Lithium Primary Battery Negative Electrode Carbon Composite
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Solution Overview
Problem
Lithium primary batteries experience significant voltage drops during large current discharge at low temperatures and increased internal resistance during high-temperature storage, particularly due to negative electrode polarization and interface resistance issues.
Innovation Solution
The battery incorporates a negative electrode with a surface layer comprising a composite of amorphous carbon material and lithium metal or alloy, along with embedded microparticles, to reduce polarization and enhance ion diffusion, thereby stabilizing the interface with the electrolyte and improving discharge performance across temperature ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a solvent mixture of 1,2-dimethoxyethane and γ-butyrolactone is used to improve low temperature discharge performance, then discharge voltage increases at low temperature, but gas generation increases during high temperature storage causing battery expansion
Solution Approach 1:
The invention changes the chemical composition parameters of the organic electrolyte by introducing cyclic carbonate esters (EC, PC) and chain carbonate esters (DMC, DEC, EMC) with specific dielectric constants and viscosities. This parameter optimization allows the electrolyte to maintain adequate ion conductivity at low temperatures without excessive gas generation at high temperatures, resolving the contradiction between low-temperature discharge performance and high-temperature storage stability
Solution Approach 2:
The invention uses a composite electrolyte system combining multiple carbonate ester solvents (cyclic and chain types) with balanced properties. The composite formulation leverages the high dielectric constant of cyclic carbonates for LiClO4 dissolution and the low viscosity of chain carbonates for ion mobility, achieving both low-temperature discharge capability and high-temperature storage stability without the severe gas generation issues of pure 1,2-dimethoxyethane/γ-butyrolactone mixtures
2Use of energy by moving object
If lithium metal is used as negative electrode active material to achieve high voltage and high energy density, then energy density increases, but negative electrode polarization increases during large current discharge at low temperature
Solution Approach 1:
The invention optimizes the electrolyte's physical parameters (viscosity, dielectric constant, freezing point) by selecting specific carbonate ester combinations. This enables adequate LiClO4 dissolution and ion mobility at low temperatures, reducing negative electrode polarization and improving large current discharge performance while maintaining the high energy density benefits of lithium metal electrodes
Solution Approach 2:
The invention creates a locally optimized electrolyte environment at the negative electrode interface by using carbonate esters with appropriate solvation capabilities. This local optimization ensures efficient lithium ion extraction from the lithium metal surface during discharge without excessive polarization, while the bulk electrolyte maintains properties suitable for high energy density
3Reliability
If graphite fluoride is used as positive electrode active material to improve long-term storage and high temperature stability, then storage characteristics improve, but voltage drop in initial discharge stage increases at low temperature
Solution Approach 1:
The invention adjusts the electrolyte's dielectric constant and viscosity parameters by using carbonate ester combinations that maintain adequate ion conductivity at low temperatures. This reduces the voltage drop in the initial discharge stage when using graphite fluoride, while the chemical stability of carbonate esters preserves the excellent long-term storage and high-temperature stability 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 reduces negative electrode polarization, enhances large current discharge performance at low temperatures, and maintains high-temperature storage stability, ensuring reliable battery operation.
Implementation Method 1
a negative electrode, and the negative electrode has at least one characteristic of (a) to (c) below. (a) At least a surface layer portion of the negative electrode comprises a composite of an amorphous carbon material and a negative electrode active material
Implementation Method 2
The negative electrode includes a surface layer portion to which microparticles are embedded; the microparticles comprise primary particles with an average particle size (median size) of 2 μm or less
Data Source
AI summary
A lithium primary battery including a positive electrode, a negative electrode, an organic electrolyte, and a separator interposed between the positive electrode and the negative electrode: the negative electrode including a negative electrode active material; the negative electrode active material being at least one selected from the group consisting of lithium metal and a lithium alloy; at least a surface layer portion of the negative electrode including a composite of amorphous carbon material and the negative electrode active material; and the surface layer portion facing the positive electrode with the separator interposed therebetween.