High-Nickel Lithium Secondary Battery with CNT Cathode Conductivity
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Solution Overview
Problem
Lithium secondary batteries face challenges in increasing energy density and high-output performance due to limitations in using lithium cobalt oxide as a positive electrode material and graphite as a negative electrode material, with issues such as high cost, unstable supply, thermal instability, and low capacity per unit mass.
Innovation Solution
A lithium secondary battery design incorporating a positive electrode with a lithium composite transition metal compound and multi-walled carbon nanotubes, and a negative electrode with silicon-based oxide, optimized in terms of composition and structure to enhance conductivity and cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If lithium cobalt oxide is used as positive electrode material, then operating voltage and capacity characteristics are improved, but cost and supply stability deteriorate
Solution Approach 1:
The patent replaces expensive lithium cobalt oxide with lithium nickel oxide, which is cheaper and more readily available. Although lithium nickel oxide has lower intrinsic stability, the patent compensates through surface modification and electrolyte additives to achieve acceptable cycle life, effectively using a cheaper material that would otherwise have short service life
Solution Approach 2:
The patent changes the chemical composition parameters of the positive electrode material from LiCoO2 to LiNiO2, altering the metal oxide ratio to reduce cobalt content. This parameter change reduces cost and improves supply stability while maintaining adequate voltage characteristics through optimized electrode structure and electrolyte formulation
2Quantity of substance
If nickel content in NCM-based lithium composite transition metal oxide is increased, then capacity is improved, but thermal stability deteriorates
Solution Approach 1:
The patent uses lithium nickel oxide which inherently has lower thermal stability but higher capacity, accepting the trade-off by implementing protective measures such as surface coating and electrolyte additives to extend usable service life while maintaining high capacity output
Solution Approach 2:
The patent introduces surface coating layers and electrolyte additives as intermediary substances between the high-nickel positive electrode material and the electrolyte. These intermediaries protect the thermally unstable nickel-rich material from direct contact with electrolyte, reducing side reactions and improving thermal stability while preserving high capacity
3Use of energy by moving object
If non-carbon-based negative electrode materials are used, then energy density is improved, but initial efficiency deteriorates
Solution Approach 1:
The patent creates a composite negative electrode structure combining silicon-based oxide particles with carbon matrix material. The silicon-based oxide provides high capacity and energy density, while the carbon matrix provides conductive pathways and structural stability, resulting in a composite material that achieves both high energy density and acceptable initial efficiency
Solution Approach 2:
The patent introduces carbon material as an intermediary substance surrounding the silicon-based oxide particles. This carbon layer acts as a mediator that provides electrical conductivity to the inherently conductive silicon-based oxide, facilitates electron transport, and maintains structural integrity during initial cycling, thereby improving initial efficiency while preserving high energy density
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 design achieves increased energy density and improved high-output performance, with enhanced battery cycle characteristics and efficiency, while reducing the content of conductive materials to increase capacity and adapt to limited space requirements.
Implementation Method 1
a conductive material including multi-walled carbon nanotubes
Implementation Method 2
electrical energy is produced by oxidation/reduction reactions at a time when lithium ions are intercalated/deintercalated into/from the positive electrode and the negative electrode
Data Source
AI summary
A lithium secondary battery includes a positive electrode; a negative electrode; a separator between the positive electrode and the negative electrode; and an electrolyte. The positive electrode includes a positive electrode current collector and a positive electrode active material layer on the positive electrode current collector. The negative electrode includes a negative electrode current collector and a negative electrode active material layer on the negative electrode current collector. The positive electrode active material layer includes a positive electrode active material including a lithium composite transition metal compound in a single particle form including cobalt, manganese, 80 mol % or more and less than 100 mol % of nickel in metals except lithium; and a conductive material including multi-walled carbon nanotubes. The negative electrode active material layer includes a negative electrode active material including a silicon-based oxide. A battery module and a battery pack including the lithium secondary battery are also disclosed.