JP3621370B2 - Electrode material for secondary battery by plating method - Google Patents

Description

［ここで、Ｒ_１はＣ_１〜Ｃ_５のアルキル基を表し、Ｘ_１は水素、水酸基、アルキル基、アリール基、アルキルアリール基、カルボキシル基、又はスルホン酸基を表し、そしてアルキル基の任意の位置にあってよく、ｎは０〜３の整数である。］
一般式（ＩＩ）
【化９】

［ここで、Ｒ_２はＣ_１〜Ｃ_５のアルキル基又はＣ_１〜Ｃ_３のアルキレン基を表し、アルキレン基の任意の位置に水酸基があってよく、Ｘ_２は塩素又は（及び）フッ素のハロゲンを表し、アルキル基又はアルキレン基の水素と置換された塩素又は（及び）フッ素の置換数は１からアルキル基又はアルキレン基に配位したすべての水素が飽和置換されたものまでを表し、置換されたハロゲン種は１種又は２種であり、塩素又はフッ素の置換基は任意の位置にあってよい。Ｙは水素又はスルホン酸基を表し、Ｙで表されるスルホン酸基の置換数は０から２の範囲にある。］一般式（ＩＩＩ）
【化１０】

［ここで、Ｘ_３は、水酸基、アルキル基、アリール基、アルキルアリール基、アルデヒド基、カルボキシル基、ニトロ基、メルカプト基、スルホン酸基又はアモノ基を表し、或いは２個のＸ３はベンゼン環と一緒になってナフタリン環を形成でき、ｍは０〜３の整数である。］
（参）：少なくとも一つのカルボキシル基を有するとともにさらにカルボキシ
ル基、水酸基、スルホン酸基、アミノ基、チオール基から選ばれる基の１種又は２種以上を一つ以上有する脂肪族カルボン酸のイオンの１種又は２種以上、
が用いられる。
【００１３】
上記縮合燐酸としては、直鎖状のポリリン酸、環状のメタリン酸のいずれもが用いられるが、特に二燐酸（ピロリン酸）が好適に用いられる。
上記スルホン酸として、メタンスルホン酸、メタンジスルホン酸、メタントリスルホン酸、トリフルオロメタンスルホン酸、エタンスルホン酸、プロパンスルホン酸、２−プロパンスルホン酸、ブタンスルホン酸、２−ブタンスルホン酸、ペンタンスルホン酸、ヘキサンスルホン酸、デカンスルホン酸、ドデカンスルホン酸、２−ヒドロキシエタン−１−スルホン酸、１−ヒドロキシプロパン−２−スルホン酸、３−ヒドロキシプロパン−１−スルホン酸、２−ヒドロキシプロパン−１−スルホン酸、２−ヒドロキシブタンスルホン酸、２−ヒドロキシペンタンスルホン酸、２−ヒドロキシヘキサン−１−スルホン酸、２−ヒドロキシデカンスルホン酸、２−ヒドロキシドデカンスルホン酸、１−カルボキシエタンスルホン酸、２−カルボキシエタンスルホン酸、１，３−プロパンジスルホン酸、アリルスルホン酸、２−スルホ酢酸、２−又は３−スルホプロピオン酸、スルホコハク酸、スルホマレイン酸、スルホフマル酸、モノクロロメタンスルホン酸、パークロロエタンスルホン酸、トリクロロジフルオロプロパンスルホン酸、パーフルオロエタンスルホン酸、モノクロロジフルオロメタンスルホン酸、トリフルオロメタンスルホン酸、トリフルオロエタンスルホン酸、テトラクロロプロパンスルホン酸、トリクロロジフルオロエタンスルホン酸、モノクロロエタノールスルホン酸、ジクロロプロパノールスルホン酸、モノクロロジフルオロヒドロキシプロパンスルホン酸、ベンゼンスルホン酸、トルエンスルホン酸、キシレンスルホン酸、ニトロベンゼンスルホン酸、スルホ安息香酸、スルホサリチル酸、ベンズアルデヒドスルホン酸、ｐ−フェノールスルホン酸、フェノール−２，４−ジスルホン酸、２−スルホ酢酸、２−スルホプロピオン酸、３−スルホプロピオン酸、スルホコハク酸、スルホメチルコハク酸、スルホフマル酸、スルホマレイン酸、２−スルホ安息香酸、３−スルホ安息香酸、４−スルホ安息香酸、５−スルホサリチル酸、４−スルホフタール酸、５−スルホイソフタール酸、２−スルホテレフタール酸等が好適に用いられる。
とりわけ、メタンスルホン酸、２−ヒドロキシエタン−１−スルホン酸、２−ヒドロキシプロパン−１−スルホン酸、フェノールスルホン酸、クレゾールスルホン酸又はトリフロロメタンスルホン酸等が特に好適に用いられる。
【００１４】
上記脂肪族カルボン酸として、シュウ酸、マロン酸、コハク酸、グリコール酸、乳酸、酒石酸、クエン酸、タルトロン酸、リンゴ酸、アスコルビン酸、グリシン、アラニン、バリン、ロイシン、イソロイシン、リジン、セリン、スレオニン、フェニルアラニン、アスパラギン酸、グルタミン酸、メチオニン、メルカプトコハク酸、シスチン、スルホコハク酸、エチレンジアミンテトラ酢酸、イミノジ酢酸、ニトリロトリ酢酸、ジエチレントリアミンペンタ酢酸、トリエチレンテトラミンヘキサ酢酸、エチレンジオキシビス（エチルアミン）−Ｎ、Ｎ、Ｎ’、Ｎ’−テトラ酢酸、グリコールエチレンジアミンテトラ酢酸、Ｎ−ヒドロキシエチルエチレンジアミンテトラ酢酸等が好適に用いられる。中でも、スルホコハク酸、グリコール酸、乳酸、酒石酸、クエン酸、エチレンジアミンテトラ酢酸、ニトリロトリ酢酸等がさらに好適に用いられる。
【００１５】
後述するように、本願発明の電極材料を作成するための錫又は錫合金めっき浴には、必須の成分ではないが、多少の４価の錫を含有させる方が望ましい。一方で、該４価の錫は、限度を越えて存在すると悪影響を及ぼすために、限度を越えて４価の錫化合物又はイオンの濃度が増大しないように、また、２価の錫イオンの濃度を一定に保つために、第３の必須の成分として、合計して少なくとも１ｐｐｍ以上の濃度の酸化防止剤の１種又は２種以上の酸化防止剤を含有させることが必要である。特に厳密な上限はないが、通常は５０ｇ／Ｌ以下の濃度で用いられる。さらに好ましくは、５ｍｇ／Ｌ以上、２ｇ／Ｌ以下で用いられ、最も好適には、１０ｍｇ／Ｌ以上、１ｇ／Ｌ以下で用いられる。
【００１６】
前記の酸化防止剤として、具体的には、下記一般式（い）から選ばれる置換又は非置換の芳香族のモノ、ジ又はトリフェノール、又は（ろ）脂肪族ポリヒドロキシ化合物から選ばれるもの１種又は２種以上が単独又は併用して用いられる。一般式（い）
【化１１】

