A secondary battery cathode material pre-ionized composition

Abstract

This invention discloses a pre-ionization composition for a secondary battery cathode material, which is prepared by mixing and reacting an alkali metal cyclic compound and an alkali metal chain compound, wherein the alkali metal cyclic compound is M2C. x O x The alkali metal chain compound is M2C. y O y+2 Where 6≥x≥3, 6≥y≥2, and the alkali metal M is Li, Na, and / or K. The pre-ionized composition of the secondary battery cathode material of the present invention features low decomposition voltage, high specific capacity, excellent cycle performance, and good rate performance.

Description

Technical Field

[0001] This invention relates to the field of secondary battery technology, specifically to a pre-ionization composition for a secondary battery cathode material. Background Technology

[0002] In secondary batteries, Pre-ionization refers to the process of pre-injecting ions into electrode materials during battery manufacturing to improve battery performance, especially in the initial cycle, because this allows storage sites to be formed in the electrodes in advance, thereby shortening the battery formation period.

[0003] Pre-ionization helps improve battery energy density and cycle stability, reduces battery formation time, and thus improves battery performance. Currently, the main pre-ionization methods focus on pre-lithiation, pre-sodiumization, and pre-potassiumization. For ease of understanding, the following section provides a detailed introduction to pre-ionization from the perspective of sodium-ion batteries.

[0004] Sodium-ion batteries offer a solution to the challenges of sustainability, safety, cost, and lithium resource supply associated with lithium-ion batteries. Furthermore, due to their abundant resources, low cost, and high safety, sodium-ion batteries are considered poised to play a crucial role in the large-scale storage of future renewable energy sources.

[0005] The current development of sodium-ion batteries mainly depends on the development of positive and negative electrode materials. Current positive electrode materials mainly include oxide positive electrode materials, polyanionic positive electrode materials, and Prussian blue-based positive electrode materials, while negative electrode materials mainly include alloy negative electrode materials, carbon-based negative electrode materials, and organic negative electrode materials. In the initial cycling phase, the formation of the interfacial film irreversibly consumes active sodium ions, a phenomenon even more pronounced in full cells. The initial coulombic efficiency of negative electrode materials is generally low, making it difficult to achieve efficiency matching between positive and negative electrode materials in full cell design. This results in insufficient utilization of electrode materials, significantly limiting the application of sodium-ion batteries. As a battery energy storage technology, improving battery energy density is a perpetual pursuit. To address the above problems and achieve more effective efficiency matching and high energy density batteries, researchers have introduced an additional sodium source (sodium supplement) into the battery system through sodium replenishment technology to compensate for the irreversible loss of active sodium ions during battery cycling.

[0006] Current sodium replenishment strategies include electrochemical sodium replenishment, chemical sodium replenishment, and sacrificial salt additives. Chemical sodium replenishment and sacrificial salt additives have attracted considerable attention due to their large-scale implementation potential. The main drawbacks of the sodium replenishing agents that have been extensively studied are excessively high decomposition voltages and severe gas generation. For example, sodium oxalate and sodium carbonate have poor conductivity, and their excessively high oxidation decomposition potential places higher demands on the electrolyte. Furthermore, their large-scale gas generation and pore-forming behavior during decomposition damages the electrode structure. While sodium chromate, sodium nickelate, and sodium phosphide have lower decomposition voltages, their decomposition products lack electrochemical activity, not only damaging the battery's conductive network but also hindering the improvement of battery energy density. Most importantly, the theoretical specific capacity of current sodium replenishing agents is too low (e.g., CN110112475 A), and their single function limits the development of sodium-ion batteries. The situation is similar for lithium-ion batteries and pre-potassium-ion batteries. Summary of the Invention

[0007] The purpose of this invention is to provide a pre-ionized composition for secondary battery cathode materials, which has the characteristics of low decomposition voltage, high specific capacity, excellent cycle performance and good rate performance.

[0008] This invention can be achieved through the following technical solutions: This invention discloses a pre-ionization composition for a secondary battery cathode material. This composition is prepared by reacting a mixture of an alkali metal cyclic compound and an alkali metal chain compound, wherein the alkali metal cyclic compound is M2C. x O x (), the alkali metal chain compound is M2C y O y+2 , where 6 ≥ x ≥ 3, 6 ≥ y ≥ 2, and the alkali metal M is Li, Na and / or K.

