CN111933914A - Vanadium pentoxide and rGO co-coated gradient ternary cathode material and preparation method thereof - Google Patents
Vanadium pentoxide and rGO co-coated gradient ternary cathode material and preparation method thereof Download PDFInfo
- Publication number
- CN111933914A CN111933914A CN202010915171.2A CN202010915171A CN111933914A CN 111933914 A CN111933914 A CN 111933914A CN 202010915171 A CN202010915171 A CN 202010915171A CN 111933914 A CN111933914 A CN 111933914A
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- Prior art keywords
- nickel
- cobalt
- manganese
- rgo
- gradient
- Prior art date
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- GNTDGMZSJNCJKK-UHFFFAOYSA-N divanadium pentaoxide Chemical compound O=[V](=O)O[V](=O)=O GNTDGMZSJNCJKK-UHFFFAOYSA-N 0.000 title claims abstract description 290
- 239000010406 cathode material Substances 0.000 title claims abstract description 35
- 238000002360 preparation method Methods 0.000 title claims abstract description 22
- HFCVPDYCRZVZDF-UHFFFAOYSA-N [Li+].[Co+2].[Ni+2].[O-][Mn]([O-])(=O)=O Chemical compound [Li+].[Co+2].[Ni+2].[O-][Mn]([O-])(=O)=O HFCVPDYCRZVZDF-UHFFFAOYSA-N 0.000 claims abstract description 26
- 239000011248 coating agent Substances 0.000 claims abstract description 23
- 238000000576 coating method Methods 0.000 claims abstract description 23
- 239000002245 particle Substances 0.000 claims abstract description 20
- 239000011258 core-shell material Substances 0.000 claims abstract description 12
- 229910000572 Lithium Nickel Cobalt Manganese Oxide (NCM) Inorganic materials 0.000 claims abstract description 8
- FBDMTTNVIIVBKI-UHFFFAOYSA-N [O-2].[Mn+2].[Co+2].[Ni+2].[Li+] Chemical compound [O-2].[Mn+2].[Co+2].[Ni+2].[Li+] FBDMTTNVIIVBKI-UHFFFAOYSA-N 0.000 claims abstract description 8
- 239000000126 substance Substances 0.000 claims abstract description 7
- 229910013415 LiNixCoyMn(1-x-y)O2 Inorganic materials 0.000 claims abstract description 3
- 229910013424 LiNixCoyMn(1−x−y)O2 Inorganic materials 0.000 claims abstract description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 124
- 239000000463 material Substances 0.000 claims description 103
- 239000011572 manganese Substances 0.000 claims description 96
- 229910052759 nickel Inorganic materials 0.000 claims description 59
- 239000000243 solution Substances 0.000 claims description 58
- 238000006243 chemical reaction Methods 0.000 claims description 50
- 239000007774 positive electrode material Substances 0.000 claims description 40
- 238000005245 sintering Methods 0.000 claims description 37
- 238000003756 stirring Methods 0.000 claims description 35
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 30
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 30
- 239000011247 coating layer Substances 0.000 claims description 29
- KFDQGLPGKXUTMZ-UHFFFAOYSA-N [Mn].[Co].[Ni] Chemical compound [Mn].[Co].[Ni] KFDQGLPGKXUTMZ-UHFFFAOYSA-N 0.000 claims description 28
- 239000010410 layer Substances 0.000 claims description 26
- 239000010941 cobalt Substances 0.000 claims description 23
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims description 23
- 238000010438 heat treatment Methods 0.000 claims description 22
- 239000011259 mixed solution Substances 0.000 claims description 22
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 19
- 239000002243 precursor Substances 0.000 claims description 19
- 229910052720 vanadium Inorganic materials 0.000 claims description 19
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 claims description 19
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 18
- 238000001035 drying Methods 0.000 claims description 17
- 239000012298 atmosphere Substances 0.000 claims description 16
- 229910052748 manganese Inorganic materials 0.000 claims description 16
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 claims description 15
- 229910017052 cobalt Inorganic materials 0.000 claims description 15
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 claims description 15
- 230000032683 aging Effects 0.000 claims description 13
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 12
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 claims description 12
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 12
- SEVNKUSLDMZOTL-UHFFFAOYSA-H cobalt(2+);manganese(2+);nickel(2+);hexahydroxide Chemical compound [OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[Mn+2].[Co+2].[Ni+2] SEVNKUSLDMZOTL-UHFFFAOYSA-H 0.000 claims description 12
- 229910052744 lithium Inorganic materials 0.000 claims description 12
- QXZUUHYBWMWJHK-UHFFFAOYSA-N [Co].[Ni] Chemical compound [Co].[Ni] QXZUUHYBWMWJHK-UHFFFAOYSA-N 0.000 claims description 11
- 238000001816 cooling Methods 0.000 claims description 10
- 238000005086 pumping Methods 0.000 claims description 10
- 230000002829 reductive effect Effects 0.000 claims description 10
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 9
- 238000005253 cladding Methods 0.000 claims description 9
- 238000000975 co-precipitation Methods 0.000 claims description 9
- 238000005406 washing Methods 0.000 claims description 9
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 8
- 229910001429 cobalt ion Inorganic materials 0.000 claims description 8
- 150000004677 hydrates Chemical class 0.000 claims description 8
- 229910001437 manganese ion Inorganic materials 0.000 claims description 8
- 229910001453 nickel ion Inorganic materials 0.000 claims description 8
- 239000001301 oxygen Substances 0.000 claims description 8
- 229910052760 oxygen Inorganic materials 0.000 claims description 8
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonium chloride Substances [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 claims description 7
- 238000001132 ultrasonic dispersion Methods 0.000 claims description 7
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 claims description 6
- 150000001868 cobalt Chemical class 0.000 claims description 6
- 229910000361 cobalt sulfate Inorganic materials 0.000 claims description 6
- 229940044175 cobalt sulfate Drugs 0.000 claims description 6
- KTVIXTQDYHMGHF-UHFFFAOYSA-L cobalt(2+) sulfate Chemical compound [Co+2].[O-]S([O-])(=O)=O KTVIXTQDYHMGHF-UHFFFAOYSA-L 0.000 claims description 6
- 239000008367 deionised water Substances 0.000 claims description 6
- 229910021641 deionized water Inorganic materials 0.000 claims description 6
- 150000002815 nickel Chemical class 0.000 claims description 6
- LGQLOGILCSXPEA-UHFFFAOYSA-L nickel sulfate Chemical compound [Ni+2].[O-]S([O-])(=O)=O LGQLOGILCSXPEA-UHFFFAOYSA-L 0.000 claims description 6
- 229910000363 nickel(II) sulfate Inorganic materials 0.000 claims description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 6
- UNTBPXHCXVWYOI-UHFFFAOYSA-O azanium;oxido(dioxo)vanadium Chemical compound [NH4+].[O-][V](=O)=O UNTBPXHCXVWYOI-UHFFFAOYSA-O 0.000 claims description 5
- 238000004821 distillation Methods 0.000 claims description 5
- 235000019441 ethanol Nutrition 0.000 claims description 5
- 238000001914 filtration Methods 0.000 claims description 5
- 238000000227 grinding Methods 0.000 claims description 5
- 229940099596 manganese sulfate Drugs 0.000 claims description 5
- 239000011702 manganese sulphate Substances 0.000 claims description 5
- 235000007079 manganese sulphate Nutrition 0.000 claims description 5
- SQQMAOCOWKFBNP-UHFFFAOYSA-L manganese(II) sulfate Chemical compound [Mn+2].[O-]S([O-])(=O)=O SQQMAOCOWKFBNP-UHFFFAOYSA-L 0.000 claims description 5
- 238000002156 mixing Methods 0.000 claims description 5
- 239000000203 mixture Substances 0.000 claims description 5
- FSJSYDFBTIVUFD-SUKNRPLKSA-N (z)-4-hydroxypent-3-en-2-one;oxovanadium Chemical compound [V]=O.C\C(O)=C\C(C)=O.C\C(O)=C\C(C)=O FSJSYDFBTIVUFD-SUKNRPLKSA-N 0.000 claims description 4
- MQRWBMAEBQOWAF-UHFFFAOYSA-N acetic acid;nickel Chemical compound [Ni].CC(O)=O.CC(O)=O MQRWBMAEBQOWAF-UHFFFAOYSA-N 0.000 claims description 4
- 229940011182 cobalt acetate Drugs 0.000 claims description 4
- QAHREYKOYSIQPH-UHFFFAOYSA-L cobalt(II) acetate Chemical compound [Co+2].CC([O-])=O.CC([O-])=O QAHREYKOYSIQPH-UHFFFAOYSA-L 0.000 claims description 4
- 150000002696 manganese Chemical class 0.000 claims description 4
- 229940071125 manganese acetate Drugs 0.000 claims description 4
- UOGMEBQRZBEZQT-UHFFFAOYSA-L manganese(2+);diacetate Chemical compound [Mn+2].CC([O-])=O.CC([O-])=O UOGMEBQRZBEZQT-UHFFFAOYSA-L 0.000 claims description 4
- 229940078494 nickel acetate Drugs 0.000 claims description 4
- 230000001590 oxidative effect Effects 0.000 claims description 4
- 239000012716 precipitator Substances 0.000 claims description 4
- 230000001681 protective effect Effects 0.000 claims description 4
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 claims description 3
- 229910052808 lithium carbonate Inorganic materials 0.000 claims description 3
- MFWFDRBPQDXFRC-LNTINUHCSA-N (z)-4-hydroxypent-3-en-2-one;vanadium Chemical compound [V].C\C(O)=C\C(C)=O.C\C(O)=C\C(C)=O.C\C(O)=C\C(C)=O MFWFDRBPQDXFRC-LNTINUHCSA-N 0.000 claims description 2
- 229910021380 Manganese Chloride Inorganic materials 0.000 claims description 2
- GLFNIEUTAYBVOC-UHFFFAOYSA-L Manganese chloride Chemical compound Cl[Mn]Cl GLFNIEUTAYBVOC-UHFFFAOYSA-L 0.000 claims description 2
- 229910021586 Nickel(II) chloride Inorganic materials 0.000 claims description 2
- XKGIZIQMMABGJQ-UHFFFAOYSA-N [Mn](=O)(=O)([O-])[O-].[Mn+2].[Co+2].[Ni+2].[Li+] Chemical compound [Mn](=O)(=O)([O-])[O-].[Mn+2].[Co+2].[Ni+2].[Li+] XKGIZIQMMABGJQ-UHFFFAOYSA-N 0.000 claims description 2
- 229910021529 ammonia Inorganic materials 0.000 claims description 2
- 239000012300 argon atmosphere Substances 0.000 claims description 2
- GVPFVAHMJGGAJG-UHFFFAOYSA-L cobalt dichloride Chemical compound [Cl-].[Cl-].[Co+2] GVPFVAHMJGGAJG-UHFFFAOYSA-L 0.000 claims description 2
- UFMZWBIQTDUYBN-UHFFFAOYSA-N cobalt dinitrate Chemical compound [Co+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O UFMZWBIQTDUYBN-UHFFFAOYSA-N 0.000 claims description 2