［ ただし、Ｘは水素又は水酸基を表し、同一又は異なっていてよく、ｎは１〜３の整数を表す。Ｘの内少なくとも一つは水酸基である。Ｙは水素、メチル基、エチル基、メトキシ基、エトキシ基、カルボキシル基、スルホン酸基又はアミノ基から選ばれた１種又は２種以上であって、同一又は異なっていてよく、ｍは６−ｎの整数である。Ｘ及びＹのベンゼン環上の結合位置は問わない。ただし、互変異性によって当該構造をとり得る化合物を含む。］
で表される置換又は非置換の芳香族のモノ、ジ又はトリフェノール。
（ろ）脂肪族ポリヒドロキシ化合物。
【００１７】
上記一般式（い）のフェノール類をさらに具体的に例示すれば、ハイドロキノン、カテコール、レゾルシン、ピロガロール、オキシヒドロキノン、フロログリシン、没食子酸、カテコールスルホン酸、グアヤコール、ハイドロキノンスルホン酸、３，４−ジヒドロキシ安息香酸、３，４，５−トリヒドロキシ安息香酸、ｐ−フェノールスルホン酸、クレゾールスルホン酸、ハイドロキノンスルホン酸、β−ナフトール等から選ばれる１種又は２種以上が特に好適に用いられる。
（ろ）の脂肪族ポリヒドロキシ化合物としては、ソルビン酸、ソルビトール、ブドー糖、アスコルビン酸、イソアスコルビン酸等が好適に用いられる。
【００１８】
上記のめっき浴には、めっき粒子の微細化とめっき浴の安定性の向上のために、第４の必須成分として０．５ｇ／Ｌ以上、２００ｇ／Ｌ以下の濃度で、炭素数が６以下の脂肪族ケトン又は炭素数が６以下の脂肪族の分岐又は非分岐のアルコールの１種又は２種以上が用いられる。さらに好適には、１ｇ／Ｌ以上２００ｇ／Ｌ以下の濃度が用いられる。
他の添加剤の濃度等にも依存するので、絶対的な濃度は限定できないが、アルコール濃度が濃くなり過ぎるとかえって浴の安定化効果に悪影響があり、特に３００ｇ／Ｌを越えるとこの影響が大きい。そのため、脂肪族アルコール又はケトンの上限の濃度は２００ｇ／Ｌ以下に厳密に規定される。また、濃度が高い場合には臭気が著しくなり作業環境上からも好ましくない。
【００１９】
前記炭素数が６以下の脂肪族の分岐又は非分岐のアルコールとして、下記一般式（イ）〜（ハ）で表されるアルコールが用いられる。
一般式（イ）
【化１２】

［ ただし、ｎはｍより大きく６以下の整数であり、ｍは１又は２の整数を表す。Ｘは水素又は水酸基であって、同一又は異なっていてよく、Ｘの内少なくとも一つは水酸基である。Ｘが結合する炭素の位置は問わず、炭素鎖は直鎖であっても分岐していてもよい。］
で表される鎖状の飽和脂肪族のモノ又はジアルコール。
一般式（ロ）
【化１３】

［ ただし、ｎはｍより大きく６以下の整数であり、ｍは１又は２の整数を表す。Ｘは水素又は水酸基であって、同一又は異なっていてよく、Ｘの内少なくとも一つは水酸基である。Ｘが結合する炭素の位置は問わず、炭素鎖は分岐していてもよい。］
で表される環状の飽和脂肪族のモノ又はジアルコール。
一般式（ハ）
【化１４】