[0009] Furthermore, the pre-ionized composition is a pre-sodiumized composition, and its preparation method includes the following steps: Step 1: Prepare the pre-sodiumization reagent; add polycyclic aromatic hydrocarbons, aromatic ketones and equimolar amounts of metallic sodium to an ether solvent, stir to dissolve and obtain the pre-sodiumization reagent; Step 2, sodium enrichment of sacrificial salt: Powders of cyclic compounds with alkali metal M of Na and chain compounds with alkali metal M of Na are put into centrifuge tubes, and pre-sodiumization reagent is added according to the stoichiometric ratio. After the reaction, the powder is collected by centrifugation and washed with ether solvent to obtain the pre-sodiumized composition.

[0010] Furthermore, the pre-ionized composition is a pre-lithiation composition, and its preparation method includes the following steps: Step 1: Prepare the pre-lithiation reagent; add polycyclic aromatic hydrocarbons, aromatic ketones and equimolar amounts of metallic lithium to an ether solvent, stir to dissolve and obtain the pre-lithiation reagent; Step 2, Lithification of sacrificial salt: Powders of cyclic compounds with alkali metal M being Li and chain compounds with alkali metal M being Li are put into centrifuge tubes, and pre-lithiation reagent is added according to the stoichiometric ratio. After the reaction, the powder is collected by centrifugation and washed with ether solvent to obtain the pre-lithiation composition.

[0011] Furthermore, the pre-ionized composition is a pre-potassium-ionized composition, and its preparation method includes the following steps: Step 1: Prepare the prepotassium-modified reagent; add polycyclic aromatic hydrocarbons, aromatic ketones and equimolar amounts of metallic potassium to an ether solvent, stir to dissolve and obtain the prepotassium-modified reagent; Step 2, Potassium enrichment of sacrificial salt: Powders of cyclic compounds with alkali metal M=K and chain compounds with alkali metal M=K are put into centrifuge tubes, and prepotassium enrichment reagent is added according to the stoichiometric ratio. After the reaction, the powder is collected by centrifugation and washed with ether solvent to obtain the prepotassium enrichment composition.

[0012] Furthermore, the polycyclic aromatic hydrocarbon is selected from one or more of naphthalene, biphenyl, anthracene, phenanthrene and / or pyrene.

[0013] Furthermore, the aromatic ketone is 9-fluorenone and / or benzophenone.

[0014] Furthermore, the ether solvent is one or more of N,N-dimethylformamide, diethyl ether, dimethyl sulfoxide, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, and acetonitrile.

[0015] Specifically, the cyclic compound for which M is Na is one or more of Na2C3O3, Na2C4O4, Na2C5O5 and / or Na2C6O6.

[0016] Specifically, M is a cyclic compound of Li, which is one or more of Li2C3O3, Li2C4O4, Li2C5O5 and / or Li2C6O6.

[0017] Specifically, the cyclic compound where M is K is one or more of K2C3O3, K2C4O4, K2C5O5 and / or K2C6O6.

[0018] The present invention provides a pre-ionization composition for a secondary battery cathode material, which has the following beneficial effects: In terms of performance, using ion-rich alkali metal supplements as sacrificial salts allows for higher ion replenishment effects with less alkali metal supplement. The ion-rich composition allows carbon generated from oxidation and decomposition to fill the pores created by CO2 release, and the deposited carbon with better conductivity optimizes the battery's conductive network, improving cycle and rate performance. Simultaneously, it significantly increases the charging capacity of the positive electrode material, completely compensating for the irreversible loss of active ions caused by the initial film formation at the negative electrode, thus greatly increasing the battery's energy density. In terms of preparation methods, a chemical pre-ionization method is used to pre-ionize low-specific-capacity alkali metal ion supplements into a high-theoretical-specific-capacity ionized composition. This method allows for large-scale, mass production. Attached Figure Description

[0019] Figure 1 The first-week charging curve of the pre-sodiumized composition in Example 2; Figure 2 The charge-discharge curve for the first week of Example 6; Figure 3 The first-week charge-discharge curves are for Comparative Example 1. Detailed Implementation

[0020] To enable those skilled in the art to better understand the technical solution of the present invention, the product of the present invention will be further described in detail below with reference to embodiments.

