Composite Li-Ion Cathode Activation for Lithium Loss Recovery
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Solution Overview
Problem
Lithium-ion batteries suffer from initial lithium loss during formation and subsequent use, leading to capacity loss and reduced cycle life, with existing materials having different operating voltage ranges that prevent effective mixing and lithium replenishment strategies being inadequate.
Innovation Solution
A positive electrode active composite comprising 60%-99% lithium iron phosphate material and 1%-40% ternary material, such as lithium nickel manganese cobalt oxide, is introduced, allowing lithium-rich ternary materials to replenish lithium within a specific voltage range (4.1 V to 4.4 V) to enhance battery capacity and cycle life, while an electrolyte additive stabilizes the interface to reduce degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium iron phosphate material is used as positive electrode material, then battery safety and cycle life are improved, but battery capacity is limited due to its operating voltage range (3.2-3.65 V)
Solution Approach 1:
The patent combines lithium iron phosphate material (providing safety and long cycle life) with ternary material (providing high capacity) in a composite positive electrode structure. This merging allows the battery to simultaneously achieve the safety and durability of LFP and the high capacity of ternary materials, resolving the contradiction between reliability and quantity of substance.
Solution Approach 2:
The patent uses composite materials by creating a positive electrode containing both lithium iron phosphate and ternary materials. This composite structure enables the battery to benefit from the complementary properties of both materials: LFP provides structural stability and safety while ternary material contributes higher capacity, thus resolving the trade-off between reliability and capacity.
2Quantity of substance
If ternary material is used as positive electrode material, then battery capacity is improved, but battery safety and cycle life deteriorate due to its operating voltage range (2.8-4.25 V)
Solution Approach 1:
The patent merges ternary material (high capacity) with lithium iron phosphate material (high safety and stability) in a composite positive electrode. This combination allows the battery to achieve high capacity from the ternary material while the LFP component provides structural stability and safety, resolving the contradiction between capacity and reliability.
Solution Approach 2:
The patent changes the operating voltage parameters by establishing a dual voltage window: 3.2-3.65 V for LFP (ensuring safety) and 2.8-4.25 V for ternary material (enabling high capacity). This parameter optimization allows both materials to operate within their optimal ranges simultaneously, resolving the contradiction between capacity and safety.
3Adaptability or versatility
If different positive electrode materials with different operating voltage ranges are used, then battery performance can be optimized, but effective mixing and lithium replenishment become difficult
Solution Approach 1:
The patent applies preliminary action by performing lithium replenishment charging at a specific activation voltage (4.1-4.4 V) after battery assembly. This preliminary high-voltage charging step pre-activates the ternary material to release lithium ions that will subsequently replenish the LFP material, making the mixing and lithium transfer process effective despite the different voltage ranges of the two materials.
Solution Approach 2:
The patent uses the electrolyte as an intermediary medium to facilitate lithium ion transfer between the ternary and LFP materials. The electrolyte enables lithium ions to move from the activated ternary material to the LFP material, resolving the difficulty of lithium replenishment between materials with different operating voltage ranges.
4Quantity of substance
If battery is charged to high voltage (4.1-4.4 V) to activate lithium replenishment, then battery capacity is improved, but electrode degradation and electrolyte decomposition increase
Solution Approach 1:
The patent applies preliminary action by performing high-voltage activation charging (4.1-4.4 V) as an initial step after battery assembly, before normal operation begins. This one-time preliminary high-voltage treatment activates the ternary material to release lithium ions for replenishment, while subsequent normal operation stays within lower voltage limits (3.2-3.65 V for LFP, 2.8-4.25 V for ternary), minimizing ongoing degradation and decomposition.
Solution Approach 2:
The patent uses periodic action by implementing a dual-stage charging protocol: initial high-voltage activation charging (4.1-4.4 V) to replenish lithium, followed by normal operation within optimized voltage windows. This periodic alternation between high-voltage replenishment mode and normal operation mode allows capacity improvement while limiting cumulative degradation through controlled voltage management.
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 composite improves battery capacity and cycle life by controlling the operating voltage within suitable ranges for both materials, achieving high safety and long service life, and the electrolyte additive reduces oxidative decomposition and gas generation, thereby enhancing battery safety and performance.
Implementation Method 1
the positive electrode active composite provided herein is composed of 60%-99% by weight of the lithium iron phosphate material and 1%-40% by weight of the ternary material, where relatively abundant lithium is stored in crystal lattices of the ternary material
Implementation Method 2
the electrolyte additive can stabilize an interface between the electrode and the electrolyte, or form a passivation film on a surface of the positive electrode, so as to reduce the degradation of electrode surfaces and the oxidative decomposition of the electrolyte
Implementation Method 3
the electrolyte additive can stabilize an interface between the electrode and the electrolyte, or form a passivation film on a surface of the positive electrode
Data Source
AI summary
A positive electrode active composite for lithium-ion batteries, consisting of 60%-99% by weight of a lithium iron phosphate material with an olivine structure and 1%-40% by weight of a layered ternary material. A lithium-ion battery, whose positive electrode includes such active composite, is provided, and in normal use, an upper voltage range is controlled between 3.8-4.0 V. When there is a certain capacity attenuation, a battery voltage can be increased to a range of greater than or equal to 4.1 V and less than or equal to 4.4 V for activation. Under the activation voltage, the lithium-rich ternary material can compensate for the active lithium loss after the battery aging.