Li-Ion Battery NP Ratio Tuning to Prevent Silicon Anode Memory Effect
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Solution Overview
Problem
Silicon-doped negative electrodes in lithium-ion batteries suffer from memory effects, leading to rapid capacity decay and performance issues, which existing battery management systems attempt to mitigate through forced charging and discharging, causing inconvenience and energy waste.
Innovation Solution
Adjusting the negative to positive electrode capacity ratio (NP ratio) to be greater than or equal to 1.105, ensuring the negative electrode potential remains higher than the crystalline phase formation potential, thereby preventing memory effects without the need for BMS control or forced charging and discharging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-doped negative electrodes are used to achieve high specific capacity, then energy density is improved, but memory effects occur causing capacity decay
Solution Approach 1:
The patent changes the NP ratio parameter to be greater than or equal to 1.105, which fundamentally alters the electrochemical environment of the negative electrode. This parameter change prevents crystalline phase formation by maintaining negative electrode potential above the crystallization threshold, thereby eliminating memory effects while preserving the high capacity benefits of silicon doping
2Reliability
If BMS performs forced full charging and discharging to eliminate memory effects, then capacity retention is improved, but user convenience deteriorates and energy is wasted
Solution Approach 1:
The battery structure itself provides the memory effect prevention function through its NP ratio design. The electrochemical parameters are inherently configured to prevent crystalline phase formation, making the system self-protecting without requiring external BMS intervention or user awareness of memory effect issues
Solution Approach 2:
The patent extracts the memory effect prevention function from the complex BMS control system and embeds it directly into the battery's physical structure through NP ratio design. This eliminates the need for software-based workarounds and creates a more reliable, maintenance-free solution
3Reliability
If BMS performs forced full charging and discharging to eliminate memory effects, then capacity retention is improved, but energy consumption increases
Solution Approach 1:
The NP ratio is pre-configured during battery manufacturing to prevent memory effects before they can occur during normal operation. This preliminary structural configuration eliminates the need for subsequent energy-intensive charging/discharging cycles that would otherwise be required to prevent crystallization
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 effectively alleviates memory effects, maximizes battery capacity utilization, and improves energy efficiency by maintaining the negative electrode potential above the crystalline phase formation threshold, eliminating the need for BMS-controlled charging and discharging.
Implementation Method 1
the negative electrode potential corresponding to an upper limit of SOC of the battery remains higher than the potential for crystalline phase formation
Data Source
AI summary
This application relates to a battery and an electric apparatus. A ratio of a capacity per unit area of a negative electrode of the battery to a capacity per unit area of a positive electrode of the battery is referred to as an NP ratio. The NP ratio of the battery is greater than or equal to 1.105, allowing the negative electrode potential corresponding to an upper limit of SOC of the battery to be higher than potential for crystalline phase formation, without BMS control or forced charging/discharging. This can alleviate or avoid battery memory effects, enabling maximum utilization of the capacity of the battery and improving energy efficiency of the battery.