- 229910001981 cobalt nitrate Inorganic materials 0.000 claims description 2
- 239000011565 manganese chloride Substances 0.000 claims description 2
- 235000002867 manganese chloride Nutrition 0.000 claims description 2
- 229940099607 manganese chloride Drugs 0.000 claims description 2
- MIVBAHRSNUNMPP-UHFFFAOYSA-N manganese(2+);dinitrate Chemical compound [Mn+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O MIVBAHRSNUNMPP-UHFFFAOYSA-N 0.000 claims description 2
- QMMRZOWCJAIUJA-UHFFFAOYSA-L nickel dichloride Chemical compound Cl[Ni]Cl QMMRZOWCJAIUJA-UHFFFAOYSA-L 0.000 claims description 2
- KBJMLQFLOWQJNF-UHFFFAOYSA-N nickel(ii) nitrate Chemical compound [Ni+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O KBJMLQFLOWQJNF-UHFFFAOYSA-N 0.000 claims description 2
- 239000012299 nitrogen atmosphere Substances 0.000 claims description 2
- 239000003960 organic solvent Substances 0.000 claims description 2
- 230000001105 regulatory effect Effects 0.000 claims 1
- 238000000034 method Methods 0.000 abstract description 21
- 238000009776 industrial production Methods 0.000 abstract description 6
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 abstract description 3
- 229910001416 lithium ion Inorganic materials 0.000 abstract description 2
- 229910021542 Vanadium(IV) oxide Inorganic materials 0.000 abstract 1
- GRUMUEUJTSXQOI-UHFFFAOYSA-N vanadium dioxide Chemical compound O=[V]=O GRUMUEUJTSXQOI-UHFFFAOYSA-N 0.000 abstract 1
- 229910013716 LiNi Inorganic materials 0.000 description 59
- 229910015680 LiNi0.84Co0.11Mn0.05O2 Inorganic materials 0.000 description 31
- 238000001514 detection method Methods 0.000 description 21
- 230000000052 comparative effect Effects 0.000 description 20
- 239000010405 anode material Substances 0.000 description 18
- 230000008569 process Effects 0.000 description 17
- 238000007599 discharging Methods 0.000 description 14
- 230000000694 effects Effects 0.000 description 12
- 239000011163 secondary particle Substances 0.000 description 12
- 150000002500 ions Chemical class 0.000 description 10
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 8
- 230000009286 beneficial effect Effects 0.000 description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 6
- 230000007423 decrease Effects 0.000 description 6
- 230000014759 maintenance of location Effects 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 6
- 230000015572 biosynthetic process Effects 0.000 description 5
- 239000013078 crystal Substances 0.000 description 5
- 230000002349 favourable effect Effects 0.000 description 5
- 230000012010 growth Effects 0.000 description 5
- 229940053662 nickel sulfate Drugs 0.000 description 5
- 238000001556 precipitation Methods 0.000 description 5
- 230000002441 reversible effect Effects 0.000 description 5
- 229910052786 argon Inorganic materials 0.000 description 4
- 239000010416 ion conductor Substances 0.000 description 4
- 229910021645 metal ion Inorganic materials 0.000 description 4
- 238000007086 side reaction Methods 0.000 description 4
- 229910003005 LiNiO2 Inorganic materials 0.000 description 3
- 239000006185 dispersion Substances 0.000 description 3
- 239000000706 filtrate Substances 0.000 description 3
- 239000002904 solvent Substances 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 2
- 238000003917 TEM image Methods 0.000 description 2
- 150000001450 anions Chemical class 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 239000004020 conductor Substances 0.000 description 2
- 238000000354 decomposition reaction Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 229910001873 dinitrogen Inorganic materials 0.000 description 2
- 239000003792 electrolyte Substances 0.000 description 2
- PQVSTLUFSYVLTO-UHFFFAOYSA-N ethyl n-ethoxycarbonylcarbamate Chemical compound CCOC(=O)NC(=O)OCC PQVSTLUFSYVLTO-UHFFFAOYSA-N 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 229910000040 hydrogen fluoride Inorganic materials 0.000 description 2
- 238000001027 hydrothermal synthesis Methods 0.000 description 2
- 230000002427 irreversible effect Effects 0.000 description 2
- GLXDVVHUTZTUQK-UHFFFAOYSA-M lithium hydroxide monohydrate Substances [Li+].O.[OH-] GLXDVVHUTZTUQK-UHFFFAOYSA-M 0.000 description 2
- 229940040692 lithium hydroxide monohydrate Drugs 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 239000011164 primary particle Substances 0.000 description 2
- 239000011241 protective layer Substances 0.000 description 2
- 238000001878 scanning electron micrograph Methods 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- 229910020632 Co Mn Inorganic materials 0.000 description 1
- 241001391944 Commicarpus scandens Species 0.000 description 1
- 229910020678 Co—Mn Inorganic materials 0.000 description 1
- 229910001290 LiPF6 Inorganic materials 0.000 description 1
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 1
- 239000002033 PVDF binder Substances 0.000 description 1
- 239000004743 Polypropylene Substances 0.000 description 1
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 239000006230 acetylene black Substances 0.000 description 1
- 239000011149 active material Substances 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 238000000498 ball milling Methods 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 239000011324 bead Substances 0.000 description 1
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- 238000013461 design Methods 0.000 description 1
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- 230000005611 electricity Effects 0.000 description 1
- 239000011532 electronic conductor Substances 0.000 description 1
- 230000009647 facial growth Effects 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 239000008187 granular material Substances 0.000 description 1
- 229910021389 graphene Inorganic materials 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- -1 polypropylene Polymers 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 235000002639 sodium chloride Nutrition 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 238000004729 solvothermal method Methods 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 229910052723 transition metal Inorganic materials 0.000 description 1
- 150000003624 transition metals Chemical class 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
Images
Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
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- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/362—Composites
- H01M4/366—Composites as layered products
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/15—Nano-sized carbon materials
- C01B32/182—Graphene
- C01B32/194—After-treatment
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G31/00—Compounds of vanadium
- C01G31/02—Oxides
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G53/00—Compounds of nickel
- C01G53/40—Nickelates
- C01G53/42—Nickelates containing alkali metals, e.g. LiNiO2
- C01G53/44—Nickelates containing alkali metals, e.g. LiNiO2 containing manganese
- C01G53/50—Nickelates containing alkali metals, e.g. LiNiO2 containing manganese of the type [MnO2]n-, e.g. Li(NixMn1-x)O2, Li(MyNixMn1-x-y)O2
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- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
- H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
- H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
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- H—ELECTRICITY
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- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
- H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
- H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
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- H—ELECTRICITY
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- H—ELECTRICITY
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Abstract
Vanadium pentoxide and rGO are coated with a gradient ternary cathode material and a preparation method, wherein the cathode material is spherical core-shell structure particles formed by coating vanadium pentoxide and inner and outer layers of rGO with nickel cobalt lithium manganate; the lithium nickel cobalt manganese oxide and the pentoxideThe mass ratio of the vanadium dioxide to the rGO is 1: 0.01-0.05; the chemical formula of the nickel cobalt lithium manganate is LiNixCoyMn(1‑x‑y)O2Wherein x is more than or equal to 0.70 and less than or equal to 0.90, y is more than or equal to 0.05 and less than or equal to 0.2, and 1-x-y is more than or equal to 0. The invention also discloses a preparation method of the vanadium pentoxide and rGO co-coated gradient ternary cathode material. The cathode material has high lithium ion and electron conductivity and good electrochemical performance; the method is simple and controllable, short in flow, low in cost and suitable for industrial production.
Description
Technical Field
The invention relates to a ternary cathode material and a preparation method thereof, in particular to a vanadium pentoxide and rGO co-coated gradient ternary cathode material and a preparation method thereof.
Background
The high nickel ternary material is one of the most attractive cathode materials at present due to the high theoretical specific capacity and the high mass specific energy. However, the high-nickel ternary material still has the problems of poor cycle stability, insufficient rate performance and the like in the charge-discharge cycle process, the surface of the material is easily corroded by HF (hydrogen fluoride), the stability of the material structure is influenced, and meanwhile, Ni on the surface of the material is4+Ions are easy to reduce into rock salt phase NiO, and the conductivity of the material is greatly influenced. Researchers carry out modification experiments on the high-nickel ternary material, particularly surface coating, and the modification experiments are widely researched at present, but the effects are not good enough.