[0021] This invention discloses a pre-ionization composition for a secondary battery cathode material. This composition is prepared by reacting a mixture of an alkali metal cyclic compound and an alkali metal chain compound, wherein the alkali metal cyclic compound is M2C. x O x (), the alkali metal chain compound is M2C y O y+2 , where 6 ≥ x ≥ 3, 6 ≥ y ≥ 2, and the alkali metal M is Li, Na and / or K.

[0022] Furthermore, the pre-ionized composition is a pre-sodiumized composition, and its preparation method includes the following steps: Step 1: Prepare the pre-sodiumization reagent; add polycyclic aromatic hydrocarbons, aromatic ketones and equimolar amounts of metallic sodium to an ether solvent, stir to dissolve and obtain the pre-sodiumization reagent; Step 2, sodium enrichment of sacrificial salt: Powders of cyclic compounds with alkali metal M of Na and chain compounds with alkali metal M of Na are put into centrifuge tubes, and pre-sodiumization reagent is added according to the stoichiometric ratio. After the reaction, the powder is collected by centrifugation and washed with ether solvent to obtain the pre-sodiumized composition.

[0023] The specific reaction process in the preparation of the pre-sodiumized composition is as follows:

[0024] Taking the pre-sodium-treated composition as an example, characterization was performed using XRD, Raman spectroscopy, and electrochemical testing. The reduction mechanism is essentially that the strongly reducing pre-sodium-treated reagent reduces Na₂C₂. x O x Na2C y O y+2 The carbonyl group (C=O) in the solution is reduced to CO-, which in turn forms a sodium salt. Subsequently, polycyclic aromatic hydrocarbons and aromatic ketones are added to an ether solvent with an equimolar amount of metallic sodium, and the mixture is stirred to dissolve and obtain a pre-sodiumized composition.

[0025] This invention addresses the problems of current sodium supplements, such as low specific capacity, limited functionality, high decomposition voltage, and severe gas production during decomposition. It utilizes a chemical pre-sodiumification method to transform sodium supplements with low theoretical specific capacity into those with high theoretical specific capacity. Leveraging this high specific capacity, a smaller amount of sodium supplement is needed to provide more active sodium to compensate for the irreversible sodium ion consumption in the battery system. Simultaneously, a smaller amount can supplement a larger capacity, significantly alleviating the gas production problem during sodium supplement decomposition. Furthermore, the residual carbon generated during decomposition optimizes the electrode conductive network, thereby improving the energy density and cycle stability of sodium-ion batteries. The general formula is Na₂C. n O n The cyclic sodium salt has a decomposition voltage as low as 3.7 V (vs. Na). + Na₂C₃O₃, Na₂C₄O₄, Na₂C₅O₅, and Na₂C₆O₆ can be enriched with sodium to become Na₃C₃O₃, Na₄C₄O₄, Na₅C₅O₅, and Na₆C₆O₆, respectively, significantly increasing their theoretical specific capacity.

[0026] Furthermore, the pre-ionized composition is a pre-lithiation composition, and its preparation method includes the following steps: Step 1: Prepare the pre-lithiation reagent; add polycyclic aromatic hydrocarbons, aromatic ketones and equimolar amounts of metallic lithium to an ether solvent, stir to dissolve and obtain the pre-lithiation reagent; Step 2, Lithification of sacrificial salt: Powders of cyclic compounds with alkali metal M being Li and chain compounds with alkali metal M being Li are put into centrifuge tubes, and pre-lithiation reagent is added according to the stoichiometric ratio. After the reaction, the powder is collected by centrifugation and washed with ether solvent to obtain the pre-lithiation composition.

[0027] Similar to the preparation of the aforementioned pre-sodiumized composition, when using a pre-lithiation reagent and Li2C n O n Li2C n O n+2The reaction can achieve lithium enrichment of sacrificial salts for lithium-ion batteries. Similarly, polycyclic aromatic hydrocarbons and aromatic ketones are added to an ether solvent with an equimolar amount of metallic lithium, and the mixture is stirred to dissolve and obtain a pre-potassium-enriched reagent.

