GB/Z 155-2025General principles of sodium ion battery cathode materials (English PDF)

Foreword

This document is a guiding technical document of the specification type.

This document was drafted in accordance with the rules given in GB/T 1.1-2020, Directives for standardization - Part 1: Rules for the structure and drafting of standardizing documents.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. The issuing body of this document is not to be held responsible for identifying any or all such patent rights.

This document was proposed by the China Nonferrous Metals Industry Association and is under the jurisdiction of the National Technical Committee on Nonferrous Metals of Standardization Administration of China (SAC/TC 243).

This document was drafted by Guangdong Brunp Recycling Technology Co., Ltd.; GEM (Wuxi) Energy Materials Co., Ltd.; Hubei Wanrun New Energy Technology Co., Ltd.; Liyang Zhongke Haina Technology Co., Ltd.; Jinchuan Group Co., Ltd.; Guoke Energy (Chuzhou) Co., Ltd.; Anhui Xinna New Material Technology Co., Ltd.; Hunan Changyuan Lico New Energy Co., Ltd.; Shenzhen BTR New Energy Technology Research Institute Co., Ltd.; Xiamen Tungsten New Energy Materials Co., Ltd.; Guizhou Zhenhua New Material Co., Ltd.; Zhejiang Meidarui New Material Technology Co., Ltd.; Wanhua Chemical Group Co., Ltd.; Yichang Brunp Recycling Technology Co., Ltd.; Jinchuan Group Nickel Salt Co., Ltd.; and Hunan Brunp Recycling Technology Co., Ltd. Twenty-four drafters are named.

1 Scope

This document specifies the classification and naming, the technical requirements, the inspection rules, the marking, packaging, transport and storage, the accompanying documents and the content of the order form for sodium ion cathode materials, and describes the corresponding test methods.

This document applies to the production and inspection of cathode materials for sodium ion batteries.

2 Normative references

The following documents contain provisions which, through normative reference in this text, constitute indispensable provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document, including any amendments, applies.

GB/T 5162, Metallic powders - Determination of tap density

GB/T 5211.6, General methods of test for pigments and extenders - Part 6: Determination of pH value of an aqueous suspension

GB/T 5314, Powders for powder metallurgical purposes - Sampling

GB/T 19077, Particle size analysis - Laser diffraction methods

GB/T 35924, Determination of moisture content in solid chemical products - Thermogravimetry

GB/T 44330, Cathode materials for lithium ion batteries - Determination of powder compacted density

GB/T 45330, Cathode materials for lithium ion batteries - Determination of moisture content - Karl Fischer coulometric method

3 Terms and definitions

For the purposes of this document, the following terms and definitions apply.

3.1 sodium ion battery - an electrochemical cell based on the migration of sodium ions in the electrolyte and their reversible intercalation into and deintercalation from the cathode and anode materials.

3.2 sodium ion battery cathode materials - materials in a sodium ion battery in which a sodium-bearing compound is the cathode active substance.

3.3 transition metal oxide cathode materials - materials made up of a compound of transition metal elements, such as nickel, cobalt, manganese and iron, with oxygen, serving as the cathode active substance of a sodium ion battery.

3.4 prussian blue cathode materials - compounds with an open three-dimensional channel structure obtained by introducing other metal ions into the prussian blue structure [Fe(CN)6]4-, serving as the cathode active substance of a sodium ion battery.

3.5 polyanionic cathode materials - compounds made up of a series of anionic tetrahedra (XO4)n- or their derived groups (XmO3m+1)n-, where X is B, S, P, Si, As, Mo, W or similar, together with transition metal-oxygen polyhedra (MOx), serving as the cathode active substance of a sodium ion battery.

