Ohmically Modulated Battery Charging at Low Temperatures

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Solution Overview

Problem

Rechargeable batteries, especially lithium-ion batteries, experience poor charge acceptance and excessively long charging times at subfreezing temperatures due to sluggish electrochemical kinetics, leading to lithium plating and potential cell shorting, which is detrimental for energy storage solutions like electric vehicles.

Innovation Solution

An ohmically modulated rechargeable battery system that includes temperature sensors and controllers to switch between high-resistance and low-resistance terminals, allowing for controlled charging protocols such as constant voltage, constant current, or pulse-based charging, and regenerative charging, to rapidly heat the battery and improve charge acceptance at low temperatures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If conventional external heating systems are used to heat batteries to suitable charging temperature, then battery temperature increases to enable fast charging, but heating time is prolonged and significant heat loss occurs to surroundings

Engineering Contradiction:

Improvebattery temperatureVSAvoidheating time

Core Design Contradiction:

TemperatureVSLoss of time

Solution Approach 1:

The battery heats itself by utilizing its internal resistance to convert electrical energy into thermal energy during the charging process. The controller manages the charging current to generate heat within the battery, eliminating the need for external heating systems and reducing heat loss to surroundings.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent replaces mechanical external heating systems with an electrical field-based approach. The controller uses electrical current to generate heat internally through resistive heating, substituting mechanical convection and conduction heating methods with an electromagnetic field-based heating mechanism.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If fast charging is attempted at low temperatures without proper heating, then charging time is reduced, but lithium plating occurs causing irreversible capacity loss and potential cell shorting

Engineering Contradiction:

Improvecharging rateVSAvoidbattery safety

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The controller continuously monitors battery temperature and adjusts the charging current accordingly. When temperature drops below the threshold, the controller reduces charging current to prevent lithium plating. Once temperature rises to the suitable range, the controller increases charging current to enable fast charging, creating a closed-loop feedback control system.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The charging current is dynamically adjusted based on real-time temperature conditions. The system transitions from a static fixed-current charging approach to a dynamic variable-current charging approach, where the charging rate adapts to temperature changes to prevent lithium plating while enabling fast charging when conditions are suitable.

Inventive Principle:

Principle #15Dynamics

3Reliability

If very low charging rates are used at low temperatures to avoid lithium plating, then battery safety is maintained, but charging time becomes excessively long

Engineering Contradiction:

Improvebattery safetyVSAvoidcharging time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The charging process uses periodic action by alternating between heating phase and fast charging phase. During the heating phase, lower current is applied to generate heat. Once temperature reaches the threshold, fast charging current is applied. This periodic switching between different charging rates optimizes both safety and charging time.

Inventive Principle:

Principle #19Periodic action

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

Enables fast charging of batteries within 20-30 minutes at low temperatures without lithium plating, maintaining battery health and enabling efficient energy storage and use in electric vehicles.

Implementation Method 1

The battery can be charged under a low temperature charging protocol when the battery is in a high resistance mode

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP3195445B1Systems and methods for fast charging batteries at low temperatures

Publication Date: 2020.12.02 EC POWER LLC

Figure 1A
Figure 1B~1C
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AI summary

Rechargeable batteries, charging methods and systems for fast charging of the battery under all environmental temperatures and without causing battery degradation are disclosed. A system includes a temperature sensor configured to monitor a temperature of a battery, a switch that can electrically engage the battery to a source of electrical current through either a low-resistance terminal or a high-resistance terminal of the battery, and a controller electrically connected to the temperature sensor and the switch. The controller can receive input from the temperature sensor and is programmed to determine whether to electrically engage the battery to the source of electrical current through either the low-resistance terminal or the high-resistance terminal through the switch based on input from the temperature sensor.