Hollow Lithium Battery Electrodes for High-Load Capacity Retention
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Solution Overview
Problem
Lithium secondary batteries with hollow structure positive electrode materials experience capacity decrease due to lithium deposition on the negative electrode during high-voltage and large current charging, leading to reduced battery performance and durability.
Innovation Solution
A lithium secondary battery design featuring a positive electrode with a hollow structure of lamellar lithium transition metal oxide and a negative electrode with a carbon material and controlled krypton adsorption amount, optimizing the surface area for lithium ion storage and preventing electrolyte decomposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a positive electrode active material of a hollow structure is used to improve output characteristics and maintain wide SOC range performance, then material exchange efficiency increases and output characteristics improve, but lithium deposition occurs on the negative electrode during rapid charging, causing capacity decrease
Solution Approach 1:
The patent changes the structural parameters of the positive electrode active material from a solid structure to a hollow structure with specific shell thickness (2 μm or less) and primary particle size (1 μm or less). This parameter change increases the contact surface area between the electrolytic solution and active material, improving material exchange efficiency and output characteristics while maintaining structural integrity to prevent lithium deposition during rapid charging
Solution Approach 2:
The patent uses a composite structure where the hollow positive electrode active material consists of a shell portion formed of lithium transition metal oxide with specific compositional ratios (0.3 ≤ y + z ≤ 0.8, 0.05 ≤ a ≤ 0.5, 0.95 ≥ b ≥ 0.05). This composite material design optimizes both the output characteristics through the hollow structure and the stability to prevent lithium deposition through controlled composition
2Reliability
If the surface area of the negative electrode active material is enlarged to suppress lithium deposition, then lithium ion adsorption capacity increases, but electrolyte decomposition becomes more prone, reducing durability
Solution Approach 1:
The patent optimizes the surface area parameter of the negative electrode active material by controlling the Kr adsorption amount to be 3.0 m²/g or more but 4.5 m²/g or less. This parameter optimization provides sufficient surface area for lithium ion adsorption to suppress lithium deposition while maintaining appropriate electrolyte contact to prevent decomposition and preserve durability
Solution Approach 2:
The patent uses the negative electrode active material surface as an intermediary that mediates between lithium ions and the electrolyte. By optimizing the surface area (Kr adsorption amount), the material effectively adsorbs lithium ions to prevent deposition while controlling the interaction with the electrolyte to avoid decomposition, thus protecting both the battery capacity and durability
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 battery exhibits improved input and output characteristics, maintaining capacity retention and durability even under high load conditions, while preventing lithium deposition and electrolyte degradation.
Implementation Method 1
suppressing such lithium deposition by enlarging the surface area of a negative electrode active material that may adsorb lithium ions physically (that is to say, by interaction of van der Waals forces)
Implementation Method 2
since the contact surface area between the electrolytic solution and the active material may be kept wide, material exchanges (for instance, movements of lithium ions) between the electrolytic solution and the active material can be carried out more efficiently
Data Source
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AI summary
A lithium secondary battery includes an electrode body containing a positive electrode and a negative electrode, a non-aqueous electrolytic solution, and a battery case in which the electrode body and the non-aqueous electrolytic solution are housed, wherein the positive electrode includes a positive electrode active material particle of a hollow structure having a shell portion formed of a lamellar lithium transition metal oxide and a hollow portion formed therein, the long diameter of a primary particle of the lithium transition metal oxide based on SEM observation is 1 mum or less, the thickness of the shell portion based on SEM observation is 2 muetaiota or less, the negative electrode is provided with a negative electrode active material particle formed of a carbon material, and a krypton adsorption amount of the negative electrode active material particle is 3.5 m2/g or greater but 4 m2/g or less.