CN-116315233-B - Method for directly repairing and regenerating waste lithium iron phosphate anode based on two-electron lithiation reagent

CN116315233BCN 116315233 BCN116315233 BCN 116315233BCN-116315233-B

Abstract

The invention discloses a method for directly repairing and regenerating a waste lithium iron phosphate anode based on a two-electron lithiation reagent, which comprises the following steps of (1) disassembling a recovered waste lithium iron phosphate battery after complete discharge, separating and collecting an anode active material, (2) adding an aromatic ketone dilithium reagent into the anode active material, stirring and reacting for 1-4h, centrifuging, washing and drying to obtain a lithium-state regenerated lithium iron phosphate anode, wherein the ratio of the molar quantity of lithium in the aromatic ketone dilithium reagent to the molar quantity of lithium deficiency in the anode active material is more than or equal to 1, the aromatic ketone dilithium reagent consists of aromatic ketone dilithium and an organic solvent, and the molar ratio of aromatic ketone molecules to lithium in the aromatic ketone dilithium is 1:2. The invention can realize twice lithiation efficiency under the same aromatic chemical reagent consumption, and is beneficial to reducing material investment in the repairing and regenerating process. And the electrochemical performance of the regenerated layered lithium iron phosphate positive electrode material obtained by the invention can be comparable with that of a commercial lithium iron phosphate positive electrode.

Inventors

QIAN JIANGFENG
WU CHEN
ZHANG FENGXUE
ZHANG YANHUI
ZHAI JIANMING
XU MINGLI
AI XINPING

Assignees

武汉大学
百杰瑞(荆门)新材料有限公司

Dates

Publication Date: 20260505
Application Date: 20230330

Claims (7)

1. A repairing and regenerating method for a lithium iron phosphate positive electrode material of a waste lithium ion battery is characterized by comprising the following steps: (1) Disassembling the recovered waste lithium iron phosphate battery after complete discharge, and separating and collecting an anode active material; (2) Adding an aromatic ketone dilithium reagent into the positive electrode active material, stirring and reacting for 1-4h hours, centrifuging, washing and drying to obtain the lithium-state regenerated lithium iron phosphate positive electrode, wherein: The ratio of the molar quantity of lithium in the aromatic ketone dilithium reagent to the molar quantity of lithium deficiency in the positive electrode active material is more than or equal to 1; The aromatic ketone dilithium reagent consists of aromatic ketone dilithium and an organic solvent, wherein the molar ratio of aromatic ketone molecules to lithium in the aromatic ketone dilithium is 1:2; The aromatic ketone dilithium reagent is at least one of diphenyl ketone dilithium or 9-fluorenone dilithium.
2. The method of claim 1, wherein the concentration of the aromatic ketdilithium in the aromatic ketdilithium reagent in the step (2) is 0.01-2.0 mol/L.
3. The method according to claim 1, wherein the aromatic ketone dilithium is 9-fluorenone dilithium.
4. The method according to claim 1, wherein the organic solvent is an aprotic solvent.
5. The method according to claim 4, wherein the organic solvent is any one of ethylene glycol dimethyl ether, tetrahydrofuran, acetonitrile, and N, N-dimethylformamide.
6. The method of claim 4, wherein the aromatic ketone dilithium reagent is prepared by the following steps: at room temperature, dissolving aromatic ketone in an organic solvent, uniformly mixing, adding metal lithium according to the stoichiometric ratio of the molar ratio of the aromatic ketone to the metal lithium of 1:2, and stirring until the mixture fully reacts to obtain a uniform solution, namely the aromatic ketone dilithium reagent.
7. The method of claim 6, wherein the reaction time is 20-40 min.

Description

Method for directly repairing and regenerating waste lithium iron phosphate anode based on two-electron lithiation reagent Technical Field The invention relates to a direct repair and regeneration technology of a waste anode of a retired lithium ion battery, in particular to a repair and regeneration method of two-electron chemical lithiation of a lithium iron phosphate anode material of a waste lithium ion battery. Background Advances in electrochemical theory and developments in the lithium ion battery industry have significantly changed the appearance of the world and the lifestyle of humans over the past several decades. However, limited electrochemical life has led to commercial lithium ion batteries coming out of service in recent years. The spent lithium ion battery needs to be properly recycled to fully exert the economic value and reduce the resource waste and the potential environmental pollution. The olivine structured lithium iron phosphate (LiFePO 4) is currently the most widely used positive electrode chemical system with highest safety and most outstanding cost advantage in vehicle power cells. In the electrochemical charging process of the lithium ion battery, active Li + is extracted from a LiFePO 4 positive electrode lattice to form a lean lithium FePO 4 phase, li + is embedded into a graphite negative electrode through an ion transmission path of electrolyte under the action of an internal electric field to complete conversion from electric energy to chemical energy, and the discharging process is opposite to the conversion. The stable FeO 6 and PO 4 structural units in the LiFePO 4 anode basically avoid the problems of active material dissolution, crystal structure collapse and the like in the long-term lithium ion deintercalation process. However, since the graphite negative electrode consumes part of Li + at the first week to form a solid electrolyte interface and the interface is continuously broken and regenerated during the subsequent cycle, the capacity degradation mechanism of the lithium ion battery based on the LiFePO 4 positive electrode is mainly loss of lithium inventory. For low-added-value anodes such as LiFePO 4 which do not contain precious transition metal elements, the economic value of metal smelting means is very limited, and the economic added value of smelting products is even difficult to cover the cost investment. The common recycling mode of the waste LiFePO 4 anode is mainly to selectively extract lithium elements with higher economic value, which often involves the use of corrosive chemical reagents or a high-temperature roasting process. The selective extraction of lithium elements by means of oxidizing agents and pickling solutions is required in the patent of the invention, for example, patent publication CN 216808939U. It should be noted that 70% -80% of residual energy is still stored in the anode of the failed LiFePO 4, and the residual energy is lost due to the destruction of chemical bonds in the process of metal smelting and lithium element extraction, which is an important reason for limited economic value of recycling of the anode of the failed LiFePO 4. From the aspect of failure mechanism, the waste LiFePO 4 anode can be directly repaired and regenerated from the old anode to the new anode by supplementing an active lithium source, and the repairing strategy can realize higher economic benefit under the condition of lower energy material investment. For example, the patent issued to CN112349989B can implement chemical lithium-compensating repair regeneration of lithium-depleted waste anode with the help of an aromatic hydrocarbon-based lithiation reagent. However, these conventional lithium arene reagents involve only one electron reactions and the lithiation capacity per unit specification of the reagent is limited. Moreover, polycyclic aromatic compounds have strong biological toxic action on human body and aquatic organisms. The present application has been made for the above reasons. Disclosure of Invention Aiming at the defects existing in the prior art, the invention aims to provide a repair and regeneration technology for a green nontoxic waste lithium ion battery lithium iron phosphate anode material with two-electron lithiation capability. Aiming at the over-lithiation potential of 0.59V vs. Li +/Li of the waste lithium iron phosphate anode, the invention utilizes the aromatic ketone dilithium reagent with the lithiation potential matching (higher than 0.59V vs. Li +/Li) to carry out chemical lithiation on the waste lithium iron phosphate anode at room temperature so as to recover the electrochemical performance of the waste lithium iron phosphate anode. The method has the advantages that the selected aromatic ketone lithiation reagent not only has good biocompatibility, but also can realize the two-electron lithium supplementing capability, can further reduce the dosage of the lithiation reagent and the solvent, and achieves the aim of lo