Primary battery is a common type of rechargeable battery, widely used in various fields. It is favored for its high energy density, lightness and stability. There are obvious differences between lithium primary battery and lithium secondary battery, and their working principles are also different. This article explores the difference between primary battery and secondary battery.
Primary batteries are batteries that can only be used once and cannot be recharged. Their chemical energy is irreversibly converted into electrical energy. Once discharged, the active substances in the battery are completely consumed and cannot be restored to their original state, so they need to be discarded directly. Common primary batteries include alkaline batteries, carbon batteries, and lithium metal batteries.
Common primary battery types:
- Alkaline Battery: Uses potassium hydroxide electrolyte, commonly found in AA and AAA batteries.
- Lithium Primary Battery: Commonly found in button batteries, such as CR2032.
- Zinc-Manganese Battery (Zinc-Carbon Battery): Also known as carbon battery, it is the earliest type of commercial dry cell battery.
- Zinc-Air Battery: Commonly used in small devices such as hearing aids.
What is secondary battery?
Secondary batteries are batteries that can be charged and discharged multiple times. External electrical energy is input to reverse the chemical reaction inside the battery, thereby restoring the charge. Secondary batteries are also called rechargeable batteries or storage batteries. The chemical reaction during the charge and discharge process is reversible, so they can be reused hundreds to thousands of times.
Common secondary battery types:
- Lithium-ion Battery: Widely used in electronic devices such as mobile phones and computers.
- Lead-acid Battery: Commonly used in car starting power supply.
- Ni-MH Battery: Commonly used in small electronic devices and early hybrid vehicles.
- Ni-Cd Battery: Once widely used in tool batteries, but now its use is reduced due to environmental issues.
- Lithium Iron Phosphate Battery: Commonly used in electric vehicles and energy storage systems.
Primary battery vs. secondary battery
The following compares primary batteries and secondary batteries from different perspectives.
Charge and discharge characteristics
Primary batteries can only be discharged once, and chemical energy is irreversibly converted into electrical energy. Once the battery is exhausted, it cannot be recharged. When the chemical substances in the primary battery react completely, the battery loses the ability to generate current. Attempting to recharge the primary battery is not only ineffective, but may also lead to safety risks such as battery leakage or explosion.
In contrast, secondary batteries can be used again by recharging the active materials and can be used for many times. Typical lithium-ion batteries can be recycled 300-500 times, while high-quality lithium iron phosphate batteries can even reach more than 2,000 times. This reusable feature makes secondary batteries more cost-effective in long-term use.
| Charging/Discharging Characteristics Comparison | Primary Battery (Single-Use) | Secondary Battery (Rechargeable) | Practical Significance to You |
|---|---|---|---|
| Number of Uses | Single Use | Rechargeable/Multiple Cycles | Secondary batteries are more economical for long-term use. |
| Chemical Reaction Reversibility | Irreversible | Reversible | Influences the fundamental way the battery is used. |
| Cycle Life | Not Applicable | 300-2000+ Cycles | Determines the battery’s usable lifespan. |
| Charging Safety | Non-Rechargeable (Dangerous) | Safe to Recharge | Incorrect use of primary batteries can lead to safety hazards. |
Energy density
Primary batteries usually have a relatively high energy density and can store more energy in the same volume and weight. This is because primary batteries do not need to consider the structural requirements of multiple charge and discharge cycles and can maximize the proportion of active materials.
Secondary batteries need to take into account the stability of charge and discharge cycles when they are designed, so the energy density of some types is relatively low. However, with the development of technology, the energy density of modern lithium-ion batteries has been greatly improved, especially in the fields of electric vehicles and portable devices.
The energy density of high-performance lithium metal primary batteries can reach 400Wh/kg, while the energy density of commercial lithium-ion secondary batteries is generally between 200-260Wh/kg, and that of lead-acid batteries is only 50-70Wh/kg.
Cost comparison
The initial purchase cost of a primary battery is usually low, but because it cannot be reused, the long-term total cost may be high. For example, the common No. 5 alkaline battery has a unit price of about ¥2-5, but if it needs to be replaced frequently, the cumulative cost will be considerable.
Secondary batteries have a relatively high initial purchase cost, but can be recycled many times, making them more cost-effective in the long run. A branded 18650 lithium-ion battery costs about ¥20-50, but can be charged and discharged hundreds of times, making it more economical to use in the long run.
For devices that are used frequently (digital cameras), it is obviously more economical to use secondary batteries; while for low-power long-term devices (wall clocks), primary batteries may be more appropriate.
Self-discharge rate
The self-discharge rate of primary batteries is generally very low, with high-quality alkaline batteries losing only about 2-3% of their charge per year. This makes primary batteries ideal for applications that require long-term storage, such as emergency equipment and low-frequency use equipment.
The self-discharge rate of secondary batteries is relatively high, for example, a typical NiMH battery can lose 20-30% of its charge per month, while a Li-ion battery can lose 2-5%. This means that secondary batteries that are not used for a long time may need regular charging maintenance to prevent them from being completely drained.
Safety
Primary batteries are usually simple in structure and relatively safe, especially common alkaline batteries, which have a low probability of dangerous accidents. However, some high-performance primary batteries (such as lithium metal batteries) still have safety risks, and improper use may cause leakage or combustion.
