Nickel Battery End-of-Charge Criterion Method
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Solution Overview
Problem
Nickel-based electrochemical batteries face challenges in determining the optimal end-of-charge criterion, particularly when charged with intermittent and variable current sources, leading to overcharging and reduced battery lifespan due to parasitic reactions.
Innovation Solution
A method that establishes an efficiency curve to select a maximum load capacity value, determines a voltage threshold based on temperature, and sets temperature range limits to prevent overcharging, ensuring the battery operates within an electrochemical window where parasitic reactions are minimized, with charging authorized only when voltage remains above a predetermined threshold corresponding to a charged capacity of 75-85% of the nominal capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If charging continues until voltage peak stabilization or temperature threshold is reached, then maximum battery capacity is achieved, but parasitic electrochemical phenomena occur causing energy loss and reduced battery lifespan
Solution Approach 1:
The patent applies preliminary action by establishing voltage curves and determining end-of-charge thresholds in advance for multiple temperature conditions. Instead of reacting to temperature thresholds during charging, the system pre-calculates appropriate voltage thresholds that correspond to optimal charge levels (75-85% of nominal capacity) across different temperature scenarios, enabling proactive prevention of overcharging and parasitic reactions before they occur.
Solution Approach 2:
The patent implements parameter changes by dynamically adjusting the end-of-charge voltage threshold based on temperature conditions. The system selects from pre-established voltage curves corresponding to different temperatures, thereby changing the charging termination parameter (voltage threshold) according to the battery's thermal state. This prevents fixed-threshold overcharging while adapting to varying operating conditions.
2Quantity of substance
If overcharging is used to compensate for parasitic reactions, then user capacity is maximized, but energy is consumed by water decomposition and battery degradation accelerates
Solution Approach 1:
The patent replaces the conventional temperature-threshold-based charging termination mechanism with a voltage-threshold mechanism. Instead of allowing charging to continue until a temperature rise indicates overcharging (reactive approach), the system uses voltage measurements against pre-established curves to determine the optimal termination point (proactive approach). This substitution prevents parasitic water decomposition reactions by stopping charge before the electrochemical window for parasitic reactions is reached.
3Ease of operation
If fixed voltage threshold is used for end-of-charge detection, then charging control is simple, but accuracy decreases under varying temperature conditions
Solution Approach 1:
The patent applies dynamics by making the end-of-charge voltage threshold adaptive rather than fixed. The system dynamically selects the appropriate voltage threshold from multiple pre-established curves based on the current temperature condition. This creates a dynamic charging control system that automatically adjusts its termination criterion to match operating conditions, combining the simplicity of threshold-based control with the precision of temperature-compensated detection.
Data Source
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AI summary
The method for charging a nickel-based electrochemical battery (1) of predetermined nominal capacity, comprising at least one measurement of the battery voltage (1) and one measurement of the temperature representative of the battery (1). The battery (1) is connected to an intermittent, variable-current power source (2). Charging of the battery (1) is interrupted when the voltage measured across the battery terminals (1) reaches a predetermined voltage threshold, a function of the measured temperature, and representative of a charged capacity in the battery (1) corresponding to a charging efficiency greater than or equal to 90% of the maximum charging efficiency.