CN 109980204A discloses a method for preparing a vanadium pentoxide-coated high-performance ternary cathode material by a surfactant-assisted hydrothermal method, specifically, a vanadium pentoxide solution generated by dissolving ammonium metavanadate in deionized water and a ternary material prepared by a solvothermal method are mixed and sintered to obtain the vanadium pentoxide-coated high-performance ternary cathode material. However, 1) the hydrothermal method is not suitable for wide use; 2) the ammonium metavanadate is dissolved in the solution, so that the vanadium pentoxide can not be obtained by complete conversion; 3) the co-firing of the ternary precursor lithium and the vanadium source can affect the structure of the ternary material. Therefore, the method is only suitable for the experimental process, and the synthesis process is complex and needs to be further improved.
CN 109546123A discloses a vanadium pentoxide coated core-shell structure gradient nickel cobalt manganese cathode material and a preparation method thereof, wherein due to the abrupt transition metal content change of a shell layer material, if metal ions and electrons diffuse at a core-shell interface in the process of high-temperature treatment, a barrier for blocking diffusion is formed, and the performance of the material is greatly reduced.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide a gradient ternary cathode material which is high in lithium ion and electron conductivity, good in structural stability, thermal stability, rate capability and long-cycle stability and highly reversible in charge-discharge reaction, wherein vanadium pentoxide and rGO are coated together.
The invention further aims to solve the technical problem of overcoming the defects in the prior art and provide a preparation method of the vanadium pentoxide and rGO co-coated gradient ternary cathode material, which is simple and controllable, has short process flow, good coating effect and low cost and is suitable for industrial production.
The technical scheme adopted by the invention for solving the technical problems is as follows: vanadium pentoxide and rGO are coated with a gradient ternary cathode material, wherein the cathode material is spherical core-shell structure particles formed by coating vanadium pentoxide and inner and outer layers of rGO with nickel cobalt lithium manganate; the mass ratio of the nickel cobalt lithium manganate to the vanadium pentoxide to the rGO is 1: 0.01-0.05; the chemical formula of the nickel cobalt lithium manganate is LiNixCoyMn(1-x-y)O2Wherein 0.70. ltoreq. x.ltoreq.0.90 (more preferably 0.80. ltoreq. x.ltoreq.0.88), 0.05. ltoreq. y.ltoreq.0.2 (more preferably 0.10. ltoreq. y.ltoreq.0.15), and 1-x-y > 0. The vanadium pentoxide of the ionic conductor is firstly coated on the surface of the nickel cobalt lithium manganate ternary material, so that the anode material is prevented from being subjected to electrolyte in the charge-discharge cycle processThe direct contact generates side reaction, enhances the ionic conductivity, improves the circulation stability, and then is coated by the electron conductor layer rGO, so that the material circulation process can be further protected, the electronic conductivity is improved, and the material can show excellent electrochemical performance particularly under the condition of large multiplying power. Through the structural design of the electron conductor protective layer, the ion conductor protective layer and the gradient ternary material from outside to inside, the stability of the ternary material in the circulation process is favorably protected, and the ionic and electronic conductivity of the anode material in the circulation process can be improved, so that excellent electrochemical performance is shown.
The rGO in the invention is a short name for reduced graphene oxide.
Preferably, the nickel cobalt lithium manganate is a full-gradient material, the content of nickel element is gradually reduced from the center to the surface of the nickel cobalt lithium manganate, the content of manganese element is gradually increased from the center to the surface of the nickel cobalt lithium manganate, and the content of cobalt element is uniformly distributed in the nickel cobalt lithium manganate.
Preferably, the average particle size of the vanadium pentoxide and rGO co-coated gradient ternary cathode material is 3-7 μm. And the secondary particles of the anode material are in the particle size range, and the anode material is regular in appearance and uniform in dispersion.
Preferably, the average thickness of the vanadium pentoxide coating layer is 1-5 nm. The vanadium pentoxide coating layer is not suitable to be too thick, otherwise, the active material is influenced by too much oxide layer, so that the first charge-discharge efficiency is reduced, and the adverse effect is also generated in the dynamic process by the too thick coating layer; the coating layer cannot be too thin, and if the coating layer is too thin, the coating effect is not good.
Preferably, the average thickness of the rGO coating layer is 1-5 nm. If the rGO coating layer is too thick, the coating strength will be poor and the cost too high; if the rGO coating layer is too thin, it is difficult to exert the effect of rGO coating to improve conductivity.
The technical scheme adopted for further solving the technical problems is as follows: the preparation method of the vanadium pentoxide and rGO co-coated gradient ternary cathode material comprises the following steps:
(1) pumping the low-nickel-content nickel-cobalt-manganese solution into a container filled with the high-nickel-content nickel-cobalt or nickel-cobalt-manganese solution, stirring to form a mixed solution, simultaneously pumping the mixed solution into a reaction kettle filled with an ammonia solution, simultaneously adjusting the ammonia concentration of the reaction system by using ammonia water, adjusting the pH value of the reaction system by using a hydroxide precipitator solution, introducing into a protective atmosphere, heating, stirring, carrying out coprecipitation reaction, stirring, aging, filtering, washing, and drying to obtain a full-gradient nickel-cobalt-manganese hydroxide precursor;
(2) mixing and grinding the full-gradient nickel-cobalt-manganese hydroxide precursor obtained in the step (1) with a lithium source, then performing two-stage sintering in an oxidizing atmosphere, and cooling to room temperature to obtain a full-gradient nickel-cobalt-manganese lithium manganate material;
(3) adding the full-gradient lithium nickel cobalt manganese oxide material obtained in the step (2) and a vanadium source into an organic solution, performing ultrasonic dispersion, heating and stirring until the mixture is dried by distillation, sintering, and cooling to room temperature to obtain a vanadium pentoxide-coated full-gradient lithium nickel cobalt manganese oxide material;
(4) and (4) rotationally stirring the vanadium pentoxide coated full-gradient nickel cobalt lithium manganate material obtained in the step (3) and rGO, and drying to obtain the vanadium pentoxide and rGO co-coated gradient ternary cathode material.
Preferably, in the step (1), the feeding speed of the low nickel content nickel-cobalt-manganese solution is 30-70 mL/h (more preferably 40-60 mL/h).
Preferably, in the step (1), the feeding speed of the mixed solution is 80-120 mL/h (more preferably 90-110 mL/h).
If the feed rate is too fast, then can lead to pH variation range great for the precipitant is difficult to carry out effectual precipitation to metal ion, is unfavorable for the formation of control reaction process crystal nucleus and growth thereof, if the feed rate is too slow, then the granule is agglomerated easily, also is unfavorable for improving production efficiency simultaneously.
Preferably, in the step (1), the total molar concentration of nickel, cobalt and manganese ions in the low-nickel-content nickel-cobalt-manganese solution is 0.3-3.0 mol/L (more preferably 1.5-2.5 mol/L), and the molar ratio of nickel, cobalt and manganese is 3-8: 1: > 0-2. If the total molar concentration of the nickel, cobalt and manganese ions is too low, the precipitation time is longer, which is not beneficial to improving the production efficiency, and if the total molar concentration of the nickel, cobalt and manganese ions is too high, which is not beneficial to controlling the pH value in the reaction process, the precipitation effect is not good.
Preferably, in the step (1), in the high nickel content nickel-cobalt or nickel-cobalt-manganese solution, the total molar concentration of nickel, cobalt and manganese ions is 0.3-4.0 mol/L (more preferably 1.5-2.5 mol/L), and the molar ratio of nickel, cobalt and manganese is 8-9: 0.5-1: 0-1. If the total molar concentration of the nickel, cobalt and manganese ions is too low, the precipitation time is longer, which is not beneficial to improving the production efficiency, and if the total molar concentration of the nickel, cobalt and manganese ions is too high, which is not beneficial to controlling the pH value in the reaction process, the precipitation effect is not good.
Preferably, in the step (1), in the same reaction system, the nickel content of the low nickel content nickel-cobalt-manganese solution is lower than that of the high nickel content nickel-cobalt or nickel-cobalt-manganese solution.
Preferably, in the step (1), the volume ratio of the ammonia water solution, the hydroxide precipitant solution, the low nickel content nickel cobalt manganese solution and the high nickel content nickel cobalt or nickel cobalt manganese solution in the reaction kettle is 0.1-10: 1-2: 1:1 (more preferably 1:2:1: 1). Under the feeding proportion, the initiation of the coprecipitation reaction and the control of the material gradient are more facilitated.
Preferably, in the step (1), the molar concentration of the ammonia water solution is 1.0-7.0 mol/L (more preferably 1.5-4.5 mol/L). If the molar concentration of the aqueous ammonia solution is too low, it is difficult to completely complex the metal ions, and if the molar concentration of the aqueous ammonia solution is too high, it is not favorable for the metal ions to form hydroxide precipitates.
Preferably, in the step (1), ammonia water is used for adjusting the ammonia water concentration of the reaction system to be kept at 1.0-7.0 mol/L (more preferably 1.5-4.5 mol/L).
Preferably, in the step (1), the mass concentration of the ammonia water for adjusting the ammonia water concentration of the reaction system is 25-28%.
Preferably, in the step (1), the pH value of the reaction system is adjusted to 10-12 by using a hydroxide precipitator solution. At the pH value, the growth speed of the particles is more favorably controlled not to be too fast or too slow.
Preferably, in the step (1), the molar concentration of the hydroxide precipitant solution is 1.0-7.0 mol/L (more preferably 4.0-6.0 mol/L). If the molar concentration of the hydroxide precipitant solution is too high or too low, the pH value of the reaction solution cannot be accurately controlled, and the shape of the precursor is unfavorable.
Preferably, in the step (1), the low nickel content nickel-cobalt-manganese solution and the high nickel content nickel-cobalt-manganese solution are mixed solutions of soluble nickel salt, soluble cobalt salt and soluble manganese salt, and the high nickel content nickel-cobalt solution is mixed solution of soluble nickel salt and soluble cobalt salt.
Preferably, in the step (1), the soluble nickel salt is one or more of nickel sulfate, nickel nitrate, nickel acetate or nickel chloride, and hydrates thereof.
Preferably, in the step (1), the soluble cobalt salt is one or more of cobalt sulfate, cobalt nitrate, cobalt acetate or cobalt chloride, and hydrates thereof.
