JP4406789B2 - Negative electrode material for lithium secondary battery and method for producing the same - Google Patents
Negative electrode material for lithium secondary battery and method for producing the same Download PDFInfo
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- JP4406789B2 JP4406789B2 JP2003391229A JP2003391229A JP4406789B2 JP 4406789 B2 JP4406789 B2 JP 4406789B2 JP 2003391229 A JP2003391229 A JP 2003391229A JP 2003391229 A JP2003391229 A JP 2003391229A JP 4406789 B2 JP4406789 B2 JP 4406789B2
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- 229910052744 lithium Inorganic materials 0.000 title claims description 102
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims description 97
- 239000007773 negative electrode material Substances 0.000 title claims description 60
- 238000004519 manufacturing process Methods 0.000 title claims description 15
- 229910052751 metal Inorganic materials 0.000 claims description 120
- 239000002184 metal Substances 0.000 claims description 120
- 239000002131 composite material Substances 0.000 claims description 58
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 53
- 239000000843 powder Substances 0.000 claims description 51
- 229910052799 carbon Inorganic materials 0.000 claims description 47
- 239000000956 alloy Substances 0.000 claims description 42
- 229910045601 alloy Inorganic materials 0.000 claims description 38
- 150000001875 compounds Chemical class 0.000 claims description 30
- 239000002245 particle Substances 0.000 claims description 28
- 239000003575 carbonaceous material Substances 0.000 claims description 27
- 229910052718 tin Inorganic materials 0.000 claims description 24
- 229910052787 antimony Inorganic materials 0.000 claims description 22
- 239000011164 primary particle Substances 0.000 claims description 21
- 238000005551 mechanical alloying Methods 0.000 claims description 20
- 229910052802 copper Inorganic materials 0.000 claims description 19
- 229910052709 silver Inorganic materials 0.000 claims description 16
- 229910052742 iron Inorganic materials 0.000 claims description 15
- 229910052710 silicon Inorganic materials 0.000 claims description 15
- 229910052759 nickel Inorganic materials 0.000 claims description 14
- 229910052719 titanium Inorganic materials 0.000 claims description 14
- 229910052782 aluminium Inorganic materials 0.000 claims description 13
- 229910052738 indium Inorganic materials 0.000 claims description 13
- 229910052720 vanadium Inorganic materials 0.000 claims description 13
- 229910052725 zinc Inorganic materials 0.000 claims description 13
- 229910052733 gallium Inorganic materials 0.000 claims description 12
- 229910052727 yttrium Inorganic materials 0.000 claims description 12
- 239000002048 multi walled nanotube Substances 0.000 claims description 11
- 229910052732 germanium Inorganic materials 0.000 claims description 10
- 229910052748 manganese Inorganic materials 0.000 claims description 9
- 229910052750 molybdenum Inorganic materials 0.000 claims description 9
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- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical group C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 5
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- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 description 2
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 2
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 description 2
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- AMXOYNBUYSYVKV-UHFFFAOYSA-M lithium bromide Chemical compound [Li+].[Br-] AMXOYNBUYSYVKV-UHFFFAOYSA-M 0.000 description 2
- KWGKDLIKAYFUFQ-UHFFFAOYSA-M lithium chloride Chemical compound [Li+].[Cl-] KWGKDLIKAYFUFQ-UHFFFAOYSA-M 0.000 description 2
- 150000002642 lithium compounds Chemical class 0.000 description 2
- 229910001416 lithium ion Inorganic materials 0.000 description 2
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- 159000000002 lithium salts Chemical class 0.000 description 2
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- 229910052771 Terbium Inorganic materials 0.000 description 1
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Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Description
本発明は、リチウム二次電池用負極材料及びその製造方法に関する。 The present invention relates to a negative electrode material for a lithium secondary battery and a method for producing the same.
リチウムイオン電池、リチウムポリマー電池等のリチウム二次電池は、高いエネルギー密度を有しており、近年、移動体通信機器、携帯用電子機器等の主電源として利用が拡大している。 Lithium secondary batteries such as lithium ion batteries and lithium polymer batteries have a high energy density, and in recent years, their use is expanding as main power sources for mobile communication devices, portable electronic devices and the like.
リチウム二次電池の負極材料としては、従来、黒鉛、結晶化度の低い炭素等の各種炭素材料が広く用いられている。しかしながら、炭素材料だけを用いる場合には、使用可能な電流密度が低く、理論容量（放電容量）も不十分である。例えば、負極材料として炭素材料の一つである黒鉛だけを用いた場合には、理論容量が３７２ｍＡｈ／ｇと少ないため、より一層の高容量化が望まれている。 Conventionally, various carbon materials such as graphite and carbon having a low crystallinity have been widely used as negative electrode materials for lithium secondary batteries. However, when only a carbon material is used, the usable current density is low and the theoretical capacity (discharge capacity) is also insufficient. For example, when only the graphite, which is one of the carbon materials, is used as the negative electrode material, the theoretical capacity is as low as 372 mAh / g, and thus further increase in capacity is desired.
これに対し、リチウム金属を負極材料とする場合には、高い理論容量が得られることが分かっている。しかしながら、リチウム金属を用いる場合には、充電時に負極にデンドライトが析出するため、充放電を繰り返すことによりデンドライトが正極側に達して、内部短絡が起きるというという問題がある。デンドライトは比表面積が大きいために反応活性度が高く、その表面に溶媒の分解生成物からなる電子伝導性のない界面被膜が形成されることにより、内部短絡を生じる以前にも、電池の内部抵抗が高くなって充放電効率の低下が生じる。このような理由により、負極材料にリチウム金属を用いるリチウム二次電池は、信頼性が低く、結果的にサイクル寿命が短いという問題があるため、広く実用化される段階には達していない。 On the other hand, it is known that a high theoretical capacity can be obtained when lithium metal is used as the negative electrode material. However, when lithium metal is used, dendrite is deposited on the negative electrode during charging, and therefore, there is a problem that the dendrite reaches the positive electrode side by repeating charge and discharge, thereby causing an internal short circuit. Since dendrites have a high specific surface area, the reaction activity is high, and an internal non-electroconductive film consisting of the decomposition products of the solvent is formed on the surface of the dendrites. As a result, the charge / discharge efficiency decreases. For these reasons, lithium secondary batteries using lithium metal as a negative electrode material have a problem of low reliability and consequently short cycle life, and thus have not yet reached a stage where they are widely put into practical use.
このような背景から、汎用の炭素材料よりも放電容量の大きい物質であり、リチウム金属以外の材料からなるリチウム二次電池用負極材料の開発が望まれている。例えば、錫、珪素、銀等の元素、これらの窒化物、酸化物等は、リチウムと合金を形成してリチウムを吸蔵することができ、その吸蔵量は炭素材料よりはるかに大きいため、これらの物質を含有する負極材料の開発が提案されている。 From such a background, development of a negative electrode material for a lithium secondary battery, which is a substance having a discharge capacity larger than that of a general-purpose carbon material and made of a material other than lithium metal, is desired. For example, elements such as tin, silicon and silver, nitrides and oxides thereof can form an alloy with lithium and occlude lithium, and the occlusion amount is much larger than that of carbon materials. Development of negative electrode materials containing substances has been proposed.
しかしながら、これらの物質を含有する負極材料には、充放電サイクルを繰り返すうちに、リチウムの吸蔵・放出に伴って電極の大きな膨張・収縮が生じ、電極自体が瓦解するおそれがあることが指摘されている。 However, it has been pointed out that the negative electrode material containing these substances may cause large expansion / contraction of the electrode as lithium is absorbed and released during repeated charge / discharge cycles, and the electrode itself may be broken down. ing.
その対策として、リチウムを吸蔵・放出し易い金属と、吸蔵・放出を行わない金属とからなる合金を負極材料とすることが試みられている。このような合金によれば、リチウムの吸蔵・放出を行わない金属が介在することにより電極の膨潤、微細化等を抑制できると考えられている。また、当該合金が併用する炭素材料表面に導電性を付与することにより、充放電効率を向上させることができるとも考えられている。 As a countermeasure, an attempt has been made to use an alloy composed of a metal that easily stores and releases lithium and a metal that does not store and release lithium as a negative electrode material. According to such an alloy, it is considered that the swelling, miniaturization, etc. of the electrode can be suppressed by interposing a metal that does not occlude / release lithium. It is also considered that charge / discharge efficiency can be improved by imparting conductivity to the surface of the carbon material used in combination with the alloy.
例えば、特許文献１には、ＬｉαＡβＢγ（Ａは、Ｎａ、Ｋ、Ｒｂ、Ｃｓ、Ｃｅ、Ｔｉ、Ｚｒ、Ｈｆ、Ｖ、Ｎｂ、Ｔａ、Ｃａ、Ｓｒ、Ｂａ、Ｙ、Ｌａ、Ｃｒ、Ｍｏ、Ｗ、Ｍｎ、Ｔｃ、Ｒｕ、Ｏｓ、Ｃｏ、Ｒｈ、Ｉｒ、Ｎｉ、Ｐｄ、Ｃｕ及びＡｇの少なくとも１種以上、Ｂは、Ｋ、Ｍｇ、Ｃａ、Ｓｒ、Ｂａ、Ａｌ、Ｇａ、Ｉｎ、Ｓｉ、Ｇｅ、Ｓｎ、Ｐｂ、Ｓｂ及びＢｉの少なくとも１種）で示される、平均粒径０．０１〜１μｍであり、平均結晶子径１〜１００ｎｍである化合物と炭素材料５〜５０重量部とからなる電極が開示されている。しかしながら、その実施例においては、初回放電容量及び１００サイクル時の容量維持率が記載されているだけであり、長期のサイクル特性については公表されていない。前記ＬｉαＡβＢγで示される化合物は、メカニカルアロイング法により合成されているが、予め合成しておくと、理由の詳細は不明であるが、前記した合金系の高い容量を確保できない。また、炭素材料含有法によって、ＬｉαＡβＢγで示される化合物及び炭素からなる電極を作製することも知られているが、一般に炭素材料としては黒鉛が用いられており、ナノオーダーでの十分な集電効果は得られていない。 For example, Patent Document 1 discloses Li α A β B γ (A is Na, K, Rb, Cs, Ce, Ti, Zr, Hf, V, Nb, Ta, Ca, Sr, Ba, Y, La, At least one of Cr, Mo, W, Mn, Tc, Ru, Os, Co, Rh, Ir, Ni, Pd, Cu and Ag, B is K, Mg, Ca, Sr, Ba, Al, Ga, A compound having an average particle diameter of 0.01 to 1 μm and an average crystallite diameter of 1 to 100 nm and a carbon material of 5 to 50 weights represented by In, Si, Ge, Sn, Pb, Sb and Bi) An electrode comprising a portion is disclosed. However, in the examples, only the initial discharge capacity and the capacity maintenance rate at 100 cycles are described, and the long-term cycle characteristics are not disclosed. The compound represented by Li α A β B γ is synthesized by a mechanical alloying method, but if it is synthesized in advance, the details of the reason are unknown, but the high capacity of the above alloy system cannot be secured. . In addition, it is also known to produce an electrode composed of a compound represented by Li α A β B γ and carbon by a carbon material containing method, but in general, graphite is used as a carbon material, A sufficient current collecting effect is not obtained.
