Lithium Battery Cathode Coating for Faster Overcharge Cutoff
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing rechargeable lithium batteries face challenges in ensuring overcharge safety due to delayed operation of current-cut-off systems, which are triggered either at high temperatures or insufficient pressure increases, leading to potential accidents such as thermal runaway and explosion.
Innovation Solution
A rechargeable lithium battery design featuring a positive electrode with radially arranged primary particles and a boron coating layer containing lithium borate, combined with vinylene carbonate in the electrolyte, which generates a large amount of gas during overcharging, quickly triggering a safety device to cut off the current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If temperature-sensing/current-cut-off system operates at high temperature (60°C or less), then current is cut off to prevent thermal runaway, but operation occurs too late during overcharge to ensure safety
Solution Approach 1:
The patent changes the triggering parameter from temperature-based detection to pressure-based detection. By monitoring internal pressure changes that occur rapidly during overcharge, the system can detect overcharge conditions much earlier than temperature-based systems, enabling timely current cutoff before thermal runaway occurs.
Solution Approach 2:
The patent replaces the thermal sensing mechanism with a pressure sensing mechanism. Instead of measuring temperature changes that lag behind overcharge conditions, the system measures pressure changes that occur immediately during overcharge, providing faster response time for safety activation.
2Loss of time
If temperature-sensing/current-cut-off system raises operation temperature threshold, then response time improves, but overcharge safety is compromised due to delayed detection
Solution Approach 1:
The patent fundamentally changes the detection parameter from temperature to pressure. This allows the system to achieve fast response time without compromising safety, as pressure changes occur immediately during overcharge conditions, providing both rapid detection and reliable safety activation.
3Loss of time
If internal pressure monitoring is used for current-cut-off, then response time improves, but safety system fails to work properly as pressure rise is insufficiently fast
Solution Approach 1:
The patent applies local quality by coating the positive electrode active material particles with boron-containing compounds. This localized modification creates specific sites that rapidly generate gas during overcharge, causing swift pressure increase that reliably triggers the safety mechanism while maintaining fast response time.
Solution Approach 2:
The boron-containing coating on the positive electrode promotes accelerated decomposition reactions during overcharge, generating gas rapidly and causing quick pressure rise. This ensures the pressure-based safety system operates both quickly and reliably.
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 design ensures rapid activation of the safety device during overcharging, preventing accidents by effectively cutting off current and heat transfer, while maintaining excellent performance characteristics such as cycle-life and capacity.
Implementation Method 1
when a large amount of gas is generated in the battery during overcharging and the pressure is sufficiently increased
Implementation Method 2
a boron coating layer on the surface of the secondary particle and including lithium borate
Data Source
AI summary
A rechargeable lithium battery includes a positive electrode including a positive electrode active material including a secondary particle in which a plurality of primary particles are aggregated, the secondary particle having at least a portion of the primary particles radially arranged and comprising a lithium nickel-based composite oxide, and a boron coating layer on the surface of the secondary particle and including lithium borate; a negative electrode; a separator between the positive electrode and the negative electrode; an electrolyte including vinylene carbonate; and a case containing the positive electrode, the negative electrode, the separator, and the electrolyte.