Segmented Current Collector for High-Rate Battery Capacity
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Solution Overview
Problem
Conventional lithium-ion secondary batteries face challenges in maintaining capacity retention when discharging and recharging at high currents, leading to rapid deterioration and inability to efficiently handle quick discharge/recharge cycles.
Innovation Solution
A lithium-ion secondary battery design featuring an ion-permeable compound and electron-conductive carbon fine particles in the cathode structure, integrated with an aluminum or copper foil current collector, which forms a film resistant to swelling or exfoliation in organic solvents, enhancing lithium-ion conductivity and electron conduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional lithium-ion secondary batteries are discharged and recharged at greater current to achieve quick discharge/recharge characteristics, then power output increases, but capacity retention deteriorates drastically
Solution Approach 1:
The current collector is divided into multiple projections extending in the width direction, creating segmented structures that reduce stress concentration during expansion and contraction cycles. This segmentation allows the current collector to better accommodate volume changes of the electroactive material at high current rates, maintaining capacity retention while delivering high power output.
Solution Approach 2:
The invention changes the geometric parameters of the current collector by forming projections with specific dimensions (width W1, length L1, thickness T1) and spacing (width W2 between projections). These parameter optimizations enable the current collector to maintain structural integrity during rapid charge/discharge cycles, resolving the contradiction between power output and capacity retention.
2Speed
If greater current is used for quick discharge and recharge, then discharge and recharge speed increases, but the period when battery cannot be used elongates due to capacity loss
Solution Approach 1:
The segmented current collector structure with multiple projections reduces mechanical stress concentration during rapid charge/discharge cycles. This enables the battery to maintain capacity retention after repeated high-speed cycles, extending the usable period while preserving fast discharge and recharge capabilities.
Solution Approach 2:
The current collector projections extend beyond the electroactive material in the width direction, providing excess structural support that prevents degradation during high-speed operation. This partial over-design ensures the battery can withstand repeated rapid cycles without capacity loss, maintaining usability.
3Ease of manufacture
If conventional current collector structure is used, then manufacturing is simple, but structural stability during expansion and contraction deteriorates
Solution Approach 1:
The current collector is designed with specific geometric parameters (projections with width W1, length L1, thickness T1, and spacing W2) that can be controlled during manufacturing. These parameter optimizations provide structural stability during electroactive material expansion and contraction while maintaining compatibility with conventional manufacturing processes.
Solution Approach 2:
The current collector forms a composite structure with the electroactive material, where the projections provide mechanical stability while the electroactive material provides electrochemical functionality. This composite design enhances structural stability without significantly complicating the manufacturing process.
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
This design significantly improves the retention rate of initial battery capacity at high current rates, enabling superior quick discharge/recharge characteristics and extending battery usability.
Implementation Method 1
an ion-permeable compound and electron-conductive carbon fine particles in the cathode structure, integrated with an aluminum or copper foil current collector, which forms a film resistant to swelling or exfoliation in organic solvents, enhancing lithium-ion conductivity and electron conduction
Data Source
AI summary
A secondary-battery current collector comprising an aluminum foil and a film containing an ion-permeable compound and carbon fine particles formed thereon or a secondary-battery current collector comprising an aluminum foil, a film containing an ion-permeable compound and carbon fine particles formed thereon as the lower layer, and a film containing a binder, carbon fine particles and a cathodic electroactive material formed thereon as the upper layer, a production method of the same, and a secondary battery having the current collector are provided.