2011A1854                          BL19B2

ࣜࢳ࣒࢘࢖࢜ࣥ஧ḟ㟁ụᮦᩱ LiCoO2 ࡢ⤖ᬗᵓ㐀ゎᯒ
Monoclinic distortion on non-stoichiometric LixCoO2 with x = 0.51
ᓊ⏣ ె኱, ྥ ࿴ᙪ, 㔝ᓮ ὒ, ᇽ๓ ࿴ᙪ
Yoshihiro Kishida, Kazuhiko Mukai, Hiroshi Nozaki and Kazuhiko Dohmae㻔ᰴ㻕㇏⏣୰ኸ◊✲ᡤ
Toyota Central Research and Development Laboratories, Inc.
ࣜࢳ࣒࢘࢖࢜ࣥ஧ḟ㟁ụࡢṇᴟά≀㉁ࡢ୍ࡘ࡛࠶ࡿ LixCoO2㻔x = 0.51㻕ࡢ⢊ᮎ X ⥺ᅇᢡ㻔XRD㻕 ᐃ
ࢆ 300 K ࠿ࡽ 100 K ࡢ ᗘ࡛⾜ࡗࡓࠋ300 K ࡛ࡢ⤖ᬗᵓ㐀ࡣ⳻㠃యᬗ㸦✵㛫⩌㸸R3m㸧࡛࠶ࡗࡓࡀࠊ
250 K ௨ୗ࡛༢ᩳᬗ㸦✵㛫⩌㸸C2/m㸧࡟㌿⛣ࡋࡓࠋࡉࡽ࡟ ᗘࢆపୗࡉࡏࡿ࡜ࠊ170 K ௨ୗ࡛༢ᩳᬗ࠿ࡽ⳻㠃యᬗ࡟㏆࠸ᵓ㐀࡟ኚ໬ࡋࡓࠋ࣮࣮࢟࣡ࢻ㸸 ࣜࢳ࣒࢘࢖࢜ࣥ஧ḟ㟁ụࠊLiCoO2ࠊ⢊ᮎ X ⥺ᅇᢡ⫼ᬒ࡜◊✲┠ⓗ㸸 ࣜࢳ࣒࢘࢖࢜ࣥ஧ḟ㟁ụࡢṇᴟά≀㉁࡜ࡋ࡚ࠊ୺࡟ LiCoO2 ࡀ౑⏝ࡉࢀ࡚࠸ࡿࠋ໬Ꮫ㔞ㄽ⤌ᡂ
LiCoO2㻔stoichiometric LiCoO2, ST-LCO䠅࠿ࡽ Li ࢆᘬᢤࡃ࡜ࠊx = 0.5䠄LixCoO2䠅㏆ഐ࡛⳻㠃యᬗ䠄R3m䠅
я༢ᩳᬗ㻔C2/m㻕я⳻㠃యᬗ㻔R3m㻕ࡢᵓ㐀ኚ໬ࢆ♧ࡍ[1-3]ࠋࡑࡢࡼ࠺࡞ᵓ㐀ኚ໬ࡣࠊṇᴟά≀㉁ෆ࡛
࣑ࢡࣟ࡞ṍࡳࢆⓎ⏕ࡉࡏࠊࢧ࢖ࢡࣝຎ໬ࡢせᅉ࡜࡞ࡿࠋࡑࡢࡓࡵࠊᕷ㈍ࣜࢳ࣒࢘࢖࢜ࣥ஧ḟ㟁ụࡢṇᴟά≀㉁ࡣ㠀໬Ꮫ㔞ㄽ⤌ᡂẚ(Li / Co > 1㻕࡛ྜᡂࡉࢀࡓ LiCoO2㻔non-stoichiometric LiCoO2ࠊ
NST-LCO㻕ࡀ౑⏝ࡉࢀ࡚࠸ࡿࠋ ࡇࢀࡲ࡛࡟ᡃࠎࡢࢢ࣮ࣝࣉ࡛ࡣࠊୖグᵓ㐀ኚ໬ࡢᶵᵓࢆゎ᫂ࡍࡿࡓࡵ࡟ ST-LCO ࡢ⢊ᮎ XRD
