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Views: 0 Author: Site Editor Publish Time: 2026-07-04 Origin: Site
Lithium Thionyl Chloride (Li‑SOCl₂), commonly known as ER series batteries, is a widely used non-rechargeable primary battery technology in industrial and precision electronic fields. Featuring ultra-low self-discharge rate, wide operating temperature range (−55 °C to +85 °C), high energy density, and long shelf life of up to 10–20 years, ER batteries are the preferred power source for long-term standby and low-power intermittent devices. Typical application scenarios include smart water/electricity/gas meters, remote IoT sensors, military equipment, medical implanted devices, and outdoor monitoring instruments.
Despite superior stability and durability compared with conventional primary batteries, ER batteries still suffer from various operational faults during long-term deployment, extreme environmental exposure, and improper application. Common abnormal phenomena include voltage delay and passivation attenuation, electrolyte leakage, abnormal internal pressure rise, low-temperature power attenuation, and failure caused by electrical misoperation. These faults easily lead to equipment shutdown, data loss, and even safety accidents, severely affecting the reliability of industrial systems. This paper systematically analyzes the typical operational faults of ER primary batteries, explores their root causes, and proposes targeted optimization and preventive solutions.
Passivation is the most inherent and common fault of Li‑SOCl₂ batteries, which is a unique electrochemical characteristic of this battery system. During long-term storage or low-load standby operation, a dense and insoluble lithium chloride (LiCl) passivation layer gradually forms on the surface of the lithium anode. This layer stably exists under static conditions and will continuously thicken with the extension of standby time and the decrease of ambient temperature.
When the battery switches from standby to loaded discharge, the thickened passivation layer will hinder the instantaneous transmission of current, resulting in obvious voltage delay and instantaneous voltage drop. In severe cases, the load voltage will be lower than the equipment working threshold, triggering false alarms of insufficient power or temporary equipment startup failure. For IoT devices that require frequent pulse discharge, repeated current impact will continuously destroy and rebuild the passivation layer, leading to fluctuating output voltage and unstable operating signals. Although passivation is a normal protective mechanism, excessive passivation is the primary cause of abnormal startup and intermittent failure of ER battery-powered equipment.
Thionyl chloride electrolyte is highly corrosive and volatile, and complete airtightness of the battery casing is the core guarantee for normal operation. Electrolyte leakage of ER batteries mainly occurs in three scenarios: long-term high-temperature operation, reverse charging misoperation, and internal short circuit caused by external mechanical damage.
Sustained high-temperature environment accelerates the internal chemical reaction of the battery, generates excess gas, and raises the internal pressure. When the internal pressure exceeds the bearing limit of the sealing structure, micro cracks will appear at the sealing port, causing slow leakage of corrosive electrolyte. Reverse charging is a fatal misoperation for primary ER batteries: it triggers uncontrolled lithium precipitation on the anode, violent internal exothermic reactions, and rapid gas accumulation, which directly ruptures the battery casing and causes large-area electrolyte leakage. In addition, mechanical extrusion, puncture and terminal vibration stress in industrial vibration environments will damage the integrity of the casing, inducing leakage and subsequent circuit board corrosion and component failure.
ER batteries are renowned for excellent low-temperature performance, but their discharge capacity and instantaneous power will still attenuate significantly under extreme low-temperature conditions below −40 °C. Low temperature reduces the activity of electrolyte ions and increases the internal ohmic impedance of the battery. Meanwhile, the low-temperature environment further accelerates the thickening of the anode passivation layer, superimposing the impedance increase effect.
In practical outdoor low-temperature scenarios such as polar monitoring and cold-region industrial meters, the instantaneous pulse discharge capacity of ER batteries decreases sharply. The battery can maintain normal static open-circuit voltage, but cannot provide sufficient peak current to support equipment startup and data transmission, resulting in functional failure of low-temperature equipment. This fault is often misjudged as battery capacity depletion, which affects the accurate judgment of equipment maintenance status.