Preferably, in the step (1), the soluble manganese salt is one or more of manganese sulfate, manganese nitrate, manganese acetate or manganese chloride, and hydrates thereof.
Preferably, in the step (1), the hydroxide precipitant is one or more of sodium hydroxide, potassium hydroxide or lithium hydroxide, and hydrates thereof.
Preferably, in step (1), the protective atmosphere is a nitrogen atmosphere and/or an argon atmosphere.
Preferably, in the step (1), the stirring speed of the coprecipitation reaction is 800-1200 r/min, the temperature is 30-70 ℃ (more preferably 40-60 ℃), and the time is 30-50 h. If the stirring speed is too slow, the primary particles are easy to agglomerate, and if the stirring speed is too fast, the grown crystals are easy to break; in the temperature range, the growth of crystals is more facilitated; the reaction time is determined by the raw material content and the feeding speed.
Preferably, in the step (1), the aging temperature is 30-70 ℃ (more preferably 40-60 ℃) and the aging time is 8-24 h. The aging process can replace anions such as sulfate radicals in the material and is beneficial to the uniformity of the particle surface. If the aging time is too short, it is difficult to ensure the ion exchange of anions, which also affects the subsequent washing process, and if the aging time is too long, it is not favorable for production application and uniformity of material surface. The aging temperature is kept consistent with the temperature of the coprecipitation reaction, which is beneficial to the uniform dispersion and non-agglomeration of materials and ensures that primary particles grow into secondary particles uniformly.
Preferably, in the step (1), the washing is to wash the filtered substances with deionized water and ethanol alternately for more than or equal to 6 times.
Preferably, in the step (1), the drying temperature is 80-100 ℃ and the drying time is 12-24 h. If the temperature is too low or the time is too short, the material is difficult to dry, and if the temperature is too high or the time is too long, other side reactions are generated on the surface of the material, so that the performance of the material is influenced, and the long period is not favorable for industrial production.
Preferably, in the step (2), the molar ratio of the sum of the moles of the nickel, cobalt and manganese elements in the full-gradient nickel-cobalt-manganese hydroxide precursor to the mole of the lithium element in the lithium source is 1: 1.05-1.11.
Preferably, in the step (2), the lithium source is lithium hydroxide and/or lithium carbonate.
Preferably, in the step (2), the oxidizing atmosphere is an air atmosphere and/or an oxygen atmosphere.
Preferably, in step (2), the two-stage sintering is: the temperature is raised to 350-550 ℃ at the speed of 1-10 ℃/min (more preferably 3-7 ℃/min), the sintering is carried out for 2-8 h (more preferably 3-6 h), and then the temperature is raised to 550-1000 ℃ at the speed of 1-10 ℃/min (more preferably 3-7 ℃/min), the sintering is carried out for 8-20 h (more preferably 10-16 h). In the first stage of sintering process, decomposition reaction of the full-gradient precursor and the lithium source mainly occurs, and in the second stage of sintering process, combination reaction of the full-gradient precursor and the oxide decomposed by the lithium source under the oxygen atmosphere mainly occurs. If the sintering temperature is too high or the sintering time is too long, the material is easy to agglomerate, the capacity is difficult to release in the charging and discharging process, and if the sintering temperature is too low or the sintering time is too short, the required morphology is difficult to form, and the electrochemical performance is influenced. If the temperature rise rate is too fast, it is difficult to ensure sufficient reaction of the material, and if the temperature rise rate is too slow, it is not favorable for industrial production.
Preferably, in the step (3), the mass-to-volume ratio (g/g/mL) of the full-gradient lithium nickel cobalt manganese oxide material, the vanadium source and the organic solution is 1: 0.01-0.12: 10-300. If the vanadium source is too much, the generated vanadium pentoxide is too much, so that the coating layer on the surface of the material is too thick, even the vanadium pentoxide is agglomerated, and the reaction process dynamics of the material is influenced, so that the performance of the material is influenced. If the amount of the organic solution is too small, the vanadium source is difficult to completely dissolve, and if the amount of the organic solution is too large, the concentration of the vanadium source is low, the coating effect is not good, and the solvent is wasted.
Preferably, in the step (3), the vanadium source is one or more of vanadyl acetylacetonate, vanadium acetylacetonate or ammonium metavanadate.
Preferably, in the step (3), the organic solvent is absolute ethyl alcohol and/or acetone, etc.
Preferably, in the step (3), the frequency of the ultrasonic dispersion is 1.5-2.5 kHz, and the time is 0.5-1.0 h. The ultrasonic dispersion is mainly used for completely decomposing and diffusing the vanadium source on the surface of the ternary material in the solution. If the ultrasonic dispersion frequency is too high or the time is too long, the structure of the material is damaged, and if the ultrasonic dispersion frequency is too low or the time is too short, the effect of uniform dispersion is difficult to achieve.
Preferably, in the step (3), the heating and stirring speed is 300-500 r/min, and the temperature is 50-70 ℃. The heating and stirring are mainly used for further coating the dispersed vanadium source on the surface of the ternary material, and the solvent is completely volatilized after the coating is finished. If the stirring speed is too high, the coating layer becomes uneven, and if the stirring speed is too low, the decomposed vanadium source itself tends to grow. The growth of secondary particles is controlled by crystal face growth, the growth rate is increased when the temperature is increased, but the temperature cannot be too high in order to control the consistency of crystal appearance, and the too high temperature can also cause resource waste.
Preferably, in the step (3), the sintering is carried out at a rate of 1-10 ℃/min (more preferably 3-7 ℃/min) until the temperature is raised to 350-550 ℃ for 2-8 h. The sintering purpose is mainly to decompose a vanadium source on the surface of the ternary material to form an ion conductor vanadium pentoxide, and the vanadium pentoxide is uniformly coated on the surface of the vanadium source. If the temperature rise rate is too fast, it is difficult to ensure sufficient reaction of the material, and if the temperature rise rate is too slow, it is not favorable for industrial production. If the sintering temperature is too low, the vanadium source is difficult to be completely decomposed into vanadium pentoxide, if the sintering temperature is too high, the oxide may be further decomposed, and if the sintering temperature is too high, the decomposition of the lithium source may cause the change of the layered structure of the positive electrode material, and waste of production resources may be caused. If the sintering time is too short, the coating may not be uniform, and if the sintering time is too long, unnecessary side reactions may occur, and the production efficiency may be deteriorated.
Preferably, in the step (4), the mass ratio of the vanadium pentoxide coated full-gradient nickel cobalt lithium manganate material to the rGO is 1: 0.01-0.05. If the rGO coating layer is too thick, the coating strength will be poor and the cost too high; if the rGO coating layer is too thin, it is difficult to exert the effect of rGO coating to improve conductivity.
Preferably, in the step (4), the rotating speed of the rotating stirring is 250-400 r/min, and the time is 8-12 h. The coating requirement of the material is easier to achieve at the rotating speed, if the time is too long, the material structure is damaged, the material is easy to harden, and if the time is too short, the coating effect is not favorably achieved. The rotary stirring can be achieved in a ball mill without the addition of ball milling beads.
Preferably, in the step (4), the drying temperature is 80-120 ℃ and the drying time is 2-3 h.
The nitrogen, argon or oxygen used in the invention is high-purity gas with the purity of more than or equal to 99.99 percent.
The invention has the following beneficial effects:
(1) the vanadium pentoxide and rGO co-coated gradient ternary cathode material is free of impurity phase generation, secondary particles are of a spherical core-shell structure, the average particle size is 3-7 mu m, an inner layer vanadium pentoxide and an outer layer vanadium pentoxide and rGO coating layers are formed on the surfaces of the secondary particles, the average thickness of the vanadium pentoxide is 1-5 nm, the average thickness of the rGO is 1-5 nm, the content of a nickel element in the nickel cobalt lithium manganate is gradually reduced from the center to the surface of the nickel cobalt lithium manganate, the content of the manganese element is gradually increased from the center to the surface of the nickel cobalt lithium manganate, and the content of the cobalt element is uniformly distributed in the nickel cobalt lithium manganate, so that the nickel cobalt lithium manganate is a gradient polycrystalline aggregate;
(2) the battery assembled by the vanadium pentoxide and rGO co-coated gradient ternary cathode material has specific discharge capacities respectively up to 199.8mAh/g, 191mAh/g and 146.5mAh/g under the current densities of 0.2C (40 mA/g), 1C and 10C, which shows that the vanadium pentoxide and rGO co-coated gradient ternary cathode material can keep the structure stable in the charging and discharging processes under different multiplying powers, and the charging and discharging reaction is highly reversible; under the charging and discharging voltage of 2.7-4.3V and the current density of 0.1C (20 mA/g), the first discharging specific capacity can reach 205.4 mAh/g, and under the current density of 1C, after circulating for 100 circles, the first discharging specific capacity still can reach 174.3 mAh/g, which shows that the charging and discharging performance of the vanadium pentoxide and rGO co-coated gradient ternary cathode material is stable and the circulation performance is good, after the cathode material is coated by the vanadium pentoxide serving as an ionic conductor and the rGO serving as an electronic conductor, the conductivity of the material is improved, the occurrence of interface side reaction is hindered, and the electrochemical performance is also improved;
(3) the method is simple and controllable, has short process flow, good coating effect and low cost, and is suitable for industrial production.
