Lithium-Ion Battery Charging Control via Inferred Surface Concentration

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Solution Overview

Problem

Conventional lithium-ion battery charging techniques face challenges in avoiding lithium surface saturation at the transport-limiting electrode while minimizing charging time, requiring accurate state of charge measurements that current systems cannot provide reliably.

Innovation Solution

A system that monitors current, voltage, and temperature to control the charging process, inferring electrode lithium surface concentrations and adjusting the charging current and voltage to maintain these concentrations within set limits, using a charging profile generated from measurements on a reference battery to ensure consistent charging without precise state of charge measurement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional constant current or constant voltage charging is used, then charging time is reduced, but lithium surface saturation occurs at the transport-limiting electrode

Engineering Contradiction:

Improvecharging speedVSAvoidlithium surface concentration control

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent implements feedback control by continuously monitoring battery voltage, current, and temperature during charging, then using these measurements to infer lithium surface concentration and adjust charging parameters accordingly. This closed-loop system prevents lithium surface saturation while maintaining high charging speeds by dynamically adapting the charging profile based on real-time battery state.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent changes charging parameters (current, voltage, temperature) dynamically during the charging process rather than maintaining constant values. By adjusting these parameters based on inferred lithium surface concentration, the system optimizes charging speed while preventing saturation, resolving the contradiction between fast charging and concentration control.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If accurate state of charge measurement is implemented, then charging control precision is improved, but system complexity and measurement requirements increase

Engineering Contradiction:

Improvestate of charge measurement accuracyVSAvoidmeasurement system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent introduces an intermediary approach by using easily measurable parameters (voltage, current, temperature) to infer the difficult-to-measure lithium surface concentration. Rather than directly measuring state of charge with complex equipment, the system uses these measurements as intermediaries to calculate and control lithium concentration, achieving precise control without complex measurement systems.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces complex direct measurement systems with an indirect computational approach. Instead of using sophisticated sensors or measurement equipment to directly measure state of charge, the system substitutes mathematical modeling and inference based on simple voltage, current, and temperature measurements, reducing hardware complexity while maintaining control precision.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If manufacturing variations are compensated, then charging consistency across batteries is improved, but charging profile complexity increases

Engineering Contradiction:

Improvecharging consistencyVSAvoidcharging profile management

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies local quality by tailoring charging profiles to individual battery characteristics. Rather than using a single universal charging profile, the system adapts charging parameters based on each battery's specific properties (capacity, internal resistance, temperature response), compensating for manufacturing variations and achieving consistent charging across diverse batteries through localized optimization.

Inventive Principle:

Principle #3Local quality

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 consistent charging of lithium-ion batteries by maintaining electrode lithium surface concentrations within specified limits, reducing charging time and compensating for manufacturing variations, without the need for accurate state of charge measurements.

Implementation Method 1

monitors a current through the battery, a voltage of the battery

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

the net effect is dominated by slow diffusion processes for filling one electrode with lithium while removing it from the other

Methodology Applied

Scientific EffectDiffusion: Diffusion

Data Source

PatentUS8624560B2Controlling battery charging based on current, voltage and temperature

Publication Date: 2014.01.07 APPLE INC

AI summary

Some embodiments of the present invention provide a system that charges a lithium-ion battery. During operation, the system monitors: a current through the battery, a voltage of the battery, and a temperature of the battery. Next, the system uses the monitored current, voltage and temperature to control a charging process for the battery. In some embodiments, controlling the charging process involves: inferring electrode lithium surface concentrations for the battery from the monitored current, voltage and temperature; and applying the charging current and/or the charging voltage in a manner that maintains the inferred electrode lithium surface concentrations for the battery within set limits.