［ ただし、ｎはｍより大きく６以下の整数であり、ｍは１又は２の整数を表す。ｌはｎ−２以下の整数を表す。Ｘは水素又は水酸基であって、同一又は異なっていてよく、Ｘの内少なくとも一つは水酸基である。Ｘが結合する炭素の位置は問わず、炭素鎖は分岐していてもよい。Ｏはエーテル性の酸素を表し、２つの炭素の間にあるが、その位置は問わない。］
で表されるエーテル結合を有した鎖状の飽和脂肪族のモノ又はジアルコール。
【００２０】
上記炭素数が６以下の脂肪族ケトン又は炭素数が６以下の脂肪族の分岐又は非分岐のアルコールをさらに具体的に例示すれば、メタノール、エタノール、（ｎ−及びｉ−）プロパノール、（ｎ−、ｉ−及びｔ−）ブタノール、１，２，６−ヘキサントリオール、チオジグリコール、ペンタンジオール、ヘキサンジオール、１，３−プロパンジオール、１，４−ブタンジオール、エチレングリコール、プロピレングリコール、アセトン、メチルエチルケトン等から選ばれる１種又は２種以上が好適に用いられ、さらに好適にはｉ−プロパノール、アセトンが用いられ、最も好適にはｉ−プロパノールが用いられる。
【００２１】
本願の二次電池用電極材料のめっき皮膜を析出させるための錫又は錫合金めっき浴には、微細な結晶の粒子のめっき皮膜を得るために、第５の必須の成分として、有機添加剤の１種又は２種以上が含有させられる。有機添加剤には、界面活性剤、平滑化添加剤、半光沢剤又は光沢剤等が含まれる。
一般には０．００１ｇ／Ｌ〜５０ｇ／Ｌの範囲で好適に用いられるが、化合物の種類や組み合わせによって用いられる濃度は適宜変更する。
【００２２】
界面活性剤としては、公知の界面活性剤を用いることができ、ノニオン系、アニオン系、両性系、カチオン系のいずれの界面活性剤も好適に用いられ、適宜単独又は混合して用いられるが、ノニオン系、アニオン系、両性系が一層好適に用いられる。
【００２３】
好適に用いられるノニオン系界面活性剤を例示すれば、ポリオキシアルキレンアルキルエーテル（又はエステル）、ポリオキシアルキレンフェニル（又はアルキルフェニル）エーテル、ポリオキシアルキレンナフチル（又はアルキルナフトチル）エーテル、ポリオキシアルキレンスチレン化フェニルエーテル（又は該フェニル基にさらにポリオキシアルキレン鎖を付加した）、ポリオキシアルキレンビスフェノールエーテル系、ポリオキシエチレンポリオキシプロピレンブロックポリマー、ポリオキシアルキレンソルビタン脂肪酸エステル、ポリオキシアルキレンソルビット脂肪酸エステル、ポリエチレングリコール脂肪酸エステル、ポリオキシアルキレングリセリン脂肪酸エステル、ポリオキシアルキレンアルキルアミン、エチレンジアミンのポリオキシアルキレン縮合物付加物、ポリオキシアルキレン脂肪酸アミド、ポリオキシアルキレンヒマシ（又は／及び硬化ヒマシ油）油、ポリオキシアルキレンアルキルフェニルホルマリン縮合物、グリセリン（又はポリグリセリン）脂肪酸エステル系界面活性剤、ペンタエリスリトール脂肪酸エステル、ソルビタンモノ（セスキ、トリ）脂肪酸エステル系界面活性剤、高級脂肪酸モノ（ジ）エタノールアミド、アルキル・アルキロードアミド、オキシエチレンアルキルアミン等を挙げることができる。
【００２４】
好適に用いられるアニオン系界面活性剤を例示すれば、アルキル（又はホルマリン縮合物）−β−ナフタレンスルホン酸（又はその塩）、脂肪酸セッケン、アルキルスルホン酸塩系、α−オレフィンスルホン酸塩、アルキルベンゼンスルホン酸塩、アルキル（又はアルコキシ）ナフタレンスルホン酸塩、アルキルジフェニルエーテルジスルホン酸塩、アルキルエーテルスルホン酸塩、アルキル硫酸エステル塩、ポリオキシエチレンアルキルエーテル硫酸エステル塩、ポリオキシエチレンアルキルフェノールエーテル硫酸エステル酸塩、高級アルコールリン酸モノエステル塩、ポリオキシアルキレンアルキルエーテルリン酸（塩）、ポリオキシアルキレンアルキルフェニルエーテルリン酸塩、ポリオキシアルキレンフェニルエーテルリン酸塩、ポリオキシエチレンアルキルエーテル酢酸塩、アルキロイルザルコシン、アルキロイルザルコシネート、アルキロイルメチルアラニン塩、Ｎアシルスルホカルボン酸塩、アルキルスルホ酢酸塩、アシルメチルタウリン酸ナトリウム、アルキル脂肪酸グリセリン硫酸エステル塩、硬化ヤシ油脂肪酸グリセリル硫酸ナトリウム、アルキルスルホカルボン酸エステル塩系、アルキルスルホコハク酸塩、ジアルキルスルホコハク酸塩、アルキルポリオキシエチレンスルホコハク酸、スルホコハク酸モノオレイルアミドナトリウム塩（又はアンモニウム、ＴＥＡ塩）等を挙げることができる。
【００２５】
好適に用いられる両性系界面活性剤を例示すれば、２−アルキル−Ｎ−カルボキシメチル（又はエチル）−Ｎ−ヒドロキシエチル（又はメチル）イミダゾリニウムベタイン、２−アルキル−Ｎ−カルボキシメチル（又はエチル）−Ｎ−カルボキシメチルオキシエチルイミダゾリニウムベタイン、ジメチルアルキルベタイン、Ｎ−アルキル−β−アミノプロピオン酸（又はそのナトリウム塩）、アルキル（ポリ）アミノエチルグリシン、Ｎ−アルキル−Ｎ−メチル−β−アラニン（又はそのナトリウム塩）、脂肪酸アミドプロピルジメチルアミノ酢酸ベタイン等を挙げることができる。
【００２６】
好適な界面活性剤としては、カチオン系界面活性剤には、テトラ低級アルキルアンモニウムハライド、アルキルトリメチルアンモニウムハライド、ヒドロキシエチルアルキルイミダゾリン、ポリオキシエチレンアルキルメチルアンモニウムハライド、アルキルベンザルコニウムハライド、ジアルキルジメチルアンモニウムハライド、アルキルジメチルベンジルアンモニウムハライド、アルキルアミン塩酸塩、アルキルアミン酢酸塩、アルキルアミンオレイン酸塩、アルキルアミノエチルグリシン、アルキルピリジニウムハライド系等が含まれる。
【００２７】
平滑化添加剤、半光沢剤又は光沢剤も公知のものを用いることができる。具体的に例を示すと、下記のような化合物が単独又は併用して用いられる。
さらに、本発明の二次電池用電極材料の作成に用いられる錫又は錫合金めっき浴において使用することができる平滑化剤、半光沢剤、光沢剤等の添加剤には錫又は錫合金めっきにおいて用いられている公知の物質が利用できるが、その中で特に効果のあるものの例としては、高分子化合物、スルファニル酸及びその誘導体並びにその塩、キノリン類、トリアゾール及びその誘導体、ベンゾチアゾール及びその誘導体、イミン類、トリアジン類、グアナミン類、芳香族オキシカルボン酸のエステル類、Ｃ＝Ｏと共役の位置に二重結合を有する化合物類、アルデヒド類、ジケトン類、アニリン及びその誘導体、ニトロ化合物又はそのナトリウム、カリウム又はアンモニウム塩類、メルカプトカルボン酸類、複素環式化合物類、アセトフェノン類、アミンアルコール類、脂肪族一級又は二級アミンとアルデヒドの縮合物等その他を挙げることができる。
これらの化合物は、単独又は適宜混合添加して使用できる。使用量は、下記の高分子物質を用いる場合は０．５〜５０ｇ／Ｌが適当であり、好ましくは１〜２０ｇ／Ｌである。その他の添加剤に対しては、０．００１〜５０ｇ／Ｌが適当であり、さらに好適には０．０２〜２０ｇ／Ｌが添加される。
【００２８】
高分子物質の一例として、ゼラチン、ペプトン、ポリエチレングリコール、ポリアクリルアミド、ポリエチレンイミン、ポリビニルピロリドン等が挙げられる。スルファニル酸誘導体およびその塩の一例として、Ｎ−ブチリデンスルファニル酸、Ｎ−（３−ヒドロキシブチリデン）−ｐ−スルファニル酸、アルドール等が挙げられる。キノリン類の一例として、８−ヒドロキシキノリンに５モルの酸化プロピレンを付加した生成物等が挙げられる。トリアゾール及びその誘導体の一例として、ベンゾトリアゾール、４−メチルベンゾトリアゾール、４−ヒドロキシベンゾトリアゾール、４−カルボキシベンゾトリアゾール等が挙げられる。ベンゾチアゾール及びその誘導体の一例として、ベンゾチアゾール、２−メチルベンゾチアゾール、２−メルカプトベンゾチアゾール、２−アミノ−４−クロロベンゾチアゾール、２−アミノ−６−メトキシベンゾチアゾール、２−ヒドロキシベンゾチアゾール、２−クロロベンゾチアゾール、２−メチル−５−クロロベンゾチアゾール、２，５−ジメチルベンゾチアゾール、５−ヒドロキシ−２−メチルベンゾチアゾール、６−クロロ−２−メチル−４−メトキシベンゾチアゾール、２−（ｎ−ブチル）メルカプト−６−アミノベンゾチアゾール、２−ベンゾチアゾールチオ酢酸、２−ベンゾチアゾールオキシ酢酸、６−エトキシ−２−メルカプトベンゾチアゾール等が挙げられる。イミン類の一例として、Ｎ、Ｎ’ジイソ−ブチリデン−ｏ−フェニレンジアミン等が挙げられる。トリアジン類の一例として、２，４−ジアミノ−６−［２’−メチルイミダゾリル（１’）エチル−１，３，５−トリアジン、２，４−ジアミノ−６−［２’−エチルイミダゾリル（１’）エチル−１，３，５−トリアジン、２，４−ジアミノ−６−［２’−ウンデシルイミダゾリル（１’）エチル−１，３，５−トリアジン等が挙げられる。グアナミン類の一例として、β−Ｎ−ドデシルアミノプロピオグアナミン、β−Ｎ−ヘキシルアミノプロピオグアナミン、ピペリジンプロピオグアナミン、シクロヘキシルアミノプロピオグアナミン、モルホリンプロピオグアナミン、β−Ｎ−（２−エチルヘキシロキシプロピルアミノ）プロピオグアナミン、β−Ｎ−（ラウリルオキシプロピルアミノ）プロピオグアナミン等が挙げられる。芳香族オキシカルボン酸のエステル類の一例として、ｏ−（又はｍ−又はｐ−）安息香酸メチル、サリチル酸フェニル等が挙げられる。Ｃ＝Ｏと共役の位置に二重結合を有する化合物の一例として、イタコン酸、プロピレン−１，３−ジカルボン酸、アクリル酸、クロトン酸、桂皮酸、アクリル酸メチル、アクリル酸エチル、メタクリル酸、メタクリル酸メチル、メタクリル酸ブチル、エタクリル酸、アクリルアミド、ジアセトンアクリルアミド、ｔ−ブチルアクリルアミド、Ｎ−メトキシジメチルアクリルアミド、クルクミン（１，７−ビス（４−ヒドロキシ−３−メトキシフェラル）−１，６−ヘプタジエン−３，５−ジオン）、イソホロン（３，５，５−トリメチル−２−シクロヘキセノン）、メシチルオキシド、ビニルフェニルケトン、フェニルプロペニルケトン、フェニルイソブテニルケトン、フェニル−１−メチルプロペニルケトン、ベンジリデンアセトフェノン（ｃｈａｌｃｏｎｅ）、２−（ω−ベンゾイル）ビニルフラン、ｐ−フロロフェニルプロペニルケトン、ｐ−クロロフェニルプロペニルケトン、ｐ−ヒドロキシフェニルプロペニルケトン、ｍ−ニトロフェニルプロペニルケトン、ｐ−メチルフェニルプロペニルケトン、２，４，６−トリメチルフェニルプロペニルケトン、ｐ−メトキシフェニルプロペニルケトン、ｐ−メトキシフェニルブテニルケトン、ｐ−メチルチオフェニルプロペニルケトン、ｐ−イソブチルフェニルプロペニルケトン、α−ナフチル−１−メチルプロペニルケトン、４−メトキシナフチルプロペニルケトン、２−チエニルプロペニルケトン、２−フリルプロペニルケトン、１−メチルピロールプロペニルケトン、ベンジリデンメチルエチルケトン、ベンジリデンアセトンアルコール、ｐ−トルイデンアセトン、アニザルアセトン（アニシリデンアセトン）、ｐ−ヒドロキシベンジリデンアセトン、ベンジリデンメチルイソブチルケトン、３−クロロベンジリデンアセトン、ベンザルアセトン（ベンジリデンアセトン）、ベンジリデンアセチルアセトン、４−（１−ナフチル）−３−ブテン−２−オン、ピリジデンアセトン、フルフリジンアセトン、４−（２−チオフェニル）−３−ブテン−２−オン、４−（２−フリル）−３−ブテン−２−オン、アクロレイン（アクリルアルデヒド、プロペナール）、アリルアルデヒド、クロトンアルデヒド、シンナムアルデヒド、ベンジルクロトンアルデヒド、テニリデンアセトン等が挙げられる。アルデヒド類の一例として、ホルムアルデヒド、アセトアルデヒド、プロピオンアルデヒド、ｎ−ブチルアルデヒド、イソブチルアルデヒド、ｎ−バレルアルデヒド（バレラール、ペンタナール）、イソバレルアルデヒド、ｎ−カプロンアルデヒド（ヘキサナール、ヘキシルアルデヒド）、スクシンアルデヒド（スクシンジアルデヒド）、グルタルアルデヒド（１，５−ペンタンジアール、グルタルジアルデヒド）、アルドール（３−ヒドロキシブチルアルデヒド、アセトアルドール）、クロトンアルデヒド、桂皮アルデヒド、プロパギルアルデヒド、ベンズアルデヒド、ｏ−フタルアルデヒド、サリチルアルデヒド（ｏ−ヒドロキシベンズアルデヒド）、ｐ−ヒドロキシベンズアルデヒド、ｐ−ニトロベンズアルデヒド、ｏ−（又はｐ−）メトキシベンズアルデヒド（アニスアルデヒド）、３−メトキシベンズアルデヒド、バニリン、ｏ−バニリン、ベラトルアルデヒド（３，４−ジメトキシベンズアルデヒド）、２，５−ジメトキシベンズアルデヒド、（２，４−、２，６−）ジクロロベンズアルデヒド、１−（又は２−）ナフトアルデヒド、２−（又は４−）クロロ−１−ナフトアルデヒド、２−（又は４−）ヒドロキシ−１−ナフトアルデヒド、５（又は２）−メトキシナフトアルデヒド、２−フルアルデヒド（２−フルアルデヒド＝フルフラール）、３−フルアルデヒド、２（３）−チオフェンカルボキシアルデヒド、ピコリンアルデヒド、３−アセナフトアルデヒド、３−インドールカルボキシアルデヒド等が挙げられる。