Secondary batteries, especially lithium-ion batteries, may pose safety risks in the event of overcharge, overdischarge or physical damage. Modern batteries are equipped with safety protection mechanisms, such as battery management systems (BMS), which greatly improve safety. The safety of secondary batteries is also constantly improving, especially the safety of material systems such as lithium iron phosphate has been outstanding.
Difficulty of recycling
Primary batteries usually contain harmful substances such as heavy metals, which may pollute the environment if not properly handled, but their recycling value is relatively low. This leads to a generally low recycling rate for primary batteries, and many used primary batteries are not properly handled.
Secondary batteries contain precious metals such as cobalt and nickel, and have a high recycling value. With the popularity of electric vehicles, secondary battery recycling has formed a relatively complete industrial chain, including two main paths: cascade utilization and material recycling.
At present, China’s recycling rate of used lithium batteries has reached more than 40% and is constantly increasing. In contrast, the recycling rate of primary batteries is less than 10%.
Application comparison
The most suitable application scenarios for primary batteries are as follows:
- Low-power long-term use equipment: such as wall clocks, remote controls, smoke detectors, etc.
- Emergency and backup equipment: such as flashlights, emergency lighting and other equipment that are not often used but need to be available at any time.
- Medical equipment: such as pacemakers and other equipment that require extremely high stability.
- Extreme environment use: such as equipment in extremely low temperature environments, some special primary batteries perform better than secondary batteries at low temperatures.
The most suitable application scenarios for secondary batteries are as follows:
- High-frequency use equipment: such as smart phones, laptops and other electronic products used in daily life.
- High-power demand equipment: such as power tools, electric bicycles and other equipment that require large current output.
- Electric vehicles: such as electric cars, electric motorcycles and other vehicles that require rechargeable energy.
- Renewable energy storage system: such as energy storage equipment for solar and wind power generation.
Practical tips and suggestions for users:
- Portable electronic device selection: For devices with high frequency of use, such as cameras and flashlights, it is recommended to use lithium-ion or nickel-metal hydride secondary batteries, which are more economical and environmentally friendly in the long run.
- Low-frequency use of small devices: For low-power devices such as remote controls and wall clocks, you can choose alkaline primary batteries to avoid self-discharge problems.
- Battery storage management: When storing secondary batteries, keep them at 40-60% power and place them in a cool and dry place; primary batteries can be directly sealed and stored in the original packaging.
- Proper disposal: Regardless of the type of battery, it should be sent to a special recycling point instead of being mixed with ordinary household garbage.
A photography enthusiast used rechargeable lithium-ion batteries to replace the disposable alkaline batteries in his camera. After two years of use, each set of batteries was charged and discharged about 150 times, saving nearly 600 yuan in battery expenses and reducing the environmental burden of 24 primary batteries.
Summarize
Primary batteries and secondary batteries each have their own advantages, and the choice should be made by comprehensively considering the usage scenario, economy and environmental protection. For devices with low usage frequency, low power consumption and long-term storage, primary batteries are an ideal choice; while for devices with frequent use and high power requirements, secondary batteries are more economical and practical.
From the perspective of long-term environmental protection and resource utilization, the reusable nature of secondary batteries makes them a more sustainable choice. With technological advances, the energy density, safety and cycle life of secondary batteries are constantly improving, and their application areas are also continuously expanding.
The latest battery technology development trends in 2025
- The commercialization process of solid-state batteries is accelerating: In 2025, solid-state battery technology is moving from the laboratory to industrialization, and is expected to completely solve the safety problems of traditional lithium-ion batteries.
- Research and development of new battery materials: Breakthroughs have been made in new battery systems such as sodium-ion batteries and lithium-sulfur batteries, providing more options for specific application scenarios.
- Battery recycling technology upgrades: The technology for recycling used batteries is constantly improving, which helps reduce the environmental impact of batteries throughout their life cycle.
- The battery recycling model is mature: the industrial chain of retired electric vehicle batteries entering the energy storage field is becoming increasingly mature, improving the utilization rate of battery resources.
When choosing a battery, you should evaluate your needs, usage environment and economic budget, and make a wise choice between primary and secondary batteries. As the world pays more attention to sustainable development, battery technology will continue to develop in the direction of high energy density, long cycle life, safety and environmental protection.
Summarize
Primary batteries and secondary batteries each have their own application scenarios and advantages, and understanding their differences is crucial to correctly selecting and using batteries. Primary batteries are suitable for low-power long-term use or emergency equipment, while secondary batteries are more suitable for frequently used high-power devices.
Hongyitai has been focusing on lithium-ion battery production for more than 10 years, helping customers in 100 countries and regions around the world to customize lithium-ion batteries. We provide full-chain services from battery research and development, production to application, ensuring that each battery meets strict safety and performance standards.
FAQs
Charging a primary battery may cause leakage, heating, or even explosion, because the internal structure and chemical composition of the primary battery do not support the charging process. Never attempt to charge a primary battery, it is extremely dangerous.
Lithium-ion batteries have advantages such as high energy density, low self-discharge rate and no memory effect, making them ideal for portable electronic devices and electric vehicles. Technological advances in recent years have also led to a significant reduction in their cost, further promoting their popularity.
All batteries should be stored in a dry, cool environment, away from direct sunlight. Secondary batteries should be charged to 40-60% before long-term storage and checked every 3-6 months; primary batteries can be stored sealed in the original packaging to avoid extreme temperatures.
