Secondary Battery Control via Electrode Potential Segmentation

Solution Overview

Problem

Existing methods for controlling secondary batteries, such as lithium ion batteries, fail to effectively suppress characteristic deterioration and ensure safety by not accounting for internal resistances of the positive and negative electrodes during charge/discharge, limiting the improvement of battery safety and longevity.

Innovation Solution

A method that determines the state of charge (SOC) and internal resistances of both electrodes, controlling the current and voltage to maintain electrode potentials within predetermined ranges, thereby enhancing safety and prolonging battery life by considering the internal resistances of the positive and negative electrodes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If battery voltage is controlled without considering internal resistances of electrodes, then control is simplified, but electrode potentials cannot be accurately determined leading to accelerated deterioration and safety issues

Engineering Contradiction:

Improvecontrol complexityVSAvoidbattery safety

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent segments the battery internal resistance into two distinct components: positive electrode resistance and negative electrode resistance. By measuring and controlling each electrode's potential separately rather than treating battery voltage as a single value, the system achieves accurate electrode potential determination while maintaining manageable control complexity through modular measurement and control steps.

Inventive Principle:

Principle #1Segmentation

2Device complexity

If battery voltage is controlled without considering internal resistances of electrodes, then control is simplified, but characteristic deterioration is accelerated

Engineering Contradiction:

Improvecontrol complexityVSAvoidbattery life

Core Design Contradiction:

Device complexityVSDuration of action of stationary object

Solution Approach 1:

The patent segments the battery internal resistance into two distinct components: positive electrode resistance and negative electrode resistance. By measuring and controlling each electrode's potential separately rather than treating battery voltage as a single value, the system achieves accurate electrode potential determination while maintaining manageable control complexity through modular measurement and control steps.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements feedback control by continuously measuring electrode potentials, comparing them against predetermined safe ranges, and adjusting charge/discharge current accordingly. This feedback mechanism prevents electrode potentials from entering deterioration-accelerating regions, thereby extending battery life while maintaining simple overall control architecture.

Inventive Principle:

Principle #23Feedback

3Device complexity

If electrode potentials are not accurately determined, then control method is simpler, but safety and characteristic suppression improvement is limited

Engineering Contradiction:

Improvecontrol method complexityVSAvoidsafety improvement effect

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent performs preliminary measurements of open circuit potentials and internal resistances of both electrodes before charge/discharge operations. By pre-characterizing the electrode properties and storing this data, the system establishes baseline values for accurate potential determination during operation, improving safety without adding complexity to the real-time control method.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS10224731B2Method of controlling secondary battery

Publication Date: 2019.03.05 HITACHI LTD

AI summary

A positive electrode potential and a negative electrode potential during charge or discharge of a secondary battery are determined, based on potentials of a positive electrode and a negative electrode in an open circuit state corresponding to a SOC of the secondary battery, and internal resistances of the positive electrode and the negative electrode corresponding to the SOC of the secondary battery, and a current of the secondary battery is controlled such that the positive electrode potential and the negative electrode potential fall within a predetermined range.