ジケトン類の一例として、グリオキサール（エタンジアール、オキサルアルデヒド、ジホルミル、ビホルミル）、ジアセチル（ビアセチル、ジメチルグリオキサール、ブタンジオン）、ヘキサンジオン−３，４、アセチルアセトン（２，４−ペンタンジオン）、ヘキサンジオン−３，４−アセチルアセトン等が挙げられる。アニリン誘導体の一例として、アニリン、ｏ−（又はｍ−又はｐ−）トルイジン、ｏ−（又はｐ−）アミノアニリン、ｏ−（又はｐ−）クロルアニリン、２，５−（又は３，４−）クロルメチルアニリン、Ｎ−モノメチルアニリン、４，４’ジアミノジフェニルメタン、Ｎ−フェニル−（α−又はβ−）ナフチルアミン、ジチゾン等が挙げられる。ニトロ化合物又はそのナトリウム、カリウム又はアンモニウム塩類の一例として、ｐ−ニトロフェノール、ニトロベンゼンスルホン酸、２，４−ジニトロベンゼンスルホン酸、ｍ−ニトロ安息香酸等が挙げられる。メルカプトカルボン酸類の一例として、メルカプト酢酸（チオグリコール酸）、メルカプトコハク酸等が挙げられる。複素環式化合物類の一例として、１，１０−フェナントロリン、２−ビニルピリジン、キノリン、インドール、イミダゾール、２−メルカプトベンゾイミダゾール、１，２，３−（又は１，２，４−又は１，３，５−）トリアジン、１，２，３−ベンゾトリアジン、２−メルカプトベンゾオキサゾール、２−シンナミルチオフェン等が挙げられる。アセトフェノン及びハロゲン化アセトフェノン。アミンアルコール類の一例として、トリエタノールアミン、ジエタノールアミン、モノエタノールアミン、Ｎ−メチルエタノールアミン縮合物等が挙げられる。脂肪族一級又は二級アミンとアルデヒドの縮合物の一例として、アミン−アルデヒド縮合物、例えば、ピペラジン、ビペリジン、モルホリン、シクロプロピルアミン、シクロヘキシルアミン、シクロオクチルアミン、エチレンジアミン、モノエタノールアミン、ジエタノールアミン、などの脂肪族第一若しくは第二アミン類又は芳香族アミン類と前記アルデヒド類との縮合物等が挙げられる。
【００２９】
本願の二次電池用電極材料のめっき皮膜を析出させるための錫又は錫合金めっき浴には、さらに０．１ｇ／Ｌ以上２０ｇ／Ｌ以下の４価の錫イオン又は化合物を含有させることが好ましい。さらに好ましくは、０．１ｇ／Ｌ以上１０ｇ／Ｌ以下の濃度を含有させる。
２価の錫イオンからの錫又は錫合金めっきにおいて、４価の錫イオンは直接には錫の析出に関与しないはずであるが、本願発明者らの検討によると、浴種によってその濃度範囲は必ずしも厳密に一定ではないが、２０ｇ／Ｌを越えるような濃度においては確かにめっき皮膜の均一性を阻害し、悪影響を及ぼすけれども、０．１ｇ／Ｌ〜１０ｇ／Ｌの濃度領域においては、結晶の微細化に寄与し、リチウム電池の電極としてむしろサイクル特性の良好なめっき皮膜を与えることを見出した。
該４価の錫化合物又はイオンは、空気攪拌等の強制的方法又は予備電解等によって、浴中の２価の錫イオンを酸化させることによって浴中に含有させることもできるし、或いは錫酸塩、４塩化錫等の化合物を添加することによっても浴中に含有させることができる。
４価の錫の濃度は、ＩＣＰ分析又は原子吸光分析によって全錫の濃度を測定し、酸化還元滴定法によって得られた２価錫の分析値を差し引くことによって分析・管理することができる。全錫の濃度は、機器分析が利用できない場合には、酸性条件下で金属アルミニウムを溶解させ４価の錫を２価に還元したのち、酸化還元滴定法によって分析することもできる。
【００３０】
本願の二次電池用電極材料のめっき皮膜を析出させるための錫又は錫合金めっき浴には、放電容量及び（又は）サイクル特性を一層向上させるために、さらに原子番号が２６〜３３、錫を除く４４〜５１又は水銀を除く７５〜８２から選ばれる合金化金属の１種又は２種以上を含有させることができる。
現時点では、電極特性を向上させるメカニズムは十分には解明されていないけ
れども、電気めっきにおいて異種金属を含有させた際には結晶が微細化することが知られているので、そのような結晶の微細化が充放電特性をさらに向上させるものと想像される。
上記原子番号によって示した合金化金属は、具体的に例示すれば、鉄、コバルト、ニッケル、亜鉛、ガリウム、ゲルマニウム、砒素、ルテニウム、ロジウム、パラジウム、銀、カドミウム、インジウム、アンチモン、オスミウム、イリジウム、白金、金、水銀、タリウム、鉛、ビスマスである。この内、鉄、コバルト、ニッケル、銅、亜鉛、ガリウム、ゲルマニウム、砒素、銀、カドミウム、インジウム、アンチモン、タリウム、鉛、ビスマスは一層好適に用いられる。
これらの合金化金属は、めっき浴中での含有量が、錫に対して合計して２０ｐｐｍ以上で結晶粒子の微細化に効果を示す。さらに好適には錫に対して０．５％以上を含有させて用いられる。
めっき皮膜中の錫以外の金属成分が何％以上であれば錫合金めっきであり、
何％以下であれば錫（単独）めっきであるとされるのかは明確な定義はない。本願に於いては便宜上、ＥＰＭＡ、Ｘ線回折等の非破壊的な方法あるいは、ＩＣＰ、原子吸光等の破壊的方法のいずれでもよいが、汎用の測定装置によって検出可能な量の錫以外の元素を含む場合を全て錫合金めっき皮膜、それ以下のものを錫（単独）めっき皮膜と定義することにする。
上記金属の内、水銀を除くＩＩＢ、ＩＩＩＢ、ＩＶＢ、ＶＢ族の金属は特に効果を示し
、該金属の１種又は２種以上を合計して錫に対して２０ｐｐｍ以上含有する錫合金めっき皮膜は、良好な充放電特性を示す。ここで、ＩＩＢ、ＩＩＩＢ、ＩＶＢ、ＶＢ族なる表現は、ＩＵＰＡＣの周期律表によるものであり、具体的には、亜鉛、ガリウム、ゲルマニウム、砒素、カドミウム、インジウム、アンチモン、タリウム、鉛、ビスマスである。これらの中でも特に鉛、アンチモン、砒素、カドミウムが一層好適に用いられる。
【００３１】
本願発明の微細結晶の錫又は錫合金めっき皮膜である電極材料は、単位重量及び単位体積当りのエネルギー密度が、現在主流となっている炭素材料の負極に比べて極めて高いので、負極の厚さを現在の炭素材料を使用した場合よりも薄くすることが可能である。特に例えばマイクロ電池等の極めて小さい電池用には０．０１μｍ以上５μｍ未満の厚さで好適に用いられる。通常のボタン電池以上のサイズの電池にはさらに厚い５μｍ以上５００μｍ以下のめっき皮膜も好適に用いることができる。
【００３２】
錫又は錫合金を負極として用いた場合に、充放電によって膨張・収縮が生じるので、錫又は錫合金は密度が高いものではなく、ある程度の空隙があった方がよいと従来考えられていた。しかし、発明者らは本願発明の研究によって、むしろ、通常の溶融して調製した錫に近い密度の錫又は錫合金めっき皮膜を用いることが良好な充放電サイクル特性が得られることを見出した。即ち、二次電池用電極としての錫又は錫合金めっき皮膜の密度は、６．６ｇ／ｃｍ^３を超え、８．５ｇ／ｃｍ^３以下のものが好適に用いられる。
【００３３】
上述した理由によって、錫又は錫合金めっきは密度をことさらに低くする必要はなく、従って該皮膜中の有機物吸蔵量は、概ね１０％を超えないことが望ましい。即ち、炭素の量に換算して０．０００１％から１０％の範囲に維持することによって好適に電池用電極材料を製造することができる。このことによって、錫又は錫合金めっき皮膜の密度を上述の６．６ｇ／ｃｍ^３を超える値に保つことができる。
【００３４】
錫又は錫合金めっき浴からめっき皮膜を析出させる工程においては、意図しない金属成分がめっき浴に蓄積してめっき皮膜中に析出しないように、陽極として、（ａ）不溶性陽極、（ｂ）３Ｎ以上の純度の錫の陽極、又は（ｃ）３Ｎ以上の純度の錫と３Ｎ以上の純度の前記合金化金属を溶融して作成された錫合金陽極の１種又は２種以上を用いてめっきを行うめっき方法が好適に用いられる。
不純物の混入を防ぐ意味からは、不溶性陽極が好ましいが、陽極表面での酸化反応によって浴の劣化をきたす場合があるので、（ｂ）又は（ｃ）がさらに好適に用いられる。
長期間にわたって安定した電極特性を有する錫又は錫合金めっき皮膜を得るためには、特に好適には、４Ｎ以上の純度の錫の陽極若しくは合金化金属の１種又は２種以上と４Ｎ以上の純度の錫とを溶融して調製した錫合金陽極の１種又は２種以上を用いて錫又は錫合金めっきを行う方法が用いられる。
【００３５】
本願の錫又は錫合金のめっき浴からめっき皮膜を析出させて二次電池用電極材料を製造するにあたっては、０．１Ａ／ｄｍ^２以上１００Ａ／ｄｍ^２以下の陰極電流密度が好適に用いられる。さらに好適には、５Ａ／ｄｍ^２を超え１００Ａ／ｄｍ^２以下の陰極電流密度が用いられる。特に連続めっき方法においてめっきを実施する場合には、５Ａ／ｄｍ^２を超える電流密度が好適に用いられる。
【００３６】
また、それらのめっきを施すにあたっては、めっきを行うに先立って電解脱脂、酸洗又は活性化から選ばれる処理の１種又は２種以上が好適に用いられる。
さらに、それらに錫又は錫合金めっきを行った後には、経時変化防止処理を用いることができる。該経時変化防止処理としては、リン酸塩処理が好適に用いられる。
【００３７】
また、錫又は錫合金めっき浴からめっき皮膜を析出させる工程においては、酸、錯化剤、錫塩、酸化防止剤又は合金化金属の塩の１種又は２種以上を予め溶解した水溶液をめっき浴の建浴又は（及び）成分補給に用いるめっき浴の建浴方法又は（及び）濃度管理法が好適に用いられる。
【００３８】
二次電池用電極に用いられる錫又は錫合金めっき皮膜は、極めて厳密に特性の管理がなされる必要があり、一般のめっきに比べて格段に厳重な管理が必要である。濃度管理を容易にするには、めっき浴への各成分の補給を成分原体で行うよりも、予め想定された濃度に調整して溶液とされた形のものを補給することによって、より容易に実施できる。このため、本願発明のめっき皮膜を用いた電極の作成には、酸、錯化剤、錫塩、酸化防止剤又は合金化金属の塩などを予め溶解した溶液を調製しておき、補給する方法が用いられる。特に、合金化金属の濃度管理においては、該金属をする陽極をめっき浴に配置し、電解の進行とともに該金属を溶解させて行う方法を用いることもできるが、厳密に濃度を一定に保つためには、むしろ陽極以外から行う方法即ち、該金属元素の可溶性塩又は可溶性錯体を予め溶解した溶液をめっき浴に適宜添加する方法が一層好適に用いられる。
【００３９】
また、本願発明の、錫又は（及び）錫合金めっき浴からめっき皮膜を析出させる工程におけるめっき浴の第３の必須成分である酸化防止剤又は（及び）第５の必須成分である有機添加剤についても、第４の必須成分である炭素数が６以下の脂肪族ケトン又は炭素数が６以下の脂肪族の分岐又は非分岐のアルコールに予め決められた濃度に溶解させておいた溶液を添加することによる管理方法が好適に用いられる。
【００４０】
板状体に、前記の錫又は錫合金のめっき或いは下地の銅、銅合金、ニッケル又はニッケル合金のめっきを施すには、公知の方法即ちバレルめっき法、ラックめっき法、連続めっき法が好適に用いられるが、中でも連続めっき法が一層好適に用いられる。連続めっき法とは、ロール状に巻いた該板状体を連続的に解きながら前後処理を含んだめっきラインに供給し、かつ、巻き取っていくめっき方法を言う。
【００４１】
本発明の二次電池用電極の集電体には、金属の種類としては、銅、ニッケル又は鉄が好適に用いられる。銅、ニッケル又は鉄には、通常工業的に用いられるＪＩＳ等に定められたそれらの公知の合金及びめっきによってそれらの金属を被覆したものが含まれる。
【００４２】
上記集電体には、通常のめっき技術に従って銅又はニッケルの下地めっきを施してもよい。めっき液の成分によっては、めっき液に集電体が浸漬された際に集電体上に置換析出が生じる場合があり、これを防止するためには銅又はニッケルの下地めっきを施すことが推奨される。
【００４３】
本発明の二次電池用電極の集電体としては、通常二次電池に用いられる形状の集電体は全て用いられるが、一般的には板状の形状のものが用いられる。板状体という表現の中には、単に平面的な板状のものの他に、シート状の多孔体、発泡体、スクリーン、ネット、エクスパンド体、パンチング体、不織布又は焼結体などマクロに見て板状の形状を示すものが含まれる。
【００４４】
本願発明の錫又は（及び）錫合金めっき皮膜から構成された二次電池用電極材料は、特にリチウム電池用の電極、特に負極材料として好適に用いられる。
【００４５】
【実施例】
以下、実施例に基づき、本発明を詳細に説明するが、本発明はこれらの実施例に限定されるものではなく、請求項に記載の範囲で適宜変更できる。
【００４６】
実施例１
負極集電体として銅箔を用い、アルカリ電解脱脂液中で１Ａ／ｄｍ^２、１分間の電解脱脂を行い、水洗後、５％メタンスルホン酸水溶液に３０秒間浸漬し活性化した。それを水洗後、下記めっき液（ａ）：