3.6 specific capacity - the electrochemical capacity charged or discharged by unit mass of active substance under specified conditions. Note: the unit is milliampere-hours per gram. [Source: GB/T 20252-2014, 3.1, modified]

3.7 efficiency - the percentage ratio of the discharge capacity to the charge capacity of the active substance under specified conditions. [Source: GB/T 20252-2014, 3.2]

4 Classification and naming

4.1 Classes. 4.1.1 Cathode materials for sodium ion batteries comprise transition metal oxide cathode materials, prussian blue cathode materials and polyanionic cathode materials. 4.1.2 Transition metal oxide cathode materials are divided by the number of metal elements into four classes: unary, binary, ternary and quaternary. 4.1.3 Prussian blue cathode materials are classified by the principal metal element into four classes: manganese-based, denoted M; iron-based, denoted F; nickel-based, denoted N; and copper-based, denoted C. 4.1.4 Polyanionic cathode materials are classified by differences in chemical composition, mainly into four classes: phosphate, denoted P; fluorophosphate, denoted f; pyrophosphate, denoted J; and sulfate, denoted S.

4.2 Transition metal oxide cathode materials. 4.2.1 These comprise layered and tunnel-type transition metal oxide materials, with the general formula NaxM'O2, where M' is a transition metal representing cobalt, iron, manganese, titanium, nickel and others. 4.2.2 They are named by the principal metal and the battery class, and the code is formed from the code of the principal metal element and the battery class code N. The classification, names and codes of typical transition metal oxide cathode materials are given in Table 1. Example: a transition metal oxide cathode material whose principal metals are nickel, iron, manganese and copper is named sodium nickel iron manganese cuprate cathode material and coded NNFMC.

Table 1 lists the unary materials NaxCoO2 (NC'), NaxMnO2 (NM), NaxVO2 (NV) and NaxFeO2 (NF), and the binary materials Na[NixCo1-x]O2 (NNC'), Na[NixFe1-x]O2 (NNF), Na[NixTi1-x]O2 (NNT), Na[FexCo1-x]O2 (NFC'), Na2/3[FexMn1-x]O2 (NFM), Na2/3[Mn1/3Co2/3]O2 (NMC') and Na2/3[Ni1/3Mn2/3]O2 (NNM).

Table 3 lists the typical polyanionic materials: the phosphates NaFePO4 (NFP), Na3V2(PO4)3 (NVP) and NaFe2Mn(PO4)3 (NFMP); the sulfate Na2Fe(SO4)2 (NFS); the pyrophosphates Na2FeP2O7 (NFJ), Na2CoP2O7 (NC'J) and Na4Fe3(PO4)2(P2O7) (NFPP); and the fluorophosphates Na3V2(PO4)2F3 (NVPf), Na2FePO4F (NFPf) and Na3V2(PO4)2O2F (NVPfO).

5 Technical requirements

5.1 Chemical composition shall meet Table 4; the chemical composition of prussian blue materials is agreed between supplier and purchaser. For transition metal oxide materials the mass fractions are: Na 15.00 % to 25.00 %; the sum of the principal metal elements 39.00 % to 70.00 %; Cd, Cr and Pb each not greater than 0.0200 %; Si not greater than 0.2000 %; and S not greater than 0.5000 %. For polyanionic materials: Na 10.00 % to 17.00 %; the sum of the principal metal elements 15.00 % to 28.00 %; the sum of the principal non-metal elements 16.00 % to 25.00 %; C 1.00 % to 6.00 %; Ca not greater than 0.0300 %; Cu, Zn and Ni each not greater than 0.0100 %; K not greater than 0.0500 %; and Cr not greater than 0.0300 %.

5.2 Appearance quality shall meet Table 5: transition metal oxide materials are a grey, grey-black or brown-grey powder, uniform in colour, free from agglomerates and free from foreign matter; prussian blue materials a blue or white powder; polyanionic materials a grey or grey-black powder, with the same requirements.

5.3 Moisture content shall meet Table 6: transition metal oxide materials not greater than 0.05 %; prussian blue materials, crystal water not greater than 10 % and free water not greater than 0.5 %; polyanionic materials not greater than 0.2 %.

