Battery Charging Control with Preheating for Wide-Temperature Safety
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Solution Overview
Problem
Power storage devices, such as lithium secondary batteries, face challenges in maintaining safe operation across a wide temperature range due to increased electrical resistance at low temperatures leading to dendrite formation and passivating film decomposition at high temperatures, which can result in short circuits, irreversible capacity, and potential fires.
Innovation Solution
Incorporating a heater and temperature sensor adjacent to the power storage device, controlled by a circuit that inhibits charging at low temperatures to prevent dendrite formation and allows charging at high temperatures while preventing overheating, using a positive temperature coefficient (PTC) thermistor or a heater with constant resistance, and setting a second temperature threshold to prevent electrolyte deterioration or ignition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If charge is performed at low temperatures, then the power storage device can be charged, but dendrite formation occurs leading to short circuits or irreversible capacity
Solution Approach 1:
The heater is activated before charging to preheat the power storage device to a safe temperature range. This preliminary heating action prevents dendrite formation during subsequent charging by ensuring the device is already at an appropriate temperature, thereby maintaining both charging capability and safety.
Solution Approach 2:
The temperature sensor continuously monitors the temperature of the power storage device and provides feedback to the control circuit. Based on this feedback, the control circuit adjusts the heater operation to maintain the temperature within a safe range, preventing dendrite formation while enabling charging when conditions are appropriate.
2Speed
If charge is performed at high temperatures, then charging speed is improved, but the passivating film decomposes leading to safety hazards
Solution Approach 1:
The temperature sensor continuously monitors the temperature and provides feedback to the control circuit. When the temperature reaches a safe level for high-speed charging, the control circuit enables charging. If the temperature approaches dangerous levels, the control circuit automatically stops charging, thus maintaining safety while allowing high-speed charging when appropriate.
Solution Approach 2:
The charging process is dynamically adjusted based on temperature conditions. The control circuit enables or disables charging based on real-time temperature monitoring, allowing high-speed charging when temperatures are safe and preventing charging when temperatures are dangerous, thus optimizing both speed and safety.
3Power
If the power storage device operates at high temperatures, then energy output is improved, but the electrolyte may deteriorate or ignite
Solution Approach 1:
The temperature sensor provides continuous feedback on the power storage device temperature to the control circuit. When the temperature approaches the threshold for electrolyte deterioration or ignition, the control circuit automatically stops charging, preventing harmful effects while allowing the device to operate at high temperatures when safe, thus maintaining both power output and electrolyte stability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Ensures safe and efficient charging across a wide temperature range, preventing short circuits, capacity loss, and fires by controlling the charging process based on temperature, thereby maintaining the stability and longevity of the power storage device.
Implementation Method 1
a heater provided adjacent to a power storage device to heat the power storage device
Implementation Method 2
a temperature sensor which is provided adjacent to the power storage device and senses the temperature of the power storage device
Data Source
AI summary
Disclosed is a power storage unit which can safely operate over a wide temperature range. The power storage unit includes: a power storage device; a heater for heating the power storage device; a temperature sensor for sensing the temperature of the power storage device; and a control circuit configured to inhibit charge of the power storage device when its temperature is lower than a first temperature or higher than a second temperature. The first temperature is exemplified by a temperature which allows the formation of a dendrite over a negative electrode of the power storage device, whereas the second temperature is exemplified by a temperature which causes decomposition of a passivating film formed over a surface of a negative electrode active material.