に浸漬し、４Ｎ純度の錫陽極を用い、電流密度８Ａ／ｄｍ^２でめっきを行い、２μｍ厚さのめっき皮膜を得た。
めっき後、走査型電子顕微鏡によって拡大倍率５０００倍で観察した結果めっき粒子の境界は識別できなかった。
別に１０ｃｍ四方の試料に同じ条件で厚付けしためっき皮膜の厚さを、断面の顕微鏡観察から得られた平均膜厚を用いて計算しためっき皮膜の体積と、めっき前後の重量差から計算した皮膜重量から密度を求めたところ７．３であった。
【００４７】
比較例１
めっき液を下記（ｂ）：
めっき液（ｂ）
硫酸第一錫 ４０ｇ／Ｌ
硫酸 ６０ｇ／Ｌ
ゼラチン ２ｇ／Ｌ
に替え、めっき時の陰極電流密度を１Ａ／ｄｍ^２とした以外は実施例１と同じ操作を行って２μｍ厚さのめっき皮膜を得た。
めっき後、走査型電子顕微鏡によって拡大倍率３０００倍で観察した結果めっき粒子の境界は明瞭に識別でき、平均粒径は約２５μｍであった。
【００４８】
実施例２
めっき液を下記（ｃ）：

に替えた以外は、実施例１と同じ操作を行って２μｍ厚さのめっき皮膜を得た。めっき後、走査型電子顕微鏡によって拡大倍率５０００倍で観察した結果めっき粒子の境界は識別できなかった。
別に１０ｃｍ四方の試料に同じ条件で厚付けしためっき皮膜の厚さを、断面の顕微鏡観察から得られた平均膜厚を用いて計算しためっき皮膜の体積と、めっき前後の重量差から計算した皮膜重量から密度を求めたところ７．３であった。
【００４９】
実施例３
めっき液を下記（ｄ）：