Drawings
FIG. 1 shows a gradient LiNi co-coated with vanadium pentoxide and rGO in example 1 of the present invention0.84Co0.11Mn0.05O2XRD pattern of the positive electrode material;
FIG. 2 shows a gradient LiNi co-coated with vanadium pentoxide and rGO in example 1 of the present invention0.84Co0.11Mn0.05O2SEM image of the positive electrode material;
FIG. 3 shows LiNi with vanadium pentoxide and rGO co-coated gradient in example 1 of the present invention0.84Co0.11Mn0.05O2TEM images of the positive electrode material;
FIG. 4 shows an embodiment of the present invention1 step (2) obtaining the full-gradient LiNi0.84Co0.11Mn0.05O2FIB slice element line scan results of material from center to surface (hemisphere);
FIG. 5 shows LiNi with vanadium pentoxide and rGO co-coated gradient in example 1 of the present invention0.84Co0.11Mn0.05O2Positive electrode material and full-gradient LiNi obtained in step (2) of example 1 of the present invention0.84Co0.11Mn0.05O2XPS plot of material (comparative example 1);
FIG. 6 shows LiNi with vanadium pentoxide and rGO co-coated gradient in example 1 of the present invention0.84Co0.11Mn0.05O2A first circle charge-discharge curve chart of a battery assembled by the positive electrode material;
FIG. 7 shows LiNi with a gradient of vanadium pentoxide and rGO co-cladding in accordance with example 1 of the present invention0.84Co0.11Mn0.05O2A discharge cycle profile of a battery assembled with the positive electrode material;
FIG. 8 shows LiNi with a gradient of vanadium pentoxide and rGO co-cladding in accordance with example 1 of the present invention0.84Co0.11Mn0.05O2A rate curve of a battery assembled by the positive electrode material;
FIG. 9 is a full gradient LiNi of comparative example 1 of the present invention0.84Co0.11Mn0.05O2SEM images of the material;
FIG. 10 is a full gradient LiNi of comparative example 1 of the present invention0.84Co0.11Mn0.05O2A discharge cycle profile of the material assembled battery;
FIG. 11 is a vanadium pentoxide coated full-gradient LiNi comparative example 2 of the present invention0.84Co0.11Mn0.05O2A TEM image of the material;
FIG. 12 is a vanadium pentoxide coated full-gradient LiNi comparative example 2 of the present invention0.84Co0.11Mn0.05O2Discharge cycle profile of the material assembled battery.
Detailed Description
The invention is further illustrated by the following examples and figures.
The purities of the high-purity nitrogen, the high-purity argon and the high-purity oxygen used in the embodiment of the invention are all 99.99 percent; the rGO used in the embodiment of the invention is purchased from Sigma-Aldrich; the starting materials or chemicals used in the examples of the present invention are, unless otherwise specified, commercially available in a conventional manner.
Example 1 vanadium pentoxide with rGO co-cladding gradient LiNi0.84Co0.11Mn0.05O2Positive electrode material
The anode material is formed by coating LiNi on an inner layer and an outer layer of vanadium pentoxide and rGO0.84Co0.11Mn0.05O2Forming spherical core-shell structure particles; the LiNi0.84Co0.11Mn0.05O2The mass ratio of vanadium pentoxide to rGO is 1:0.03: 0.03; the LiNi0.84Co0.11Mn0.05O2The nickel element content is from LiNi for full gradient material0.84Co0.11Mn0.05O2Gradually decreases from the center to the surface, and the content of manganese element is from LiNi0.84Co0.11Mn0.05O2Gradually increases from the center to the surface, and the content of the cobalt element is LiNi0.84Co0.11Mn0.05O2Uniformly distributing; the vanadium pentoxide and rGO are coated with gradient LiNi0.84Co0.11Mn0.05O2Has an average particle diameter of 6 μm; the average thickness of the vanadium pentoxide coating layer is 3 nm; the average thickness of the rGO coating layer was 3 nm.
Example 1 vanadium pentoxide with rGO co-cladding gradient LiNi0.84Co0.11Mn0.05O2Preparation method of positive electrode material
(1) Pumping 2L of low nickel content nickel cobalt manganese solution (mixed solution of nickel sulfate, cobalt sulfate and manganese sulfate, wherein the total molar concentration of Ni, Co and Mn ions is 2.0mol/L, the molar ratio of Ni, Co and Mn is 7:1: 2) into a container filled with 2L of high nickel content nickel cobalt solution (mixed solution of nickel sulfate and cobalt sulfate, wherein the total molar concentration of Ni and Co ions is 2.0mol/L, and the molar ratio of Ni and Co ions is 9: 1) at a feeding speed of 50 mL/h, stirring to form mixed solution, simultaneously pumping the mixed solution into a reaction kettle filled with 2L and 2mol/L of aqueous ammonia solution at a feeding speed of 100mL/h, adjusting the aqueous ammonia concentration of the reaction system to be 2mol/L by using 25 mass percent of aqueous ammonia, adjusting the pH value of the reaction system to be 11.4 by using 4L and 5mol/L of sodium hydroxide precipitant solution, introducing high-purity nitrogen gas, heating and stirring at 1000 r/min and 50 ℃, carrying out coprecipitation reaction for 42h, stirring and aging for 16h at 50 ℃, filtering, respectively and alternately washing the filtrate with deionized water and ethanol for 6 times, and drying for 20h at 90 ℃ to obtain a full-gradient nickel-cobalt-manganese hydroxide precursor;
(2) mixing and grinding 1.0g of the full-gradient nickel-cobalt-manganese hydroxide precursor (Ni 8.404mmol, Co 1.0805 mmol and Mn 0.5155 mmol) obtained in the step (1) and 0.4635 g (11.0452 mmol) of lithium hydroxide monohydrate, heating to 450 ℃ at the speed of 5 ℃/min in the atmosphere of high-purity oxygen, sintering for 4h, heating to 750 ℃ at the speed of 5 ℃/min, sintering for 12h, performing two-stage sintering, and cooling to room temperature to obtain the full-gradient LiNi-Co-Mn hydroxide precursor0.84Co0.11Mn0.05O2A material;
(3) 1.0g of full-gradient LiNi obtained in the step (2)0.84Co0.11Mn0.05O2Adding the material and 0.0874g of vanadyl acetylacetonate into 60 mL of absolute ethanol solution, ultrasonically dispersing for 1h at 2 kHz, heating and stirring at 400 r/min and 60 ℃ until the mixture is dried by distillation, heating to 500 ℃ at the speed of 5 ℃/min, sintering for 6h, and cooling to room temperature to obtain vanadium pentoxide coated full-gradient LiNi0.84Co0.11Mn0.05O2A material;
(4) coating 1.03 g of vanadium pentoxide obtained in the step (3) with full-gradient LiNi0.84Co0.11Mn0.05O2The material and 0.03 g rGO are rotationally stirred for 10 hours at 300r/min, dried for 2 hours at 100 ℃ and dried to obtain vanadium pentoxide and rGO co-coated gradient LiNi0.84Co0.11Mn0.05O2And (3) a positive electrode material.
As shown in FIG. 1, the vanadium pentoxide and rGO co-coated ladder of the embodiment of the inventionLiNi0.84Co0.11Mn0.05O2Positive electrode material and PDF card LiNiO2(PDF # 85-1966) with no hetero-phase formation.
As shown in FIG. 2, the vanadium pentoxide and rGO co-coated gradient LiNi in the embodiment of the present invention0.84Co0.11Mn0.05O2The appearance of the positive electrode material well inherits the appearance of the high nickel gradient ternary material, the secondary particles are of a spherical-like core-shell structure, the average particle size is 6 mu m, and an inner layer and an outer layer of vanadium pentoxide and rGO coating layers are formed on the surfaces of the secondary particles.
As shown in FIG. 3, the vanadium pentoxide and rGO co-coated gradient LiNi in the embodiment of the present invention0.84Co0.11Mn0.05O2An inner layer of vanadium pentoxide and an outer layer of rGO coating layers are respectively arranged on the surface of the positive electrode material, the average thickness of the vanadium pentoxide is 3nm, and the average thickness of the rGO is 3 nm.
As shown in FIG. 4, the full-gradient nickel LiNi obtained in step (2) of the example of the present invention0.84Co0.11Mn0.05O2The content of nickel element in the positive electrode material is from LiNi0.84Co0.11Mn0.05O2Gradually decreases from the center to the surface, and the content of manganese element is from LiNi0.84Co0.11Mn0.05O2Gradually increases from the center to the surface, and the content of the cobalt element is LiNi0.84Co0.11Mn0.05O2Is uniformly distributed, indicating that it is a gradient polycrystalline agglomerate.
As shown in FIG. 5, the vanadium pentoxide and rGO co-coated gradient LiNi in the embodiment of the present invention0.84Co0.11Mn0.05O2The positive electrode material is opposite to the full gradient LiNi obtained in the step (2)0.84Co0.11Mn0.05O2After the material is coated by vanadium pentoxide and rGO, a characteristic peak of vanadium can be seen in an XPS full spectrogram.
Assembling the battery: weighing 0.80 g of LiNi with vanadium pentoxide and rGO co-coated gradient in the embodiment of the invention0.84Co0.11Mn0.05O2The positive electrode material was charged with 0.1g of acetylene black as a conductive agent and 0.1g ofPVDF polyvinylidene fluoride is used as a binder, and N-methyl pyrrolidone is used as a solvent to be mixed and ground to form a positive electrode material; coating the obtained anode material on the surface of an aluminum foil to prepare a pole piece; in a sealed glove box filled with argon, the pole piece is taken as a positive electrode, a metal lithium piece is taken as a negative electrode, a microporous polypropylene film is taken as a diaphragm, and 1mol/L LiPF6DMC (volume ratio 1: 1) is used as electrolyte, a CR2025 button cell is assembled, and charging and discharging performance tests are carried out.
As shown in FIG. 6, the vanadium pentoxide and rGO co-coated gradient LiNi in the embodiment of the present invention0.84Co0.11Mn0.05O2The battery assembled by the anode material has the specific first discharge capacity of 201.5 mAh/g, the specific first charge capacity of 234.3 mAh/g and the first charge-discharge coulombic efficiency of 86% within the range of 2.7-4.3V and the current density of 0.1C (20 mA/g).
