Lithium Battery Activation Using Stepwise High-Voltage Charging
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Solution Overview
Problem
The increasing demand for large-sized, high-capacity, or high-energy-density rechargeable lithium batteries poses a challenge due to the limited supply and high cost of cobalt, a rare metal used in traditional positive electrode active materials.
Innovation Solution
A method for activating rechargeable lithium batteries using a positive electrode active material based on a layered lithium nickel-manganese composite oxide, involving a sequential first and second charging and discharging process, with an upper limit voltage of the second charging being higher than that of the first charging, to prevent lithium precipitation and enhance capacity and cycle-life characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If cobalt-containing positive electrode active materials are used to achieve high energy density, then battery capacity and energy density are improved, but material cost increases and supply security deteriorates due to cobalt being a rare and expensive metal
Solution Approach 1:
The patent removes cobalt from the positive electrode active material composition, using a lithium nickel-manganese composite oxide instead. This extraction of the problematic substance (cobalt) eliminates supply security issues and cost problems while maintaining battery performance through the alternative material system.
Solution Approach 2:
The patent employs a composite oxide material consisting of lithium, nickel, and manganese in specific ratios. This composite material combines the advantages of nickel (high capacity) and manganese (structural stability) to achieve high energy density without cobalt, resolving the contradiction between performance and material availability.
2Productivity
If high voltage activation is applied to increase capacity, then battery capacity is improved, but lithium precipitation occurs due to reversal of N/P ratio
Solution Approach 1:
The patent applies a preliminary high voltage activation treatment during the initial charging cycle to optimize the electrode structure and establish appropriate N/P ratio. This preliminary action prevents subsequent lithium precipitation by ensuring proper ion distribution and electrode balance before normal operation begins.
Solution Approach 2:
The patent modifies the charging voltage parameters, specifically applying higher voltage (up to 4.8V or more) during activation cycles to transform the electrode material structure and activate high-capacity regions. This parameter change enables capacity increase while the controlled activation process prevents harmful lithium precipitation.
3Productivity
If high voltage charging is used to maximize capacity, then reversible capacity is improved, but cycle-life characteristics deteriorate due to structural degradation
Solution Approach 1:
The patent optimizes multiple parameters including voltage (4.8V or more during activation), temperature (15-30°C during activation), and charging/discharging rates to achieve a balance between reversible capacity and cycle-life. These controlled parameter changes enable high capacity utilization while maintaining structural integrity over multiple cycles.
Solution Approach 2:
The lithium nickel-manganese composite oxide material provides structural stability through manganese while nickel contributes to high capacity. This composite structure resists degradation during high voltage charging, simultaneously improving reversible capacity and maintaining cycle-life characteristics.
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
This activation method effectively prevents lithium precipitation, maximizes capacity, and improves reversible capacity and cycle-life characteristics of rechargeable lithium batteries without increasing the designed N/P ratio, thus addressing the cobalt supply constraints.
Implementation Method 1
a positive electrode including a positive electrode active material including a layered lithium nickel-manganese-based composite oxide
Data Source
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AI summary
Disclosed are an activation method of a rechargeable lithium battery and a rechargeable lithium battery, the activation method including sequentially performing a first charging and discharging process and a second charging and discharging with respect to a rechargeable lithium battery including a positive electrode including a positive electrode active material including a layered lithium nickel-manganese-based composite oxide, a negative electrode, a separator between the positive electrode and the negative electrode, and an electrolyte solution, wherein an upper limit voltage of the second charging is higher than an upper limit voltage of the first charging.