特許文献２には、ＬｉαＭ１βＭ２γ（Ｍ１は、Ｃｅ、Ｔｉ、Ｚｒ、Ｂ、Ｐ、Ｍｇ、Ｃａ、Ｓｒ、Ｂａ、Ｙ、Ｌａ、Ｃｒ、Ｍｏ、Ｗ、Ｍｎ、Ｃｏ、Ｉｒ、Ｎｉ、Ｆｅ、Ｐｄ、Ｃｕ、Ａｇ、Ｚｎ、Ｎａ、Ｋ、Ｖ、Ｎｂ、Ａｌ、Ｇａ、Ｉｎ、Ｓｉ、Ｇｅ、Ｓｎ、Ｐｂ、Ｓｂ及びＢｉの少なくとも２種、Ｍ２は、Ａｌ、Ｇａ、Ｉｎ、Ｓｉ、Ｇｅ、Ｓｎ、Ｐｂ、Ｓｂ及びＢｉの少なくとも１種）で示される化合物を含む負極であって、前記化合物の平均粒径が０．０５〜６０μｍであり、平均結晶子径が０．０１〜１０μｍであり、炭素材料含有量が５〜５０重量部であるものが開示されている。しかしながら、この文献でも、その実施例において初回放電容量及び１００サイクル時の容量維持率が記載されているだけであり、長期のサイクル特性については公表されていない。ＬｉαＭ１βＭ２γで示される化合物についても、メカニカルアロイング法で合成されているが、前記同様、予め合成しておくと合金系の高い容量を確保できない。また、炭素材料含有法によって、ＬｉαＭ１βＭ２γで示される化合物及び炭素からなる電極を作製することも知られているが、一般に炭素材料としては黒鉛が用いられており、ナノオーダーでの十分な集電効果は得られていない。 In Patent Document 2, Li α M1 β M2 γ (M1 is Ce, Ti, Zr, B, P, Mg, Ca, Sr, Ba, Y, La, Cr, Mo, W, Mn, Co, Ir, Ni, Fe, Pd, Cu, Ag, Zn, Na, K, V, Nb, Al, Ga, In, Si, Ge, Sn, Pb, Sb, and Bi, M2 is Al, Ga, In , Si, Ge, Sn, Pb, Sb and Bi), wherein the compound has an average particle size of 0.05 to 60 μm and an average crystallite size of 0.8. What is 01-10 micrometers and whose carbon material content is 5-50 weight part is disclosed. However, in this document, only the initial discharge capacity and the capacity maintenance rate at 100 cycles are described in the examples, and the long-term cycle characteristics are not disclosed. The compound represented by Li α M1 β M2 γ is also synthesized by the mechanical alloying method. However, as described above, if synthesized beforehand, a high capacity of the alloy system cannot be secured. In addition, it is also known to produce an electrode composed of a compound represented by Li α M1 β M2 γ and carbon by a carbon material containing method, but generally graphite is used as a carbon material, A sufficient current collecting effect is not obtained.
特許文献３には、急冷凝固させた組織を有する合金が開示されており、特許文献４には、Ａ相及びＢ相のどちらか一方の相が他方の相のマトリックス中に島状に分散した構造（島の平均粒径０．０５〜２０μｍ）の合金が開示されている。しかしながら、この合金材料では、大きな初期放電容量は得られるが、充放電を繰り返すうちに電極の膨張、微細化が避けられず、放電容量の低下を十分に抑制するには達していない。 Patent Document 3 discloses an alloy having a rapidly solidified structure, and Patent Document 4 discloses that one of the phases A and B is dispersed in an island shape in the matrix of the other phase. Alloys having a structure (island average particle size 0.05-20 μm) are disclosed. However, with this alloy material, a large initial discharge capacity can be obtained, but expansion and miniaturization of the electrode cannot be avoided while charging and discharging are repeated, and the reduction in discharge capacity has not been sufficiently suppressed.
特許文献５には、リチウム二次電池の充放電効率を向上させるために、炭素系材料表面にＬｉと合金を作らない金属（Ｃｕ）を付着させ、さらにその上にＬｉを付着させることが開示されている。しかしながら、当該リチウム二次電池では、充放電効率は９０．７％と向上しているが、実用レベルでは９９％以上の充放電効率が要求されていることを鑑みると未だ性能が不十分である。しかも、Ｃｕを蒸着した表面にＬｉをさらに蒸着する方法は、安全面、コスト面等から実用的ではない。 Patent Document 5 discloses that in order to improve the charge / discharge efficiency of a lithium secondary battery, a metal (Cu) that does not form an alloy with Li is attached to the surface of the carbon-based material, and Li is further attached thereon. Has been. However, in the lithium secondary battery, the charge / discharge efficiency is improved to 90.7%, but the performance is still insufficient in view of the fact that the charge / discharge efficiency of 99% or more is required at a practical level. . Moreover, the method of further depositing Li on the surface on which Cu is deposited is not practical from the viewpoint of safety, cost, and the like.
また、特許文献６には、Ｌｉを吸蔵放出する合金層表面に炭素材料を積層した負極が開示されている。しかしながら、この文献に開示された負極では、合金層形成に際してめっきをする必要があり、炭素材料の積層に際して塗布をする必要がある等、負極形成工程が複雑であり製造費用が高価という問題がある。
本発明は、従来技術に比して製造が容易であり、高い放電容量を維持しつつ、優れたサイクル特性を発揮するリチウム二次電池用負極材料を提供することを主な目的とする。 The main object of the present invention is to provide a negative electrode material for a lithium secondary battery that is easier to manufacture than the prior art and that exhibits excellent cycle characteristics while maintaining a high discharge capacity.
本発明者は、上記目的を達成すべく鋭意研究を重ねた結果、特定の成分から構成されるリチウム二次電池用負極材料が上記目的を達成できることを見出し、本発明を完成するに至った。 As a result of intensive studies to achieve the above object, the present inventor has found that a negative electrode material for a lithium secondary battery composed of specific components can achieve the above object, and has completed the present invention.
即ち、本発明は、下記のリチウム二次電池用負極材料及びその製造方法に係るものである。
１．金属Ａ成分、金属Ｂ成分、金属Ｃ成分、前記Ｂ成分とＣ成分との合金成分、及び炭素成分から構成される複合粉末からなるリチウム二次電池用負極材料であって、
（１）金属Ａ成分が、Ｃｏ、Ｃｒ、Ｆｅ、Ｍｎ、Ｍｏ、Ｎｂ、Ｎｉ、Ｔｉ、Ｖ、Ｗ、Ｚｒ及び希土類元素からなる群から選ばれる少なくとも１種であり、
（２）金属Ｂ成分が、Ａｇ、Ａｌ、Ａｕ、Ｃｕ、Ｉｎ、Ｍｇ、Ｐｄ、Ｐｔ、Ｙ及びＺｎからなる群から選ばれる少なくとも１種であり、
（３）金属Ｃ成分が、Ｇａ、Ｇｅ、Ｓｂ、Ｓｉ及びＳｎからなる群から選ばれる少なくとも１種であり、
（４）金属Ａ成分、金属Ｂ成分、金属Ｃ成分及び炭素成分の含有割合（但し、金属Ｂ成分及び金属Ｃ成分には、合金成分中の金属Ｂ成分及び金属Ｃ成分も含む）が、各成分の合計量を１００原子％とした場合に、金属Ａ成分５〜２０原子％、金属Ｂ成分５〜３５原子％、金属Ｃ成分２０〜５５原子％及び炭素成分５〜５０原子％であり、
（５）複合粉末の一次粒子の１０％以上が粒径１０〜５００ｎｍの範囲内であり、
（６）炭素成分が、径５０〜３００ｎｍ、且つ、長さ１〜２０μｍの微細炭素材料である
ことを特徴とするリチウム二次電池用負極材料。
２．炭素成分が、カーボンファイバー、多層カーボンナノチューブ、又は単層カーボンナノチューブと多層カーボンナノチューブとの混合物である上記項１記載のリチウム二次電池用負極材料。
３．炭素成分からなる導電性の３次元網目構造を含む上記項１又は２に記載のリチウム二次電池用負極材料。
４．金属Ａ成分、金属Ｂ成分、金属Ｃ成分及び炭素成分の含有割合（但し、金属Ｂ成分及び金属Ｃ成分には、合金成分中の金属Ｂ成分及び金属Ｃ成分も含む）が、各成分の合計量を１００原子％とした場合に、金属Ａ成分５〜１５原子％、金属Ｂ成分２０〜３５原子％、金属Ｃ成分３５〜５５原子％及び炭素成分２０〜４０原子％である上記項１〜３のいずれかに記載のリチウム二次電池用負極材料。
５．金属Ａ成分が、Ｃｏ、Ｆｅ、Ｎｉ、Ｔｉ、Ｖ及びＷの少なくとも１種であり、金属Ｂ成分が、Ａｇ、Ａｌ、Ｃｕ、Ｉｎ、Ｍｇ、Ｙ及びＺｎの少なくとも１種であり、金属Ｃ成分が、Ｓｂ、Ｓｉ及びＳｎの少なくとも１種である上記項１〜４のいずれかに記載のリチウム二次電池用負極材料。
６．金属Ｂ成分−金属Ｃ成分の組み合わせが、Ａｇ−Ｓｂ、Ａｇ−Ｓｎ、Ａｌ−Ｓｉ、Ａｕ−Ｇａ、Ａｕ−Ｇｅ、Ａｕ−Ｓｂ、Ａｕ−Ｓｉ、Ａｕ−Ｓｎ、Ｃｕ−Ｓｂ、Ｃｕ−Ｓｉ、Ｃｕ−Ｓｎ、Ｉｎ−Ｓｎ、Ｍｇ−Ｓｎ、Ｐｄ−Ｓｎ、Ｐｔ−Ｓｎ、Ｙ−Ｓｉ、Ｙ−Ｓｎ、Ｚｎ−Ｓｂ及びＺｎ−Ｓｉの少なくとも１種である上記項１〜４のいずれかに記載のリチウム二次電池用負極材料。
７．下記工程を有するリチウム二次電池用負極材料の製造方法：
（１）Ｃｏ、Ｃｒ、Ｆｅ、Ｍｎ、Ｍｏ、Ｎｂ、Ｎｉ、Ｔｉ、Ｖ、Ｗ、Ｚｒ及び希土類元素の少なくとも１種である金属Ａ成分、Ａｇ、Ａｌ、Ａｕ、Ｃｕ、Ｉｎ、Ｍｇ、Ｐｄ、Ｐｔ、Ｙ及びＺｎの少なくとも１種である金属Ｂ成分並びにＧａ、Ｇｅ、Ｓｂ、Ｓｉ及びＳｎの少なくとも１種である金属Ｃ成分を混合後、メカニカルアロイング処理により前記３成分からなる複合粉末を得る工程１、及び
（２）前記複合粉末に炭素成分として径５０〜３００ｎｍ、且つ、長さ１〜２０μｍの微細炭素材料を混合後、さらにメカニカルアロイング処理する工程２。
８．上記項１〜６のいずれかに記載のリチウム二次電池用負極材料からなる層を集電体上に有するリチウム二次電池用負極。
９．上記項８記載の負極を搭載したリチウム二次電池であって、初充電を経た後に負極材料中にＬｉ２ＢＣ型化合物（但し、Ｂ及びＣは、金属Ｂ成分及び金属Ｃ成分を示す）を有しているリチウム二次電池。
That is, this invention relates to the following negative electrode material for lithium secondary batteries, and its manufacturing method.
