Nano-composite Lithium Battery Electrode for High Power Density
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Solution Overview
Problem
Available lithium ion batteries do not achieve a good high rate discharge system, leading to deficiencies in energy density and power density, particularly in applications like power tools and electric vehicles.
Innovation Solution
A nano-crystalline composite positive electrode material with a layered-layered or layered-spinel structure, coated with inert oxides, phosphates, or fluorides, is synthesized using methods like co-precipitation or sol-gel synthesis, enhancing the morphology and performance of the electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional composite structures are used in positive electrode material, then structural integration is achieved, but high rate discharge performance is insufficient
Solution Approach 1:
The positive electrode material is segmented into nanoscale composite particles consisting of layered Li2MnO3 and spinel LiMn2−yMyO4 phases distributed at the nanoscale level. This segmentation increases the surface area to volume ratio and creates multiple pathways for ion transport, enabling high rate discharge while maintaining structural integrity
Solution Approach 2:
A composite material system is designed combining layered Li2MnO3 and spinel LiMn2−yMyO4 phases in a nanoscale composite structure. The layered phase provides high capacity while the spinel phase provides structural stability and fast ion transport channels, achieving both high energy and power density
2Productivity
If particle size is reduced to nanoscale, then discharge capacity is improved, but surface reactivity and stability may worsen
Solution Approach 1:
A thin coating layer is introduced as an intermediary between the nanoscale active material particles and the electrolyte. This coating layer passivates the particle surface, reducing unwanted side reactions while maintaining ionic conductivity, thus improving surface stability without compromising discharge capacity
Solution Approach 2:
The particle size parameter is changed to nanoscale dimensions, which fundamentally alters the surface-to-volume ratio and surface energy characteristics. This parameter change requires corresponding adjustments in surface treatment and coating strategies to maintain stability
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 nano-crystalline composite structure with inert coatings improves discharge capacity, maintains high power density, and extends cycle life, achieving over 900 cycles and continuous power densities of 2500 W/kg in lithium ion batteries for high-power applications.
Implementation Method 1
a positive electrode material having a nano-crystalline layered-layered composite structure of a material having the general formula xLi2MO3(1−x)LiM′O2
Implementation Method 2
a thin layer of inert oxide is applied on composite positive electrode particles
Data Source
AI summary
Provided is a positive electrode for a lithium ion battery, the electrode comprising a nano-crystalline layered-layered composite structure of a material having the general formula xLi2MO3(1−x)LiM′O2 in which 0<x<1, where M′ is one or more ion with an average oxidation state of three and with at least one ion being Mn or Ni, and where M is one or more ions with an average oxidation state of four. Another aspect provides a positive electrode for a lithium ion battery, the electrode comprising a nano-crystalline layered-spinel composite structure of a material having the general formula xLi2MnO3. (1−x)LiMn2−yMyO4 in which 0.5<x<1.0, 0≤y<1, and where M is one or more metal cations. Also provided is the positive electrode which comprises a nano-coating of inert oxide, inert phosphate or inert fluoride on the nano-crystalline composite structure. Additional aspects provide a lithium ion battery comprising a negative electrode, an electrolyte and the positive electrode, as well as methods of preparing the positive electrode composite structure and the nano-coating of inert oxide, inert phosphate or inert fluoride.