Lithium-ion Battery Negative Electrode Coating for Zero-Voltage Stability
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Solution Overview
Problem
Conventional lithium-ion batteries suffer from capacity loss and corrosion of the negative electrode current collector when discharged to near zero volts, leading to degradation in subsequent charging and discharging operations.
Innovation Solution
Incorporating a lithium titanate material on the negative current collector and a secondary active material on the positive current collector that provides charging and discharging capacity below the corrosion potential of the negative current collector and above the decomposition potential of the primary active material, allowing for stable operation at near-zero voltage conditions without capacity degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the battery is discharged to near zero volts, then the deliverable capacity is maximized, but the negative electrode current collector corrodes and capacity is lost
Solution Approach 1:
A coating layer comprising metal fluoride, metal oxide, or metal oxyfluoride is applied to the negative electrode current collector to act as an intermediary barrier. This coating prevents direct contact between the copper current collector and the electrolyte, thereby preventing corrosion while allowing lithium ion transport during charging and discharging cycles.
Solution Approach 2:
The invention changes the surface properties of the negative electrode current collector by applying a protective coating that alters the electrochemical potential environment. The coating modifies the interface between the current collector and electrolyte, preventing the copper from reaching potentials that cause corrosion while maintaining functional performance.
2Reliability
If protection circuitry is added to prevent over-discharge, then the battery reliability is improved, but the device complexity increases
Solution Approach 1:
The protective coating on the negative electrode current collector provides inherent, passive protection against corrosion during over-discharge conditions. The battery structure itself becomes self-protecting through the coating's ability to prevent copper corrosion even when discharged to zero volts, eliminating the need for external active protection circuitry.
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
The lithium-ion battery maintains its capacity and prevents corrosion of the negative electrode and battery case, enabling repeated cycling to near-zero-voltage conditions without significant performance decline, potentially eliminating the need for protective circuitry and enhancing the battery's lifespan.
Implementation Method 1
During charging and discharging of the battery 10, lithium ions move between the positive electrode 20 and the negative electrode 30
Implementation Method 2
The second active material exhibits charging and discharging capacity below a corrosion potential of the negative current collector and above a decomposition potential of the first active material
Data Source
AI summary
A lithium-ion battery includes a positive electrode including a positive current collector, a first active material, and a second active material. The battery also includes a negative electrode having a negative current collector and a third active material, the third active material including a lithium titanate material. The first active material, second active material, and third active materials are configured to allow doping and undoping of lithium ions. The second active material exhibits charging and discharging capacity below a corrosion potential of the negative current collector and above a decomposition potential of the first active material.