Cyclic Coulometry for Concurrent Battery Efficiency and Resistance Testing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current battery evaluation methods, such as high precision coulometry, are limited in accurately measuring cycle life and internal resistance growth in lithium-ion batteries, as they require long cycling periods and cannot concurrently measure coulombic efficiency and internal resistance, leading to incomplete characterization of battery performance.
Innovation Solution
The cyclic coulometry system generates symmetric charge and discharge currents with adjustable timing to maintain cell voltage at a setpoint, allowing concurrent measurement of coulombic efficiency and internal resistance, and provides detailed loss rate maps across various conditions, enabling more comprehensive battery testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional high precision coulometry is used to measure battery performance, then measurement precision of coulombic efficiency is improved, but the testing time is excessively long and internal resistance cannot be concurrently measured
Solution Approach 1:
The patent applies periodic square wave current pulses instead of continuous slow cycling. The current alternates between positive and negative directions in periodic cycles, allowing the battery to be charged and discharged in rapid succession. This periodic action enables concurrent measurement of multiple parameters within each cycle period, dramatically reducing total testing time while maintaining measurement precision through controlled potential conditions during each pulse phase.
Solution Approach 2:
The patent maintains continuous measurement and control throughout the testing process. The potentiostat continuously monitors cell potential and adjusts current to maintain controlled conditions, while measurement circuits continuously record electrical parameters. This continuous action eliminates idle time between measurements and allows simultaneous acquisition of coulombic efficiency and internal resistance data throughout the entire testing duration.
2Device complexity
If traditional coulometry methods are used, then simple measurement setup is maintained, but the ability to concurrently measure multiple parameters is lost
Solution Approach 1:
The patent implements a multi-functional measurement system where a single testing apparatus simultaneously performs coulombic efficiency measurement, internal resistance measurement, and voltage control. The potentiostat serves multiple functions by controlling current while measuring potential, and additional measurement circuits capture multiple electrical parameters concurrently. This universal system replaces multiple separate measurement devices, maintaining reasonable complexity while enabling comprehensive battery performance characterization.
Solution Approach 2:
The patent merges previously separate measurement functions into a unified testing protocol. Coulombic efficiency measurement and internal resistance measurement are combined into the same square wave cycling test, eliminating the need for separate measurement procedures. The measurement circuits are integrated to simultaneously capture multiple electrical parameters during each current cycle, consolidating multiple measurement functions into a single coordinated system.
3Ease of operation
If fixed current cycling is applied, then ease of operation is maintained, but adaptability to different testing conditions and performance optimization is reduced
Solution Approach 1:
The patent employs dynamic control of current timing and magnitude through the potentiostat. Instead of fixed current cycling, the system dynamically adjusts current parameters based on real-time cell potential feedback. The square wave current duration and amplitude can be modified adaptively to optimize testing for different battery types, states of charge, and temperature conditions while maintaining ease of operation through automated control algorithms.
Solution Approach 2:
The patent enables flexible modification of testing parameters including current amplitude, pulse duration, duty cycle, and frequency. These parameters can be changed to adapt the testing protocol to different battery chemistries, capacities, and operating conditions. The system maintains ease of operation by providing automated parameter adjustment based on pre-programmed test profiles, allowing versatile testing without requiring manual intervention for each parameter change.
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 approach enhances the accuracy of battery performance characterization by measuring both coulombic efficiency and internal resistance growth concurrently, providing a more complete picture of cycle life and enabling faster iteration in battery design and manufacturing.
Implementation Method 1
Coulometry is an electrochemical technique that measures the total coulombs of electricity consumed or produced during electrochemical reactions
Implementation Method 2
In both cases, the total charge, Q, passed through the electrochemical cells is calculated by integrating the current as a function of time
Data Source
AI summary
Systems, devices, and methods of diagnosing an electrochemical cell using cyclic coulometry are discussed. An exemplary battery diagnostic system comprises a current generator to generate symmetric charge current and discharge current to excite an electrochemical cell, and a cyclic coulometer to evaluate performance of the electrochemical cell. The cyclic coulometer can adjust at least one of a charge time for applying the charge current, or a discharge time for applying the discharge current, to keep a monitored cell voltage toward a specific setpoint. The adjustment of charge or discharge time can be achieved by changing a current switch timing for reversing current from a first to a second current direction. The cyclic coulometer measures one or more electrical parameters during the charge or discharge cycle, and generates a performance metric using the measured electrical parameters.