RU2847215C1 - Method of dry discharge of lithium current sources - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to chemical processing of used lithium current sources. Proposed method of dry discharge of lithium current sources comprises discharging lithium current sources in dry medium consisting of loose graphite, wherein allowable grain size of graphite fraction varies from 0.5 mm to 5.0 mm.

EFFECT: creation of method of dry discharge of lithium current sources, which makes it possible to eliminate formation of liquid, dangerous gaseous and solid wastes, prevents losses of valuable components of accumulators as a result of electrochemical processes taking place in solutions, and simplifies process of discharge.

1 cl, 3 ex

Description

The invention relates to chemical technology for recycling spent lithium batteries. Batteries received for recycling may be charged or have a residual charge and must first be discharged to prevent combustion during the opening and shredding processes. This stage of recycling is one of the most important, as it determines the safety and efficiency of the facility.

Currently, the best-known and most commonly used method for discharging lithium batteries is to soak them in sodium chloride solutions (Pražanová, A. Literature review, recycling of lithium-ion batteries from electric vehicles, part i: recycling technology / A. Pražanová, V. Knap, and D.-I. Stroe // Energies, 2022, 15, 1086). However, the electrochemical processes that occur in this method lead to corrosion of the outer shell of the battery, damage to its integrity, and, as a result, the loss of some valuable components of the processed raw materials and the formation of liquid and gaseous waste, which is a significant drawback of this method.

Controlled discharge methods using specialized equipment are also known (patent RU 2676806 C1, January 11, 2019). These methods allow for the safe and efficient discharge of individual batches of large, standardized batteries, such as those used in public transportation. The disadvantage is that this method is not applicable to the mass discharge of dissimilar batteries.

The closest approach to the proposed method in terms of technical essence and achievable result is a method of discharging batteries in a solution containing sulfuric acid salts with admixtures of hydroxides and carbonates. This method, adopted as a prototype, is a waste product in the production of nickel(II) hydroxide generated during the recycling of spent lithium-ion batteries (patent RU 2789852 C1, February 14, 2023). The disadvantages of this method include the formation of hydrogen gas, which requires purging the system to prevent its accumulation, and the need for subsequent filtration and rinsing of the battery mixture before shredding.

The technical result of the proposed invention is the creation of a method for dry discharging lithium power sources, which eliminates the formation of liquid, hazardous gaseous and solid waste, prevents the loss of valuable battery components due to electrochemical processes occurring in solutions, and simplifies the discharge process.

The technical result is achieved in that the method for dry discharging lithium power sources includes discharging lithium power sources in a dry medium consisting of loose graphite, wherein the permissible grain size of graphite fractions is from 0.5 to 5.0 mm.

Increasing the graphite fraction size to more than 5 mm leads to a significant increase in battery discharge time.

Reducing the size of graphite particles to less than 0.5 mm leads to dust formation, dirtiness and can provoke caking of the graphite mass during the battery discharge process.

Example 1.

Spent lithium-ion batteries weighing 1 kg are evenly filled with 1 kg of loose crushed graphite (0.5-1.0 mm). The mixture is maintained, with the battery discharge level monitored every half hour, until a voltage of no more than 0.5 V is reached. After this, the mixture is transferred to a 10 mm sieve, where shaking separates the graphite and battery mixture. It has been established that a safe voltage level of no more than 0.5 V is achieved in batteries after 20 hours of filling with 0.5-1.0 mm graphite. No dust formation or staining from 0.5-1.0 mm graphite is observed.

Example 2.

Spent lithium-ion batteries weighing 1 kg are uniformly filled with 1 kg of loose crushed/granular graphite (1.0-3.0 mm). The mixture is maintained, with the battery discharge level monitored every half hour, until the voltage reaches no more than 0.5 V. After this, the mixture is transferred to a 10 mm sieve, where shaking separates the graphite and battery mixture. It has been established that a safe voltage level of no more than 0.5 V is achieved in batteries after 30 hours of filling with 1.0-3.0 mm graphite. No dust formation or soiling from 1.0-3.0 mm graphite is observed.

Example 3.

Spent lithium-ion batteries weighing 1 kg are uniformly filled with 1 kg of loose crushed/granular graphite (3.0-5.0 mm fraction). The mixture is maintained, with the battery discharge level monitored every half hour, until the voltage reaches no more than 0.5 V. The mixture is then transferred to a 10 mm sieve, where shaking separates the graphite and battery mixture. It has been established that a safe voltage level of no more than 0.5 V is achieved in batteries after 72 hours of filling with 3.0-5.0 mm fraction graphite. No dust formation or soiling from 3.0-5.0 mm fraction graphite is observed.

All of the examples presented demonstrate a method for dry-discharging spent lithium batteries for safe shredding and recycling. It has been shown that using graphite with a particle size of 0.5 to 5.0 mm does not produce dust or soiling. It has been established that the discharge time increases with increasing graphite backfill grain size, from 20 to 72 hours.

Claims (1)

A method for dry discharging lithium current sources, characterized in that the discharge of lithium current sources is carried out in a dry environment consisting of loose graphite, with the permissible grain size of graphite fractions being from 0.5 to 5.0 mm.