[0028] Furthermore, the pre-ionized composition is a pre-potassium-ionized composition, and its preparation method includes the following steps: Step 1: Prepare the prepotassium-modified reagent; add polycyclic aromatic hydrocarbons, aromatic ketones and equimolar amounts of metallic potassium to an ether solvent, stir to dissolve and obtain the prepotassium-modified reagent; Step 2, Potassium enrichment of sacrificial salt: Powders of cyclic compounds with alkali metal M=K and chain compounds with alkali metal M=K are put into centrifuge tubes, and prepotassium enrichment reagent is added according to the stoichiometric ratio. After the reaction, the powder is collected by centrifugation and washed with ether solvent to obtain the prepotassium enrichment composition.

[0029] Similar to the preparation of the aforementioned pre-sodiumized composition, a pre-potassiumization reagent and K2C are used. n O n K2C n O n+2 The reaction can achieve potassium enrichment of sacrificial salts for potassium-ion batteries.

[0030] Furthermore, the polycyclic aromatic hydrocarbon is selected from one or more of naphthalene, biphenyl, anthracene, phenanthrene and / or pyrene.

[0031] Furthermore, the aromatic ketone is 9-fluorenone and / or benzophenone.

[0032] Furthermore, the ether solvent is one or more of N,N-dimethylformamide, diethyl ether, dimethyl sulfoxide, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, and acetonitrile.

[0033] Specifically, the cyclic compound for which M is Na is one or more of Na2C3O3, Na2C4O4, Na2C5O5 and / or Na2C6O6.

[0034] Specifically, M is a cyclic compound of Li, which is one or more of Li2C3O3, Li2C4O4, Li2C5O5 and / or Li2C6O6.

[0035] Specifically, the cyclic compound where M is K is one or more of K2C3O3, K2C4O4, K2C5O5 and / or K2C6O6. Example 1

[0036] This embodiment provides a pre-sodiumized composition, the preparation method of which includes the following steps: (1) Na2C5O5 was used as raw material. Using the chemical pre-sodiumization method, 1 g of sodium crotonate powder was weighed into a 10 mL centrifuge tube, and 5 mL of 0.1 mol / L sodium naphthalene was added and reacted for 1 h under stirring.

[0037] (2) Using ethylene glycol dimethyl ether as a washing agent, the sodium-rich Na5C5O5 was obtained by centrifugation at 3000 r / min three times.

[0038] (3) After washing, Na5C5O5 is pumped in the transition chamber of the glove box for 10 minutes to obtain dry Na5C5O5 powder. Example 2

[0039] This embodiment provides a pre-sodiumized composition, the preparation method of which includes the following steps: (1) Take 1 mL of 0.1 mol / L sodium biphenyl in ethylene glycol dimethyl ether solution and react it with a Na2C5O5 electrode (with a loading of about 1 mg) for 2 minutes under an inert atmosphere. After the reaction is complete, wash three times with ethylene glycol dimethyl ether and dry for later use.

[0040] (2) Using Na₂C₅O₅ before and after sodium enrichment as the positive electrode and sodium metal as the negative electrode, half-cells were assembled with 1M NaClO₄ EC / DEC / FEC (v:v:v = 10:10:1) as the electrolyte, and charge-discharge tests were performed. The first-cycle charging curve of Na₂C₅O₅ before sodium enrichment is shown below. Figure 1 As shown, the charging capacity in the first week is 278.2 mAh g. -1 The Na5C5O5 electrode achieved a charging capacity of 520mAh g in the first week. -1 . Example 3

[0041] This embodiment provides a pre-sodiumized composition, the preparation method of which includes the following steps: (1) In an argon-atmosphere glove box, weigh 0.38 g of naphthalene and 0.07 g of metallic sodium, measure 30 mL of ethylene glycol dimethyl ether and add it to a 40 mL glass bottle. Stir for 24 h to obtain 0.1 M sodium naphthalene reagent. Then weigh 1 g of Na2C3O3 powder into a 10 mL centrifuge tube, add 5 mL of 0.1 mol / L sodium naphthalene and react for 1 h with stirring, then stop stirring.

[0042] (2) Using ethylene glycol dimethyl ether as a washing agent, the sodium-rich Na3C3O3 was obtained by centrifugation at 3000 r / min three times.