1. A negative electrode material for a lithium secondary battery comprising a composite powder composed of a metal A component, a metal B component, a metal C component, an alloy component of the B component and the C component, and a carbon component,
(1) The metal A component is at least one selected from the group consisting of Co, Cr, Fe, Mn, Mo, Nb, Ni, Ti, V, W, Zr, and a rare earth element,
(2) The metal B component is at least one selected from the group consisting of Ag, Al, Au, Cu, In, Mg, Pd, Pt, Y and Zn,
(3) The metal C component is at least one selected from the group consisting of Ga, Ge, Sb, Si and Sn,
(4) The content ratio of the metal A component, the metal B component, the metal C component and the carbon component (however, the metal B component and the metal C component include the metal B component and the metal C component in the alloy component), respectively. When the total amount of the components is 100 atomic%, the metal A component is 5 to 20 atomic%, the metal B component is 5 to 35 atomic%, the metal C component is 20 to 55 atomic%, and the carbon component is 5 to 50 atomic%.
(5) Ri Der range more than 10% of the particle size 10~500nm of the primary particles of the composite powder,
(6) A negative electrode material for a lithium secondary battery , wherein the carbon component is a fine carbon material having a diameter of 50 to 300 nm and a length of 1 to 20 m .
2 . Item 2. The negative electrode material for a lithium secondary battery according to Item 1, wherein the carbon component is carbon fiber, multi-walled carbon nanotube, or a mixture of single-walled carbon nanotube and multi-walled carbon nanotube.
3 . Item 3. The negative electrode material for a lithium secondary battery according to Item 1 or 2 , comprising a conductive three-dimensional network structure made of a carbon component.
4. The content ratio of the metal A component, the metal B component, the metal C component, and the carbon component (however, the metal B component and the metal C component include the metal B component and the metal C component in the alloy component) are the total of each component. Items 1 to 5 above when the amount is 100 atomic%, metal A component 5-15 atomic%, metal B component 20-35 atomic%, metal C component 35-55 atomic%, and carbon component 20-40 atomic%. 4. The negative electrode material for a lithium secondary battery according to any one of 3 above.
5 . The metal A component is at least one of Co, Fe, Ni, Ti, V and W, the metal B component is at least one of Ag, Al, Cu, In, Mg, Y and Zn, and the metal C Item 5. The negative electrode material for a lithium secondary battery according to any one of Items 1 to 4 , wherein the component is at least one of Sb, Si, and Sn.
6 . The combination of metal B component-metal C component is Ag-Sb, Ag-Sn, Al-Si, Au-Ga, Au-Ge, Au-Sb, Au-Si, Au-Sn, Cu-Sb, Cu-Si. Any one of the above items 1 to 4 , which is at least one of Cu, Sn, In-Sn, Mg-Sn, Pd-Sn, Pt-Sn, Y-Si, Y-Sn, Zn-Sb, and Zn-Si The negative electrode material for lithium secondary batteries as described in 2.
7 . Manufacturing method of negative electrode material for lithium secondary battery having the following steps:
(1) Co, Cr, Fe, Mn, Mo, Nb, Ni, Ti, V, W, Zr and a metal A component which is at least one of rare earth elements, Ag, Al, Au, Cu, In, Mg, Pd , Pt, Y and Zn at least one metal B component and Ga, Ge, Sb, Si and Sn at least one metal C component mixed, and then a composite powder comprising the above three components by mechanical alloying treatment And (2) Step 2 of further subjecting the composite powder to a mechanical alloying treatment after mixing a fine carbon material having a diameter of 50 to 300 nm and a length of 1 to 20 μm as a carbon component.
8 . The negative electrode for lithium secondary batteries which has a layer which consists of a negative electrode material for lithium secondary batteries in any one of said claim | item 1-6 on a collector.
9 . A lithium secondary battery including the negative electrode according to Item 8 , wherein a Li 2 BC type compound (where B and C are a metal B component and a metal C component) is contained in the negative electrode material after initial charging. Has a lithium secondary battery.
本発明のリチウム二次電池用負極材料からなる層を集電体上に有する負極を搭載したリチウム二次電池（リチウムイオン電池、リチウムポリマー電池等）は、初充電により負極材料中にＬｉ2ＢＣ（但し、Ｂ及びＣは、金属Ｂ成分及び金属Ｃ成分を示す）で示されるリチウム含有三元化合物を生成する。そのため、リチウム二次電池の初期放電容量が大きく、しかもサイクル特性が優れている。 A lithium secondary battery (lithium ion battery, lithium polymer battery, etc.) equipped with a negative electrode having a layer made of a negative electrode material for a lithium secondary battery according to the present invention on a current collector has Li 2 BC in the negative electrode material when initially charged. (However, B and C represent a metal B component and a metal C component). For this reason, the lithium secondary battery has a large initial discharge capacity and excellent cycle characteristics.
本発明の製造方法によれば、上記効果を奏するリチウム二次電池用負極材料を容易且つ確実に製造できる。 According to the production method of the present invention, a negative electrode material for a lithium secondary battery that exhibits the above effects can be produced easily and reliably.
リチウム二次電池用負極材料
本発明のリチウム二次電池用負極材料は、金属Ａ成分、金属Ｂ成分、金属Ｃ成分、前記Ｂ成分とＣ成分との合金成分、及び炭素成分から構成される複合粉末からなるリチウム二次電池用負極材料であって、
（１）金属Ａ成分が、Ｃｏ、Ｃｒ、Ｆｅ、Ｍｎ、Ｍｏ、Ｎｂ、Ｎｉ、Ｔｉ、Ｖ、Ｗ、Ｚｒ及び希土類元素からなる群から選ばれる少なくとも１種であり、
（２）金属Ｂ成分が、Ａｇ、Ａｌ、Ａｕ、Ｃｕ、Ｉｎ、Ｍｇ、Ｐｄ、Ｐｔ、Ｙ及びＺｎからなる群から選ばれる少なくとも１種であり、
（３）金属Ｃ成分が、Ｇａ、Ｇｅ、Ｓｂ、Ｓｉ及びＳｎからなる群から選ばれる少なくとも１種であり、
（４）金属Ａ成分、金属Ｂ成分、金属Ｃ成分及び炭素成分の含有割合（但し、金属Ｂ成分及び金属Ｃ成分には、合金成分中の金属Ｂ成分及び金属Ｃ成分も含む）が、各成分の合計量を１００原子％とした場合に、金属Ａ成分５〜２０原子％、金属Ｂ成分５〜３５原子％、金属Ｃ成分２０〜５５原子％及び炭素成分５〜５０原子％であり、
（５）複合粉末の一次粒子の１０％以上が粒径１０〜５００ｎｍの範囲内である
ことを特徴とする
〔金属Ａ成分〕
金属Ａ成分は、Ｃｏ、Ｃｒ、Ｆｅ、Ｍｎ、Ｍｏ、Ｎｂ、Ｎｉ、Ｔｉ、Ｖ、Ｗ、Ｚｒ及び希土類元素からなる群から選ばれる少なくとも１種である。希土類元素としては、Ｌａ、Ｃｅ、Ｐｒ、Ｎｄ、Ｓｍ、Ｅｕ、Ｇｄ、Ｔｂ、Ｄｙ、Ｈｏ、Ｅｒ、Ｔｍ及びＬｕの少なくとも１種が挙げられる。この中でも、特にＣｏ、Ｆｅ、Ｎｉ、Ｔｉ、Ｖ及びＷの少なくとも１種が好ましく、Ｃｏ、Ｆｅ、Ｎｉ、Ｔｉ及びＶの少なくとも１種がより好ましい。
〔金属Ｂ成分〕
金属Ｂ成分は、Ａｇ、Ａｌ、Ａｕ、Ｃｕ、Ｉｎ、Ｍｇ、Ｐｄ、Ｐｔ、Ｙ及びＺｎからなる群から選ばれる少なくとも１種である。この中でも、特にＡｇ、Ａｌ、Ｃｕ、Ｉｎ、Ｍｇ、Ｙ及びＺｎの少なくとも１種が好ましく、Ａｇ、Ａｌ、Ｃｕ及びＺｎの少なくとも１種がより好ましい。
〔金属Ｃ成分〕
金属Ｃ成分は、Ｇａ、Ｇｅ、Ｓｂ、Ｓｉ及びＳｎから選ばれる少なくとも１種である。この中でも、特にＳｂ、Ｓｉ及びＳｎの少なくとも１種が好ましい。
〔前記Ｂ成分とＣ成分との合金成分〕
合金成分は、前記Ｂ成分及びＣ成分からなる合金であればよく、例えば、１）Ｂ成分にＣ成分が固溶した合金、２）Ｂ成分とＣ成分との金属間化合物、３）Ｃ成分にＢ成分が固溶した合金、等が挙げられる。
Negative electrode material for lithium secondary battery The negative electrode material for lithium secondary battery of the present invention is a composite comprising a metal A component, a metal B component, a metal C component, an alloy component of the B component and the C component, and a carbon component. A negative electrode material for a lithium secondary battery made of powder,
(1) The metal A component is at least one selected from the group consisting of Co, Cr, Fe, Mn, Mo, Nb, Ni, Ti, V, W, Zr, and a rare earth element,
(2) The metal B component is at least one selected from the group consisting of Ag, Al, Au, Cu, In, Mg, Pd, Pt, Y and Zn,
(3) The metal C component is at least one selected from the group consisting of Ga, Ge, Sb, Si and Sn,
(4) The content ratio of the metal A component, the metal B component, the metal C component and the carbon component (however, the metal B component and the metal C component include the metal B component and the metal C component in the alloy component), respectively. When the total amount of the components is 100 atomic%, the metal A component is 5 to 20 atomic%, the metal B component is 5 to 35 atomic%, the metal C component is 20 to 55 atomic%, and the carbon component is 5 to 50 atomic%.
