Lithium Compound Recovery With Low-Impurity Battery Heat Treatment
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Solution Overview
Problem
The recovery of valuable metals from waste lithium secondary batteries is hindered by high impurity content, particularly Na, K, Mg, and Ca, which increase facility maintenance costs and process complexity, and existing methods pose safety risks due to battery disassembly and high-temperature treatments.
Innovation Solution
A method involving freezing and forcibly discharging batteries, followed by crushing and heating at controlled temperatures and vacuum levels to produce a lithium compound with low impurity content, specifically controlling Na, K, Mg, and Ca to ≤1.8%, ≤0.06%, ≤0.62%, and ≤0.47% respectively, using inert gas atmospheres.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If salt water discharge is performed to remove impurities, then chlorine content is reduced, but sodium, potassium, and magnesium impurities remain in the crushed material
Solution Approach 1:
The patent applies preliminary action by performing freezing and discharging operations before crushing and heat treatment. The battery is frozen to -60°C or lower and then forcibly discharged to remove residual voltage, which prevents safety hazards during subsequent processing. This preliminary treatment reduces impurity content in the final lithium compound while avoiding facility corrosion from chlorine ions.
2Ease of manufacture
If high-temperature heat treatment is applied to remove water and electrolyte, then processing is simplified, but chlorine causes increased corrosion of pipes and facility maintenance costs
Solution Approach 1:
The patent applies the extraction principle by removing harmful chlorine ions through the freezing and discharging process before heat treatment. The electrolyte is extracted and removed during the freezing stage, so that subsequent high-temperature heat treatment does not generate corrosive chlorine gases that would damage facility pipes and equipment.
3Productivity
If physical disassembly is performed to access battery components, then valuable metals become accessible, but safety risks such as battery explosion and electric shock increase
Solution Approach 1:
The patent replaces mechanical disassembly with a freezing-based processing method. Instead of physically opening the battery to access components, the entire battery is frozen to -60°C or lower, then subjected to heat treatment and crushing. This substitution eliminates safety risks associated with manual disassembly while maintaining efficient access to valuable metals.
4Loss of time
If crushed material is directly processed without preliminary treatment, then processing time is reduced, but impurity content including Na, K, and Mg increases in the final product
Solution Approach 1:
The patent applies preliminary action by implementing freezing and discharging before crushing and heat treatment. This preliminary treatment removes residual electrolyte and reduces impurity content, enabling direct processing of the frozen material without additional washing or purification steps. The result is high-purity lithium compound with Na, K, and Mg content controlled within specified limits.
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 method reduces impurity loads, suppresses fire risks, and enhances lithium recovery efficiency by stabilizing the lithium compound formation, thereby lowering facility costs and improving the recovery process.
Implementation Method 1
freezing and forcibly discharging batteries, followed by crushing and heating
Implementation Method 2
heating at controlled temperatures and vacuum levels to produce a lithium compound with low impurity content
Implementation Method 3
heat treatment at a high temperature for removing water and an electrolyte solution
Implementation Method 4
heating at controlled temperatures and vacuum levels
Data Source
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Figure 3A
AI summary
Provided are a lithium compound for recovering valuable metals and a method for recovering the same. The method for recovering a lithium compound for recovering valuable metals includes: preparing a battery, freezing and forcibly discharging the battery, crushing the battery, and heating the crushed battery material, wherein the heating is performed in a temperature range of 1,100 to 1,400°C, the heating is performed at a vacuum degree (LogP [atm]) in a range of -4 to 0, the lithium compound recovered by the heating includes impurities, and the impurities include 1.8 wt% or less (excluding 0 wt%) of Na, 0.06 wt% or less (excluding 0 wt%) of K, 0.62 wt% or less (excluding 0 wt%) of Ca, and 0.47 wt% or less (excluding 0 wt%) of Mg, in % by weight.