に替えた以外は、実施例１及び２と同じ操作を行って２μｍ厚さのめっき皮膜を得た。
めっき後、走査型電子顕微鏡によって拡大倍率５０００倍で観察した結果めっき粒子の境界は識別できなかった。
別に１０ｃｍ四方の試料に同じ条件で厚付けしためっき皮膜の厚さを、断面の顕微鏡観察から得られた平均膜厚を用いて計算しためっき皮膜の体積と、めっき前後の重量差から計算した皮膜重量から密度を求めたところ７．３であった。
【００５０】
実施例４
めっき液を下記（ｅ）：

に替えた以外は、実施例１，２及び３と同じ操作を行って２μｍ厚さのめっき皮膜を得た。
めっき後、走査型電子顕微鏡によって拡大倍率５０００倍で観察した結果めっき粒子の境界は識別できなかった。
【００５１】
実施例５
負極集電体として銅箔を用い、アルカリ電解脱脂液中で１Ａ／ｄｍ^２、１分間の電解脱脂を行い、水洗後、５％メタンスルホン酸水溶液に３０秒間浸漬し活性化した。それを水洗後、下記めっき液（ｆ）：

に浸漬し、白金めっきチタンの不溶性陽極を用い、電流密度６Ａ／ｄｍ^２でめっきを行い、２μｍ厚さのめっき皮膜を得た。
めっき後、走査型電子顕微鏡によって拡大倍率３０００倍で観察した結果めっき粒子の境界は識別できなかった。
別に１０ｃｍ四方の試料に同じ条件で厚付けしためっき皮膜の厚さを、断面の顕微鏡観察から得られた平均膜厚を用いて計算しためっき皮膜の体積と、めっき前後の重量差から計算した皮膜重量から密度を求めたところ７．３であった。
【００５２】
比較例２
めっき液を下記めっき液（ｇ）：
めっき液（ｇ）
ピロリン酸カリウム １７８ｇ／ｌ
ヨウ化カリウム ３３２ｇ／ｌ
塩化第一錫（２価錫として） ２３ｇ／Ｌ
ヨウ化銀（銀として） ０．５ｇ／Ｌ
ｐＨ（ＫＯＨで調整） ８．９
に替え、めっき時の陰極電流密度を１Ａ／ｄｍ^２とした以外は実施例１と同じ操作を行って２μｍ厚さのめっき皮膜を得た。
めっき後、走査型電子顕微鏡によって拡大倍率３０００倍で観察した結果めっき粒子の境界は明瞭に識別でき、径約２μｍ程度の粒子と火山状に穴の開いた連山状に連なる１μｍ程度の粒子が共存していた。
【００５３】
実施例６
負極集電体として銅箔を用い、アルカリ電解脱脂液中で１Ａ／ｄｍ^２、１分間の電解脱脂を行い、水洗後、５％メタンスルホン酸水溶液に３０秒間浸漬し活性化した。それを水洗後、常法にしたがいワット浴から３μｍのニッケル下地めっきを施した後水洗し、下記めっき液（ｈ）：
めっき液（ｈ）
スルホコハク錫（２価錫として） ４０ｇ／Ｌ
スルホコハク酸亜鉛（亜鉛として） １０ｇ／Ｌ
スルホコハク酸鉛（鉛として） ５ｍｇ／Ｌ
硫酸カドミウム（カドミウムとして） １０ｍｇ／Ｌ
亜砒酸（砒素として） ５ｍｇ／Ｌ
スルホコハク酸 １００ｇ／Ｌ
グルコン酸ナトリウム ２０ｇ／Ｌ
ヒドロキノン ８ｇ／Ｌ
エタノール １０ｇ／Ｌ
界面活性剤（アルキロイルザルコシネート） １ｇ／Ｌ
に浸漬し、４Ｎ純度の錫と亜鉛を溶融して合金化した陽極を用い、電流密度２０Ａ／ｄｍ^２でめっきを行い、２μｍ厚さのめっき皮膜を得た。
めっき後、走査型電子顕微鏡によって拡大倍率５０００倍で観察した結果めっき粒子の境界は識別できなかった。
【００５４】
実施例７
負極集電体として銅ネットを用い、アルカリ電解脱脂液中で１Ａ／ｄｍ^２、１分間の電解脱脂を行い、水洗後、５％メタンスルホン酸水溶液に３０秒間浸漬し活性化した。それを水洗後、下記めっき液（ｉ）：
めっき液（ｉ）
メタンスルホン酸錫（２価錫として） ３０ｇ／ｌ
スルファミン酸インジウム（インジウムとして）２ｇ／Ｌ
メタンスルホン酸 ８０ｇ／Ｌ
没食子酸 ５ｍｇ／Ｌ
エタノール ５ｇ／Ｌ
界面活性剤（ポリオキシエチレンアルキルアミン）１０ｇ／Ｌ
に浸漬し、４Ｎ純度の錫とインジウムを溶融して合金化した陽極を用い電流密度５０Ａ／ｄｍ^２で、２μｍ厚さのめっき皮膜を得た。
めっき後、走査型電子顕微鏡によって拡大倍率５０００倍で観察した結果めっき粒子の境界は識別できなかった。
【００５５】
実施例８
負極集電体としてニッケル多孔体を用い、アルカリ電解脱脂液中で１Ａ／ｄｍ^２、１分間の電解脱脂を行い、水洗後、５％メタンスルホン酸水溶液に３０秒間浸漬し活性化した。それを水洗後、下記めっき液（ｊ）：
めっき液（ｊ）
フェノールスルホン酸錫（２価錫として） ２０ｇ／Ｌ
フェノールスルホン酸鉛（鉛として） １０ｇ／Ｌ
フェノールスルホン酸 １００ｇ／Ｌ
３，４，５−トリヒドロキシ安息香酸 ０．１ｇ／Ｌ
エタノール ５ｇ／Ｌ
界面活性剤（２−アルキル−Ｎ−カルボキシメチル−Ｎ−ヒドロキシエチル
イミダゾリニウムベタイン） ５ｇ／Ｌ
２−メルカプトベンゾチアゾール ０．０１ｇ／Ｌ
ホルマリン ３ｇ／Ｌ
に浸漬し、３Ｎ純度の錫と鉛を溶融して合金化した陽極を用い、電流密度８Ａ／ｄｍ^２でめっきを行い、２μｍ厚さのめっき皮膜を得た。
めっき後、走査型電子顕微鏡によって拡大倍率５０００倍で観察した結果めっき粒子の境界は識別できなかった。
別に１０ｃｍ四方の試料に同じ条件で厚付けしためっき皮膜の厚さを、断面の顕微鏡観察から得られた平均膜厚を用いて計算しためっき皮膜の体積と、めっき前後の重量差から計算した皮膜重量から密度を求めたところ８．１であった。
【００５６】
実施例９
負極集電体として銅パンチングメタルを用い、アルカリ電解脱脂液中で１Ａ／ｄｍ^２、１分間の電解脱脂を行い、水洗後、５％メタンスルホン酸水溶液に３０秒間浸漬し活性化した。それを水洗後、下記めっき液（ｋ）：