As shown in FIG. 7, the vanadium pentoxide and rGO co-coated gradient LiNi of the embodiment of the present invention0.84Co0.11Mn0.05O2The battery assembled by the anode material has the specific discharge capacity of 188.5 mAh/g for the first time under the conditions that the voltage is 2.7-4.3V and the current density is 1C (200 mA/g), can still reach 172.1 mAh/g after the current density of 1C is cycled for 100 circles, and has the capacity retention rate of 91.30 percent, which indicates that the vanadium pentoxide and rGO co-coated gradient ternary anode material has stable charge-discharge performance and good cycle performance.
As shown in FIG. 8, the vanadium pentoxide and rGO co-coated gradient LiNi of the embodiment of the present invention0.84Co0.11Mn0.05O2The battery assembled by the positive electrode material has specific discharge capacities of 199.8mAh/g, 188.5 mAh/g and 146.5mAh/g respectively under the current densities of 0.2C (40 mA/g), 1C and 10C within the range of 2.7-4.3V, and shows better rate performance, which indicates that the vanadium pentoxide and rGO co-coated gradient ternary positive electrode material can keep the structure stable in the charging and discharging process and the charging and discharging reaction is highly reversible under different rates.
Example 2 vanadium pentoxide and rGO co-cladding gradient LiNi0.84Co0.11Mn0.05O2Positive electrode material
The anode material is formed by coating LiNi on an inner layer and an outer layer of vanadium pentoxide and rGO0.84Co0.11Mn0.05O2Forming spherical core-shell structure particles; the LiNi0.84Co0.11Mn0.05O2The mass ratio of vanadium pentoxide to rGO is 1:0.03: 0.02; the LiNi0.84Co0.11Mn0.05O2The nickel element content is from LiNi for full gradient material0.84Co0.11Mn0.05O2Gradually decreases from the center to the surface, and the content of manganese element is from LiNi0.84Co0.11Mn0.05O2Gradually increases from the center to the surface, and the content of the cobalt element is LiNi0.84Co0.11Mn0.05O2Uniformly distributing; the vanadium pentoxide and rGO are coated with gradient LiNi0.84Co0.11Mn0.05O2The average particle size of the positive electrode material was 5 μm; the average thickness of the vanadium pentoxide coating layer is 2 nm; the average thickness of the rGO coating layer was 2 nm.
Example 2 vanadium pentoxide and rGO co-cladding gradient LiNi0.84Co0.11Mn0.05O2Preparation method of positive electrode material
(1) Pumping 2L of low nickel content nickel cobalt manganese solution (mixed solution of nickel sulfate, cobalt sulfate and manganese sulfate, wherein the total molar concentration of Ni, Co and Mn ions is 2.0mol/L, the molar ratio of Ni, Co and Mn is 7:1.5: 1.5) into a container filled with 2L of high nickel content nickel cobalt manganese solution (mixed solution of nickel sulfate, cobalt sulfate and manganese sulfate, wherein the total molar concentration of Ni, Co and Mn ions is 2.0mol/L, the molar ratio of Ni, Co and Mn ions is 9:0.5: 0.5) at a feeding speed of 55 mL/h, stirring to form mixed solution, simultaneously pumping the mixed solution into a reaction kettle filled with 2L and 2mol/L of aqueous ammonia solution at a feeding speed of 110mL/h, adjusting the aqueous ammonia concentration of the reaction system to be 2mol/L by using 25% by mass concentration of aqueous ammonia, and keeping the aqueous ammonia concentration of the reaction system to be 2mol/L by using 4L, Adjusting the pH value of a reaction system to 11.3 by using 5mol/L potassium hydroxide precipitant solution, introducing high-purity nitrogen gas, heating and stirring at 1100 r/min and 55 ℃, carrying out coprecipitation reaction for 36 hours, stirring and aging for 20 hours at 55 ℃, filtering, respectively and alternately washing the filtrate for 6 times by using deionized water and ethanol, and drying for 24 hours at 80 ℃ to obtain a full-gradient nickel-cobalt-manganese hydroxide precursor;
(2) mixing and grinding 1.0g of the full-gradient nickel-cobalt-manganese hydroxide precursor (Ni 8.404mmol, Co 1.0805 mmol and Mn 0.5155 mmol) obtained in the step (1) and 0.4082 g (5.5243 mol) of lithium carbonate, heating to 400 ℃ at the rate of 3 ℃/min in the atmosphere of high-purity oxygen, sintering for 5 h, heating to 700 ℃ at the rate of 3 ℃/min, sintering for 10h, performing two-stage sintering, and cooling to room temperature to obtain the full-gradient LiNi-Mn hydroxide precursor0.84Co0.11Mn0.05O2A material;
(3) 1.0g of full-gradient LiNi obtained in the step (2)0.84Co0.11Mn0.05O2Adding the material and 0.0386 g of ammonium metavanadate into 40 mL of acetone, ultrasonically dispersing for 0.8h at 2 kHz, heating and stirring at 350r/min and 65 ℃ until the mixture is dried by distillation, heating to 450 ℃ at the speed of 3 ℃/min, sintering for 8h, and cooling to room temperature to obtain vanadium pentoxide coated full-gradient LiNi0.84Co0.11Mn0.05O2A material;
(4) and (3) rotating and stirring 1.03 g of vanadium pentoxide coated full-gradient nickel cobalt lithium manganate material obtained in the step (3) and 0.02 g of rGO at 250r/min for 12h, drying at 90 ℃ for 3h, and drying to obtain vanadium pentoxide and rGO co-coated gradient LiNi0.84Co0.11Mn0.05O2And (3) a positive electrode material.
Through detection, vanadium pentoxide and rGO are coated with LiNi with gradient in an embodiment of the invention0.84Co0.11Mn0.05O2Positive electrode material and PDF card LiNiO2(PDF # 85-1966) with no hetero-phase formation.
Through detection, vanadium pentoxide and rGO are coated with LiNi with gradient in an embodiment of the invention0.84Co0.11Mn0.05O2The appearance of the anode material well inherits the appearance of the high nickel gradient ternary material, the secondary particles are of a sphere-like core-shell structure, the average particle size is 5 mu m, and an inner layer and an outer layer of vanadium pentoxide are formed on the surfaces of the secondary particlesAnd a rGO coating layer.
Through detection, vanadium pentoxide and rGO are coated with LiNi with gradient in an embodiment of the invention0.84Co0.11Mn0.05O2An inner layer of vanadium pentoxide and an outer layer of rGO coating layers are respectively arranged on the surface of the positive electrode material, the average thickness of the vanadium pentoxide is 2 nm, and the average thickness of the rGO is 2 nm.
Through detection, vanadium pentoxide and rGO are coated with LiNi with gradient in an embodiment of the invention0.84Co0.11Mn0.05O2The content of nickel element in the positive electrode material is from LiNi0.84Co0.11Mn0.05O2Gradually decreases from the center to the surface, and the content of manganese element is from LiNi0.84Co0.11Mn0.05O2Gradually increases from the center to the surface, and the content of the cobalt element is LiNi0.84Co0.11Mn0.05O2Is uniformly distributed, indicating that it is a gradient polycrystalline agglomerate.
Through detection, vanadium pentoxide and rGO are coated with LiNi with gradient in an embodiment of the invention0.84Co0.11Mn0.05O2The positive electrode material is opposite to the full gradient LiNi obtained in the step (2)0.84Co0.11Mn0.05O2After the material is coated by vanadium pentoxide and rGO, a characteristic peak of vanadium can be seen in an XPS full spectrogram.
Assembling the battery: the same as in example 1.
Through detection, vanadium pentoxide and rGO are coated with LiNi with gradient in an embodiment of the invention0.84Co0.11Mn0.05O2The battery assembled by the anode material has the specific first discharge capacity of 205.4 mAh/g, the specific first charge capacity of 236.1 mAh/g and the first charge-discharge coulombic efficiency of 87% in the range of 2.7-4.3V and the current density of 0.1C (20 mA/g).
Through detection, vanadium pentoxide and rGO are coated with LiNi with gradient in an embodiment of the invention0.84Co0.11Mn0.05O2The battery assembled by the anode material has the first discharge specific capacity as high as 191.2 mAh/g and the 1C current density within the range of 2.7-4.3V and the current density of 1C (200 mA/g)After circulating for 100 circles, the capacity retention rate can still reach 174.3 mAh/g, and the capacity retention rate is 91.16%, which shows that the vanadium pentoxide and rGO co-coated gradient ternary cathode material has stable charge and discharge performance and good circulation performance.
Through detection, vanadium pentoxide and rGO are coated with LiNi with gradient in an embodiment of the invention0.84Co0.11Mn0.05O2The battery assembled by the positive electrode material has specific discharge capacities of 198.8 mAh/g, 191mAh/g and 143.5 mAh/g respectively under the current densities of 0.2C (40 mA/g), 1C and 10C within the range of 2.7-4.3V, and shows better rate performance, which indicates that the vanadium pentoxide and rGO co-coated gradient ternary positive electrode material can keep the structure stable in the charging and discharging process and has highly reversible charging and discharging reaction under different rates.
Example 3 vanadium pentoxide and rGO co-cladding gradient LiNi0.82Co0.12Mn0.06O2Positive electrode material
The anode material is formed by coating LiNi on an inner layer and an outer layer of vanadium pentoxide and rGO0.82Co0.12Mn0.06O2Forming spherical core-shell structure particles; the LiNi0.82Co0.12Mn0.06O2The mass ratio of vanadium pentoxide to rGO is 1:0.04: 0.03; the LiNi0.82Co0.12Mn0.06O2The nickel element content is from LiNi for full gradient material0.82Co0.12Mn0.06O2Gradually decreases from the center to the surface, and the content of manganese element is from LiNi0.82Co0.12Mn0.06O2Gradually increases from the center to the surface, and the content of the cobalt element is LiNi0.82Co0.12Mn0.06O2Uniformly distributing; the vanadium pentoxide and rGO are coated with gradient LiNi0.82Co0.12Mn0.06O2The average particle size of the positive electrode material was 7 μm; the average thickness of the vanadium pentoxide coating layer is 4 nm; the average thickness of the rGO coating layer was 4 nm.