5.4 Powder compacted density shall meet Table 7, in grams per cubic centimetre: transition metal oxide P2 phase not less than 3.0 and O3 phase not less than 2.6; prussian blue manganese- and iron-based not less than 0.6 and nickel- and copper-based not less than 0.5; polyanionic phosphate type not less than 1.5, sulfate type not less than 2.0, pyrophosphate type not less than 1.8 and fluorophosphate type not less than 2.0.

5.5 Tap density shall meet Table 8, 5.6 particle size distribution Table 9 and 5.7 pH value Table 10.

5.8 Electrochemical performance shall meet Table 11, which gives the first discharge specific capacity at 0.1C in milliampere-hours per gram and the first charge-discharge efficiency at 0.1C: transition metal oxide P2 phase not less than 70 and 90 %, O3 phase not less than 120 and 90 %; prussian blue manganese-based not less than 120 and 95 %, iron-based not less than 130 and 95 %, nickel-based not less than 120 and 95 %, copper-based not less than 130 and 95 %; polyanionic phosphate type not less than 95 and 90 %, sulfate type not less than 80 and 90 %, pyrophosphate type not less than 90 and 85 %, fluorophosphate type not less than 100 and 90 %.

6 Test methods

6.1 Chemical composition. The methods for determining the chemical composition of transition metal oxide and polyanionic cathode materials are given in Annex A and Annex B; the fluorine content of polyanionic materials is determined by ion chromatography and the carbon content by high-frequency induction furnace combustion with infrared absorption. The method for prussian blue materials is agreed between supplier and purchaser.

6.2 Appearance quality is examined visually. 6.3 The free water content is determined according to GB/T 45330 and the crystal water content according to GB/T 35924.

6.4 Powder compacted density is determined according to GB/T 44330, applying pressures of 10 kN, 20 kN, 30 kN, 40 kN and 50 kN in that order. 6.5 Tap density is determined according to GB/T 5162. 6.6 Particle size distribution is determined according to GB/T 19077. 6.7 The pH value is determined according to GB/T 5211.6.

6.8 The electrochemical performance of transition metal oxide, prussian blue and polyanionic cathode materials is determined by reference to Annex C.

7 Inspection rules

7.1 Inspection and acceptance. 7.1.1 The product shall be inspected by the supplier or by a third party, who shall ensure that its quality meets Clause 5 and the order form and shall complete the accompanying documents. 7.1.2 The purchaser may inspect the product received against Clause 5 and the order form. Where the results do not conform, the purchaser shall raise the matter with the supplier within three months of receipt and the two shall settle it by consultation. Where arbitration is needed, the sample is taken at the purchaser's premises jointly by the two parties.

7.2 Lot. The product shall be submitted for acceptance in lots, each lot made up of product of the same class, the same production period and the same chemical composition, and each lot not exceeding 6 t in weight. Where the purchaser has particular requirements, the lot is agreed between the two parties.

7.3 Inspection items and sampling. 7.3.1 The items and the sampling quantities for lot-by-lot inspection are given in Table 12, which pairs each item with the clause of the requirement and the clause of the test method: chemical composition 5.1 and 6.1, one sample per lot; appearance quality 5.2 and 6.2, drum by drum or bag by bag; and moisture content, powder compacted density, tap density, particle size distribution, pH value and electrochemical performance, 5.3 to 5.8 and 6.3 to 6.8, one sample per lot. 7.3.2 Sampling follows GB/T 5314, with a total of 2 kg to 3 kg taken per lot.

7.4 Judgement of the results. 7.4.1 Where any one of the chemical composition, moisture content, powder compacted density, tap density, particle size distribution or pH value fails, the lot is judged non-conforming. 7.4.2 Where the appearance quality fails, that drum or bag is judged non-conforming. 7.4.3 Six test cells are made by the method of Annex C and three of them taken at random for the first discharge specific capacity and the first charge-discharge efficiency; if two of them fail to reach Clause 5 the lot is judged non-conforming, but three further cells may be taken for a repeat test, and if any one or more of them still fails to reach Clause 5 the lot is judged non-conforming.