に浸漬し、白金めっきチタンの不溶性陽極を用い、電流密度１０Ａ／ｄｍ^２でめっきを行い、２μｍ厚さのめっき皮膜を得た。
めっき後、走査型電子顕微鏡によって拡大倍率５０００倍で観察した結果めっき粒子の平均粒径は約０．３μｍ程度であった。
【００５７】
実施例１０
負極集電体として銅不織布を用い、アルカリ電解脱脂液中で１Ａ／ｄｍ^２、１分間の電解脱脂を行い、水洗後、５％メタンスルホン酸水溶液に３０秒間浸漬し活性化した。それを水洗後、下記めっき液（ｌ）：

に浸漬し、白金めっきチタンの不溶性陽極を用い、電流密度６Ａ／ｄｍ^２でめっきを行い、２μｍ厚さのめっき皮膜を得た。
めっき後、走査型電子顕微鏡によって拡大倍率５０００倍で観察した結果めっき粒子の境界は識別できなかった。
【００５８】
実施例１１
負極集電体として銅箔を用い、アルカリ電解脱脂液中で１Ａ／ｄｍ^２、１分間の電解脱脂を行い、水洗後、５％メタンスルホン酸水溶液に３０秒間浸漬し活性化した。それを水洗後、下記めっき液（ｍ）：

に浸漬し、白金めっきチタンの不溶性陽極を用い、電流密度１５Ａ／ｄｍ^２でめっきを行い、２μｍ厚さのめっき皮膜を得た。
めっき後、走査型電子顕微鏡によって拡大倍率５０００倍で観察した結果めっき粒子の境界は識別できなかった。
【００５９】
実施例１２
負極集電体として銅箔を用い、アルカリ電解脱脂液中で１Ａ／ｄｍ^２、１分間の電解脱脂を行い、水洗後、５％メタンスルホン酸水溶液に３０秒間浸漬し活性化した。それを水洗後、下記めっき液（ｎ）：

に浸漬し、白金めっきチタンの不溶性陽極を用い、電流密度１２Ａ／ｄｍ^２でめっきを行い、２μｍ厚さのめっき皮膜を得た。
めっき後、走査型電子顕微鏡によって拡大倍率５０００倍で観察した結果めっき粒子の平均粒径は約０．３μｍ程度であった。
別に１０ｃｍ四方の試料に同じ条件で厚付けしためっき皮膜の厚さを、断面の顕微鏡観察から得られた平均膜厚を用いて計算しためっき皮膜の体積と、めっき前後の重量差から計算した皮膜重量から密度を求めたところ７．３であった。
【００６０】
実施例１３
負極集電体として銅箔を用い、アルカリ電解脱脂液中で１Ａ／ｄｍ^２、１分間の電解脱脂を行い、水洗後、５％硫酸に３０秒間浸漬し活性化した。それを水洗後、下記めっき液（ｏ）：
めっき液（ｏ）
硫酸錫（２価錫として） ３３ｇ／Ｌ
硫酸銅（５水塩） １５ｇ／Ｌ
硫酸 ９８ｇ／Ｌ
クレゾールスルホン酸 １０ｇ／Ｌ
カテコール ３ｇ／Ｌ
エチレングリコール ５０ｇ／Ｌ
界面活性剤（エマルゲンＢ６６（花王石鹸））２ｇ／Ｌ
ベンザルアセトン ０．３ｇ／Ｌ
に浸漬し、白金めっきチタンの不溶性陽極を用い、電流密度６Ａ／ｄｍ^２でめっきを行い、２μｍ厚さのめっき皮膜を得た。
めっき後、走査型電子顕微鏡によって拡大倍率５０００倍で観察した結果めっき粒子の平均粒径は約０．３μｍ程度であった。
【００６１】
実施例１４
負極集電体として鉄箔を用い、アルカリ電解脱脂液中で１Ａ／ｄｍ^２、１分間の電解脱脂を行い、水洗後、５％メタンスルホン酸水溶液に３０秒間浸漬し活性化した。それを水洗後、常法にしたがい硫酸銅浴から３μｍの銅下地めっきを施した後水洗し、下記めっき液（ｐ）：

に浸漬し、白金めっきチタンの不溶性陽極を用い、電流密度６Ａ／ｄｍ^２でめっきを行い、２μｍ厚さのめっき皮膜を得た。
めっき後、走査型電子顕微鏡によって拡大倍率５０００倍で観察した結果めっき粒子の境界は識別できなかった。
【００６２】
電池評価
上記、実施例および比較例の負極の単極としての性能を見るため、対極をリチウム箔としたコイン型セルを作製し、評価した。１ｍｏｌ／ＬのＬｉＰＦ_６を溶解させたプロピレンカーボネートとジメチルカーボネートの１：１混合電解液を含浸させたポリプロピレン製セパレーターを該負極とリチウム箔で挟み込み、これをコイン型セルにセットした。充放電試験は０〜１Ｖの電圧範囲、１ｍＡ／ｃｍ^２の電流密度で行った。
その時の１サイクル目の放電容量（ここでは挿入されたリチウムが脱離する反応を放電という）および１００サイクル目における１サイクル目の放電容量の維持率を表に示す。
実施例１〜１４はいずれも０．５μｍ以下の粒径の粒子から構成されるめっき皮膜を用いて電極を作成した例である。これに対して、比較例１は、実施例１と同じく錫単独のめっき皮膜であるが粒子径が約２５μｍのめっき皮膜の例、また比較例２は、実施例５と同じく錫−銀合金めっき皮膜であるが、１μｍおよび２μｍ程度の粒子が共存しためっき皮膜の例である。いずれの実施例、比較例においても、１サイクル目の放電容量は現在の炭素系材料よりも高い値を示し、錫及び錫合金めっきが高容量負極であることが示された。
しかしながら、めっき皮膜の結晶粒径が放電容量やサイクル特性に与える影響は大きく、錫単独めっき皮膜の場合、拡大倍率５０００倍の走査型電子顕微鏡観察によって粒子の境界が識別できないレベルに粒子径が小さかった実施例１においては、１サイクル目の放電容量、容量維持率が共に良好な値を示したが、それに対してめっき皮膜の平均粒径が２５μｍの比較例１においては、１サイクル目の放電容量、容量維持率が共に実施例１より低く、特に容量維持率が格段に低く、充放電特性は単に錫という元素の種類にのみ依存するのではなく、粒子径に大きく依存することがわかる。
鉛、アンチモン、カドミウム、砒素、タリウムをめっき浴に微量添加した実施例２、３、４においては、これら微量添加金属の有無を除いて同一条件で作成した実施例１よりも１サイクル目の放電容量、容量維持率が共に良好な値を示し、これらの金属はめっき浴に微量だけ添加しても結晶の微細化に寄与して、充放電特性を向上させる。
また、合金めっき皮膜を用いた例として、実施例５に錫−銀合金めっき皮膜の実施例を示した。粒径の小さい皮膜である実施例５においては、１サイクル目の放電容量、容量維持率共に良好な値を示したにもかかわらず、１および２μｍ程度の粒子が共存した比較例２においては、１サイクル目の放電容量が低く、また容量維持率は格段に低かった。
【００６３】
めっき浴寿命試験
電池負極として錫及び錫合金をめっき法により工業的に作製するには、コストや作業性を考慮すると、めっき浴の寿命が長いことが必須である。新規に建浴しためっき浴で、電流密度１Ａ／ｄｍ^２、５０Ａｈｒ／Ｌの連続めっきを行い、１０Ａｈｒ／Ｌの電解後のめっき浴の外観を評価した。めっき浴の安定化に寄与する必須の成分として、２価の錫イオンに対して化学量論的に当量以上の酸又は錯化剤、酸化防止剤、アルコール又はケトンの全てを含有する実施例１〜１４においては、５０Ａｈｒ／Ｌの電解後においてもめっき浴は安定で建浴初期と同等のめっき皮膜が得られたが、それらの成分を欠く比較例１及び２では１０Ａｈｒ／Ｌの電解後、沈殿と濁りが生じ、めっき外観もデンドライトが発生し、粒子も粗くなった。
【００６４】
【表１】
表