ᐃࢆ 300 K ࠿ࡽ 90 K ࡢ ᗘ࡛⾜ࡗࡓࠋࡑࡢ⤖ᯝࠊx = 0.53 ヨᩱࡣ 300 K ࡛ࡣ༢ᩳᬗ࡛࠶ࡗࡓࡀࠊᗘࡀୗࡀࡿ࡟ᚑ࠸⳻㠃యᬗ࡟㏆࠸ᵓ㐀࡟ኚ໬ࡋࡓ[4]ࠋ௒ᅇࡣࠊNST-LCO㻔x = 0.51㻕ヨᩱࡢప
XRD ᐃࢆ⾜࠸ࠊ⤖ᬗᵓ㐀ࡢ ᗘ౫Ꮡᛶࢆㄪ࡭ࡓࠋᐇ㦂㸸ཎᩱ࡟ Li2CO3 ࡜ Co3O4 ⢊ᮎࢆ⏝࠸ࠊLi / Co = 1.05 ࡢ௙㎸ࡳࣔࣝẚ࡛ NST-LCO ࢆྜᡂࡋࡓࠋᑐᴟ࡟㔠ᒓ Li ࢆ⏝࠸ࡓ 2 ᴟᘧࢭࣝࢆస〇ࡋࠊᐃ㟁ὶ᪉ᘧ࡛ 4.10 ࡲࡓࡣ 4.15 V ࡲ࡛඘㟁ࡋࡓࠋ඘㟁ᚋࠊ࢔ࣝࢦࣥ㞺ᅖẼࢢ࣮ࣟࣈ࣎ࢵࢡࢫෆ࡛ࢭࣝࢆゎయࡋࠊヨᩱࢆ┤ᚄ 0.3 mm ࡢ࣎ࣟࢩࣜࢣ࣮ࢺ〇࢟ࣕࣆ࣮ࣛࣜ࡟඘ሸࡋࡓࠋࡑࡢᚋࠊ300 K ࠿ࡽ 200 K ࡢ㛫ࡣ 50 K ้ࡳ࡛ࠊࡲࡓ 200 K ࠿ࡽ 100 Kࡢ㛫ࡣ 10 K ้ࡳ࡛㝆 ࡋ࡞ࡀࡽ XRD ᐃࢆ⾜ࡗࡓ㹙Ἴ㛗㸸0.70042㻔10㻕ύ㹛ࠋ⤖ᯝ࠾ࡼࡧ⪃ᐹ㸸
ᅗ 1 ࡟ 4.15 V ࡲ࡛඘㟁ࡋ࡚స〇ࡋࡓ NST-LCO㻔x = 0.51㻕ࡢ XRD ࣃࢱ࣮ࣥࢆ♧ࡍࠋ300 K ࡢ XRDࣃࢱ࣮ࣥࡣ᪤ሗ[5]ࡢ࡜࠾ࡾ⳻㠃యᬗ࡛ᖐᒓࡍࡿࡇ࡜ࡀ࡛ࡁࡓࠋ300 K ࠿ࡽ ᗘࢆୗࡆࡿ࡜ࠊ104ᅇᢡ⥺ࡢࣆ࣮ࢡᙉᗘࡀᛴ⃭࡟ῶᑡࡋࠊᅗ 1 ▮༳࡟♧ࡍࡼ࠺࡟ࠊ㧗ゅഃ࡟᪂ࡓ࡞ࣆ࣮ࢡࡀฟ⌧ࡋࡓࠋ⳻㠃యᬗ࠿ࡽ༢ᩳᬗ࡟ኚ໬ࡍࡿ࡜ࠊ104 ᅇᢡ⥺ࡣ 111 ᅇᢡ⥺࡜ 202ᅇᢡ⥺࡟ 2 : 1 ࡢᙉᗘẚ࡛ศ㞳ࡍࡿ[2]ࠋࡑࡇ࡛ RIETAN-FP[6]ࢆ⏝࠸࡚࣮ࣜࢺ࣋ࣝࢺゎᯒࢆ⾜࡞ࡗࡓ࡜ࡇࢁࠊ200 K ௨ୗࡢ XRDࣃࢱ࣮ࣥࡣ༢ᩳᬗ༢┦࡛ゎᯒࡍࡿࡇ࡜ࡀ࡛ࡁࡓࠋᚑࡗ࡚ࠊNST-LCO䠄x = 0.51䠅ࡣ 200 K ௨ୗ࡛⳻㠃యᬗ࠿ࡽ༢ᩳᬗ࡟㌿⛣ࡍࡿࡇ࡜ࡀศ࠿ࡗࡓࠋᅗ 2㻔a㻕ཬࡧ㻔b㻕࡟ NST-LCO㻔x = 0.51㻕ࡢ᱁Ꮚᐃᩘࡢ ᗘ౫Ꮡᛶࢆ♧ࡍࠋᅗ 2 ୰࠾ࡼࡧ௨ୗ࡟♧ࡍῧ࠼Ꮠ M ࡣ༢ᩳᬗࢆࠊࡲࡓ H ࡣ⳻㠃యᬗࢆ⾲ࡍࠋcM ࡣᗘࡀୗࡀࡿ࡟ᚑ࠸༢ㄪ࡟ῶᑡࡋࡓࠋ୍᪉ࠊaM ཬࡧ bM ࡣ ᗘ࡟౫ࡽࡎ࡯ࡰ୍ᐃ࡛࠶ࡗࡓࠋࡲࡓࠊșM ࡣ 300 K ࠿ࡽ ᗘࡀୗࡀࡿ࡟ᚑ࠸ᛴ⃭࡟ῶᑡࡋࠊ170 K ௜㏆࡛ᴟᑠࢆ♧ࡋࡓᚋࠊ⦆ࡸ࠿࡟ቑຍ