(5) 10% or more of the primary particles of the composite powder are in the range of particle size of 10 to 500 nm [Metal A component]
The metal A component is at least one selected from the group consisting of Co, Cr, Fe, Mn, Mo, Nb, Ni, Ti, V, W, Zr, and rare earth elements. The rare earth element includes at least one of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Lu. Among these, at least one of Co, Fe, Ni, Ti, V, and W is particularly preferable, and at least one of Co, Fe, Ni, Ti, and V is more preferable.
[Metal B component]
The metal B component is at least one selected from the group consisting of Ag, Al, Au, Cu, In, Mg, Pd, Pt, Y, and Zn. Among these, at least one of Ag, Al, Cu, In, Mg, Y, and Zn is particularly preferable, and at least one of Ag, Al, Cu, and Zn is more preferable.
[Metal C component]
The metal C component is at least one selected from Ga, Ge, Sb, Si and Sn. Among these, at least one of Sb, Si and Sn is particularly preferable.
[Alloy component of the B component and the C component]
The alloy component may be an alloy composed of the B component and the C component. For example, 1) an alloy in which the C component is dissolved in the B component, 2) an intermetallic compound of the B component and the C component, and 3) the C component. And alloys in which the B component is dissolved.
Ｂ成分−Ｃ成分の組み合わせは特に限定されず、例えば、Ａｇ−Ｓｂ、Ａｇ−Ｓｎ、Ａｌ−Ｓｉ、Ａｕ−Ｓｂ、Ａｕ−Ｓｉ、Ａｕ−Ｓｎ、Ａｕ−Ｇａ、Ａｕ−Ｇｅ、Ｃｕ−Ｓｂ、Ｃｕ−Ｓｉ、Ｃｕ−Ｓｎ、Ｉｎ−Ｓｎ、Ｍｇ−Ｓｎ、Ｐｄ−Ｓｎ、Ｐｔ−Ｓｎ、Ｙ−Ｓｉ、Ｙ−Ｓｎ、Ｚｎ−Ｓｂ、Ｚｎ−Ｓｉ等が挙げられる。この中でも、特にＡｇ−Ｓｂ、Ａｇ−Ｓｎ、Ａｌ−Ｓｉ、Ｃｕ−Ｓｂ、Ｃｕ−Ｓｉ、Ｃｕ−Ｓｎ、Ｍｇ−Ｓｎ、Ｚｎ−Ｓｂ及びＺｎ−Ｓｉの組み合わせが好ましい。 The combination of the B component and the C component is not particularly limited. For example, Ag-Sb, Ag-Sn, Al-Si, Au-Sb, Au-Si, Au-Sn, Au-Ga, Au-Ge, Cu-Sb Cu—Si, Cu—Sn, In—Sn, Mg—Sn, Pd—Sn, Pt—Sn, Y—Si, Y—Sn, Zn—Sb, Zn—Si, and the like. Among these, combinations of Ag—Sb, Ag—Sn, Al—Si, Cu—Sb, Cu—Si, Cu—Sn, Mg—Sn, Zn—Sb, and Zn—Si are particularly preferable.
金属間化合物としては、例えば、Ａｇ13Ｓｂ3、Ａｇ3Ｓｎ、Ｃｕ3Ｓｂ、Ｃｕ2Ｓｂ、Ｃｕ3Ｓｉ、Ｃｕ3Ｓｎ、Ｃｕ6Ｓｎ5、Ｍｇ2Ｓｎ、Ｚｎ3Ｓｂ2、Ｚｎ4Ｓｂ3、ＺｎＳｂ等が挙げられる。 Examples of the intermetallic compound include Ag 13 Sb 3 , Ag 3 Sn, Cu 3 Sb, Cu 2 Sb, Cu 3 Si, Cu 3 Sn, Cu 6 Sn 5 , Mg 2 Sn, Zn 3 Sb 2 , and Zn 4 Sb. 3 and ZnSb.
合金成分中のＢ成分−Ｃ成分の割合は特に限定されないが、例えば、１）Ｂ成分とＣ成分の合金であれば、Ｂ成分１８〜８２原子％、好ましくは２５〜７５原子％、Ｃ成分１８〜８２原子％、好ましくは２５〜７５原子％程度である。２）Ｂ成分とＣ成分との金属間化合物であれば、Ｂ成分１８〜８２原子％、好ましくは２５〜７５原子％、Ｃ成分１８〜８２原子％、好ましくは２５〜７５原子％程度である。
〔炭素成分〕
炭素成分としては特に限定されないが、複合粉末中に導電性の３次元網目構造を形成できるものであれば好ましい。導電性の３次元網目構造が形成されていれば、リチウム二次電池用負極材料として十分な集電効果が得られるとともに、リチウム吸蔵時の電極（特に合金成分）の体積膨張を効果的に抑制できる。
The ratio of the B component to the C component in the alloy component is not particularly limited. For example, in the case of 1) an alloy of the B component and the C component, the B component is 18 to 82 atomic%, preferably 25 to 75 atomic%, and the C component. It is 18 to 82 atomic%, preferably about 25 to 75 atomic%. 2) If it is an intermetallic compound of the B component and the C component, the B component is 18 to 82 atomic%, preferably 25 to 75 atomic%, the C component is 18 to 82 atomic%, preferably about 25 to 75 atomic%. .
[Carbon component]
Although it does not specifically limit as a carbon component, If a conductive three-dimensional network structure can be formed in composite powder, it is preferable. If a conductive three-dimensional network structure is formed, a sufficient current collecting effect can be obtained as a negative electrode material for lithium secondary batteries, and volume expansion of electrodes (particularly alloy components) during lithium occlusion can be effectively suppressed. it can.
炭素成分としては、例えば、微細炭素材料が挙げられる。具体的には、径５０〜３００ｎｍ、好ましくは７５〜２００ｎｍ、且つ、長さ１〜２０μｍ、好ましくは２〜１０μｍの微細炭素材料が挙げられる。このような形状特性は、導電性の３次元網目構造を形成し易いため有利である。 Examples of the carbon component include a fine carbon material. Specifically, a fine carbon material having a diameter of 50 to 300 nm, preferably 75 to 200 nm, and a length of 1 to 20 μm, preferably 2 to 10 μm can be mentioned. Such a shape characteristic is advantageous because it is easy to form a conductive three-dimensional network structure.
微細炭素材料としては、具体的には、カーボンファイバー；単層カーボンナノチューブ；多層カーボンナノチューブ；単層カーボンナノチューブと多層カーボンナノチューブとの混合物等が挙げられる。この中でも、特にカーボンファイバー；多層カーボンナノチューブ；又は単層カーボンナノチューブと多層カーボンナノチューブとの混合物を好適に使用できる。尚、多層カーボンナノチューブは、チューブ径の異なる大小の単層カーボンナノチューブが入れ子状に数層重なったものである。 Specific examples of the fine carbon material include carbon fiber; single-walled carbon nanotube; multi-walled carbon nanotube; and a mixture of single-walled carbon nanotube and multi-walled carbon nanotube. Among these, carbon fiber; multi-walled carbon nanotubes; or a mixture of single-walled carbon nanotubes and multi-walled carbon nanotubes can be preferably used. Multi-walled carbon nanotubes are obtained by nesting several single-walled carbon nanotubes having different tube diameters in a nested manner.
カーボンナノチューブを用いる場合には、金属的な導電性が発現されるため高い集電機能が得られる。またカーボンナノチューブはしなやかな柔軟構造を有しているため、Ｌｉ吸蔵時の体積膨張を緩和させる機能が得られ、高容量且つサイクル特性の維持に寄与する。単層カーボンナノチューブと多層カーボンナノチューブとの混合物であれば、多層カーボンナノチューブのみを用いる場合に比して、複合粉末のより内部（微細）にまで３次元網目構造を形成し得るため好ましい。図１に、微細炭素材料が導電性の３次元網目構造を形成している複合粉末の内部構造の模式図を示す。 When carbon nanotubes are used, a high current collecting function can be obtained because metallic conductivity is exhibited. Moreover, since the carbon nanotube has a supple flexible structure, the function which relieves the volume expansion at the time of Li occlusion is acquired, and it contributes to maintenance of a high capacity | capacitance and cycling characteristics. A mixture of single-walled carbon nanotubes and multi-walled carbon nanotubes is preferable because a three-dimensional network structure can be formed even inside (fine) the composite powder as compared with the case of using only multi-walled carbon nanotubes. FIG. 1 shows a schematic diagram of the internal structure of a composite powder in which a fine carbon material forms a conductive three-dimensional network structure.
上記炭素材料に加えて、カーボンブラックを併用することが好ましい。カーボンブラックを併用することにより、複合粉末のより内部（細部）にまで導電性を付与できる。カーボンブラックの粒子径は特に限定されないが、一次粒子径が通常１５〜６０ｎｍ、好ましくは２５〜５０ｎｍ程度である。カーボンブラックの添加量は特に限定されず、所望の導電性の程度に応じて適宜設定できる。
〔複合粉末の特性〕
本発明における複合粉末は、金属Ａ成分、金属Ｂ成分、金属Ｃ成分及び炭素成分の含有割合（但し、金属Ｂ成分及び金属Ｃ成分には、合金成分中の金属Ｂ成分及び金属Ｃ成分も含む）が、各成分の合計量を１００原子％とした場合に、金属Ａ成分５〜２０原子％、金属Ｂ成分５〜３５原子％、金属Ｃ成分２０〜５５原子％及び炭素成分５〜５０原子％であればよい。この中でも、特に金属Ａ成分５〜１５原子％、金属Ｂ成分２０〜３５原子％、金属Ｃ成分３５〜５５原子％及び炭素成分２０〜４０原子％が好ましい。特に炭素成分の含有割合に関しては、５〜５０原子％の範囲内に設定すれば、導電性の３次元網目構造が形成され易く、且つ、炭素成分（特にカーボンナノチューブ）の凝集及び容量の低下を抑制できる。
In addition to the carbon material, carbon black is preferably used in combination. By using carbon black in combination, conductivity can be imparted to the interior (details) of the composite powder. The particle diameter of carbon black is not particularly limited, but the primary particle diameter is usually 15 to 60 nm, preferably about 25 to 50 nm. The amount of carbon black added is not particularly limited, and can be appropriately set according to the desired degree of conductivity.