[0043] (3) The washed Na3C3O3 was pumped in the transition chamber of the glove box for 10 minutes to obtain dry Na3C3O3 powder.

[0044] (4) Using Na2C3O3 before and after sodium enrichment as the positive electrode and sodium metal as the negative electrode, half-cells were assembled with 1M NaClO4 EC / DEC / FEC (v:v:v=10:10:1) as the electrolyte, and charge-discharge tests were conducted. The first-week charging capacity was 365.7 mAh g⁻¹ for Na2C3O3 before sodium enrichment. -1 The Na3C3O3 electrode achieved a charging capacity of 504.8 mAh g in the first week. -1 . Example 4

[0045] This embodiment provides a pre-sodiumized composition, the preparation method of which includes the following steps: (1) In an argon-atmosphere glove box, weigh 0.38 g of naphthalene and 0.07 g of metallic sodium, measure 30 mL of ethylene glycol dimethyl ether and add it to a 40 mL glass bottle, stir for 24 h to obtain 0.1 M sodium naphthalene reagent. Then weigh 1 g of Na2C6O6 powder into a 10 mL centrifuge tube, add 5 mL of 0.1 mol / L sodium naphthalene and react for 1 h with stirring.

[0046] (2) Using ethylene glycol dimethyl ether as a washing agent, the sodium-rich Na6C6O6 was obtained by centrifugation three times at 3000 r / min.

[0047] (3) The washed Na6C6O6 was pumped in the transition chamber of the glove box for 60 minutes to obtain dry Na6C6O6 powder.

[0048] (4) Using Na2C6O6 before and after sodium enrichment as the positive electrode and sodium metal as the negative electrode, half-cells were assembled with 1M NaClO4 EC / DEC / FEC (v:v:v=10:10:1) as the electrolyte, and charge-discharge tests were conducted. The first-week charging capacity increased from 208.7 mAh g of Na2C6O6 before sodium enrichment. -1 The Na6C6O6 electrode achieved a charging capacity of 482.7 mAh g in the first week. -1 . Example 5

[0049] This embodiment provides a process for preparing an electrode containing a pre-sodiumized composition, the process comprising the following steps: (1) The positive electrode active material Na3V4(PO4)3, the conductive additive Ketjen black, and the binder PVDF are mixed in 80 parts by weight, 10 parts by weight, and 10 parts by weight, and then 4 parts by weight of Na6C6O6 are added to prepare the Na3V4(PO4)3 electrode with Na6C6O6 added.

[0050] (2) A half-cell was assembled using 1M NaClO4 EC / DEC / FEC (v:v:v=10:10:1) as the electrolyte, and charge-discharge tests were conducted. The first-week charge-discharge curve reached 138.7 mAh g⁻¹. -1 The Coulomb efficiency in the first week was 81.5%. Example 6

[0051] This embodiment provides a process for preparing an electrode containing a pre-sodiumized composition, the process comprising the following steps: (1) The positive electrode active material Na4Fe 2.91 (PO4)2P2O7, conductive additive Ketten black, and binder PVDF are mixed in 80 parts, 10 parts, and 10 parts by weight, respectively, and then 4 parts by weight of Na2C5O5 are added to prepare Na4Fe with Na2C5O5. 2.91 (PO4)2P2O7 electrode.

[0052] (2) A half-cell was assembled using 1M NaClO4 EC / DEC / FEC (v:v:v = 10:10:1) as the electrolyte, and charge-discharge tests were performed. The charge-discharge curves for the first week are shown below. Figure 2 As shown, its charging capacity reached 122.4 mAh g in the first week. -1 The discharge capacity is 105.9 mAh g. -1 The first-week coulomb efficiency was 85%. Compared to Comparative Example 1, its charging capacity is 24.9 mAh g. -1 The increase in [the amount of energy] means that when assembling a full battery, the energy density of the battery will also be greatly improved. Comparative Example 1

[0053] This embodiment provides a process for preparing an electrode without a pre-sodiumated composition, the process including the following steps: (1) The positive electrode active material Na4Fe 2.91 A mixture of (PO4)2P2O7, conductive additive Ketten black, and binder PVDF in 80 parts, 10 parts, and 10 parts by weight was used to prepare Na4Fe without Na5C5O5. 2.91 (PO4)2P2O7 electrode.