8 Marking, packaging, transport, storage and accompanying documents

8.1 The outer packaging should carry: a) the product name; b) the batch number; c) the net weight; d) the name of the supplier; e) the address of the works; f) a rain protection mark.

8.2 Packaging. 8.2.1 The product shall be packed in an aluminium-plastic lined bag, vacuum heat-sealed and placed in an outer drum or bag; drums at a net weight of 25 kg each, bags at 500 kg or 1 000 kg each. 8.2.2 Where the purchaser has particular requirements for packaging, these are agreed between the two parties.

8.3 Transport and storage. 8.3.1 Damage to the packaging shall be prevented in transport. 8.3.2 The product shall be protected from moisture and corrosion in storage, and has a shelf life of one year from the date of production.

8.4 Accompanying documents. Every lot shall be accompanied by documents which, besides the supplier information, the product information, the number of this document and the date of despatch or packaging, should include: a) a product quality certificate, giving the main performance and technical parameters, the characteristics of the product including those of the manufacturing process and the raw materials, and the quality certifications obtained together with the analysis and inspection results bearing the stamp of the supplier's quality inspection department; b) a certificate of conformity, giving the inspection items and their results or the inspection conclusion, the lot size or batch number, the date of production, the date of inspection and the signature or stamp of the inspector; c) the finished product inspection report; d) instructions for use, covering correct handling, use and storage; e) others.

9 Content of the order form

The purchaser may, according to its own needs, list the following in the order form for the products covered by this document: a) the product name; b) the class; c) the chemical composition and the test method, where there are particular requirements; d) the net weight and the number of packages; e) the number of this document; f) others.

Annex A (informative) Determination of the chemical composition of transition metal oxide cathode materials - Inductively coupled plasma atomic emission spectrometry

A.1 Principle. The test portion is dissolved in hydrochloric acid and, in a dilute hydrochloric acid medium, the emission intensity of each element is measured on an inductively coupled plasma atomic emission spectrometer using the working curve method; the mass concentration of each element is read from the working curve and its mass fraction calculated.

A.2 Reagents and materials. A.2.1 Water, grade 2 or better as specified in GB/T 6682. A.2.2 Hydrochloric acid (1+1). A.2.3 Mixed standard stock solution of silicon, lead, cadmium, chromium and sulfur at 1 000 micrograms per millilitre, a commercially available certified stock solution. A.2.4 Standard stock solutions of sodium, nickel, iron, copper, cobalt, manganese, vanadium and titanium at 1 000 micrograms per millilitre, commercially available certified stock solutions. A.2.5 Mixed standard solution A of silicon, lead, cadmium, chromium and sulfur at 20 micrograms per millilitre, prepared by transferring 2.00 mL of the mixed stock solution into a 100 mL volumetric flask, adding 2 mL of hydrochloric acid, diluting to the mark with water and mixing. A.2.6 and A.2.7 give the corresponding mixed standard solutions A at 20 micrograms per millilitre and B at 50 micrograms per millilitre for sodium, nickel, iron, copper, cobalt, manganese, vanadium and titanium.

A.3 Apparatus. A.3.1 An inductively coupled plasma atomic emission spectrometer with an optical resolution at 200 nm not greater than 0.01 nm. A.3.2 The recommended analytical lines are given in Table A.1, in nanometres: Ni 231.604, Cu 327.393, Fe 259.940, Mn 257.610 and Na 589.592.

Annex B (informative) Determination of the chemical composition of polyanionic cathode materials - Inductively coupled plasma atomic emission spectrometry

Table B.1 gives the recommended analytical lines in nanometres, among them Cr 206.157, Na 589.592, Fe 259.940, P 214.914, Mn 257.610 and S 182.034.