[Characteristics of composite powder]
The composite powder in the present invention is a content ratio of a metal A component, a metal B component, a metal C component and a carbon component (however, the metal B component and the metal C component include the metal B component and the metal C component in the alloy component). ) When the total amount of each component is 100 atomic%, the metal A component is 5 to 20 atomic%, the metal B component is 5 to 35 atomic%, the metal C component is 20 to 55 atomic%, and the carbon component is 5 to 50 atomic%. %. Among these, metal A component 5-15 atomic%, metal B component 20-35 atomic%, metal C component 35-55 atomic%, and carbon component 20-40 atomic% are preferable. In particular, when the content ratio of the carbon component is set within the range of 5 to 50 atomic%, a conductive three-dimensional network structure is easily formed, and the carbon component (particularly, carbon nanotube) is aggregated and the capacity is reduced. Can be suppressed.
本発明における複合粉末は、一次粒子の１０重量％以上が粒径１０〜５００ｎｍの範囲内であればよい。ナノオーダーの一次粒子が含まれることにより、後述するように優れた効果が得られる。但し、後述するメカニカルアロイング法により当該複合粉末を調製した場合には、各成分の組み合わせによって複合粉末中にミクロンオーダーの一次粒子が含まれ得る。この場合でも、一次粒子の１０％以上が粒径１０〜５００ｎｍの範囲内であれば、ミクロンオーダーの一次粒子が混在することは許容される。また、ミクロンオーダーの一次粒子は、複合粉末の微粉化の防止、導電性の向上等に寄与し得る。尚、本願明細書における一次粒子の粒径は、透過型電子顕微鏡観察により求めた値である。 The composite powder in this invention should just have 10 weight% or more of primary particles in the range of 10-500 nm of particle sizes. By including nano-order primary particles, excellent effects can be obtained as described later. However, when the composite powder is prepared by a mechanical alloying method to be described later, primary particles of micron order can be included in the composite powder by a combination of components. Even in this case, if 10% or more of the primary particles are within the range of the particle size of 10 to 500 nm, it is allowed to mix primary particles of micron order. Further, primary particles of micron order can contribute to prevention of pulverization of the composite powder, improvement of conductivity, and the like. In addition, the particle diameter of the primary particle in this specification is the value calculated | required by transmission electron microscope observation.
上記の観点から、複合粉末中の一次粒子の粒径は、１０％以上、好ましくは５０％以上、より好ましくは９０％以上の一次粒子が粒径１０〜５００ｎｍの範囲内、好ましくは１０〜２００ｎｍの範囲内にあればよい。特に、粒径１０〜５００ｎｍの所定のナノオーダー一次粒子が多く存在すると、電極の長寿命化・高容量化の効果が得られる。 From the above viewpoint, the particle size of the primary particles in the composite powder is 10% or more, preferably 50% or more, more preferably 90% or more of the primary particles in the range of 10 to 500 nm, preferably 10 to 200 nm. If it is in the range. In particular, when a large number of predetermined nano-order primary particles having a particle size of 10 to 500 nm are present, the effect of extending the life and capacity of the electrode can be obtained.
所定割合の一次粒子の粒径が上記範囲内にあることによって、リチウム吸蔵時に原子の再配列が可逆的に生じ易くなり、所期の特性が発揮される。また、複合粉末中に炭素成分からなる導電性の３次元網目構造を形成し易くなる。粒径についてより具体的に説明すると、粒径１０ｎｍを下回る一次粒子は、粉砕に長時間を要するため好ましくなく、粒径５００ｎｍを上回る一次粒子は、リチウム吸蔵時に原子の可逆的な再配列が起こり難いため好ましくない。 When the particle size of the primary particles at a predetermined ratio is within the above range, the rearrangement of atoms is likely to occur reversibly during lithium occlusion, and the desired characteristics are exhibited. Moreover, it becomes easy to form a conductive three-dimensional network structure composed of carbon components in the composite powder. More specifically, regarding the particle size, primary particles having a particle size of less than 10 nm are not preferable because a long time is required for pulverization, and primary particles having a particle size of more than 500 nm cause reversible rearrangement of atoms during lithium occlusion. It is not preferable because it is difficult.
リチウム二次電池用負極材料の製造方法
本発明のリチウム二次電池用負極材料の製造方法は特に限定されないが、例えば、下記工程を有する製造方法により好適に製造できる：
（１）Ｃｏ、Ｃｒ、Ｆｅ、Ｍｎ、Ｍｏ、Ｎｂ、Ｎｉ、Ｔｉ、Ｖ、Ｗ、Ｚｒ及び希土類元素の少なくとも１種である金属Ａ成分、Ａｇ、Ａｌ、Ａｕ、Ｃｕ、Ｉｎ、Ｍｇ、Ｐｄ、Ｐｔ、Ｙ及びＺｎの少なくとも１種である金属Ｂ成分並びにＧａ、Ｇｅ、Ｓｂ、Ｓｉ及びＳｎの少なくとも１種である金属Ｃ成分を混合後、メカニカルアロイング処理により前記３成分からなる複合粉末を得る工程１、及び
（２）前記複合粉末に炭素成分を混合後、さらにメカニカルアロイング処理する工程２。
Manufacturing method of negative electrode material for lithium secondary battery The manufacturing method of the negative electrode material for lithium secondary battery of this invention is not specifically limited, For example, it can manufacture suitably with the manufacturing method which has the following process:
(1) Co, Cr, Fe, Mn, Mo, Nb, Ni, Ti, V, W, Zr and a metal A component which is at least one of rare earth elements, Ag, Al, Au, Cu, In, Mg, Pd , Pt, Y and Zn at least one metal B component and Ga, Ge, Sb, Si and Sn at least one metal C component mixed, and then a composite powder comprising the above three components by mechanical alloying treatment And (2) a step 2 in which a carbon component is mixed with the composite powder and then mechanical alloying is performed.
この製造方法では、先ず炭素成分以外を混合してメカニカルアロイング処理を行った後、炭素成分を加えてさらにメカニカルアロイング処理を行う。即ち、ＡＢＣの３成分を複合化後、さらに炭素成分を加えて複合化して 複合粉末を得る。メカニカルアロイング処理では、Ｂ成分及びＣ成分の一部が合金化する。この製造方法は、複合粉末中に炭素成分からなる導電性の３次元網目構造が形成され易いため好ましい。 In this manufacturing method, the components other than the carbon component are first mixed and mechanically alloyed, and then the carbon component is added and further mechanically alloyed. That is, after combining the three components of ABC, a carbon component is further added to form a composite powder. In the mechanical alloying process, a part of the B component and the C component are alloyed. This manufacturing method is preferable because a conductive three-dimensional network structure composed of a carbon component is easily formed in the composite powder.
メカニカルアロイング処理は公知の方法を適用できる。例えば、機械的接合力により原料成分の混合・付着を繰返しながら全体を複合化（一部合金化）する装置を用いて処理すればよい。処理装置としては、メカニカルアロイング処理が可能な、一般に粉体分野で使用される混合機、分散機、粉砕機等が使用できる。具体的には、ライカイ機、ボールミル、振動ミル、アジテーターミル等が例示される。特に、ネットワーク間に存在する主に電池活物質を含む粉末であって積層・凝集状態にあるものを効率よく分散させるために、剪断力を付与できる混合機を用いるのが好ましい。 A known method can be applied to the mechanical alloying process. For example, the processing may be performed using a device that combines (partially alloys) the whole while repeating mixing and adhesion of raw material components by mechanical bonding force. As the processing apparatus, a mixer, a disperser, a pulverizer, etc., which can be mechanically alloyed and are generally used in the powder field, can be used. Specific examples include a reiki machine, a ball mill, a vibration mill, an agitator mill, and the like. In particular, it is preferable to use a mixer capable of applying a shearing force in order to efficiently disperse the powders mainly containing the battery active material present between the networks and in a laminated / aggregated state.
処理装置の操作条件は特に限定されないが、遠心加速度（投入エネルギー）としては、通常５〜２０Ｇ程度、好ましくは７〜１５Ｇ程度とすればよい。処理時間は各成分の種類に応じて適宜設定できる。例えば、ＡＢＣ成分の混合物の処理では、ＡＢＣ成分が複合化し、且つ、ＢＣ成分が一部合金化する限り処理時間は特に限定されないが、通常１〜１０時間程度である。また、炭素成分添加後の処理では、ＡＢＣ及び炭素成分の全てが複合化する限り特に限定されないが、通常０．５〜１０時間程度である。 The operating conditions of the processing apparatus are not particularly limited, but the centrifugal acceleration (input energy) is usually about 5 to 20 G, preferably about 7 to 15 G. The treatment time can be appropriately set according to the type of each component. For example, in the treatment of a mixture of ABC components, the treatment time is not particularly limited as long as the ABC component is complexed and the BC component is partially alloyed, but it is usually about 1 to 10 hours. Moreover, in the process after carbon component addition, although it will not specifically limit as long as all ABC and a carbon component are compounded, it is about 0.5 to 10 hours normally.
メカニカルアロイング処理に供するＡ、Ｂ及びＣ成分の粒径としては限定的ではないが、通常１〜４０μｍ、好ましくは２〜２０μｍ程度である。上記範囲内であれば、メカニカルアロイング処理において各成分を均一に分散させ易く、粒径１０〜２００ｎｍ程度の微細な複合粉末一次粒子が得られ易い。 Although it does not limit as a particle size of A, B, and C component which are provided to a mechanical alloying process, it is 1-40 micrometers normally, Preferably it is about 2-20 micrometers. If it is in the said range, it will be easy to disperse | distribute each component uniformly in a mechanical alloying process, and a fine composite powder primary particle | grain with a particle size of about 10-200 nm will be easy to be obtained.
上記処理により得られる微細な一次粒子は、通常は凝集して二次凝集物となっている。例えば、メカニカルアロイング法で複合粉末を製造する場合には、レーザー回折法により調べると、二次凝集物の粒径は最大で３８〜１５０μｍ程度である。 The fine primary particles obtained by the above treatment are usually aggregated into secondary aggregates. For example, when the composite powder is produced by the mechanical alloying method, the particle size of the secondary aggregate is about 38 to 150 μm at the maximum when examined by the laser diffraction method.
二次凝集物の粒度は特に限定されないが、負極材料として用いる場合には、二次凝集物の９０％以上、好ましくは９９．９％以上が粒径１〜１０５μｍの範囲内にあることが好ましく、１〜５０μｍの範囲内がより好ましい。また、二次凝集物の粒径については、５〜５０μｍの範囲内が好ましく、５〜１０μｍ程度がより好ましい。二次凝集物の粒径が上記範囲内であれば、電極の作製を高精度に行うことができる。尚、二次凝集物の粒径は、レーザー回折法又は走査電子顕微鏡観察により求めたものである。 The particle size of the secondary aggregate is not particularly limited, but when used as a negative electrode material, 90% or more, preferably 99.9% or more of the secondary aggregate is preferably in the range of 1 to 105 μm in particle size. The range of 1 to 50 μm is more preferable. Moreover, about the particle size of a secondary aggregate, the inside of the range of 5-50 micrometers is preferable, and about 5-10 micrometers is more preferable. If the particle size of the secondary aggregate is within the above range, the electrode can be produced with high accuracy. The particle size of the secondary aggregate is determined by laser diffraction method or scanning electron microscope observation.
