Battery Safety Device Using Pressure-Sensitive Conducting Film
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries, such as lithium secondary batteries, are prone to ignition or explosion due to increased reactivity between the positive electrode and electrolyte when subjected to external pressure or impact, posing a safety risk as they charge and voltage rises.
Innovation Solution
A safety device comprising a first and second metal plate with a pressure-sensitive conducting film (PSCF) interposed between them, which remains non-conductive until a predetermined pressure is applied, connecting the plates and discharging the battery to prevent damage from external impacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the battery is charged to high voltage to increase energy density, then the energy density is improved, but the reactivity between the positive electrode and electrolyte increases causing safety risks
Solution Approach 1:
The patent applies preliminary action by installing the safety device (pressure-sensitive conducting film with metal plates) into the battery before any damage occurs. The device is pre-positioned between the positive electrode and separator, ready to activate immediately when external pressure is applied, converting the charged state to discharged state before the battery can be damaged by nails, nippers, or compression forces.
2Reliability
If the battery structure is made more robust to resist external pressure, then the safety is improved, but the energy density decreases due to additional structural components
Solution Approach 1:
The patent employs thin films by using a pressure-sensitive conducting film that is only 1-10 micrometers thick. This ultra-thin safety mechanism provides robust protection against external pressure and impact forces without adding significant structural bulk, thereby maintaining high energy density while improving safety.
Solution Approach 2:
The safety device combines multiple materials with different properties: a pressure-sensitive conducting film (which remains non-conductive under normal conditions but becomes conductive under pressure), metal plates for structural support and electrical connection, and insulation layers. This composite structure achieves both safety and energy density requirements.
3Reliability
If a safety device is added to prevent external impact damage, then the safety is improved, but the device complexity increases
Solution Approach 1:
The patent merges the safety function with existing battery components. The pressure-sensitive conducting film is positioned between the positive electrode and separator, utilizing the existing electrode structure as part of the safety mechanism. The metal plates are electrically connected to the positive and negative electrodes, integrating the safety device into the battery's electrical circuit rather than adding separate complex systems.
Solution Approach 2:
The safety device is self-activating and requires no external control systems. When external pressure is applied, the conducting film automatically transitions from non-conductive to conductive state, forming an electrical circuit that discharges the battery. This passive, self-service mechanism avoids complex control electronics, sensors, or power sources.
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
The safety device effectively lowers the battery's charged state upon external pressure, preventing explosions and fires by discharging the battery before damage occurs, thus enhancing safety and stability while allowing higher energy density.
Implementation Method 1
a PSCF (pressure-sensitive conducting film) interposed between both metal plates and adapted to exhibit electrical conductivity when a predetermined pressure or higher is applied
Data Source
AI summary
Disclosed is a battery safety device having a first metal plate, a second metal plate, and a pressure-sensitive conducting film interposed between both metal plates and adapted to exhibit electrical conductivity when a predetermined pressure or higher is applied. The first and second metal plates are electrically connected to the positive and negative electrodes of the battery, respectively. The safety device connected to a battery prevents the battery from being damaged or at least from igniting or exploding, even when an external impact caused by pressure, a nail, or a nipper or an external pressure is applied to the battery, by conducting the current of the battery to the safety device and discharging the battery before the battery is damaged by the external impact or external pressure.