Lithium-Ion Battery Formation Charging for Cathode Prelithiation Control
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Solution Overview
Problem
High specific capacity anode materials in lithium-ion batteries suffer from larger initial irreversible capacity and lower cycling stability, necessitating prelithiation to compensate for irreversible capacity loss, while existing methods like anode prelithiation pose safety risks and cathode prelithiation face issues with lithium deposition and electrolyte stability.
Innovation Solution
A customized initial charging and capacity verification method for lithium-ion batteries with positive electrode lithium supplementation additives, involving specific voltage ranges and charging/discharging steps to fully delithiate lithium replenishment additives without affecting electrolyte stability, ensuring full lithium removal and maintaining battery stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional initial charging and capacity verification methods are applied to batteries containing cathode lithium additives, then the battery can be charged and discharged, but insufficient lithium removal by the lithium additives results in lithium deposition in the battery cells
Solution Approach 1:
The charging process is divided into multiple stages with different voltage ranges. The first stage charges to a lower voltage (3.7-3.9V) to allow complete lithium removal from the cathode additive without simultaneous removal from the transition metal oxide. Subsequent stages complete the charging process, ensuring full delithiation of the additive while preventing lithium deposition.
Solution Approach 2:
The method performs preliminary charging at a controlled voltage range before completing the full charge. This preliminary action allows the lithium replenishment additive to release lithium ions gradually without causing excessive voltage that would trigger simultaneous delithiation from the transition metal oxide, thereby preventing lithium deposition.
2Quantity of substance
If the voltage range for large amount of lithium removal by lithium additives overlaps with the voltage range for large amount of lithium removal by transition metal oxides, then both materials release lithium simultaneously, but this affects the stability of other chemical elements in the electrolyte
Solution Approach 1:
The charging voltage range is segmented into distinct stages. The first stage operates at 3.7-3.9V where only the lithium additive undergoes significant delithiation. Later stages operate at higher voltages to complete the charge. This segmentation ensures that lithium removal from the additive occurs before simultaneous removal from the transition metal oxide, preventing electrolyte instability.
3Use of energy by moving object
If high specific capacity anode materials are used to improve battery energy density, then the energy density increases, but the initial irreversible capacity loss and cycling stability deteriorate
Solution Approach 1:
The patent applies preliminary charging at a controlled voltage range (3.7-3.9V) before completing the full charge. This preliminary action allows the lithium replenishment additive to compensate for the irreversible capacity loss of high specific capacity anode materials by releasing lithium ions during the first charge, thereby improving cycling stability without sacrificing energy density.
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 method ensures complete lithium removal from additives, preventing lithium deposition and maintaining electrolyte stability, thereby enhancing battery energy density and cycle life.
Implementation Method 1
By utilizing the high initial lithium removal and low initial lithium insertion of the lithium replenishment additives, excess lithium ions are released from the cathode during the first charge of the battery
Implementation Method 2
excess lithium ions are released from the cathode during the first charge of the battery, and there is no significant increase in cathode lithium insertion vacancies during the first discharge
Data Source
Figure 1~2
AI summary
The present invention relates to an initial charging and capacity verification method for a lithium-ion battery containing a positive electrode lithium supplementation additive. A positive pole piece of the utilized lithium-ion battery comprises a positive electrode current collector and a positive electrode film layer arranged on at least one surface of the positive electrode current collector, the positive electrode film layer comprising a positive electrode active material; the positive electrode active material comprises a lithium transition metal oxide and a lithium supplementation additive; the present invention sets a lithium supplementation additive initial deintercalation low percentage interval gram capacity average voltage to be V1, an initial deintercalation high percentage interval gram capacity average voltage to be V2, and the maximum operating voltage of the lithium transition metal oxide to be V3; with regard to the delithiation characteristics of the positive electrode lithium supplementation additive, the invention customizes an initial charging and capacity verification process suited to the battery containing the positive electrode lithium supplementation additive, thereby avoiding an influence on the stability of other chemical elements in an electrolyte when the lithium supplementation additive and the transition metal oxide are simultaneously delithiated under a high voltage; and ensuring the complete delithiation of the lithium ions in the positive electrode lithium supplementation additive, thereby improving the energy density of the battery, and increasing cycle life.