リチウム二次電池用負極及びそれを搭載した電池
本発明のリチウム二次電池用負極は、本発明のリチウム二次電池用負極材料からなる層を集電体上に有する。負極の構成としては、前記した本発明における複合粉末を負極材料とする他は、公知のものが使用できる。例えば、該複合粉末に必要に応じて樹脂系バインダー、導電助材等を配合後、金属箔集電体等の公知の集電体上に複合粉末層（負極層）を形成して一体化（乾燥・プレス等）することにより負極を作製できる。
Negative electrode for lithium secondary battery and battery equipped with the same The negative electrode for lithium secondary battery of the present invention has a layer made of the negative electrode material for lithium secondary battery of the present invention on a current collector. As the structure of the negative electrode, known materials can be used except that the composite powder in the present invention described above is used as a negative electrode material. For example, after blending the composite powder as necessary with a resin binder, a conductive additive, etc., a composite powder layer (negative electrode layer) is formed on a known current collector such as a metal foil current collector and integrated ( The negative electrode can be produced by drying and pressing.
樹脂系バインダーとしては、例えば、ポリビリニデンフルオライド（ＰＶｄＦ）をＮ−メチルピロリドン（ＮＭＰ）に溶解させたペースト等が使用できる。導電助材としては、例えば、カーボンブラック等が使用できる。金属箔集電体としては、例えば、銅、ニッケル、鉄、チタン、コバルト等の少なくとも１種からなる金属箔が使用できる。 As the resin binder, for example, a paste in which polybilinidene fluoride (PVdF) is dissolved in N-methylpyrrolidone (NMP) can be used. As the conductive aid, for example, carbon black or the like can be used. As the metal foil current collector, for example, a metal foil made of at least one of copper, nickel, iron, titanium, cobalt and the like can be used.
負極層の厚みは特に限定されないが、一般に２〜１００μｍ、好ましくは５〜６０μｍ程度とすればよい。厚みが２μｍ未満では、実用的な電気容量を得ることが困難な場合がある。厚みが１００μｍ超過では、集電体が負極材料を支持できない場合がある。 The thickness of the negative electrode layer is not particularly limited, but is generally 2 to 100 μm, preferably about 5 to 60 μm. If the thickness is less than 2 μm, it may be difficult to obtain a practical electric capacity. When the thickness exceeds 100 μm, the current collector may not support the negative electrode material.
次いで、該負極を搭載したリチウム二次電池を作製する場合には、公知のリチウム二次電池の電池要素（正極、セパレーター、電解液等）を用いて、常法に従って、角型、円筒型、コイン型等のリチウム二次電池に組み立てればよい。 Next, when producing a lithium secondary battery equipped with the negative electrode, a battery element (positive electrode, separator, electrolyte, etc.) of a known lithium secondary battery is used, and a square shape, a cylindrical shape, What is necessary is just to assemble to lithium secondary batteries, such as a coin type.
正極材料としては、例えば、ＬｉＣｏＯ2、ＬｉＮｉＯ2、ＬｉＮｎ2Ｏ4等のリチウム含有酸化物等を使用できる。セパレーターとしては、公知のリチウム二次電池に用いられるものが使用できる。電解液を構成する溶媒としては、公知のリチウム塩を溶解できる非プロトン性及び低誘電率の溶媒が好ましい。例えば、エチレンカーボネート（ＥＣ）、プロピレンカーボネート、ジメチルカーボネート（ＤＭＣ）、ジエチレンカーボネート、アセトニトリル、プロピオニトリル、テトラヒドロフラン、γ−ブチロラクトン、２−メチルテトラヒドロフラン、１，３−ジオキソラン、４−メチル−１，３−ジオキソラン、１，２−ジメトキシエタン、１，２−ジエトキシエタン、ジエチルエーテル、スルホラン、メチルスルホラン、ニトロメタン、Ｎ，Ｎ−ジメチルホルムアミド、ジメチルスルホキシド等の少なくとも１種が挙げられる。電解質リチウム塩としては、例えば、ＬｉＣｌＯ4、ＬｉＡｓＦ6、ＬｉＰＦ6、ＬｉＢＦ4、ＬｉＢ（Ｃ6Ｈ5）4、ＬｉＣｌ、ＬｉＢｒ、ＣＨ3ＳＯ3Ｌｉ、ＣＦ3ＳＯ3Ｌｉ等の少なくとも１種が挙げられる。 Examples of the positive electrode material that can be used include lithium-containing oxides such as LiCoO 2 , LiNiO 2 , and LiNn 2 O 4 . As a separator, what is used for a well-known lithium secondary battery can be used. As the solvent constituting the electrolytic solution, an aprotic and low dielectric constant solvent capable of dissolving a known lithium salt is preferable. For example, ethylene carbonate (EC), propylene carbonate, dimethyl carbonate (DMC), diethylene carbonate, acetonitrile, propionitrile, tetrahydrofuran, γ-butyrolactone, 2-methyltetrahydrofuran, 1,3-dioxolane, 4-methyl-1,3 Examples include at least one of -dioxolane, 1,2-dimethoxyethane, 1,2-diethoxyethane, diethyl ether, sulfolane, methyl sulfolane, nitromethane, N, N-dimethylformamide, dimethyl sulfoxide and the like. Examples of the electrolyte lithium salt include at least one of LiClO 4 , LiAsF 6 , LiPF 6 , LiBF 4 , LiB (C 6 H 5 ) 4 , LiCl, LiBr, CH 3 SO 3 Li, CF 3 SO 3 Li, and the like. Can be mentioned.
得られた本発明のリチウム二次電池は、負極材料として所定成分を所定割合で含むため、初充電によるリチウム吸蔵時に、負極材料中にＬｉ2ＢＣ（但し、Ｂ及びＣはＢ成分及びＣ成分を示す）で示される面心立方構造のリチウム含有三元化合物を形成する。この三元化合物は、合金の分相がなくリチウム吸蔵することが可能であり、リチウム吸蔵時の体積変化の抑制に寄与する。これにより、単に従来法のようにリチウムを吸蔵・放出する金属と吸蔵・放出しない金属との合金からなる負極材料とは異なる効果が得られる。 Since the obtained lithium secondary battery of the present invention contains a predetermined component as a negative electrode material in a predetermined ratio, Li 2 BC (where B and C are B component and C component) in the negative electrode material at the time of lithium occlusion by initial charge. A lithium-containing ternary compound having a face-centered cubic structure shown in FIG. This ternary compound has no phase separation of the alloy and can occlude lithium and contributes to suppression of volume change during occlusion of lithium. Thus, an effect different from that of a negative electrode material made of an alloy of a metal that occludes / releases lithium and a metal that does not occlude / release as in the conventional method can be obtained.
即ち、初充電でリチウム含有三元化合物を形成することにより、高容量を長期に亘り維持できる。予め、メカニカルアロイング処理でリチウム含有三元化合物を製造した場合には、原因の詳細は未解明であるが、Ｌｉ吸蔵量が本来合金のもつ容量まで得られず、低容量になる問題がある。これに対し、本発明の負極材料では、初充電（リチウム吸蔵）時に上記リチウム含有三元化合物を形成し、次の放電（リチウム放出）時に元の複合材料に戻り、一部リチウムを含む不可逆な化合物が残る。かかるメカニズムにより、初充電（１回目）で形成した不可逆なリチウム化合物が骨格として存在し、２回目以後の充放電では、そのリチウム化合物を介してリチウムの吸蔵・放出が行われる。これにより、充放電による電極の体積変化・微粉化が抑制されつつ、電極の劣化抑制・サイクル特性寿命向上の効果が実現される。 That is, high capacity can be maintained over a long period of time by forming a lithium-containing ternary compound by initial charging. When lithium-containing ternary compounds are produced in advance by mechanical alloying, the details of the cause are unclear, but the amount of Li occlusion cannot be obtained up to the capacity of the alloy, and there is a problem that the capacity becomes low. . On the other hand, in the negative electrode material of the present invention, the lithium-containing ternary compound is formed at the time of initial charge (lithium occlusion), returns to the original composite material at the next discharge (lithium release), and is irreversible partially containing lithium. The compound remains. By this mechanism, an irreversible lithium compound formed in the first charge (first time) exists as a skeleton, and in the second and subsequent charge / discharge, lithium is occluded / released via the lithium compound. Thereby, while suppressing the volume change / micronization of the electrode due to charge / discharge, the effect of suppressing the deterioration of the electrode and improving the cycle characteristic life can be realized.
以下、具体的に、リチウム含有三元化合物を介して行われるリチウムの吸蔵・放出のメカニズムについて説明する。 Hereinafter, the mechanism of the occlusion / release of lithium performed through the lithium-containing ternary compound will be specifically described.
本発明の負極材料では、リチウムの吸蔵放出過程がリチウム含有三元化合物ＬｉＢ2ＣとＬｉ2ＢＣとを介して行われる。 In the negative electrode material of the present invention, the process of occluding and releasing lithium is performed via lithium-containing ternary compounds LiB 2 C and Li 2 BC.
例えば、Ｆｅ／Ａｇ／Ｓｎ／Ｃ（原子比）＝１８／１８／３４／３０の複合材料を用いた負極では、２サイクル目の放電容量は５９０ｍＡｈ／ｇとなり、１サイクル目よりも容量が約３７０ｍＡｈ／ｇ低下する。この不可逆な容量変化は、１回目の充電で生成したＡｇＬｉ2Ｓｎ相に起因するものと考えられる。Ｆｅ／Ａｇ／Ｓｎ／Ｃ（原子比）＝１８／１８／３４／３０の複合材料で、Ｌｉ吸蔵放出に関与する相は、Ａｇ3Ｓｎ及びＳｎである。リチウム吸蔵過程で、上記の相が、三元化合物Ａｇ2ＬｉＳｎ相及びＡｇＬｉ2Ｓｎ相に変化する。さらにＬｉを吸蔵した場合には、二元化合物のＬｉＡｇ相、Ｌｉ4.4Ｓｎ相等に分相するため、リチウム含有量の観点からは、三元化合物ＡｇＬｉ2Ｓｎ相までに留めることが好ましい。 For example, in a negative electrode using a composite material of Fe / Ag / Sn / C (atomic ratio) = 18/18/34/30, the discharge capacity at the second cycle is 590 mAh / g, and the capacity is about more than that at the first cycle. Decrease by 370 mAh / g. This irreversible capacity change is considered to be caused by the AgLi 2 Sn phase generated by the first charge. In the composite material of Fe / Ag / Sn / C (atomic ratio) = 18/18/34/30, the phases involved in Li storage / release are Ag 3 Sn and Sn. During the lithium occlusion process, the above phase changes into a ternary compound Ag 2 LiSn phase and an AgLi 2 Sn phase. Further, when Li is occluded, it is separated into LiAg phase, Li 4.4 Sn phase, etc. of the binary compound. From the viewpoint of lithium content, it is preferable to keep it up to the ternary compound AgLi 2 Sn phase.
