature stamping, welding, and surface treatment processes. Through deep drawing, CNC finishing, and automated welding, structural components such as pack aluminum housings or power battery shells can be efficiently manufactured with high process stability, making them suitable for large-scale production.

 

Although soft-pack batteries offer lower material costs, the packaging process is complex and places extremely high demands on sealing and cleanliness. This is particularly true during the aluminum-plastic film punching and heat-sealing stages, which place even stricter demands on the production environment and automation precision. Therefore, their cost advantage is often diluted during system-level integration.

 

 

 

 

Overall, soft-pack and aluminum-shell batteries represent different approaches to performance flexibility and structural reliability, respectively.

 

Soft-pack batteries (LiFePO4 Soft Pack Cells): Strive for extreme lightweight and high energy density, and are suitable for high-end laptops, consumer electronics, and some high-range new energy vehicles.

 

Aluminum-shell batteries (Automotive Battery Aluminum Cases/Power Battery Shells): Characterized by durability, controllability, safety, and ease of assembly, they are widely used in electric vehicles, electric buses, energy storage systems, and other fields, and are currently the mainstream power battery packaging format.

 

It's worth noting that the industry is experiencing a trend of convergence. New structures, such as the "Blade Battery," combine the high energy density of soft packs with the mechanical strength of aluminum shells through the Prismatic Cell Aluminum Battery Case, a soft-pack lamination process. This represents the future development direction of aluminum battery cases for new energy vehicles.

 

 

 

 

Whether it's the sturdiness of battery aluminum cases or the lightweightness of rechargeable aluminum shells, the evolution of battery packaging structures is bringing greater safety and efficiency to new energy vehicles and energy storage systems. With continued breakthroughs in integrated technologies like Deep Drawn Aluminum Battery Housing and Battery Pack with Aluminum Housing, aluminum-cased batteries will continue to play a key role in smart manufacturing and sustainable energy applications.