ࡋࡓࠋᅗ 2㻔c㻕࡟♧ࡍࡼ࠺࡟ࠊCo㻔O㻕㠃ෆࡢṍࡳࢆ⾲ࡍ aM / bM ࡣ ᗘ࡟౫ࡽࡎ࡯ࡰ 3 㻔㹼1.732㻕࡛࠶ࡗࡓࠋᚑࡗ࡚ࠊ⳻㠃యᬗ࠿ࡽ༢ᩳᬗ࡬ࡢኚ໬ࡣࠊCo㻔O㻕㠃ෆࡢṍࡳ࡟౫ࡿࡶࡢ࡛ࡣ࡞ࡃࠊCo㻔O㻕ᒙ㛫ࡢࡎࢀ࡟౫ࡿࡇ࡜ࡀศ࠿ࡗࡓࠋࡇࡇ࡛ Co㻔O㻕ᒙ㛫ࡢࡎࢀࡢ኱ࡁࡉࢆ⾲ࡍࣃ࣓࣮ࣛࢱ࣮࡛࠶ࡿǼșࢆᘧ㻔1㻕࡟ࡼࡾồࡵࡓ[4]ࠋǼșࡣ 300 K ࠿ࡽ ᗘࡀୗࡀࡿ࡟ᚑ࠸ᛴ⃭࡟ቑຍࡋࠊ170 K ௜㏆࡛ᴟ኱ࢆ♧ࡋࡓᚋࠊ⦆ࡸ࠿࡟ῶᑡࡋࡓ㹙ᅗ 2㻔d㻕㹛ࠋ170 K ௨ୗࡢǼșࡢῶᑡࡣࠊ༢ᩳᬗ࠿ࡽ⳻㠃యᬗ࡬ࡢኚ໬ࢆ⾲ࡋ࡚࠾ࡾࠊྠᵝࡢ⌧㇟ࡀ ST-LCO㻔x = 0.53㻕࡟࠾࠸࡚ࡶほ ࡉࢀ࡚࠸ࡿ[4]ࠋ࡞࠾ࠊ4.10 Vࡲ࡛඘㟁ࡋ࡚స〇ࡋࡓ NST-LCO㻔x = 0.57㻕࡛ࡶࠊNST-LCO㻔x = 0.51㻕࡜ྠࡌࡃ 200 K ࡛⳻㠃యᬗ࠿ࡽ༢ᩳᬗ࡟ኚ໬ࡋࡓࠋࡋ࠿ࡋࠊǼșࡣ⣙ 0.12 ࡛࠶ࡗࡓࡇ࡜࠿ࡽࠊNST-LCO㻔x = 0.51㻕ࡼࡾࡶ⳻㠃యᬗ࡟㏆࠸ᵓ㐀࡜⪃࠼ࡽࢀࡿࠋ
­§ 3c sin E M ·½¸¸¾  E M'E E H  E M ®180q  tan 1 ¨¨ M

㻔1㻕
aM
©
¹¿
¯
ᚑ᮶ NST-LCO ࡣ༢ᩳᬗ࡟ኚ໬ࡋ࡞࠸࡜⪃࠼ࡽࢀ࡚࠸ࡓࠋࡋ࠿ࡋࠊ௒ᅇࡢ⤖ᯝ࡟ࡼࡾ 200 K ௨ୗࡢప ࡛ࡣ༢ᩳᬗ࡟ኚ໬ࡍࡿࡇ࡜ࡀศ࠿ࡗࡓࠋLi ⤌ᡂኚື࡟క࠺⤖ᬗᵓ㐀ኚ໬ࡣࠊࣜࢳ࣒࢘࢖࢜ࣥ஧ḟ㟁ụᮦᩱඹ㏻ࡢ≉ᚩ࡛࠶ࡿࠋᚑࡗ࡚ࠊLi ⤌ᡂࡸ ᗘ࡟ࡼࡿᵓ㐀ኚ໬ࢆ⣔⤫ⓗ࡟ㄪ࡭ࡿࡇ࡜ࡣࠊ⤖ᬗᵓ㐀ኚ໬ࡢᶵᵓゎ᫂࡟⧅ࡀࡾࠊࡑࢀ࡟ࡼࡗ࡚ᵓ㐀ኚ໬ࡢᑡ࡞࠸㛗ᑑ࿨࡞㟁ụᮦᩱࡢ㛤Ⓨᣦ㔪ࡀᚓࡽࢀࡿ࡜⪃࠼ࡽࢀࡿࠋ

ᅗ 1 LixCoO2㻔x = 0.51㻕ࡢ⢊ᮎ X ⥺ᅇᢡ㻔XRD㻕ࣃࢱ࣮ࣥࠋ࣮ࣜࢺ࣋ࣝࢺゎᯒࡢ⤖ᯝࠊ300 K
