High-Nickel Cathode Surface Doping for Sulfide Solid-State Batteries
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Secondary batteries using sulfide solid electrolytes with high nickel-type positive electrode active materials face challenges in achieving sufficient initial capacity and cycle durability due to issues like increased battery resistance and decreased energy density.
Innovation Solution
A lithium-containing composite oxide with a specific composition is used as the positive electrode active material, where additional elements like B, P, or Si are introduced in higher concentrations in the surface layer region, combined with a sulfide solid electrolyte containing sulfur and phosphorus, to enhance performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a high nickel-type positive electrode active material is used to increase capacity, then energy density is improved, but battery resistance increases and cycle durability decreases
Solution Approach 1:
The patent applies local quality by creating a surface layer region with different composition from the central portion. The surface layer has modified elemental distribution (particularly Ni, Co, Mn, and O concentrations) to provide protective properties, while the central portion maintains high Ni content for high capacity. This local differentiation allows the surface to protect against degradation while the core provides high energy density.
Solution Approach 2:
The patent uses composite materials by combining a lithium-containing composite oxide with a sulfide solid electrolyte containing sulfur and phosphorus. The composite positive electrode active material consists of multiple elements (Li, Ni, Co, Mn, O) in specific proportions, creating a material that balances high capacity with improved stability and resistance to oxidation.
2Power
If a reaction-inhibiting layer is formed on the positive electrode active material to prevent resistance increase, then output characteristics are improved, but manufacturing complexity increases
Solution Approach 1:
The patent merges the positive electrode active material and the reaction-inhibiting layer into a single composite material. The surface layer region is formed by controlling the elemental distribution during material synthesis rather than by separate coating processes. This integration simplifies manufacturing while maintaining the protective function against oxidation and resistance increase.
3Power
If conductive material is added to improve electron conductivity, then output characteristics improve, but positive electrode active material content decreases and energy density drops
Solution Approach 1:
The patent changes the compositional parameters of the positive electrode active material itself to achieve conductivity improvement. By adjusting the ratios of Ni, Co, Mn, and O in the lithium-containing composite oxide, the material achieves appropriate electron conductivity without needing separate conductive additives. This parameter optimization maintains high active material content while improving output characteristics.
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 configuration significantly improves the initial capacity and cycle durability of the secondary battery by stabilizing the metal-oxygen bond and reducing oxidation reactions, leading to better battery performance.
Implementation Method 1
stabilizing the metal-oxygen bond and reducing oxidation reactions
Data Source
AI summary
The initial capacity and cycle durability are improved in a secondary battery which uses a sulfide solid electrolyte containing sulfur and phosphorus and high nickel-type positive electrode active material. In the secondary battery having a power generating element containing, laminated in this order, a positive electrode with a positive electrode active material layer containing a positive electrode active material composed of a so-called high nickel-type lithium-containing composite oxide, an electrolyte layer which contains a sulfide solid electrolyte containing sulfur and phosphorus, and a negative electrode with a negative electrode active material layer containing a negative electrode active material, one or more added element selected from the group consisting of B, P, S and Si is made to be present in a molar concentration larger than that of Ni, into a surface layer region having a depth within 100 nm from the surface of a particle of the lithium-containing composite oxide.