Abstract: With the rapid advancement of technology, lithium… Battery PACK Its applications across numerous fields are steadily expanding. This article provides an in-depth analysis of the various types of lithium‑battery packs, thoroughly outlining their distinctive features, and, drawing on the latest industry news, discusses key considerations in their deployment. With a particular focus on their use in two‑ and three‑wheeled vehicles, the paper aims to offer practitioners and technology enthusiasts a comprehensive, state‑of‑the‑art resource, supporting the safe and efficient application of lithium‑battery pack technology.

I. Introduction

Lithium batteries, with their high energy density, long cycle life, and low self-discharge, have become a cornerstone of modern energy storage and power supply. A lithium‑battery pack—comprising multiple battery cells connected in series, parallel, or a combination thereof, and equipped with an appropriate management system—meets the diverse power requirements of various devices. With a wide variety of types and complex application scenarios, a thorough understanding of these packs is essential. Today, in the two‑ and three‑wheel vehicle sector, lithium‑battery packs are gradually replacing traditional lead‑acid batteries, ushering in a new era of mobility.

II. Common Types of Lithium Battery Packs

(1) Cylindrical Lithium-Ion Battery PACK

Cylindrical lithium batteries are most commonly found in models such as 18650 and 21700. The 18650 battery has a diameter of 18 mm and a length of 65 mm; it benefits from mature manufacturing processes, relatively low costs, and widespread use in small devices like laptops and high‑intensity flashlights. It also plays an important role in auxiliary systems—such as lighting and instrument‑panel power supplies—in two‑ and three‑wheel electric vehicles. By contrast, the 21700 battery offers superior energy density and is extensively adopted by electric‑vehicle manufacturers like Tesla. Its larger size accommodates more active material, thereby extending driving range. In certain three‑wheel e‑vehicles designed for long‑distance commuting, 21700 lithium‑battery packs are gaining prominence. For example, one particular delivery‑oriented three‑wheel e‑vehicle uses a 21700 lithium‑battery pack that, compared with conventional lead‑acid batteries, reduces weight by 30% and increases the number of parcels deliverable per charge by 20%, significantly boosting couriers’ productivity while markedly improving vehicle handling, making turns and stops on narrow streets much more convenient.

(2) Square Lithium-Ion Battery Pack

Square lithium‑ion batteries feature a compact design and high space utilization, allowing for flexible customization to suit various product form factors. Soft‑pack square lithium‑ion batteries are encapsulated in aluminum‑plastic film, offering light weight and excellent safety; they are commonly used in weight‑sensitive consumer electronics such as tablets and wearable devices. Some lightweight two‑wheel electric vehicles, in pursuit of extreme lightness, also adopt soft‑pack square lithium‑ion battery packs, which not only meet the range requirements for urban commuting but also lend the vehicle a more refined, compact appearance that is easy to carry and park. By contrast, hard‑case square lithium‑ion batteries typically use aluminum alloy casings, providing superior mechanical strength and delivering outstanding performance in electric vehicles and energy‑storage systems. For certain cargo‑carrying three‑wheel electric vehicles, hard‑case square lithium‑ion battery packs, with their robust enclosures, better withstand the bumps and impacts of transportation, helping to maintain the stability of the internal cell structure and ensuring a steady, reliable power output—thus safeguarding cargo transport. Recently, a news report highlighted how a large fleet of commercial three‑wheel electric vehicles, equipped with square lithium‑ion battery packs, achieved over 95% charge–discharge efficiency through an optimized battery management system, reducing operating costs and providing strong support for cost reduction and efficiency gains in last‑mile logistics and delivery.

(3) Soft-pack Lithium-ion Battery PACK

Soft‑pack lithium batteries stand out thanks to their slim profile and high energy density. With no metal casing, they feature uniform internal stress distribution, minimizing the risk of swelling or bulging. In the premium smartphone segment, soft‑pack lithium batteries have become virtually standard, delivering long‑lasting power within constrained spaces. In the two‑wheel electric‑vehicle market—particularly in emerging shared e‑scooter fleets—soft‑pack lithium battery packs are making a strong impression. For instance, one leading shared‑e‑scooter brand equips its fleet with next‑generation soft‑pack lithium battery packs, paired with an intelligent power‑management chip. Even under heavy‑load conditions and with frequent stop‑and‑go usage, battery life remains unaffected, ensuring full‑day operation. Meanwhile, the sleek, streamlined design of the vehicles seamlessly integrates the battery pack, with a thickness kept below 8 mm, balancing aesthetics and practicality to deliver a comfortable, convenient riding experience.

