Development of battery pack technology

Powering the Future: What Path is Battery Pack Technology Taking in the Evolution of Energy?

The rise of electric vehicles has spurred the rapid development of battery technology, and the evolution of battery pack technology is a crucial component of this technological revolution. From the initial stages of CTP to CTB, MTC, and further to the CTC phase, each stage of innovation aims to enhance energy density, reduce costs, and improve the overall performance of the battery system. The continuous innovation in battery pack technology has not only brought about a qualitative improvement in the range of electric vehicles but also propelled the entire industry forward.

CTP (Cell-To-Pack)

CTP display

CTP (Cell-To-Pack) is a technology that reduces or eliminates the three-tier pack structure of battery cells, modules, and the overall pack. It bypasses the standard module step by directly integrating the battery cells onto the pack, eliminating the intermediate module stage and effectively enhancing the space utilization and energy density of the battery pack.

Currently, there are two main technological approaches: the fully module-less method and the use of larger modules replacing smaller ones.

The release of the Kirin battery by CATL adopts the third-generation CTP technology. This technology completely eliminates the module-based layout, discarding the separate design of battery pack crossbeams, bottom cooling plates, and thermal insulation pads. 

Instead, it integrates them into a multifunctional elastic interlayer. This design enables the Kirin battery to possess advantages such as rapid temperature control, improved safety, support for 4C high-voltage fast charging technology, and increased battery lifespan.

Advantages

Lower manufacturing cost

Relatively simple maintenance

Easy adaptation to different vehicle models and application scenarios

Improved volume utilization

Increased energy density

Disadvantages

Increased difficulty in managing thermal runaway

High process requirements

Difficulties in maintenance and replacement

Long battery pack assembly time

Challenges in the reuse of cells

CTB (Cell-To-Body)

CTB display

In CTB technology, the design of modules and the casing on the battery pack are eliminated. This allows for the loading of more battery cells within a limited space, thereby increasing the battery capacity and providing electric vehicles with longer range capabilities.

Additionally, CTB technology can reduce the weight of the vehicle’s battery components while enhancing the overall strength of the vehicle. Furthermore, this technology involves bonding blade cells with trays and upper covers, creating a ‘sandwich’ structure similar to a honeycomb aluminum plate, thereby improving the overall structural strength of the battery pack.

CTB technology is the latest integrated battery cell approach introduced by BYD. In its structural design, this technology combines the vehicle floor panel with the upper casing of the battery pack, creating a unified surface with the battery cover, thresholds, and front and rear crossbeams. Sealing of the passenger cabin is achieved through adhesive sealing, while the bottom is secured to the vehicle body through mounting points.

Advantages

Increased battery capacity

Higher space utilization efficiency

Extended range

High safety performance

Improved production efficiency

Disadvantages

High requirements for battery cell structural strength

Increased overall complexity

Lower universality

Rise in production and maintenance costs

MTC (Module-To-Chassis)

MTC technology adopts the approach of directly integrating battery modules into the vehicle chassis. By combining the battery tray frame structure with the vehicle body beam structure, it forms a dual-frame circular beam structure.The innovation of this technology lies in simultaneously achieving structural efficiency and lightweighting, while achieving battery sealing through the vehicle body beams.

leapmoter battery pack display

the MTC technology used by Leapmotor eliminates the traditional battery pack cover, integrating the battery modules under the vehicle floor. The battery itself is composed of large modules, with square cells connected in series and parallel. The module’s model, size, and parameters remain consistent with the previous design, resulting in minimal changes to the overall battery structure, except for the absence of an upper cover.

Additionally, Leapmotor’s MTC technology includes an additional layer of heat-insulating and fire-resistant material between the chassis and battery cells. This not only limits rapid heat transfer to steel components but also provides insulation for the battery during winter.

Advantages

Lightweight design

Improved structural efficiency

Enhanced range capability

High safety performance

Environmental friendliness

Disadvantages

Integration efficiency needs improvemen

Higher costs

Greater threat of battery thermal runaway

Complex manufacturing processes and technologies

CTC (Cell-To-Chassis)

CTC technology involves directly integrating battery cells within the floor frame, using the floor’s upper and lower panels as the battery casing. It represents a further integration of CTP technology, fully utilizing the upper and lower panels of the floor in place of a dedicated battery casing and cover. This design is integrated with the vehicle floor and chassis, fundamentally changing the installation form of the battery.

The objective of CTC technology is highly integrated and modular, aiming to simplify assembly processes and reduce costs, emphasizing an integrated design approach.

CTC display

Tesla’s Battery Day, they introduced the 4680 battery cell, CTC technology, and integrated die-casting technology and announced that its Berlin factory would utilize CTC technology to produce the Model Y.

Tesla’s approach involves arranging the battery cells directly on the chassis, eliminating the cabin floor. Seats are directly mounted on the battery pack cover. The battery structure is integrated with the vehicle body as a whole, achieving a thorough integration level and meeting the enclosed requirements of the battery system.

Additionally, the side cooling method and adhesive-filled structure of Tesla’s battery cells contribute to some extent in limiting heat transfer.

Advantages

Improved space utilization efficiency (enhanced range performance and increased interior space)

Formation of a CTC dual-frame circular beam structure (improved handling sensation and NVH)

Simplified battery pack structure

Reduced component management pressure

Streamlined installation and manufacturing processes

Effective protection of physical collision safety for the battery pack

Mid-to-long-term warnings for battery state and lifespan

Disadvantages

Non-replaceable battery

Higher maintenance costs

Safety and heat dissipation issues associated with high integration levels

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