リチウムの吸蔵放出過程がＡｇ2ＬｉＳｎ（密度７９２０ｋｇ／ｍ3）及びＡｇＬｉ2Ｓｎ（密度５６３０ｋｇ／ｍ3）を介して行われることにより、Ａｇ3Ｓｎ（密度９９３２ｋｇ／ｍ3）に対する体積変化は、各々１．２５倍（Ａｇ2ＬｉＳｎ）及び１．７６倍（ＡｇＬｉ2Ｓｎ）となる。Ｓｎ（密度７２８６ｋｇ／ｍ3）がＬｉを吸蔵してＬｉ4.4Ｓｎ（密度１９２０ｋｇ／ｍ3）になる場合の体積変化が３．８倍であることと比較すると、三元化合物が形成される場合には体積増加が非常に少ない。このため、電極の膨潤・微細化による容量低下が抑制されてサイクル寿命が向上すると考えられる。その結果、本発明のリチウム二次電池用負極材料を用いれば、放電容量が高く、充放電に伴う劣化が少ないサイクル特性に優れたリチウム二次電池が得られる。 The volume change with respect to Ag 3 Sn (density 9932 kg / m 3 ) is carried out through the process of occluding and releasing lithium via Ag 2 LiSn (density 7920 kg / m 3 ) and AgLi 2 Sn (density 5630 kg / m 3 ). 1.25 times (Ag 2 LiSn) and 1.76 times (AgLi 2 Sn), respectively. Sn the volume change may become (density 7286kg / m 3) is occludes Li Li 4.4 Sn (density 1920kg / m 3) is compared with that which is 3.8 times, if ternary compound is formed There is very little volume increase. For this reason, it is thought that the capacity | capacitance fall by swelling and refinement | miniaturization of an electrode is suppressed and cycle life improves. As a result, when the negative electrode material for a lithium secondary battery of the present invention is used, a lithium secondary battery having a high discharge capacity and less cycle characteristics with charge / discharge can be obtained.
以下、実施例を挙げて本発明を更に詳細に説明する。 Hereinafter, the present invention will be described in more detail with reference to examples.
実施例１〜３８及び比較例１〜１７
表１（実施例１〜３８）及び表２（比較例１〜１６）に示す通りにＡ成分、Ｂ成分及びＣ成分の金属粉末を混合後、混合物１００重量部に対して滑剤としてステアリン酸０．５重量部添加し、フリッチェ製遊星ボ−ルミルに投入し、メカニカルアロイング処理を２時間行ってＡＢＣ複合体を得た。メカニカルアロイング処理に供した各成分の粒径は、５〜２０ｎｍであった。さらに複合体に表１の所定比率（原子％）の微細炭素材料粉末（径１００ｎｍ、長さ１０μｍのカーボンファイバー）を混合後、同様のメカニカルアロイング処理を２時間行ってリチウム二次電池用負極材料（複合粉末）を得た。複合粉末は、Ａ、Ｂ、Ｃ、ＢＣ合金成分及び炭素成分から構成されていた。
Examples 1-38 and Comparative Examples 1-17
As shown in Table 1 (Examples 1 to 38) and Table 2 (Comparative Examples 1 to 16), after mixing metal powders of component A, component B and component C, stearic acid 0 as a lubricant with respect to 100 parts by weight of the mixture .5 parts by weight was added, put into a planetary ball mill manufactured by Fritche, and subjected to mechanical alloying for 2 hours to obtain an ABC composite. The particle size of each component subjected to the mechanical alloying treatment was 5 to 20 nm. Further, after mixing the composite with fine carbon material powder (carbon fiber having a diameter of 100 nm and a length of 10 μm) at a predetermined ratio (atomic%) shown in Table 1, the same mechanical alloying treatment was performed for 2 hours to form a negative electrode for a lithium secondary battery. A material (composite powder) was obtained. The composite powder was composed of A, B, C, BC alloy component and carbon component.
複合粉末の一次粒子の粒径を透過型電子顕微鏡で測定した結果、実施例１〜３８及び比較例１〜１６で得られた全ての一次粒子径が５０〜２００ｎｍの範囲内であった。 As a result of measuring the particle size of the primary particles of the composite powder with a transmission electron microscope, all the primary particle sizes obtained in Examples 1 to 38 and Comparative Examples 1 to 16 were in the range of 50 to 200 nm.
比較例１７では、表２に示す通りのＡ成分、Ｂ成分及びＣ成分の金属粉末を混合後、実施例と同様のメカニカルアロイング処理を２時間行った。次いで、炭素成分を加えた後、メカニカルアロイング処理ではなく、搖動回転型混合機を用いて２時間混合して複合粉末を調製した。比較例１７では、ＡＢＣ成分は複合化（ＢＣ成分は一部合金化）していたが、炭素成分は複合化しておらず、ＡＢＣ複合体と炭素成分とが単に混合された状態であった。以下、比較例１７で得られた粉末も便宜的に複合粉末と称する。 In Comparative Example 17, after the metal powders of A component, B component and C component as shown in Table 2 were mixed, the mechanical alloying treatment similar to the example was performed for 2 hours. Subsequently, after adding a carbon component, it mixed for 2 hours using not a mechanical alloying process but the peristaltic rotary mixer, and prepared composite powder. In Comparative Example 17, the ABC component was composited (the BC component was partially alloyed), but the carbon component was not composited, and the ABC composite and the carbon component were simply mixed. Hereinafter, the powder obtained in Comparative Example 17 is also referred to as a composite powder for convenience.
次いで、複合粉末８５重量部に、ポリビニリデンフルオライド（ＰＶｄＦ）をＮ−メチルピロリドン（ＮＭＰ）に溶解させたペースト１０重量部及びカーボンブラック５重量部を添加・混合してスラリーを調製した。 Next, 10 parts by weight of a paste prepared by dissolving polyvinylidene fluoride (PVdF) in N-methylpyrrolidone (NMP) and 5 parts by weight of carbon black were added to and mixed with 85 parts by weight of the composite powder to prepare a slurry.
次いで、厚さ１２μｍの電解銅箔に上記スラリーを乗せて、ドクターブレードでラミネートしてシート化した。得られたシートを８０℃で１０分間乾燥してＮＭＰを揮発除去後、ロールプレス機により、電解銅箔からなる集電体及び複合粉末からなる負極層を強固に密着接合させた。これを１ｃｍ2の円形ポンチで抜き取り、１２０℃で６時間真空乾燥させて厚さ１０μｍの負極とした。 Next, the slurry was placed on an electrolytic copper foil having a thickness of 12 μm, and laminated with a doctor blade to form a sheet. The obtained sheet was dried at 80 ° C. for 10 minutes to volatilize and remove NMP, and then a current collector made of an electrolytic copper foil and a negative electrode layer made of a composite powder were firmly adhered and bonded by a roll press. This was extracted with a 1 cm 2 circular punch and vacuum dried at 120 ° C. for 6 hours to obtain a negative electrode having a thickness of 10 μm.
上記電極を負極とし、金属リチウムを正極として、１モルのリチウムＰＦ6をエチレンカーボネート（ＥＣ）＋ジメチルカーボネ−ト（ＤＭＣ）（ＥＣ：ＤＭＣ＝１：２（体積比））に溶解したものを電解液として、ドライボックス中でコイン型モデル電池（ＣＲ２０３２タイプ）を作製した。 1 mol of lithium PF 6 dissolved in ethylene carbonate (EC) + dimethyl carbonate (DMC) (EC: DMC = 1: 2 (volume ratio)) using the above electrode as a negative electrode, metallic lithium as a positive electrode Was used as an electrolyte solution to prepare a coin-type model battery (CR2032 type) in a dry box.
このモデル電池の評価を次の方法により行った。即ち、モデル電池を、０．２ｍＡ／ｃｍ2 の定電流で０Ｖに達するまで放電し、１０分間の休止後、０．２ｍＡ／ｃｍ2の定電流で１．０Ｖに達するまで充電した。これを１サイクルとして、繰り返し充放電を行って放電容量を調べた。 This model battery was evaluated by the following method. That is, the model battery was discharged at a constant current of 0.2 mA / cm 2 until reaching 0 V, and after resting for 10 minutes, it was charged at a constant current of 0.2 mA / cm 2 until reaching 1.0 V. With this as one cycle, charge / discharge was repeated and the discharge capacity was examined.
実施例１〜３８の複合粉末を負極材料として用いたモデル電池の評価結果を表１に示す。比較例１〜１７の複合粉末を負極材料として用いたモデル電池の評価結果を表２に示す。 Table 1 shows the evaluation results of model batteries using the composite powders of Examples 1 to 38 as the negative electrode material. Table 2 shows the evaluation results of the model batteries using the composite powders of Comparative Examples 1 to 17 as the negative electrode material.
一方、実施例の製造方法により得られた複合粉末を用いた電池では、良好なサイクル特性が得られた。これは、複合粉末中に所定のＢＣ成分からなる合金成分を含むこと、及びおそらく炭素成分からなる導電性の３次元網目構造が形成されたことが要因と考えられる。 On the other hand, in the battery using the composite powder obtained by the manufacturing method of the example, good cycle characteristics were obtained. This is considered to be due to the fact that the composite powder contains an alloy component composed of a predetermined BC component and that a conductive three-dimensional network structure composed of a carbon component is probably formed.
表１及び表２の結果から明らかなように、各実施例の複合粉末を負極としたリチウム二次電池（モデル電池）では、初期放電容量が高く、５０サイクル後の放電容量も２５０ｍＡ／ｇ以上、３００サイクル後でも２００ｍＡｈ／ｇ以上と十分に容量維持されている。 As is clear from the results in Tables 1 and 2, the lithium secondary battery (model battery) using the composite powder of each example as a negative electrode has a high initial discharge capacity and a discharge capacity after 50 cycles of 250 mA / g or more. Even after 300 cycles, the capacity is sufficiently maintained at 200 mAh / g or more.