Example 3 vanadium pentoxide and rGO co-cladding gradient LiNi0.82Co0.12Mn0.06O2Positive electrodeMethod for producing a material
(1) Pumping 2L of low nickel content nickel cobalt manganese solution (mixed solution of nickel acetate, cobalt acetate and manganese acetate, wherein the total molar concentration of Ni, Co and Mn ions is 2.0mol/L, the molar ratio of Ni, Co and Mn is 7:1.5: 1.5) into a container filled with 2L of high nickel content nickel cobalt manganese solution (mixed solution of nickel acetate, cobalt acetate and manganese acetate, wherein the total molar concentration of Ni, Co and Mn ions is 2.0mol/L, and the molar ratio of Ni, Co and Mn ions is 9:0.5: 0.5) at a feeding speed of 45 mL/h, stirring to form mixed solution, simultaneously pumping the mixed solution into a reaction kettle filled with 2L and 2mol/L of aqueous ammonia solution at a feeding speed of 90mL/h, adjusting the aqueous ammonia concentration of the reaction system to be 2mol/L by using 25% by mass concentration of aqueous ammonia, and keeping the aqueous ammonia concentration of the reaction system to be 2mol/L by using 4L of aqueous ammonia, Adjusting the pH value of a reaction system to 11.2 by using 5mol/L sodium hydroxide precipitant solution, introducing high-purity argon gas, heating and stirring at 900 r/min and 45 ℃, carrying out coprecipitation reaction for 48 hours, stirring and aging for 12 hours at 45 ℃, filtering, respectively and alternately washing the filtrate for 7 times by using deionized water and ethanol, and drying for 16 hours at 100 ℃ to obtain a full-gradient nickel-cobalt-manganese hydroxide precursor;
(2) mixing and grinding 1.0g of the full-gradient nickel-cobalt-manganese hydroxide precursor (Ni 8.214mmol, Co 1.1503 mmol and Mn 0.6357 mmol) obtained in the step (1) and 0.4477g (10.6688 mol) of lithium hydroxide monohydrate, heating to 500 ℃ at the speed of 7 ℃/min in the atmosphere of high-purity oxygen, sintering for 3h, heating to 800 ℃ at the speed of 7 ℃/min, sintering for 14 h, performing two-stage sintering, and cooling to room temperature to obtain the full-gradient LiNi-Mn hydroxide precursor0.82Co0.12Mn0.06O2A material;
(3) 1.0g of full-gradient LiNi obtained in the step (2)0.82Co0.12Mn0.06O2Adding the material and 0.1165 g of vanadyl acetylacetonate into 80 mL of absolute ethanol solution, ultrasonically dispersing for 0.6h at 2 kHz, heating and stirring at 450 r/min and 55 ℃ until the mixture is dried by distillation, heating to 550 ℃ at the speed of 7 ℃/min, sintering for 4h, and cooling to room temperature to obtain vanadium pentoxide coated full-gradient LiNi0.82Co0.12Mn0.06O2A material;
(4) coating 1.04 g of vanadium pentoxide obtained in the step (3) with full-gradient LiNi0.82Co0.12Mn0.06O2The material and 0.03 g rGO are rotationally stirred for 8 hours at 350r/min, dried for 2 hours at 110 ℃ and dried to obtain vanadium pentoxide and rGO co-coated gradient LiNi0.82Co0.12Mn0.06O2And (3) a positive electrode material.
Through detection, vanadium pentoxide and rGO are coated with LiNi with gradient in an embodiment of the invention0.82Co0.12Mn0.06O2Positive electrode material and PDF card LiNiO2(PDF # 85-1966) with no hetero-phase formation.
Through detection, vanadium pentoxide and rGO are coated with LiNi with gradient in an embodiment of the invention0.82Co0.12Mn0.06O2The shape of the anode material well inherits the shape of the high nickel gradient ternary material, the secondary particles are of a sphere-like core-shell structure, the average particle size is 7 mu m, and an inner layer and an outer layer of vanadium pentoxide and rGO coating layers are formed on the surfaces of the secondary particles.
Through detection, vanadium pentoxide and rGO are coated with LiNi with gradient in an embodiment of the invention0.82Co0.12Mn0.06O2An inner layer of vanadium pentoxide and an outer layer of rGO coating layers are respectively arranged on the surface of the positive electrode material, the average thickness of the vanadium pentoxide is 4 nm, and the average thickness of the rGO is 4 nm.
Through detection, vanadium pentoxide and rGO are coated with LiNi with gradient in an embodiment of the invention0.82Co0.12Mn0.06O2The content of nickel element in the positive electrode material is from LiNi0.82Co0.12Mn0.06O2Gradually decreases from the center to the surface, and the content of manganese element is from LiNi0.82Co0.12Mn0.06O2Gradually increases from the center to the surface, and the content of the cobalt element is LiNi0.82Co0.12Mn0.06O2Is uniformly distributed, indicating that it is a gradient polycrystalline agglomerate.
Through detection, vanadium pentoxide and rGO are coated with LiNi with gradient in an embodiment of the invention0.82Co0.12Mn0.06O2The positive electrode material is opposite to the full gradient LiNi obtained in the step (2)0.82Co0.12Mn0.06O2After the material is coated by vanadium pentoxide and rGO, a characteristic peak of vanadium can be seen in an XPS full spectrogram.
Assembling the battery: the same as in example 1.
Through detection, vanadium pentoxide and rGO are coated with LiNi with gradient in an embodiment of the invention0.82Co0.12Mn0.06O2The battery assembled by the anode material has the specific first discharge capacity of 197.6 mAh/g, the specific first charge capacity of 227.13 mAh/g and the first charge-discharge coulombic efficiency of 87% in the range of 2.7-4.3V and the current density of 0.1C (20 mA/g).
Through detection, vanadium pentoxide and rGO are coated with LiNi with gradient in an embodiment of the invention0.82Co0.12Mn0.06O2The battery assembled by the anode material has the specific discharge capacity of 188.2 mAh/g for the first time under the conditions that the voltage is 2.7-4.3V and the current density is 1C (200 mA/g), still can reach 168.7 mAh/g after the current density of 1C is cycled for 100 circles, and has the capacity retention rate of 89.64 percent, which indicates that the vanadium pentoxide and rGO co-coated gradient ternary anode material has stable charge-discharge performance and good cycle performance.
Through detection, vanadium pentoxide and rGO are coated with LiNi with gradient in an embodiment of the invention0.82Co0.12Mn0.06O2The battery assembled by the positive electrode material has specific discharge capacities of 192.8 mAh/g, 188.2 mAh/g and 141.3 mAh/g respectively in the range of 2.7-4.3V and under the current densities of 0.2C (40 mA/g), 1C and 10C, and shows better rate performance, which shows that the vanadium pentoxide and rGO co-coated gradient ternary positive electrode material can keep the structure stable in the charging and discharging process and the charging and discharging reaction is highly reversible under different rates.
Comparative example 1 full gradient LiNi0.84Co0.11Mn0.05O2Material
This comparative example is the full-gradient LiNi obtained in step (2) of example 10.84Co0.11Mn0.05O2A material.
As shown in FIG. 9, this comparative example was a full-gradient LiNi0.84Co0.11Mn0.05O2The secondary particles of the material are uniformly distributed and are in a sphere-like shape, and the average particle size is 6 mu m.
Through detection, the full-gradient LiNi of the comparative example0.84Co0.11Mn0.05O2The battery assembled by the material has the first discharge specific capacity of 205.4 mAh/g, the first charge specific capacity of 249.8 mAh/g and the first charge-discharge coulombic efficiency of 82.2% in the range of 2.7-4.3V and the current density of 0.1C (20 mA/g), which indicates that the full-gradient LiNi of the comparative example is0.84Co0.11Mn0.05O2The irreversible capacity of the first ring of the material is larger before the material is coated by vanadium pentoxide and rGO together.
As shown in FIG. 10, this comparative example was a full-gradient LiNi0.84Co0.11Mn0.05O2The battery assembled by the material has the first discharge specific capacity of 198.8 mAh/g under the condition that the current density is 1C (200 mA/g) and is 2.7-4.3V, and after the battery is cycled for 100 circles by the 1C current density, the first discharge specific capacity is reduced to 151.2 mAh/g, and the capacity retention rate is only 76.06 percent, which shows that although the initial discharge specific capacity of the ternary material is higher, the discharge specific capacity is reduced more seriously along with the increase of the charge-discharge cycle times, and the cycle performance is poor.
Through detection, the full-gradient LiNi of the comparative example0.84Co0.11Mn0.05O2The battery assembled by the material has specific discharge capacities of 201.8mAh/g, 198.8 mAh/g and 126.5 mAh/g respectively under the current densities of 0.2C (40 mA/g), 1C and 10C within the range of 2.7-4.3V, and although the uncoated ternary material has better electrochemical performance under the low current density, the ternary material has lower specific discharge capacity under the high current density.
Comparative example 2 vanadium pentoxide coated full-gradient LiNi0.84Co0.11Mn0.05O2Material
The comparative example is the vanadium pentoxide coated full-gradient LiNi obtained in the step (3) of the example 10.84Co0.11Mn0.05O2A material.
Through detection, the vanadium pentoxide-coated full-gradient LiNi of the comparative example0.84Co0.11Mn0.05O2The morphology of the material well inherits the morphology of the gradient ternary material, the secondary particles are spherical-like, and the average particle size is 6 mu m.
As shown in FIG. 11, the vanadium pentoxide-coated full-gradient LiNi of this comparative example was0.84Co0.11Mn0.05O2The surface of the material is provided with a vanadium pentoxide coating layer with the average thickness of 3nm, and the coating layer is amorphous.