[0054] (2) A half-cell was assembled using 1M NaClO4 EC / DEC / FEC (v:v:v = 10:10:1) as the electrolyte, and charge-discharge tests were performed. The charge-discharge curves for the first week are shown below. Figure 3 As shown, its first-week charging capacity reached 97.5 mAh g. -1 Its first-week discharge capacity reached 94.3 mAh g. -1 The Coulomb efficiency was 98.8% in the first week. Example 7

[0055] This embodiment provides a process for preparing an electrode containing a pre-sodiumized composition, the process comprising the following steps: (1) The positive electrode active material Na4Fe 2.91 (PO4)2P2O7, conductive additive Ketten black, and binder PVDF are mixed in 80 parts, 10 parts, and 10 parts by weight, respectively, and then 1 part by weight of Na5C5O5 is added to prepare Na4Fe with Na5C5O5. 2.91 (PO4)2P2O7 electrode.

[0056] (2) Hard carbon negative electrode is prepared by mixing the negative electrode active material hard carbon (HC), conductive additive Super P, and binder PAA in 80 parts, 10 parts and 10 parts by weight respectively.

[0057] (3) Na4Fe with added Na5C5O5 2.91 The full cell, assembled with a (PO4)2P2O7 electrode as the positive electrode and a hard carbon electrode as the negative electrode, achieved a first-week charging capacity of 131.3 mAh g⁻¹. -1 The discharge capacity is 98.5 mAh g. -1 The first-week coulomb efficiency was 75.1%. At a rate of 40C, the reversible capacity reached 67 mAh g. -1 . Comparative Example 2

[0058] This embodiment provides a process for preparing an electrode without a pre-sodiumated composition, the process including the following steps: (1) The positive electrode active material Na4Fe 2.91 Na4Fe was prepared by mixing (PO4)2P2O7, conductive additive Ketten black, and binder PVDF in 80 parts, 10 parts, and 10 parts by weight, respectively. 2.91 (PO4)2P2O7 electrode.

[0059] (2) Hard carbon negative electrode is prepared by mixing the negative electrode active material hard carbon (HC), conductive additive Super P, and binder PAA in 80 parts, 10 parts and 10 parts by weight respectively.

[0060] (3) Na4Fe with added Na5C5O5 2.91 The full cell, assembled with a (PO4)2P2O7 electrode as the positive electrode and a hard carbon electrode as the negative electrode, achieved a first-week charging capacity of 98.2 mAh g⁻¹. -1 The discharge capacity is 71.2 mAh g. -1 The first-week coulomb efficiency was 72.5%. At a rate of 40C, the reversible capacity was only 60 mAh g.-1 . Example 8

[0061] This embodiment provides a pre-lithiation composition, the preparation method of which includes the following steps: (1) In an argon atmosphere glove box, weigh 0.46 g of biphenyl and 0.02 g of lithium metal, measure 30 mL of ethylene glycol dimethyl ether and add it to a 40 mL glass bottle, stir for 24 h to obtain 0.1 M lithium biphenyl reagent, weigh 1 g of Li5C5O5 powder into a 10 mL centrifuge tube, add 5 mL of 0.1 mol / L lithium biphenyl and react for 1 h with stirring.

[0062] (2) Using ethylene glycol dimethyl ether as a washing agent, the lithium-rich Li5C5O5 was obtained by centrifugation three times at 3000 r / min.

[0063] (3) After washing, Li5C5O5 was pumped in the transition chamber of the glove box for 10 minutes to obtain dry Li5C5O5 powder.

[0064] (4) Using Li₂C₅O₅ before and after lithiation as the positive electrode and sodium metal as the negative electrode, half-cells were assembled with 1M LiClO₄ EC / DEC / FEC (v:v:v=10:10:1) as the electrolyte, and charge-discharge tests were performed. The first-week charging capacity increased from 303.2 mAh g⁻¹ in Li₂C₅O₅ before lithiation. -1 The Li5C5O5 electrode achieved a charging capacity of 689.1 mAh g in the first week. -1 . Example 9

[0065] This embodiment provides a prepotassium-modified composition, the preparation method of which includes the following steps: (1) In an argon atmosphere glove box, weigh 0.38 g naphthalene and 0.12 g potassium metal, measure 30 mL of ethylene glycol dimethyl ether and add it to a 40 mL glass bottle, stir for 24 h to obtain 0.1 M potassium biphenyl reagent, weigh 1 g K2C3O3 powder into a 10 mL centrifuge tube, add 5 mL of 0.1 mol / L potassium naphthalene and react for 1 h with stirring.

