SiOx Lithium Secondary Battery for High Capacity and Cycle Life
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Solution Overview
Problem
Lithium secondary batteries face limitations in achieving high energy density and long life characteristics due to the rapid volume expansion and disconnection of conductive paths in silicon-based negative electrode materials during charging, and the low capacity of carbon-based materials.
Innovation Solution
A lithium secondary battery design incorporating SiOx and a lithium-rich manganese-based oxide as active materials, with a specific depth of SiOx usage and a mixed rock-salt and layered structure to stabilize the negative electrode and enhance capacity, while minimizing volume expansion and reaction non-uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based negative electrode active material is applied to achieve higher capacity, then capacity is improved, but the negative electrode is damaged and conductive path is disconnected due to rapid volume expansion during charging
Solution Approach 1:
A carbon coating layer is applied on the surface of SiOx particles to form a flexible protective shell. This carbon layer accommodates volume expansion during charging while maintaining structural integrity and preventing electrode damage and conductive path disconnection.
Solution Approach 2:
A composite negative electrode active material comprising SiOx and carbon-based material is used. The carbon-based material forms a matrix that supports SiOx particles, providing mechanical strength and maintaining conductive paths while allowing SiOx to expand during charging cycles.
2Quantity of substance
If silicon-based negative electrode active material is applied to achieve higher capacity, then capacity is improved, but battery performance is rapidly deteriorated
Solution Approach 1:
The carbon coating layer on SiOx particles prevents direct contact between silicon oxide and electrolyte, reducing side reactions and performance deterioration. The flexible carbon shell maintains electrical contact during volume changes, ensuring stable performance over cycling.
Solution Approach 2:
The composite structure of SiOx and carbon-based material combines the high capacity of silicon oxide with the stability and conductivity of carbon. This composite maintains structural integrity during expansion, preventing performance deterioration while achieving high capacity.
3Reliability
If carbon-based negative electrode active material is used to maintain structural stability, then reliability is improved, but capacity is limited
Solution Approach 1:
The invention merges SiOx particles with carbon-based material to create a composite negative electrode active material. This combination allows the carbon component to provide structural stability and conductivity while SiOx contributes high capacity, achieving both reliability and high 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 battery achieves excellent energy density, quick charging performance, and extended life characteristics by stabilizing SiOx expansion and compensating for irreversible capacity, thereby improving overall battery performance.
Implementation Method 1
a negative electrode including SiOx and a carbon-based negative electrode active material
Implementation Method 2
a positive electrode including a lithium-rich manganese-based oxide... excess of lithium generated from the LiMnO2 phase in the activation process may compensate for an irreversible capacity of the silicon-based negative electrode active material
Data Source
AI summary
A lithium secondary battery including: a negative electrode; a positive electrode; a separator disposed between the negative electrode and the positive electrode; and an electrolyte, wherein the negative electrode includes SiOx (where 0<x<2) and a carbon-based negative electrode active material, the positive electrode includes a positive electrode active material including a lithium-rich manganese-based oxide in which a manganese content in the total metal except lithium is greater than 50 mol %, and a ratio (Li/Me) of the number of moles of lithium to a total number of moles of metals except lithium is greater than 1, and the depth of using SiOx defined by the disclosed Equation (1) in a state of SOC 0% is 1 to 15, preferably 3 to 15.