Non-aqueous Electrolyte Battery Charging Control for Cycle Performance
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries using manganese oxide with a spinel structure suffer from degraded performance due to phase changes during charging, and existing methods to prevent high-temperature storage degradation do not achieve sufficient cycle performance.
Innovation Solution
A method involving a non-aqueous electrolyte secondary battery with a positive electrode active material composed of a mixture of lithium-transition metal composite oxides containing Ni and Mn, and lithium-manganese composite oxide, where the charging is controlled to maintain an end-of-charge voltage higher than 4.3 V, preferably 4.34 V, to enhance cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If manganese oxide with spinel structure is used as positive electrode active material, then high energy density is achieved, but structure degrades due to phase change during charging
Solution Approach 1:
The patent applies parameter changes by controlling the end-of-charge voltage to be higher than 4.3 V, which alters the charging parameters to prevent phase change in the manganese oxide spinel structure. This voltage control parameter change resolves the contradiction by maintaining structural stability while preserving high energy density.
Solution Approach 2:
The patent uses a composite material approach by formulating a positive electrode active material that is a mixture of lithium-transition metal composite oxide containing Ni and Mn, and lithium-manganese composite oxide. This composite structure prevents phase change degradation while maintaining high energy density.
2Reliability
If Li-Ni-Co composite oxide is added to prevent high-temperature storage degradation, then storage performance is improved, but cycle performance remains insufficient
Solution Approach 1:
The patent changes the charging parameter (end-of-charge voltage > 4.3 V) to simultaneously improve both high-temperature storage performance and cycle performance, resolving the contradiction where previous methods could only improve storage performance but not cycle performance.
Solution Approach 2:
The patent optimizes the composite material formulation by specifying a mixture of lithium-transition metal composite oxide containing both Ni and Mn, and lithium-manganese composite oxide, which together provide both storage stability and cycle durability when combined with the voltage control method.
3Duration of action of moving object
If end-of-charge voltage is controlled higher than 4.3 V, then cycle performance is improved, but risk of overcharging increases
Solution Approach 1:
The patent applies a precise parameter change by setting a specific voltage threshold (> 4.3 V) that enables improved cycle performance while avoiding overcharging. This controlled parameter change resolves the contradiction by establishing a safe operating boundary.
Solution Approach 2:
The patent implements feedback control by monitoring and controlling the end-of-charge voltage to maintain it above 4.3 V, which provides feedback-based regulation to achieve good cycle performance while preventing harmful overcharging conditions.
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 results in improved cycle performance and reduced I-V resistance increase, maintaining battery efficiency and stability by controlling the end-of-charge voltage, thereby addressing the degradation issues associated with manganese oxide-based batteries.
Implementation Method 1
the negative electrode active material is composed of metallic lithium, a carbon material, or an alloy capable of intercalating and deintercalating lithium ions
Implementation Method 2
a non-aqueous electrolyte secondary battery comprising a positive electrode having a positive electrode active material made of a mixture of a lithium-transition metal composite oxide containing at least Ni and Mn as transition metals and a lithium-manganese composite oxide
Data Source
AI summary
Good cycle performance is obtained with a non-aqueous electrolyte secondary battery having a positive electrode, a negative electrode, and a non-aqueous electrolyte. The positive electrode contains as positive electrode active material a mixture of a lithium-manganese composite oxide and a lithium-transition metal composite oxide containing at least Ni and Mn as transition metals. The negative electrode contains as a negative electrode active material a material capable of intercalating and deintercalating lithium. Charging of the non-aqueous electrolyte secondary battery is controlled so that the end-of-charge voltage becomes higher than 4.3 V.