Through detection, the vanadium pentoxide-coated full-gradient LiNi of the comparative example0.84Co0.11Mn0.05O2The battery assembled by the material has the first discharge specific capacity of 193.5 mAh/g, the first charge specific capacity of 233.1mAh/g and the first charge-discharge coulombic efficiency of 83% in the range of 2.7-4.3V and the current density of 0.1C (20 mA/g), which indicates that the vanadium pentoxide coated full-gradient LiNi of the comparative example is coated with the full-gradient LiNi0.84Co0.11Mn0.05O2The irreversible capacity of the material in the first ring is larger before vanadium pentoxide and rGO are coated.
As shown in FIG. 12, the vanadium pentoxide-coated full-gradient LiNi of this comparative example was0.84Co0.11Mn0.05O2The battery assembled by the material has the specific discharge capacity of 186.5 mAh/g for the first time under the current density of 1C (200 mA/g) within the range of 2.7-4.3V, and the specific discharge capacity of the battery is reduced to 147.4 mAh/g after the battery is cycled for 100 circles under the current density of 1C, and the capacity retention rate is only 79.03%, which indicates that although the vanadium pentoxide coated ternary material has higher initial discharge specific capacity and the specific discharge capacity is reduced to a certain extent compared with the uncoated ternary material along with the increase of the charge-discharge cycle times, the cycle performance is still poorer.
Through detection, the vanadium pentoxide-coated full-gradient LiNi of the comparative example0.84Co0.11Mn0.05O2The battery assembled by the material has specific discharge capacities of 190 mAh/g, 186.5 mAh/g and 131.4 mAh/g respectively under the current densities of 0.2C (40 mA/g), 1C and 10C within the range of 2.7-4.3V, although the vanadium pentoxide coated ternary material shows better electricity under the low current densityThe chemical property and the specific discharge capacity under high current density are slightly improved but still poorer than those of the uncoated ternary material.
Claims (8)
1. The utility model provides a vanadium pentoxide and rGO cladding gradient ternary cathode material which characterized in that: the positive electrode material is spherical core-shell structure particles formed by coating nickel cobalt lithium manganate on an inner layer and an outer layer of vanadium pentoxide and rGO; the mass ratio of the nickel cobalt lithium manganate to the vanadium pentoxide to the rGO is 1: 0.01-0.05; the chemical formula of the nickel cobalt lithium manganate is LiNixCoyMn(1-x-y)O2Wherein x is more than or equal to 0.70 and less than or equal to 0.90, y is more than or equal to 0.05 and less than or equal to 0.2, and 1-x-y is more than or equal to 0.
2. The vanadium pentoxide and rGO co-coated gradient ternary cathode material according to claim 1, wherein: the nickel cobalt lithium manganate is a full-gradient material, the content of nickel element is gradually reduced from the center to the surface of the nickel cobalt lithium manganate, the content of manganese element is gradually increased from the center to the surface of the nickel cobalt lithium manganate, and the content of cobalt element is uniformly distributed in the nickel cobalt lithium manganate; the average particle size of the vanadium pentoxide and rGO co-coated gradient ternary cathode material is 3-7 μm; the average thickness of the vanadium pentoxide coating layer is 1-5 nm; the average thickness of the rGO coating layer is 1-5 nm.
3. The preparation method of the vanadium pentoxide and rGO co-coated gradient ternary cathode material as claimed in claim 1 or 2, characterized by comprising the following steps:
(1) pumping the low-nickel-content nickel-cobalt-manganese solution into a container filled with the high-nickel-content nickel-cobalt or nickel-cobalt-manganese solution, stirring to form a mixed solution, simultaneously pumping the mixed solution into a reaction kettle filled with an ammonia solution, simultaneously adjusting the ammonia concentration of the reaction system by using ammonia water, adjusting the pH value of the reaction system by using a hydroxide precipitator solution, introducing into a protective atmosphere, heating, stirring, carrying out coprecipitation reaction, stirring, aging, filtering, washing, and drying to obtain a full-gradient nickel-cobalt-manganese hydroxide precursor;
(2) mixing and grinding the full-gradient nickel-cobalt-manganese hydroxide precursor obtained in the step (1) with a lithium source, then performing two-stage sintering in an oxidizing atmosphere, and cooling to room temperature to obtain a full-gradient nickel-cobalt-manganese lithium manganate material;
(3) adding the full-gradient lithium nickel cobalt manganese oxide material obtained in the step (2) and a vanadium source into an organic solution, performing ultrasonic dispersion, heating and stirring until the mixture is dried by distillation, sintering, and cooling to room temperature to obtain a vanadium pentoxide-coated full-gradient lithium nickel cobalt manganese oxide material;
(4) and (4) rotationally stirring the vanadium pentoxide coated full-gradient nickel cobalt lithium manganate material obtained in the step (3) and rGO, and drying to obtain the vanadium pentoxide and rGO co-coated gradient ternary cathode material.
4. The preparation method of the vanadium pentoxide and rGO co-coated gradient ternary cathode material according to claim 3, wherein the preparation method comprises the following steps: in the step (1), the feeding speed of the low-nickel-content nickel-cobalt-manganese solution is 30-70 mL/h; the feeding speed of the mixed solution is 80-120 mL/h; in the nickel-cobalt-manganese solution with low nickel content, the total molar concentration of nickel, cobalt and manganese ions is 0.3-3.0 mol/L, and the molar ratio of nickel, cobalt and manganese is 3-8: 1: more than 0-2; in the high-nickel-content nickel-cobalt or nickel-cobalt-manganese solution, the total molar concentration of nickel, cobalt and manganese ions is 0.3-4.0 mol/L, and the molar ratio of nickel, cobalt and manganese is 8-9: 0.5-1: 0-1; in the same reaction system, the nickel content of the nickel-cobalt-manganese solution with low nickel content is lower than that of the nickel-cobalt or nickel-cobalt-manganese solution with high nickel content; the volume ratio of the ammonia water solution, the hydroxide precipitant solution, the low nickel content nickel cobalt manganese solution and the high nickel content nickel cobalt or nickel cobalt manganese solution in the reaction kettle is 0.1-10: 1-2: 1: 1; the molar concentration of the ammonia water solution is 1.0-7.0 mol/L; adjusting the concentration of ammonia water in the reaction system to be 1.0-7.0 mol/L by using ammonia water; the mass concentration of the ammonia water for adjusting the ammonia water concentration of the reaction system is 25-28%; regulating the pH value of the reaction system to be 10-12 by using a hydroxide precipitant solution; the molar concentration of the hydroxide precipitant solution is 1.0-7.0 mol/L; the low nickel content nickel cobalt manganese solution and the high nickel content nickel cobalt manganese solution are mixed solutions of soluble nickel salt, soluble cobalt salt and soluble manganese salt, and the high nickel content nickel cobalt solution is mixed solution of soluble nickel salt and soluble cobalt salt; the soluble nickel salt is one or more of nickel sulfate, nickel nitrate, nickel acetate or nickel chloride and hydrates thereof; the soluble cobalt salt is one or more of cobalt sulfate, cobalt nitrate, cobalt acetate or cobalt chloride and hydrates thereof; the soluble manganese salt is one or more of manganese sulfate, manganese nitrate, manganese acetate or manganese chloride and hydrates thereof; the hydroxide precipitator is one or more of sodium hydroxide, potassium hydroxide or lithium hydroxide and hydrates thereof.
5. The preparation method of the vanadium pentoxide and rGO co-coated gradient ternary cathode material according to claim 3 or 4, wherein the preparation method comprises the following steps: in the step (1), the protective atmosphere is a nitrogen atmosphere and/or an argon atmosphere; the stirring speed of the coprecipitation reaction is 800-1200 r/min, the temperature is 30-70 ℃, and the time is 30-50 h; the aging temperature is 30-70 ℃, and the aging time is 8-24 hours; the washing is that deionized water and ethanol are respectively used for alternately washing the filtered substances for more than or equal to 6 times; the drying temperature is 80-100 ℃, and the drying time is 12-24 hours.
6. The preparation method of the vanadium pentoxide and rGO co-coated gradient ternary cathode material according to any one of claims 3 to 5, wherein the preparation method comprises the following steps: in the step (2), the molar ratio of the sum of the mole numbers of nickel, cobalt and manganese elements in the full-gradient nickel-cobalt-manganese hydroxide precursor to the mole number of lithium elements in a lithium source is 1: 1.05-1.11; the lithium source is lithium hydroxide and/or lithium carbonate; the oxidizing atmosphere is an air atmosphere and/or an oxygen atmosphere; the two-stage sintering is as follows: the temperature is raised to 350-550 ℃ at the speed of 1-10 ℃/min, the sintering is carried out for 2-8 h, and then the temperature is raised to 550-1000 ℃ at the speed of 1-10 ℃/min, and the sintering is carried out for 8-20 h.
7. The preparation method of the vanadium pentoxide and rGO co-coated gradient ternary cathode material according to any one of claims 3 to 6, wherein the preparation method comprises the following steps: in the step (3), the mass volume ratio of the full-gradient lithium nickel cobalt manganese oxide material to the vanadium source to the organic solution is 1: 0.01-0.12: 10-300; the vanadium source is one or more of vanadyl acetylacetonate, vanadium acetylacetonate or ammonium metavanadate; the organic solvent is absolute ethyl alcohol and/or acetone; the frequency of the ultrasonic dispersion is 1.5-2.5 kHz, and the time is 0.5-1.0 h; the heating and stirring speed is 300-500 r/min, and the temperature is 50-70 ℃; the sintering is carried out at the speed of 1-10 ℃/min until the temperature is raised to 350-550 ℃ and the sintering time is 2-8 h.
8. The preparation method of the vanadium pentoxide and rGO co-coated gradient ternary cathode material according to any one of claims 3 to 7, wherein the preparation method comprises the following steps: in the step (4), the mass ratio of the vanadium pentoxide coated full-gradient lithium nickel cobalt manganese oxide material to rGO is 1: 0.01-0.05; the rotating speed of the rotary stirring is 250-400 r/min, and the time is 8-12 h; the drying temperature is 80-120 ℃, and the drying time is 2-3 h.
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