࠾ࡼࡧ 250 K ࡢ XRD ࣃࢱ࣮ࣥࡣ⳻㠃యᬗࠊ200 K ௨ୗ࡛ࡣ༢ᩳᬗ࡛ᖐᒓ࡛ࡁࡓࠋ
࡞࠾ LiCoO2 ࡣ㠀໬Ꮫ㔞ㄽ⤌ᡂ㻔Li / Co = 1.05㻕࡛ྜᡂࡉࢀࡓࡶࡢ࡛࠶ࡿࠋ

ᅗ 2 LixCoO2㻔x = 0.51㻕ࡢ᱁Ꮚࣃ࣓࣮ࣛࢱ࣮㻔a㻕aMࠊbMࠊcMࠊ㻔b㻕șMࠊ㻔c㻕aM / bMࠊ㻔d㻕㻌Ǽșࡢ ᗘ౫ᏑᛶࠋǼșࡣ Co䠄O䠅ᒙ㛫ࡢࡎࢀࢆ⾲ࡍࣃ࣓࣮ࣛࢱ࣮࡛࠶ࡾࠊᘧ
㻔1㻕ࡼࡾồࡵࡓࠋ300 K ࠾ࡼࡧ 250 K ࡢ᱁Ꮚᐃᩘࡣࠊ⳻㠃యᬗ࠿ࡽ༢ᩳᬗ࡟㍈ኚ᥮ࡋࡓ࡜ࡁࡢ್࡛࠶ࡿ[7]ࠋཧ⪃ᩥ⊩㸸[1] T .Ohzuku and A .Ueda, J. Electrochem. Soc., 141 㻔1994㻕 2972-2977.
[2] J .N .Reimers and J .R .Dahn, J. Electrochem. Soc., 139 㻔1992㻕 2091-2097.
[3] J .N .Reimers, J .R .Dahn and U .von Sacken, J. Electrochem. Soc., 140 (1993) 2752-2754.
[4] K .Mukai, H .Nozaki, Y .Ikedo, J .Sugiyama, K .Ariyoshi and T .Ohzuku, J. Power Sources, 192 㻔2009㻕
684-688.
[5] S .Levasseur, M .Ménétrier, E .Suard and C .Delmas, Solid State Ionics, 128 㻔2000㻕 11-24.
[6] F .Izumi and K .Monma, Solid State Phenom., 130 㻔2007㻕 15-20.
[7] T .Ohzuku, A .Ueda and M .Nagayama, J. Electrochem. Soc., 140 㻔1993㻕 1862-1870.