Li-Ion Charging Cut-Off Voltage Control to Prevent Lithium Plating
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Solution Overview
Problem
Existing lithium-ion batteries face challenges in achieving high energy density and ultra-long life simultaneously due to side reactions at high discharge cut-off voltages, and the conventional design with an N/P ratio greater than 1 leads to premature capacity loss and reduced service life.
Innovation Solution
A battery management system (BMS) optimizes the charge cut-off voltage by monitoring state of health (SOH) loss and adjusting the charge cut-off voltage based on the SOH loss and a voltage correction factor, maintaining maximum lithiation capability of the negative electrode to prevent capacity attenuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the discharge cut-off voltage is increased to achieve high energy density, then the battery can release more power, but side reactions occur inside the battery affecting battery life
Solution Approach 1:
The patent implements dynamic adjustment of charge cut-off voltage based on battery state of health (SOH). The BMS continuously monitors battery conditions and adapts the charge cut-off voltage in real-time, transitioning from a static fixed voltage approach to a dynamic adaptive approach. This allows the system to optimize energy density while preventing side reactions that would degrade battery life.
Solution Approach 2:
The patent changes the parameter of charge cut-off voltage from a fixed design value to a dynamically adjustable parameter based on battery SOH. By modifying this critical voltage parameter adaptively, the system resolves the contradiction between achieving high energy density (requiring higher voltage) and maintaining battery life (requiring lower voltage to prevent side reactions).
2Productivity
If the N/P ratio is reduced to improve cost-effectiveness and energy density, then the battery becomes more efficient, but capacity attenuation occurs and service life is reduced
Solution Approach 1:
The patent implements a feedback mechanism where the BMS continuously monitors battery SOH and uses this information to adjust the charge cut-off voltage. This closed-loop feedback system ensures that even with a reduced N/P ratio, the battery operates within safe parameters that prevent capacity attenuation and extend service life, thereby resolving the contradiction between productivity and reliability.
Solution Approach 2:
The battery management system performs self-adjustment based on monitored battery conditions. The BMS automatically modifies charging parameters according to the battery's actual state, enabling the system to self-optimize performance and longevity without external intervention, thus maintaining service life despite reduced N/P ratio.
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 ensures a long service life and high energy density by maximizing the utilization of the negative electrode's lithiation and deintercalation capacity while reducing the N/P ratio, thereby enhancing the battery's performance and cost-effectiveness.
Implementation Method 1
a negative electrode of the lithium-ion battery achieves a maximum lithiation capability without lithium plating
Implementation Method 2
more lithium is deintercalated from a positive electrode in the next charge process to make up for a loss of active lithium
Data Source
AI summary
Provided are a battery charging method and device, and a storage medium that are applicable to a lithium-ion battery with an N/P range of 0.5 to 1.1. The method includes: obtaining, by a power management system, a state of health (SOH) loss of the lithium-ion battery; and determining a charge cut-off voltage of a next charge process based on the SOH loss, an initial charge cut-off voltage of the lithium-ion battery, and a voltage correction factor, where the initial charge cut-off voltage is determined based on the N/P, and the charge cut-off voltage increases with increase of a count of charging. The N/P range is 0.5 to 1.1, thereby reducing the dosage of the negative electrode and reducing cost. In addition, the charge cut-off voltage of the next charge process is increased based on the SOH loss, thereby ensuring that the lithium-ion battery is free from lithium plating.