図２は、実施例８（Ａｇ／Ｆｅ／Ｓｎ／Ｃ＝１８／１８／３４／３０（原子％））の負極材料を用いた電池と、比較例８（Ｓｎ＝１００（原子％））、比較例９（Ｃ＝１００（原子％））の負極材料を用いたモデル電池について、放電容量とサイクル数との関係を示すグラフである。図２から明らかなように、実施例の電池については、初期容量が９６０ｍＡｈ／ｇであって、３００サイクル後でも４１２ｍＡｈ／ｇの容量を維持しており、サイクル特性の低下が少なく、比較例の負極材料を用いた電池と比較して、優れたサイクル寿命を有することが分かる。なお、炭素材料を用いない電池（Ａｇ／Ｆｅ／Ｓｎ＝２６／２６／５２（原子％））は、３００サイクル後でも３０７ｍＡｈ／ｇの高容量を示しているが、サイクル特性の低下が大きく、容量維持に課題がある。 FIG. 2 shows a battery using the negative electrode material of Example 8 (Ag / Fe / Sn / C = 18/18/34/30 (atomic%)), Comparative Example 8 (Sn = 100 (atomic%)), It is a graph which shows the relationship between discharge capacity and the number of cycles about the model battery using the negative electrode material of the comparative example 9 (C = 100 (atomic%)). As is clear from FIG. 2, the battery of the example has an initial capacity of 960 mAh / g, maintains a capacity of 412 mAh / g even after 300 cycles, and has little deterioration in cycle characteristics. It can be seen that the battery has an excellent cycle life as compared with the battery using the negative electrode material. Note that a battery not using a carbon material (Ag / Fe / Sn = 26/26/52 (atomic%)) shows a high capacity of 307 mAh / g even after 300 cycles, but the cycle characteristics are greatly reduced. There is a problem in capacity maintenance.
充電時にＬｉが吸蔵されると、下記式（１）に示すように、Ｃ成分のＬｉ化合化が進む。また下記式（２）に示すように Ｂ3Ｃでは、Ｌｉ吸蔵量が増加するとともに、ＬｉＢ2ＣからＬｉ2ＢＣを生成する反応が生じる。同時に下記式（３）で示すような反応もあると考えられる。さらに下記式（４）に示すように、Ｌｉ含有率の高いリチウム含有三元化合物が生成すると考えられる。Ｌｉ吸蔵時に、Ｌｉ含有量の上限をＬｉ2ＢＣ化合物に留めることにより、良好な電極特性が得られ易い。これは、Ｌｉ2ＢＣよりもさらにＬｉ吸蔵量を増やすと、Ｌｉ2ＢＣ化合物が二元化合物のＬｉＢ化合物、ＬｉＣ化合物等に分相して電極特性が劣化し易くなるためである。図３に、ＢＣ型複合合金のリチウム吸蔵による構造変化模式図により、ナノメーターサイズのＢＣ合金粒子とＬｉとの反応から、リチウム含有三元化合物の形成過程を示す。図３中のＬｉｗＣは、下記式のＬｉｘＣと同義である。
（１）ｘＬｉ＋Ｃ⇔ＬｉｘＣ（ｘ≦４．４）
（２）２Ｌｉ＋Ｂ3Ｃ⇔ＬｉＢ2Ｃ＋Ｂ＋Ｌｉ⇔Ｌｉ2ＢＣ＋Ｂ2
（３）ＬｉＢＣ＋Ｂ＋ＬｉｘＣ⇔Ｌｉ2ＢＣ＋ＬｉｙＣ（拡散反応）
（４）（ｙ＋ｚ）Ｌｉ＋Ｌｉ2ＢＣ⇔Ｌｉ2+yＢ1-zＣ＋ｚＬｉＢ（ｙ≦２．４、ｚ≦１）
図４は、透過電子顕微鏡Ｆｅ／Ａｇ／Ｓｎ／Ｃ＝１８／１８／３４／３０（原子％）複合合金電極のリチウム吸蔵状態の内部構造組織を示す。図中の濃色（点１、２）はＬｉＡｇ2Ｓｎ、灰色（点３，４）はＬｉ2ＡｇＳｎの各三元化合物を、明色（５、６）はＬｉＳｎ系、ＬｉＡｇ化合物を示し、ＢＣ複合合金がＬｉを吸蔵してリチウム三元化合物を形成していることが分かる。
If Li is occluded at the time of charge, as shown in the following formula (1), the Li compound of the C component proceeds. Further, as shown in the following formula (2), in B 3 C, the amount of Li occlusion increases and a reaction for generating Li 2 BC from LiB 2 C occurs. At the same time, it is considered that there is a reaction represented by the following formula (3). Furthermore, as shown in the following formula (4), it is considered that a lithium-containing ternary compound having a high Li content is generated. It is easy to obtain good electrode characteristics by keeping the upper limit of the Li content in the Li 2 BC compound during Li storage. This is because when the Li storage amount is further increased than Li 2 BC, the Li 2 BC compound is phase-divided into binary LiB compounds, LiC compounds, etc., and the electrode characteristics are likely to deteriorate. FIG. 3 shows a process of forming a lithium-containing ternary compound from a reaction between nanometer-sized BC alloy particles and Li, using a schematic diagram of structural changes caused by occlusion of lithium in a BC type composite alloy. LiwC in FIG. 3 is synonymous with LixC in the following formula.
(1) xLi + C⇔LixC (x ≦ 4.4)
(2) 2Li + B 3 C⇔LiB 2 C + B + Li⇔Li 2 BC + B 2
(3) LiBC + B + LixC⇔Li 2 BC + LiyC (diffusion reaction)
(4) (y + z) Li + Li 2 BC⇔Li 2 + y B 1-z C + zLiB (y ≦ 2.4, z ≦ 1)
FIG. 4 shows the internal structure of the lithium occlusion state of the transmission electron microscope Fe / Ag / Sn / C = 18/18/34/30 (atomic%) composite alloy electrode. In the figure, dark colors (points 1 and 2) are LiAg 2 Sn, gray (points 3 and 4) are Li 3 AgSn ternary compounds, and light colors (5 and 6) are LiSn-based and LiAg compounds, It can be seen that the BC composite alloy occludes Li to form a lithium ternary compound.
図５には、実施例３の透過電子顕微鏡による複合合金材料の内部構造組織を示す。（ａ）の結果からは、この複合合金材料の内部構造は数１０ｎｍオーダーの微結晶粒子から構成されていることが分かる。また、（ｂ）の透過電子顕微鏡とＥＤＳ分布の結果からは、Ｓｎ微結結晶中にＡｇ及びＦｅが存在していることが分かり、複合合金材料中に微細に存在していることが分かる。 In FIG. 5, the internal structure of the composite alloy material by the transmission electron microscope of Example 3 is shown. From the result of (a), it can be seen that the internal structure of the composite alloy material is composed of microcrystalline particles of the order of several tens of nm. Further, from the results of the transmission electron microscope and the EDS distribution of (b), it can be seen that Ag and Fe are present in the Sn fine crystals, and that they are finely present in the composite alloy material.
Claims (9)
（１）金属Ａ成分が、Ｃｏ、Ｃｒ、Ｆｅ、Ｍｎ、Ｍｏ、Ｎｂ、Ｎｉ、Ｔｉ、Ｖ、Ｗ、Ｚｒ及び希土類元素からなる群から選ばれる少なくとも１種であり、
（２）金属Ｂ成分が、Ａｇ、Ａｌ、Ａｕ、Ｃｕ、Ｉｎ、Ｍｇ、Ｐｄ、Ｐｔ、Ｙ及びＺｎからなる群から選ばれる少なくとも１種であり、
（３）金属Ｃ成分が、Ｇａ、Ｇｅ、Ｓｂ、Ｓｉ及びＳｎからなる群から選ばれる少なくとも１種であり、
（４）金属Ａ成分、金属Ｂ成分、金属Ｃ成分及び炭素成分の含有割合（但し、金属Ｂ成分及び金属Ｃ成分には、合金成分中の金属Ｂ成分及び金属Ｃ成分も含む）が、各成分の合計量を１００原子％とした場合に、金属Ａ成分５〜２０原子％、金属Ｂ成分５〜３５原子％、金属Ｃ成分２０〜５５原子％及び炭素成分５〜５０原子％であり、
（５）複合粉末の一次粒子の１０％以上が粒径１０〜５００ｎｍの範囲内であり、
（６）炭素成分が、径５０〜３００ｎｍ、且つ、長さ１〜２０μｍの微細炭素材料である
ことを特徴とするリチウム二次電池用負極材料。 A negative electrode material for a lithium secondary battery comprising a composite powder composed of a metal A component, a metal B component, a metal C component, an alloy component of the B component and the C component, and a carbon component,
(1) The metal A component is at least one selected from the group consisting of Co, Cr, Fe, Mn, Mo, Nb, Ni, Ti, V, W, Zr, and a rare earth element,
(2) The metal B component is at least one selected from the group consisting of Ag, Al, Au, Cu, In, Mg, Pd, Pt, Y and Zn,
(3) The metal C component is at least one selected from the group consisting of Ga, Ge, Sb, Si and Sn,
(4) The content ratio of the metal A component, the metal B component, the metal C component and the carbon component (however, the metal B component and the metal C component include the metal B component and the metal C component in the alloy component), respectively. When the total amount of the components is 100 atomic%, the metal A component is 5 to 20 atomic%, the metal B component is 5 to 35 atomic%, the metal C component is 20 to 55 atomic%, and the carbon component is 5 to 50 atomic%.
(5) Ri Der range more than 10% of the particle size 10~500nm of the primary particles of the composite powder,
(6) A negative electrode material for a lithium secondary battery , wherein the carbon component is a fine carbon material having a diameter of 50 to 300 nm and a length of 1 to 20 m .
（１）Ｃｏ、Ｃｒ、Ｆｅ、Ｍｎ、Ｍｏ、Ｎｂ、Ｎｉ、Ｔｉ、Ｖ、Ｗ、Ｚｒ及び希土類元素の少なくとも１種である金属Ａ成分、Ａｇ、Ａｌ、Ａｕ、Ｃｕ、Ｉｎ、Ｍｇ、Ｐｄ、Ｐｔ、Ｙ及びＺｎの少なくとも１種である金属Ｂ成分並びにＧａ、Ｇｅ、Ｓｂ、Ｓｉ及びＳｎの少なくとも１種である金属Ｃ成分を混合後、メカニカルアロイング処理により前記３成分からなる複合粉末を得る工程１、及び
（２）前記複合粉末に炭素成分として径５０〜３００ｎｍ、且つ、長さ１〜２０μｍの微細炭素材料を混合後、さらにメカニカルアロイング処理する工程２。 Manufacturing method of negative electrode material for lithium secondary battery having the following steps:
(1) Co, Cr, Fe, Mn, Mo, Nb, Ni, Ti, V, W, Zr and a metal A component which is at least one of rare earth elements, Ag, Al, Au, Cu, In, Mg, Pd , Pt, Y and Zn at least one metal B component and Ga, Ge, Sb, Si and Sn at least one metal C component mixed, and then a composite powder comprising the above three components by mechanical alloying treatment And (2) Step 2 of further subjecting the composite powder to a mechanical alloying treatment after mixing a fine carbon material having a diameter of 50 to 300 nm and a length of 1 to 20 μm as a carbon component.
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