Supercapacitor-Emulating Battery Module for EV Fast-Charging
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Solution Overview
Problem
Electric vehicles using fast-charging batteries face limitations in delivering high power densities and long cycle lifetimes due to the inherent differences between supercapacitors and lithium-ion batteries, with supercapacitors excelling in short-term energy bursts but suffering from high self-discharge rates and low energy density, while lithium-ion batteries provide higher energy density but lower power density and shorter cycle life.
Innovation Solution
A power train configuration for electric vehicles incorporating a main fast-charging lithium-ion module and a supercapacitor-emulating fast-charging lithium-ion module, both with the same anode active material, operating within a specific charging range to mimic supercapacitor performance, managed by a control unit to optimize power delivery and extend cycle life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If supercapacitors are used to deliver high power bursts, then power density is improved, but cycle life and energy retention deteriorate due to high self-discharge rates
Solution Approach 1:
The battery is divided into multiple individual cells that can be independently managed and controlled. This segmentation allows the system to activate only the necessary number of cells based on current power demands, reducing overall stress on the battery system and extending cycle life while maintaining high power density when needed.
Solution Approach 2:
The battery management system dynamically adjusts the operating parameters of individual cells based on real-time conditions including state of charge, temperature, and power demand. This dynamic control optimizes power delivery while preventing individual cells from operating in conditions that would reduce cycle life.
2Productivity
If lithium-ion batteries operate at high charging rates to provide fast charging, then charging speed is improved, but depth of discharge increases reducing overall battery life
Solution Approach 1:
The system uses partial charging actions by activating only the necessary portion of total battery capacity based on current needs. Instead of charging or discharging the entire battery pack, only the required number of cells are engaged, reducing cumulative stress and extending battery life while maintaining fast charging capability.
Solution Approach 2:
The battery management system changes operating parameters including current distribution, voltage levels, and state of charge targets for individual cells based on real-time conditions. This allows optimization of charging speed while controlling depth of discharge to extend battery life.
3Use of energy by moving object
If the battery operates over a wide state of charge range to maximize energy capacity, then energy density is improved, but power delivery capability and cycle life deteriorate
Solution Approach 1:
The system dynamically adjusts the operational state of charge range for individual cells based on current power demands and battery conditions. When high power delivery is needed, the system operates cells within an optimized charge range that maximizes power capability. When sustained energy delivery is needed, the system can expand the charge range utilization, thereby dynamically balancing power delivery and energy capacity.
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 configuration enhances power density and cycle life by allowing the battery to operate within a narrow, high-power range, effectively bridging the gap between supercapacitors and lithium-ion batteries, providing superior performance in terms of energy and power delivery while minimizing depth of discharge and extending the overall battery life.
Implementation Method 1
Lithium-ion batteries provide higher energy density but lower power density and shorter cycle life
Implementation Method 2
Supercapacitors are superior to batteries in their ability to deliver much more charge at a shorter time
Data Source
AI summary
Electric vehicles (EVs), power trains and control units and methods are provided. Power trains comprise a main fast-charging lithium ion battery (FC), configured to deliver power to the electric vehicle, a supercapacitor-emulating fast-charging lithium ion battery (SCeFC), configured to receive power and deliver power to the FC and/or to the EV, and a control unit. Both the FC and the SCeFC have anodes based on the same anode active material, and the SCeFC is configured to operate at high rates within a limited operation range of state of charge (SoC), maintained by the control unit, which is further configured to manage the FC and the SCeFC with respect to power delivery to and from the EV, respectively, and manage power delivery from the SCeFC to the FC according to specified criteria that minimize a depth of discharge and/or a number of cycles of the FC.