Lithium Ion Battery Electrode Design for High Energy Density
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Solution Overview
Problem
Lithium ion secondary batteries face challenges in achieving high energy density and output characteristics while maintaining durability, particularly due to issues with conductive filler linkage in the positive electrode active material layer and increased resistance from thick solid electrolyte layers at high temperatures.
Innovation Solution
A lithium ion secondary battery design featuring a positive electrode with a transition metal oxide and specific compounds in the positive electrode active material layer, along with a negative electrode alloy-type material, and a nonaqueous electrolytic solution, which includes pre-doping of the negative electrode with lithium ions without using lithium metal, to enhance energy density and charge/discharge cycle durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the conductive filler amount and pore sizes in the positive electrode active material layer are increased to improve output characteristic, then the lithium ion conductivity is enhanced, but the positive electrode bulk density is reduced and energy density is lowered
Solution Approach 1:
The patent optimizes the pore size distribution and conductive filler content parameters to achieve a balance between output characteristic and energy density. By controlling the pore size within specific ranges and adjusting the conductive filler amount, the patent enhances lithium ion conductivity while maintaining positive electrode bulk density, thereby resolving the contradiction between power output and energy density
2Reliability
If a thick solid electrolyte layer is formed on the negative electrode to suppress degradation under high temperature, then reliability is improved, but the resistance increases and output characteristic deteriorates
Solution Approach 1:
The patent employs a thin film solid electrolyte layer that provides sufficient protection against high-temperature degradation while maintaining low resistance. By optimizing the thickness and composition of the solid electrolyte coating, the patent achieves reliable degradation suppression without compromising output characteristic, thus resolving the contradiction between reliability and power
3Duration of action of stationary object
If the depth of discharge range is limited to improve durability and high-temperature storage characteristic, then the cycle life is extended, but the usable capacity is reduced
Solution Approach 1:
The patent modifies the electrochemical parameters of the electrode materials and electrolyte composition to enable stable operation over a wider depth of discharge range. By changing these parameters, the patent extends cycle life and improves high-temperature storage characteristic while maintaining high usable capacity, thus resolving the contradiction between durability and usable capacity
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 solution provides a lithium ion secondary battery with improved high energy density, high output characteristics, and excellent durability, including low gas generation during high-temperature storage, and accelerated charge/discharge cycles under high load conditions.
Implementation Method 1
the common method is to add an additive to the electrolyte that can form a satisfactory solid electrolyte on the negative electrode by reductive decomposition
Implementation Method 2
a lithium ion-containing nonaqueous electrolytic solution
Implementation Method 3
a positive electrode active material containing a transition metal oxide capable of intercalating and releasing lithium ions
Data Source
AI summary
A lithium ion secondary battery of the present disclosure is provided with a positive electrode, a negative electrode, a separator, and a nonaqueous electrolyte containing lithium ions.