Bulk-Current Charging for Fast and Low-Temperature Li-Ion Batteries
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Solution Overview
Problem
Lithium plating during battery charging leads to capacity loss, increased internal resistance, and safety risks, while low-temperature charging results in reduced ionic conductivity and charging failure, with conventional solutions being energy-intensive and impractical.
Innovation Solution
Applying a bulk-current, specifically a high-frequency alternating current, to lithium-ion batteries during charging to enhance lithium-ion mobility, prevent plating, and self-heat the battery, thereby facilitating faster charging at low temperatures without external heating systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fast charging is performed at high C-rate, then charging speed is improved, but lithium plating occurs leading to capacity loss and safety risks
Solution Approach 1:
The patent applies periodic pulsed current charging instead of continuous high C-rate charging. The charging current is delivered in pulses with on-time and off-time intervals, allowing the battery to relax between pulses. This periodic action prevents lithium plating by giving time for lithium ions to redistribute and avoid excessive deposition on the anode surface, while still achieving fast charging overall.
Solution Approach 2:
The patent dynamically adjusts charging parameters based on real-time battery state monitoring. The charging protocol adapts the pulse width, duty cycle, and current magnitude based on temperature, voltage, and charge level. This dynamic adjustment optimizes charging speed while preventing lithium plating by reducing current when conditions approach dangerous thresholds.
2Reliability
If external heating systems are used to warm battery at low temperatures, then charge acceptance is improved, but energy consumption increases and device complexity increases
Solution Approach 1:
The patent employs self-heating through the application of pulsed current that generates heat within the battery itself via internal resistance. This self-service heating eliminates the need for external heating systems. The pulsed current protocol is designed to generate controlled heat that raises battery temperature to optimal charging range, improving charge acceptance without requiring external energy input for heating.
Solution Approach 2:
The patent changes the electrical parameters of the charging protocol to include high-frequency alternating current components that generate dielectric heating and resistive heating within the battery. This parameter change transforms the charging approach from simple DC to a more complex AC-pulsed protocol that simultaneously heats and charges the battery, improving low-temperature performance without external heaters.
3Reliability
If bulk-current with high-frequency alternating current is applied, then lithium-ion mobility is enhanced and plating is prevented, but device complexity increases
Solution Approach 1:
The patent makes the charging system multi-functional by combining heating, charging, and plating prevention into a single bulk-current application protocol. The same high-frequency alternating current that generates heat for low-temperature operation also enhances lithium-ion mobility and prevents plating through its oscillating nature. This universality reduces overall system complexity despite the advanced protocol.
Solution Approach 2:
The patent replaces mechanical heating systems (external heaters, thermal management hardware) with an electrical field-based solution. The high-frequency alternating current creates electromagnetic effects that generate heat and enhance ion mobility without mechanical components. This substitution reduces device complexity by eliminating mechanical heating apparatus while achieving the same thermal and electrochemical benefits.
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 bulk-current method effectively suppresses lithium deposition, improves charge acceptance, and maintains thermal stability, enhancing specific capacity retention and cycle life while eliminating the need for external heating equipment.
Implementation Method 1
providing a bulk-current to the lithium-ion battery to increase the temperature of the lithium-ion battery from the first temperature level to a second temperature level
Implementation Method 2
providing a source of power comprising direct current to the lithium-ion battery increases the state-of-charge of the lithium-ion battery
Data Source
AI summary
Systems and methods for improved fast-charging and low-temperature charging of batteries. For fast-charging applications, bulk-current injection is applied in bursts during charging to promote ion mobility therein. For low-temperature charging applications, bulk-current injection is applied for an extended period of time to warm the battery through internal resistance. Systems configured to provide bulk-current injection to a battery are also described. The system includes an alternating current source, a direct current source, a battery to be charged, and a battery management system (BMS) configured to selectively engage and disengage the power sources to optimally charge the battery using bulk-current injection.