III. Precautions for the Application of Lithium‑Battery Packs in Two‑ and Three‑Wheeled Vehicles

(1) Thermal Management

The operating environment of two- and three-wheeled vehicles is complex and variable. Lithium‑ion batteries are highly sensitive to temperature: high temperatures accelerate aging, shorten their lifespan, and can even trigger thermal runaway, while low temperatures reduce capacity and increase internal resistance. Under the scorching summer sun, the temperature of a lithium‑battery pack beneath the seat or in the trunk can rise sharply, whereas cold winter conditions can leave the battery “shivering.” Consequently, some high‑end two- and three‑wheeled models are equipped with basic thermal management systems, such as cooling fans or insulating blankets. For example, a certain high‑performance electric motorcycle features a built-in temperature sensor in its lithium‑battery pack; when the temperature exceeds 40°C, a cooling fan automatically activates to vent hot air, keeping the battery within an optimal operating range. This effectively extends battery life by 15% and ensures riding safety and stable range.

(2) Battery Management System (BMS)

The BMS serves as the “brain” of a lithium‑battery pack, monitoring cell voltage, current, and temperature while managing balanced charging and discharging. During the frequent charge‑and‑discharge cycles typical of two‑ and three‑wheel vehicles, a malfunctioning BMS can lead to overcharging, deep discharging, and other issues that severely degrade battery performance. There have been reports of low‑cost, substandard e‑bikes whose poorly designed BMS, after prolonged charging, causes certain cells to overcharge and swell—compromising battery life and posing a fire risk. Today, advanced BMS solutions tailored for the two‑ and three‑wheel vehicle market offer multi‑layered protection: in addition to basic voltage and current monitoring, they incorporate short‑circuit protection and charge‑balancing functions that dynamically equalize state‑of‑charge differences among cells, ensuring consistent performance and safety across the entire pack. This gives users peace of mind when charging and confidence on the road.

(3) Mechanical Protection

Two- and three-wheeled vehicles travel on a variety of road surfaces, experiencing frequent vibrations and impacts. Lithium Battery Pack Adequate mechanical protection is essential. On the one hand, the enclosure must be made of high‑strength materials to withstand external forces; on the other, the internal battery module mounting structure should be carefully engineered to absorb and mitigate vibrations. For example, in a certain off‑road three‑wheel electric vehicle, the lithium‑ion battery pack features a composite housing that combines engineering plastics with a metal frame, complemented by rubber vibration‑damping pads. Testing has shown that after 500 kilometers of driving on rough mountain roads, the battery pack remained securely in place with no damage, and the internal battery modules maintained tight connections, ensuring a stable power supply and enabling the vehicle to perform confidently across a wide range of challenging terrains.

IV. New Industry Trends and Challenges

Recently, solid-state lithium‑battery technology has achieved a breakthrough, positioning it to replace conventional liquid‑electrolyte lithium batteries in next‑generation battery packs. Solid‑state batteries use solid electrolytes, offering higher energy density, improved safety, and significantly reduced charging times. However, large‑scale production faces challenges such as high costs and complex manufacturing processes. In the two‑ and three‑wheel vehicle sector, if solid‑state batteries can be mass‑produced at low cost, they could fundamentally reshape the current market landscape: vehicle range could double, and charging times could be cut to under 30 minutes. Meanwhile, lithium‑battery recycling has also come into focus. As the number of end‑of‑life lithium batteries from two‑ and three‑wheel vehicles grows, efficiently recovering key materials like lithium and cobalt—while minimizing environmental impact and reducing battery‑production costs—has become an urgent industry priority. Some innovative companies have begun deploying recycling stations within their sales networks and establishing full‑lifecycle management systems that track batteries from manufacture to disposal, paving the way for sustainable development in the sector.

V. Conclusion

Lithium‑battery PACKs come in a wide variety of types, each with its own strengths and weaknesses, playing a critical role in two‑ and three‑wheel vehicles as well as in diverse application areas. From portable electronic devices to electric vehicles and energy‑storage systems, their potential applications are vast. However, during deployment—particularly in the context of two‑ and three‑wheel vehicles—key considerations such as thermal management, battery management systems (BMS), and mechanical protection must not be overlooked. In the face of emerging technologies like solid‑state batteries and persistent challenges in recycling, the industry must pursue collaborative innovation and continuously refine lithium‑battery PACK technology to navigate the coming wave of energy transformation and sustainably drive global progress.

In the future, as research deepens and technology continues to evolve, lithium‑ion battery packs will become smarter, more efficient, and safer, further integrating into and transforming our daily lives. Whether it’s enhancing the riding experience of two- and three-wheeled vehicles or ensuring reliable power supply in remote areas, lithium‑ion battery packs hold limitless potential.