B.4 Sample. The sample is in powder form. B.5 Test procedure. B.5.1 Weigh 0.40 g of the sample to the nearest 0.1000 g. B.5.2 Carry out two tests in parallel and take the mean. B.5.3 Run a blank test alongside the test portion.

B.6 Determination. B.6.1 Plotting the working curve for the impurity elements. B.6.1.1 Transfer 0 mL, 1.00 mL, 2.50 mL, 5.00 mL, 10.00 mL and 12.50 mL of the mixed standard solution A of calcium, copper, zinc, nickel, potassium and chromium into a set of 100 mL volumetric flasks, add 2 mL of nitric acid to each, dilute to the mark with water and mix. B.6.1.2 On the spectrometer, measure the emission intensity of the elements at the analytical lines chosen, and plot the working curve with the mass concentration of the element on the abscissa and the corresponding emission intensity, less that of the zero solution, on the ordinate; the linear correlation coefficient of the working curve is not less than 0.9995.

B.6.2 Determination of the impurity element content. B.6.2.1 Place the test portion in a 100 mL beaker, add about 5 mL of nitric acid and about 10 mL of sulfuric acid, heat until milky white, remove and cool to room temperature, add about 15 mL of hydrochloric acid, heat until the solution is clear, cool to room temperature, transfer to a 100 mL volumetric flask, add 2 mL of nitric acid, dilute to the mark with water and mix. B.6.2.2 On the spectrometer, measure the emission intensity of the elements in the blank solution and in the test solution at the analytical lines chosen, and read from the working curve the mass concentration of the element in the blank and in the test solution.

Annex C (informative) Method for the determination of the electrochemical performance of cathode materials for sodium ion batteries

C.1 General. This method applies to the determination of the first charge-discharge efficiency and the first discharge specific capacity of transition metal oxide, prussian blue and polyanionic cathode materials for sodium ion batteries.

C.2 Reagents and materials. C.2.1 The cathode material, comprising transition metal oxide, prussian blue and polyanionic materials. C.2.2 Sodium ion battery electrolyte: ethylene carbonate and diethyl carbonate in a volume ratio of 1:1, containing 1 mol/L sodium hexafluorophosphate. C.2.3 N-methylpyrrolidone, battery grade, purity not less than 99.9 %, moisture not greater than 0.02 %. C.2.4 Binder: polyvinylidene fluoride, battery grade, weight-average molecular weight not less than 5 x 10^5, moisture not greater than 0.10 %. C.2.5 Conductive agent: acetylene black, carbon black or Ketjen black. C.2.6 Aluminium foil, battery grade, thickness 10 to 25 micrometres. C.2.7 Sodium sheet, thickness 0.1 mm to 0.6 mm. C.2.8 Separator: polyolefin porous membrane or glass fibre separator. C.2.9 Standard components for a coin cell.

C.3 Apparatus. C.3.1 An electronic balance reading to 0.00001 g. C.3.2 A dispersing mixer. C.3.3 A flat plate coater. C.3.4 A vacuum oven. C.3.5 A punching machine. C.3.6 A bench digital thickness gauge with a resolution of 1 micrometre. C.3.7 A micrometer. C.3.8 A roller press. C.3.9 An inert gas glove box with moisture and oxygen content each not greater than 0.0001 %. C.3.10 A thermostatic chamber at 25 degrees plus or minus 1 degree and relative humidity below 40 %. C.3.11 An electrochemical performance tester with a full-scale current and voltage accuracy of 0.1 %.

C.4 Preparation of the cathode sheet. C.4.1 Weighing. The cathode material, the conductive agent and the binder are taken at mass fractions of 85 % to 95 %, 2 % to 10 % and 2 % to 10 % respectively and weighed on the electronic balance to 0.00001 g. Note: the material is packed in a vacuum bag and weighed for sample preparation immediately after opening. C.4.2 Slurry preparation. N-methylpyrrolidone and polyvinylidene fluoride are added to a beaker and the beaker placed under the dispersing mixer and stirred until dispersed.