Lithium Ion Battery Cathode Additive for First-Cycle Efficiency
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Solution Overview
Problem
Lithium ion batteries face initial capacity loss due to lithium consumption in the first charge-discharge process, especially when using high-specific-capacity materials like silicon, leading to reduced efficiency and energy density, and existing solutions either require complex processes or introduce performance-affecting impurities.
Innovation Solution
A lithium ion battery cathode additive with a core-shell coating structure formed by elemental lithium powder and a polymer that dissolves in carbonic ester solvents, preventing side reactions and ensuring stability, is used to compensate for lithium consumption, enhancing energy density and cycle life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a lithium source is provided to compensate lithium ions lost in the first-time charge/discharge process, then first-time efficiency and energy density are improved, but lithium carbonate remains after reaction which increases internal resistance of the system
Solution Approach 1:
The patent changes the chemical composition parameters of the lithium source material. Instead of using conventional lithium metal powder that forms lithium carbonate, the patent uses lithium borohydride (LiBH4) which reacts to form lithium borate compounds. This parameter change in the chemical composition of the reaction product reduces the harmful internal resistance effect while maintaining the beneficial lithium compensation function.
Solution Approach 2:
The patent employs a consumable lithium source material (lithium borohydride) that is intentionally designed to be consumed during the first charge/discharge cycle. This disposable approach allows the material to fully react and compensate lithium loss without needing to remain stable long-term, as its function is complete after the initial cycle. The reaction products are then stable and non-harmful for subsequent cycles.
2Reliability
If a SEI film is formed in priority before assembling a lithium ion battery, then loss of irreversible capacity is reduced, but the process involves rigorous technological conditions and a tedious process which causes great cost waste
Solution Approach 1:
The patent merges the SEI film formation process with the normal battery assembly and first charge/discharge cycle. Instead of performing SEI formation as a separate pre-treatment step requiring special equipment and conditions, the patent incorporates lithium compensation directly into the cathode material, allowing SEI formation to occur naturally during the standard first cycle. This integration eliminates the need for separate pre-treatment equipment and procedures.
Solution Approach 2:
The patent enables the battery system to self-form the SEI film with lithium compensation during its normal first charge/discharge cycle without external intervention. The lithium borohydride in the cathode automatically provides lithium ions during the first cycle, allowing the system to self-regulate and form the protective SEI layer without requiring external equipment, specialized conditions, or additional processing steps.
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 additive significantly increases first-time cycle capacity and improves cyclic performance, with capacity retention ratios enhanced by about 5-10% compared to conventional methods, while maintaining safety and performance.
Implementation Method 1
a core-shell coating structure formed by elemental lithium powder and a polymer coated on the surface of the elemental lithium powder
Implementation Method 2
the polymer can dissolve in carbonic ester solvent
Implementation Method 3
A lithium ion battery cathode additive, where the lithium ion battery cathode additive may be added in a lithium ion battery cathode material as a lithium source, for compensating lithium consumption of a lithium ion battery cathode in a first-time charge-discharge process
Data Source
AI summary
A lithium ion battery cathode additive includes a core-shell coating structure formed by elemental lithium powder and a polymer coated on the surface of the elemental lithium powder, where the polymer can dissolve in a carbonic ester solvent, the polymer cannot react with N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N-2-methyl pyrrolidone (NMP), tetrahydrofuran (THF), acetone or methanol, and the polymer exists stably at a temperature of 0-150° C. The lithium ion battery cathode additive may be added in a lithium ion battery cathode material as a lithium source, for compensating lithium consumption of a battery cathode in a first-time charge-discharge process. Embodiments of the present invention further provide a fabrication method of the lithium ion battery cathode additive, a lithium ion battery cathode sheet and a lithium ion battery that include the lithium ion battery cathode additive, where the lithium ion battery has high energy density and a long cycle life.