Silicon-Coated Oxide Cathode for Battery Cycle Life
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Solution Overview
Problem
Current lithium secondary battery cathode materials, particularly chalcogenide materials, fail to achieve their theoretical capacities and exhibit poor cycle characteristics, despite efforts to improve them through mechanical mixing with carbon and using specific solvents or reducing silicon concentrations.
Innovation Solution
A battery cathode material is developed by chemically bonding silicon to the surface of oxides containing cobalt, nickel, manganese, iron, or copper, which stabilizes the surface conditions and enhances cycle characteristics, even when using smaller particle sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the particle size of the active material is decreased to bring capacity closer to theoretical value, then the capacity is improved, but the cycle characteristics deteriorate
Solution Approach 1:
A silicon-containing compound forms a surface layer (shell/film) on the oxide particles. This surface layer stabilizes the surface conditions of the oxide, preventing degradation that would normally occur with small particle sizes, thereby maintaining good cycle characteristics while preserving high capacity.
Solution Approach 2:
The invention uses a composite structure combining oxide particles with a silicon-containing compound on the surface. This composite approach leverages the high capacity of fine oxide particles while the silicon-containing compound provides surface stabilization, resolving the contradiction between capacity and cycle characteristics.
2Reliability
If mechanical mixing with carbon material is used to improve capacity and cycle characteristics, then both are improved to a degree, but the cycle characteristics do not reach satisfactory level
Solution Approach 1:
Instead of mechanical mixing with carbon, the invention changes the chemical composition parameter by introducing a silicon-containing compound on the oxide surface. This chemical modification approach provides satisfactory cycle characteristics without requiring complex mechanical mixing processes.
3Quantity of substance
If silicon concentration in cobalt oxide is decreased to 500 ppm or less to achieve acceptable characteristics, then discharge capacity and capacity retention rate are improved, but the level is not satisfactory
Solution Approach 1:
Instead of treating silicon as an impurity to be minimized (as in conventional approaches), the invention inverts the approach by deliberately introducing a silicon-containing compound on the oxide surface. This inverted strategy transforms silicon from a harmful impurity into a beneficial surface stabilizer, achieving satisfactory capacity retention rate while maintaining high discharge capacity.
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 approach results in a battery with improved capacity and cycle characteristics, maintaining high performance even with smaller particle sizes, while ensuring surface stability and electrical conductivity.
Implementation Method 1
silicon Si chemically bonded to the surface of the oxide
Data Source
AI summary
A substance includes an oxide including at least one element selected from the group including cobalt Co, nickel Ni, manganese Mn, iron Fe, and copper Cu; and silicon Si chemically bonded to the surface of the oxide. Also, a battery includes a cathode, an anode, and an electrolyte, wherein the cathode includes an oxide including at least one selected from the group including cobalt Co, nickel Ni, manganese Mn, iron Fe, and copper Cu; and a substance including silicon Si chemically bonded to the surface of the oxide.