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Views: 0 Author: Site Editor Publish Time: 2026-06-17 Origin: Site
The CR1025 ultra-thin 3V coin battery is ubiquitous in slim miniature electronics, from mini compasses and wearable pedometers to wireless sensor backup power modules. Most users only focus on its outer size (10mm × 2.5mm) and basic 3V voltage output, but rarely understand its internal core structure, built-in lithium-manganese electrochemical working mechanism, and its outstanding pulse discharge capability tailored for intermittent power supply demands.
This article conducts a complete physical teardown of a standard CR1025 primary coin cell. We will visualize every internal component, elaborate on the full chemical reaction principle of lithium-manganese dioxide cells, and deeply analyze its pulse discharge characteristics, advantages and application limits. This teardown science article helps electronic engineers, battery buyers and electronics enthusiasts fully grasp the core working logic of this widely-used micro power supply.
Different from thick coin batteries like CR2032, the CR1025 features an ultra-thin 2.5mm shell, with compact and highly integrated internal structure without redundant gaps. The battery adopts a fully sealed crimped shell structure, and we disassemble it layer by layer from outer casing to inner core materials as below:
Positive Can (Top Shell): Stainless steel conductive shell, serving as the battery positive terminal, with anti-corrosion electroplating treatment to avoid shell oxidation and leakage.
Insulating Gasket: High-temperature resistant PP plastic sealing ring sandwiched between positive and negative shells. It isolates positive and negative poles to prevent internal short circuit, and realizes full airtight sealing to block moisture and air invasion.
Negative Cup (Bottom Shell): Integrated negative conductive shell, contacting tightly with lithium anode materials inside.
Cathode Pellet (Positive Electrode): Compressed manganese dioxide (MnO₂) mixed with conductive additives and adhesive. This is the core active material for voltage output, accounting for most internal space of the ultra-thin battery.
Isolation Membrane: Microporous non-woven separator with ultra-thin thickness. It separates positive and negative electrodes physically to avoid direct short circuit, while allowing free passage of lithium ions during discharge.
Anode Lithium Sheet (Negative Electrode): Ultra-thin pure lithium metal sheet, the electron supply source of the whole battery. Thanks to high energy density of lithium metal, the tiny CR1025 cell can still maintain stable 3V voltage output despite its miniature volume.
Organic Electrolyte: Non-aqueous organic liquid electrolyte filled inside the sealed cavity. It provides a migration channel for lithium ions and supports continuous electrochemical reactions.
Teardown Key Finding: Limited by its ultra-thin 2.5mm thickness, CR1025 has less internal active materials than conventional coin cells. Therefore, it is not designed for long-time continuous high-current discharge, but perfectly optimized for intermittent pulse discharge scenarios.
CR1025 belongs to non-rechargeable primary lithium manganese dioxide battery, relying on irreversible redox chemical reactions to generate stable current. No reverse charging reaction is supported, so charging operation is strictly forbidden.
Negative Electrode Reaction (Lithium Anode): Lithium metal loses electrons and turns into lithium ions, releasing free electrons to the external circuit. Reaction Formula: Li → Li⁺ + e⁻
Positive Electrode Reaction (Manganese Dioxide Cathode): Manganese dioxide captures lithium ions and electrons passing through external circuit to complete reduction reaction.
Overall Discharge Reaction: Lithium metal reacts with manganese dioxide stably, sustaining a constant open-circuit voltage of 3.0V throughout most of the discharge cycle.
During normal operation, lithium ions generated from the negative lithium sheet pass through the isolation membrane and organic electrolyte to migrate to the positive electrode. Electrons flow through the external circuit to supply power to electronic equipment. The whole reaction system is highly stable, with almost no extra side reactions, which is why CR1025 owns ultra-low self-discharge rate and long storage life.
Pulse discharge is the most critical performance advantage of CR1025, and also its core design orientation matching miniature sensors and wearable devices. Different from continuous steady discharge, pulse discharge refers to periodic short-time high current output + long-time low current standby working mode.
Rated Standby Current: 0.01mA ~ 0.5mA (long-term static standby)
Instant Pulse Peak Current: Up to 3mA instantaneous pulse current without obvious voltage drop
Standard Pulse Cycle: 0.5s high-current pulse output + 5s low-current standby circulation
Voltage Stability Under Pulse Load: Voltage fluctuation controlled within ±0.05V during repeated pulse discharge, far more stable than alkaline button batteries
Low Internal Impedance Design: Optimized electrode formula reduces internal battery resistance, ensuring instantaneous large current output without sharp voltage collapse during pulse activation.
Stable Lithium Ion Activity: The lithium metal anode can quickly supplement electrons and lithium ions in a short time, responding rapidly to sudden current demand of equipment.
Recovery Characteristic After Pulse Load: After each short pulse discharge, the battery voltage can quickly return to the 2.9V-3.0V steady platform, without cumulative voltage attenuation after thousands of pulse cycles.
Working Mode | Available Actual Capacity | Voltage Stability | Service Life |
|---|---|---|---|
Intermittent Pulse Discharge | ≥95% rated capacity | Excellent, negligible fluctuation | Longest, matching design standard |
Long-term Continuous Micro-current Discharge | 80%-85% rated capacity | Slight slow voltage decline | Moderate |
Continuous High-current Discharge | <50% rated capacity | Severe voltage drop | Sharply shortened |
Combined with its excellent pulse response capability, CR1025 is perfectly matched with devices that work intermittently instead of running all the time:
Wireless Micro Sensors: Periodic wake-up signal transmission + long sleep standby mode
Vehicle-mounted Auxiliary Chips: Instant signal triggering during remote control unlocking, static standby in daily state
Wearable Sports Devices: Pulsed data collection of pedometers and motion sensors
Ultra-thin Electronic Alarm Modules: Instant pulse power supply when abnormal signals are detected
Forbid Charging: The irreversible lithium-manganese chemical system cannot support charging. Charging will cause internal gas expansion, battery bulging and leakage risks.
Avoid Long-time Continuous Heavy Load: Do not apply CR1025 to devices requiring continuous large current output, which will cause premature battery failure.
Prohibit Physical Damage: The ultra-thin internal electrode sheet is fragile; extrusion or piercing will lead to internal short circuit and safety hazards.
From layer-by-layer teardown observation, the compact internal structure of CR1025 adapts to its ultra-thin appearance size perfectly. Relying on mature lithium-manganese dioxide electrochemical principle, this micro 3V coin cell delivers stable and reliable voltage output. Its core competitiveness lies in outstanding instant pulse discharge performance and fast voltage recovery capability.
It is not a high-capacity battery for continuous power supply, but a professional micro power supply customized for intermittent pulse working electronic devices. Understanding its internal structure and pulse discharge characteristics helps engineers avoid power supply mismatch and maximize the service life of CR1025 batteries in slim miniature electronic products.