In addition to high-temperature induced pressure rise, impure production materials and improper storage environment will also cause abnormal internal pressure of ER batteries. Moisture intrusion during production or long-term storage in high-humidity air will trigger side reactions between water molecules and thionyl chloride electrolyte, generating hydrogen chloride and sulfur dioxide gas. The continuously accumulated gas cannot be discharged, leading to sustained rise of internal pressure.
Batteries with excessive internal pressure will have bulged casings in the early stage, and will experience casing rupture, gas ejection and even combustion and explosion in severe cases. Moreover, disorderly stacking and mixed storage of ER batteries with metal conductors will cause accidental short circuits, instantaneous high current discharge, violent heat generation, and instantaneous surge of internal pressure, bringing serious safety hazards to industrial storage and field operation.
The theoretical shelf life of ER batteries is more than 10 years, but many batteries suffer from premature capacity attenuation in actual use. The main causes include unreasonable load matching and long-term high-frequency pulse discharge. For equipment with excessive instantaneous peak current demand, the battery will be in a high-impedance discharge state for a long time, accelerating the consumption of active materials and aggravating passivation aging.
In addition, unreasonable power budget design of terminal equipment is also a key factor. Many devices do not reserve capacity attenuation margin for battery end-of-life stage, resulting in the battery failing to meet the operating requirements after slight capacity decline, which manifests as premature failure of the power supply system. Long-term alternating high and low temperature environment will also accelerate the aging of internal materials, greatly shortening the actual service life of ER batteries.
To solve the passivation and voltage delay problem, terminal equipment can be embedded with pulse pre-discharge circuit and periodic activation program. Regular low-current pulse discharge can destroy the thickened passivation layer, maintain the stability of anode surface state, and effectively eliminate instantaneous voltage drop during equipment startup. For low-temperature application scenarios, select low-passivation ER battery models optimized for cold environments, and properly adjust the equipment startup delay parameters to avoid misjudgment of power failure caused by voltage delay.
Strictly prohibit reverse charging of ER primary batteries in circuit design and field operation, and add reverse connection protection modules at the battery terminal. For equipment working in vibration environments, adopt flexible connection structures to reduce terminal stress and avoid casing damage caused by mechanical vibration. Standardize battery storage and management, avoid mixed placement with metal conductors, and prevent accidental short circuits. Regularly inspect the battery casing integrity in daily maintenance to eliminate hidden leakage dangers in advance.
For extreme low-temperature scenarios, select high-power low-temperature resistant ER batteries with optimized electrolyte formula and anode structure. Optimize the equipment discharge strategy, appropriately reduce the instantaneous peak current demand in low-temperature environment, and set graded power output modes. Meanwhile, reserve sufficient capacity margin in the power budget design to cope with capacity attenuation caused by low temperature and long-term aging, ensuring stable operation of equipment in full temperature range.
Control the battery operating and storage environment, avoid long-term high-temperature (above 60 °C) and high-humidity working conditions, and reduce side reactions and gas generation inside the battery. Adopt standardized battery packaging and storage specifications to prevent moisture intrusion and casing extrusion damage. For high-risk industrial scenarios, equip batteries with overpressure protection structures and real-time temperature monitoring modules to realize early warning and power-off protection of abnormal states.
Lithium Thionyl Chloride (ER) primary batteries have irreplaceable advantages in long-term low-power industrial scenarios, but their unique electrochemical characteristics and application environment easily induce typical operational faults such as passivation voltage delay, electrolyte leakage, low-temperature power attenuation and abnormal internal pressure. Most ER battery failures are not caused by product quality defects, but by mismatched application scenarios, improper operation and inadequate environmental adaptation design.
In actual engineering applications, targeted optimization should be carried out from three dimensions: battery model selection, terminal circuit design and field operation management. By suppressing passivation interference, standardizing electrical and mechanical operation, optimizing low-temperature discharge strategies and strengthening environmental safety control, the operational stability and full-life-cycle reliability of ER batteries can be effectively improved. This provides a solid guarantee for the long-term stable operation of industrial monitoring, smart energy and remote sensing equipment.
