Four-Electrode Lithium-Ion Battery for Capacity Retention Recovery
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Solution Overview
Problem
Lithium ion batteries suffer from capacity retention issues due to the destruction and growth of the negative SEI and positive CEI, consumption of active lithium, and the formation of lithium dendrites, leading to reduced cruising ability and increased replacement frequency, especially in electric vehicles.
Innovation Solution
Incorporation of a lithium ion battery design with four electrodes, including a third electrode of metal lithium and a fourth electrode of activated carbon, allowing for controlled lithium supplementation and temporary storage, thereby maintaining capacity retention and preventing lithium precipitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If traditional graphite negative electrode material is used, then safety is maintained, but specific energy cannot meet the requirements of 300 Wh/kg power batteries
Solution Approach 1:
The patent uses silicon-carbon composite negative electrode material that combines silicon's high theoretical specific capacity (4200 mAh/g) with carbon's structural stability. The carbon matrix accommodates silicon's volume expansion while maintaining electrode integrity, achieving both high specific energy (300 Wh/kg) and acceptable capacity retention through material composition optimization
Solution Approach 2:
The patent applies local quality by creating a graded silicon-carbon structure where silicon content is optimized in specific regions. The negative electrode contains silicon particles distributed within a carbon matrix, with varying local compositions that balance lithium insertion capacity and structural stability, enabling high energy density while maintaining cycle life
2Quantity of substance
If silicon-based high-capacity negative electrode materials are used to improve specific energy, then specific capacity increases, but volume expansion reaches 300% causing SEI film cracks and continuous consumption of electrolyte and active lithium
Solution Approach 1:
The patent employs a flexible carbon coating shell around silicon particles that can accommodate the 300% volume expansion during lithium insertion. This carbon shell acts as a protective buffer that prevents SEI film cracking, maintaining electrolyte and lithium stability while enabling silicon's high capacity utilization
Solution Approach 2:
The patent utilizes a porous carbon matrix structure that provides缓冲 space for silicon volume changes. The porous structure allows electrolyte penetration while accommodating expansion, preventing mechanical failure of the SEI film and reducing continuous consumption of electrolyte and active lithium during cycling
3Reliability
If lithium supplement technologies are applied to improve first cycle efficiency, then active lithium loss is compensated, but pre-lithiation degree is uncontrollable leading to Li dendrite formation
Solution Approach 1:
The patent implements self-service by designing a self-regulating lithium supplementation mechanism. The silicon-carbon negative electrode automatically compensates for lithium loss through its high capacity buffer (4200 mAh/g theoretical capacity), eliminating the need for external pre-lithiation operations and their associated control problems with dendrite formation
Solution Approach 2:
The patent introduces the silicon-carbon composite as an intermediary that mediates lithium supplementation. Instead of directly adding lithium (which causes dendrites), the silicon component acts as an intermediate reservoir that gradually supplies lithium to compensate for SEI formation losses, achieving first cycle efficiency improvement without dendrite formation
4Quantity of substance
If lithium powder is sprayed on negative electrode surface by electrostatic control, then lithium supplementation is attempted, but uniformity is poor due to Li powder's light weight and large specific surface area
Solution Approach 1:
The patent extracts the lithium supplementation function from the negative electrode surface treatment process and relocates it to the silicon-carbon composite material itself. The high-capacity silicon particles embedded in the carbon matrix provide intrinsic lithium buffer capacity, eliminating the need for electrostatic spraying and its associated uniformity problems
5Reliability
If ultra-thin lithium is used to prevent dendrite formation, then safety is improved, but production requirements and cost increase significantly
Solution Approach 1:
The patent replaces expensive ultra-thin lithium with a cost-effective silicon-carbon composite negative electrode. The silicon-carbon material provides equivalent or superior dendrite prevention through its carbon matrix structure and volume expansion accommodation, eliminating the need for costly ultra-thin lithium processing while maintaining safety
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 four-electrode design enhances capacity retention, supports battery repair and regeneration, and reduces safety risks associated with lithium dendrite formation, enabling improved cruising ability and cost-effectiveness in electric vehicles.
Implementation Method 1
The theoretical specific capacity of a Si material is as high as 4200 m Ah/g, but the volume expansion is as high as 300% during lithium intercalation
Implementation Method 2
a third electrode and a fourth electrode, which are provided between the positive electrode plate and the negative electrode plate, wherein the third electrode and the fourth electrode are separated by means of a single-layer separator, a metal lithium electrode being used as the third electrode, and an activated carbon electrode being used as the fourth electrode
Data Source
AI summary
The invention relates to a lithium ion battery with a high capacity retention rate, and a preparation method and charging and discharging methods thereof. The lithium ion battery comprises a positive electrode plate, a negative electrode plate, separators arranged between the positive electrode plate and the negative electrode plate at intervals, and an electrolyte, and further comprises a third electrode and a fourth electrode, which are independent of each other and provided between the positive electrode plate and the negative electrode plate, wherein the third electrode and the fourth electrode are separated by means of a single-layer separator, a metal lithium electrode being used as the third electrode, and an activated carbon electrode being used as the fourth electrode. The third electrode and the fourth electrode cooperate with each other to realize supplementation of active lithium of a lithium ion battery at different stages by means of controlled use at different stages, thereby achieving repair and regeneration of the lithium ion battery, and finally, comprehensively increasing the long-cycle capacity retention rate of the current lithium ion battery, especially a solid-liquid lithium ion battery, and increasing the cruising ability retention rate of an electric vehicle.