Anode-Free Lithium Battery Charging for Dendrite Control
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Solution Overview
Problem
Conventional lithium secondary batteries face challenges in achieving sufficient energy density and cycle characteristics, with anode-free batteries prone to dendrite formation leading to short circuits and capacity decrease.
Innovation Solution
A battery system and charging method that includes a precharge step using a predetermined precharge current followed by a normal charge with a higher current, ensuring uniform lithium metal precipitation on the negative electrode, improving cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional charging is used in anode-free lithium secondary batteries, then charging speed is maintained, but dendrite formation occurs leading to short circuits and capacity decrease
Solution Approach 1:
The patent applies preliminary action by performing a precharge step at a first charging rate before the normal charge step at a second charging rate. This preliminary charging action prepares the battery in a controlled manner, preventing dendrite formation during subsequent fast charging while maintaining high charging speed during the normal charge phase.
2Reliability
If negative electrode active material is used, then cycle stability is improved, but energy density is reduced due to volume and mass occupation
Solution Approach 1:
The patent applies the taking out principle by removing the negative electrode active material from the battery structure. Instead of using conventional negative electrode materials, the patent uses a lithium metal foil as the negative electrode, which provides higher energy density while maintaining cycle stability through the controlled two-stage charging method that prevents dendrite formation.
3Quantity of substance
If lithium metal is used as negative electrode active material, then energy density is increased, but dendrite formation occurs during repeated charging and discharging
Solution Approach 1:
The patent applies preliminary action by performing a precharge step at a first charging rate before the normal charge step at a second charging rate. This preliminary charging action prepares the battery in a controlled manner, preventing dendrite formation during subsequent fast charging while maintaining high charging speed during the normal charge phase.
Solution Approach 2:
The patent applies periodic action by dividing the charging process into two distinct periodic stages: a precharge period at a lower charging rate followed by a normal charge period at a higher charging rate. This periodic charging pattern allows the battery to be charged efficiently while preventing dendrite formation during the high-rate charging phase.
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 proposed method enhances the cycle characteristics of lithium secondary batteries by promoting uniform lithium metal precipitation, thereby increasing energy density and extending battery life.
Implementation Method 1
a lithium secondary battery including a positive electrode and a negative electrode not having a negative electrode active material... metal particles formed on a negative electrode current collector are transferred from the positive electrode when the battery is charged and a lithium metal is formed on the negative electrode current collector
Implementation Method 2
perform normal charge performing charging up to a normal capacity larger than the precharge capacity by a predetermined normal charge current higher than the precharge current... uniform lithium metal precipitation on the negative electrode
Data Source
AI summary
The purpose of the present invention is to provide a battery system particularly excellent in cycle characteristics. A battery system according to one embodiment is configured to include a lithium secondary battery and a charging device which charges the lithium secondary battery. The lithium secondary battery includes a positive electrode and a negative electrode not having a negative electrode active material. The charging device includes a power supply unit which supplies power for charging to the lithium secondary battery, and a charge control unit which controls the power supply unit so as to, after precharge to charge up to a predetermined precharge capacity by a predetermined precharge current, perform normal charge performing charging up to a normal capacity larger than the precharge capacity by a predetermined normal charge current higher than the precharge current. The precharge is performed before each of the repeated normal charges.