Positive Electrode Phosphate Coating for High-Temperature Battery Stability
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries, particularly lithium-ion batteries, experience capacity degradation and heat generation during high-temperature storage due to oxidative decomposition of the electrolyte, which existing techniques fail to adequately prevent.
Innovation Solution
A positive electrode comprising a mixture of first particles with lithium transition metal oxide and second particles with electrochemically inactive metal oxide, where an electrochemically inactive phosphate adheres to the surface of the second particles, selectively reducing the degradation of the positive-electrode active material and maintaining crystal structure stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium transition metal oxide is used as positive-electrode active material to achieve high voltage and high energy density, then battery energy density is improved, but oxidative decomposition of electrolyte occurs during high-temperature storage causing capacity loss
Solution Approach 1:
The phosphate-containing surface coating acts as an intermediary layer between the lithium transition metal oxide and the non-aqueous electrolyte. This intermediate surface layer prevents direct contact and harmful interactions between the high-voltage positive electrode material and the electrolyte, thereby suppressing oxidative decomposition during high-temperature storage while preserving the high energy density characteristics.
2Ease of operation
If high-temperature storage is performed with charged battery to maintain readiness, then operational readiness is maintained, but electrolyte oxidatively decomposes and positive-electrode active material reduces
Solution Approach 1:
The invention applies preliminary protective action by forming a stable phosphate-containing surface coating on the positive electrode before high-temperature storage occurs. This pre-formed protective layer prevents oxidative decomposition during subsequent high-temperature storage, allowing the battery to maintain operational readiness without suffering capacity loss.
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 proposed solution effectively reduces capacity loss and heat generation in non-aqueous electrolyte secondary batteries during high-temperature storage by suppressing the reduction of the positive-electrode active material and oxidative decomposition of the electrolyte, thereby enhancing battery performance and safety.
Implementation Method 1
selective reduction of the phosphate adhering to the surface of the second particle suppresses the reduction of the positive-electrode active material
Implementation Method 2
a non-aqueous electrolyte may be oxidatively decomposed
Data Source
AI summary
A positive electrode for a non-aqueous electrolyte secondary battery contains a first particle and a second particle. The first particle contains an electrochemically active positive-electrode active material, and the positive-electrode active material contains a lithium transition metal oxide. The second particle contains an electrochemically inactive metal oxide. An electrochemically inactive phosphate adheres to the surface of the second particle.