Mixed-Active-Material Battery Current Control for Longer Cycle Life
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Solution Overview
Problem
Conventional lithium-ion secondary batteries with single active material electrodes struggle to accurately estimate and manage the charging reaction between different active materials, leading to uneven load distribution and potential battery deterioration.
Innovation Solution
A secondary battery system that includes a current ratio calculator and controller, which calculates the current ratio between multiple active materials based on their capacity and capacity-versus-potential properties, allowing for precise control of the charging and discharging current to optimize battery performance and extend lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If electrodes are prepared from a mixture of multiple active materials to increase capacity and lifespan, then battery capacity and lifespan are improved, but accurate estimation of charging reaction distribution becomes difficult
Solution Approach 1:
The patent divides the charging reaction into separate components corresponding to each active material type. By calculating the potential of each active material independently and comparing it with the measured battery potential, the system segments the total charging current into contributions from each material type, enabling accurate estimation of charging reaction distribution in mixed active material electrodes
Solution Approach 2:
The patent introduces an intermediary calculation model that uses the relationship between electrode potential and state of charge for each active material type as a mediator. This model allows the system to estimate the charging reaction distribution by comparing the measured battery potential with calculated potentials at different assumed charging reaction ratios, without directly measuring the charging reactions themselves
2Reliability
If charge current is restricted to protect active materials undergoing charging reaction, then battery deterioration is reduced, but charging speed decreases
Solution Approach 1:
The patent implements dynamic charge current control by continuously estimating the charging reaction distribution and adjusting the charge current accordingly. The system calculates the charging reaction ratio at different state of charge ranges and dynamically adjusts the charge current to prevent excessive charging reactions in specific ranges, optimizing both battery durability and charging speed
Solution Approach 2:
The patent uses feedback control by measuring the battery potential, comparing it with calculated potentials at different assumed charging reaction ratios, and using this information to estimate the actual charging reaction distribution. This feedback mechanism enables real-time adjustment of charge current to protect the battery while maintaining optimal charging performance
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 system effectively reduces battery deterioration by accurately managing the load on each active material, optimizing charging and discharging rates, and extending the battery's operational range, thereby enhancing the overall performance and lifespan of lithium-ion secondary batteries.
Implementation Method 1
calculates a current ratio of a current passing through the first active material and a current passing through the second active material for each of different values of a charge amount of the first electrode, based on a capacity and capacity-versus-potential properties of the first active material and a capacity and capacity-versus-potential properties of the second active material
Implementation Method 2
The lithium-ion secondary battery charges and discharges electric energy with the active material of the cathode and anode absorbing and releasing lithium ions
Implementation Method 3
at the time of charging, lithium ions released from the cathode are absorbed by the anode, whereas at the time of discharging, lithium ions discharged from the anode are absorbed by the cathode
Data Source
AI summary
According to an embodiment, a secondary battery system includes a secondary battery, a calculator, and a controller. The secondary battery includes a first electrode including a first and second active materials, and a second electrode including a third active material. The calculator calculates a current ratio of currents passing through the first and second active materials for each of different values of a charge amount of the first electrode, based on capacities and capacity-versus-potential properties of the first and second active materials. The controller, based on the capacities of the first and second active materials and the current ratio when the charge amount of the first electrode takes a first value, controls the current passing through the secondary battery when the charge amount indicates the first value.