[0066] (2) Using ethylene glycol dimethyl ether as a washing agent, the product was centrifuged three times at 3000 r / min to obtain potassium-rich K3C3O3.

[0067] (3) After washing, K3C3O3 was pumped in the transition chamber of the glove box for 10 minutes to obtain dry K3C3O3 powder.

[0068] The above embodiments are merely specific examples of the present invention, and their descriptions are quite specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these obvious substitutions all fall within the protection scope of the present invention.

Claims

1. A method for preparing a pre-ionized composition for a secondary battery cathode material, characterized in that: The composition was prepared by reacting an alkali metal cyclic compound, wherein the alkali metal cyclic compound was M2C. x O x , where 6 ≥ x ≥ 3, and the alkali metal M is Li, Na and / or K; When the pre-ionized composition is a pre-sodiumized composition, its preparation method includes the following steps: Step 1: Prepare the pre-sodiumization reagent; add polycyclic aromatic hydrocarbons or aromatic ketones and an equimolar amount of metallic sodium to an ether solvent, stir and dissolve to obtain the pre-sodiumization reagent; Step 2, sodium enrichment of sacrificial salt; The powders of cyclic compounds with alkali metal M of Na and chain compounds with alkali metal M of Na are put into centrifuge tubes, and pre-sodiumization reagent is added according to the stoichiometric ratio. After the reaction, the powder is collected by centrifugation and washed with ether solvent to obtain the pre-sodiumization composition. When the pre-ionized composition is a pre-lithiation composition, its preparation method includes the following steps: Step 1: Prepare the pre-lithiation reagent; add polycyclic aromatic hydrocarbons or aromatic ketones and equimolar amounts of metallic lithium to an ether solvent, stir and dissolve to obtain the pre-lithiation reagent; Step 2, Lithification of sacrificial salt: Powders of cyclic compounds with alkali metal M being Li and chain compounds with alkali metal M being Li are put into centrifuge tubes, and pre-lithiation reagent is added according to the stoichiometric ratio. After the reaction, the powder is collected by centrifugation and washed with ether solvent to obtain the pre-lithiation composition. When the pre-ionized composition is a pre-potassium-ionized composition, its preparation method includes the following steps: Step 1: Prepare the prepotassium-modified reagent; add polycyclic aromatic hydrocarbons or aromatic ketones and equimolar amounts of metallic potassium to an ether solvent, stir and dissolve to obtain the prepotassium-modified reagent; Step 2, Potassium enrichment of sacrificial salt: Powders of cyclic compounds with alkali metal M=K and chain compounds with alkali metal M=K are put into centrifuge tubes, and prepotassium enrichment reagent is added according to the stoichiometric ratio. After the reaction, the powder is collected by centrifugation and washed with ether solvent to obtain the prepotassium enrichment composition. The aromatic ketone is 9-fluorenone and / or benzophenone; the polycyclic aromatic hydrocarbon is selected from one or more of naphthalene, biphenyl, anthracene, phenanthrene and / or pyrene.

2. The method for preparing the pre-ionization composition of the secondary battery cathode material according to claim 1, characterized in that: The ether solvent is one or more of N,N-dimethylformamide, diethyl ether, dimethyl sulfoxide, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, and acetonitrile.

3. The method for preparing the pre-ionization composition of the secondary battery cathode material according to claim 1, characterized in that: cyclic compounds where M is Na are , , , One or more of them.

4. The method for preparing the pre-ionization composition of the secondary battery cathode material according to claim 1, characterized in that: For cyclic compounds where M is Li, , Li2C5O5, One or more of them.

5. The method for preparing the pre-ionized composition of the secondary battery cathode material according to claim 1, characterized in that: Cyclic compounds where M is K are , , , One or more of them.

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