【００６５】
【発明の効果】
以上説明したように、本発明によれば、限定された浴組成の錫又は錫合金めっき浴から析出された結晶の微細な錫又は錫合金めっき皮膜を二次電池用電極材料として用いることによって、優れた充放電特性をもつ二次電池用電極が製造でき、優れた充放電特性をもつ二次電池を製造し、提供することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention belongs to an electrode material and a manufacturing technique thereof, and particularly relates to an electrode material for a secondary battery, an electrode, a secondary battery, and a manufacturing technique thereof.
[0002]
[Prior art]
In recent years, mobile devices such as mobile phones and notebook computers have rapidly become mobile, and this has led to the rapid production of rechargeable secondary batteries that can withstand long-term use. Has increased. Under such circumstances, lithium secondary batteries rich in light weight have made great progress, but further performance improvement is required.
Currently, combinations of various carbonaceous materials for the negative electrode and composite oxides of lithium and other metals for the positive electrode are the most widely used as electrodes for lithium batteries. It is considered that the improvement of characteristics such as life has almost reached its limit. In place of the carbonaceous material, various metals and alloys, or their oxides, sulfides, nitrides, etc. are studied and disclosed in patents and academic papers.
[0003]
The use of metals and alloys capable of inserting and removing lithium metal or lithium ions was done before carbonaceous electrodes were generally used, but new studies are underway. .
Regarding the use of a metal for the electrode, tin or a tin alloy is considered as a promising metal. For example, in JP-A-8-7884 (Fujitsu Limited), tin, lead, A negative electrode in which indium, bismuth or the like is laminated is disclosed. JP-A-10-162823 (Hitachi Maxell Co., Ltd.) discloses Sn—Fe and Sn—Ni alloys as well as Si alloys. Japanese Patent Laid-Open No. 10-144351 (Matsushita Electric Industrial Co., Ltd.) discloses alloys of In, Al, Pb, Bi, Sb, Ga, Sn, Si, Zn, Cd, As, and Ti or alloys of these with lithium. ing. In JP-A-11-343109 (Osaka Gas Co., Ltd.), carbonaceous materials and Ca, Sr, Ba, Ir, Ag, Cd, Hg, B, Al, Ga, In, Tl, Si, Sn, Pb, Sb, Mixtures with Bi, Te, etc. are disclosed. JP 2000-173670 (Matsushita Electric Industrial Co., Ltd.) describes a solid solution or intermetallic compound of tin and a group 2 element, a transition element, a group 12 element, a group 13 element, or a group 14 element excluding carbon in the periodic table. A material is disclosed.
[0004]
In general, these metal or alloy electrodes are often manufactured by metallurgical methods, but it is also disclosed that they can be obtained by plating.
That is, Sonoda, Sakai et al. Disclosed a tin negative electrode obtained by an electroplating method, and reported that the negative electrode has a larger charge / discharge capacity than a graphite negative electrode and can be an electrode of a good lithium secondary battery. . The presenters disclose that an electrode is prepared using a nearly neutral sulfate bath containing gluconate as a complexing agent. [Abstracts of Sonoda, Sakai, Surface Technology Association 99th Lecture Meeting, page 114] and [Sonoda, Fujieda, Sakai, Second Kansai Surface Technology Forum, page 11]. Tamura, Ohshita, Fujimoto, Fujitani, Kanno, Yonezu and others have reported negative electrodes using plated tin metal, but they do not disclose detailed plating conditions. [Tamura, Ohshita, Fujimoto, Fujitani, Kanno, Yonezu, 540th Annual Meeting of Battery Discussion Meeting, page 540]. Further, for example, Japanese Patent Laid-Open No. 11-242594 (Canon Inc.) discloses a method for manufacturing an electrode structure in which a step of forming an electrode material such as metallic tin or a tin alloy is performed by plating.
However, what kind of characteristics tin or tin alloy plating film has good electrode characteristics is at the stage of exploration and there is no clarified report or disclosure. The tin or tin alloy plating disclosed in Japanese Patent Laid-Open No. 11-242594 (Canon Inc.) is also a well-known general condition, and is always a plating suitable for forming an electrode of a secondary battery. It was not a condition.
[0005]
[Problems to be solved by the invention]
The inventors of the present application use a tin or tin-based alloy instead of an electrode using a current carbon material as described above for a lithium secondary battery excellent in capacity and charge / discharge characteristics. The research subject of the present invention was to develop an electrode material and therefore an electrode and a battery using the electrode material, and to establish a manufacturing method thereof.
[0006]
[Means for Solving the Problems]
The inventors of the present application have intensively studied to solve the above problems, and as a result, found that a plating film having extremely fine crystals exhibits good electrode characteristics, and stably manufactured such a plating film. As a result, the inventors have found the conditions to do so and have completed the present invention.
That is, for example, the above-mentioned Japanese Patent Application Laid-Open No. 11-242955 discloses an electrode material composed of metallic tin or a tin alloy, but is composed of particles having an average particle diameter of 0.5 to 60 μm. However, according to the study by the present inventors, it has been clarified that finer metal particles have good electrode characteristics. The details of the mechanism are not clear at the present time, but by making the crystal finer, the contact area between the crystals increases dramatically, the movement of lithium inside the electrode material becomes easier, and the utilization rate of the film increases. This is probably because of this.
The refinement of the plating film crystal is usually achieved by an organic additive added to the plating bath, but a method of further refinement by adding a metal component other than tin can also be used.
[0007]
Accordingly, the subject of the present invention is an electrode material for a secondary battery in which a tin or tin alloy plating film deposited from a tin or tin alloy plating bath is formed on one side or both sides of a current collector. That the plating particles having an average particle diameter of less than 0.5 μm form a substantially continuous film, and the plating film has at least the following components (i) to (v):
(I) a divalent tin ion of 5 g / L or more and 200 g / L or less,
(Ii) One or more acids or complexing agents that form a water-soluble salt or complex with a divalent tin ion in a total stoichiometric equivalent or more with respect to the divalent tin ion ,
(Iii) one or more antioxidants having a total concentration of at least 1 ppm or more,
(Iv) one or more aliphatic ketones having a carbon number of 6 or less and an aliphatic branched or unbranched alcohol having 6 or less carbon atoms of 0.5 g / L or more and 200 g / L or less, (v ) One or more organic additives
It is an electrode material for a secondary battery characterized by being precipitated from a tin or tin alloy plating bath containing as an essential component.
Here, the plating particles forming a substantially continuous film means that the plating particles do not have a crystalline form like dendrites, but are in contact with each other to form a film. There may be some cracks on the surface.
[0008]
The particles having an average particle size of less than 0.5 μm are small enough that the boundary of the particles cannot be observed when observed from the surface direction at a magnification of 3000 to 5000 with a scanning electron microscope. It is a more preferable condition.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The electrode material for a secondary battery of the present invention is an essential condition that it is a plating film obtained from a plating bath as described above, and the above-mentioned components (i) to (v) are essential for the plating bath. Included as
[0010]
The tin or tin alloy plating bath for depositing the plating film of the electrode material for a secondary battery of the present application is basically deposited from divalent tin ions. In general, a tin or tin alloy plating bath includes a bath that precipitates from divalent tin ions and a bath that precipitates from tetravalent tin ions, but deposits from tetravalent tin ions have a good visual appearance. Since the particle size is large, it is unsuitable as a plating film for an electrode of the present application. Accordingly, a bath for precipitation from divalent tin ions is used for the tin or tin alloy plating bath used in the method for producing the electrode for a secondary battery of the present application.
In the plating bath, divalent tin ions are contained as a first essential component at a concentration in the range of 5 g / L to 200 g / L. More preferably, the range of 10 g / L to 100 g / L is used.
[0011]
In the tin or tin alloy plating bath for depositing the plating film of the electrode material for secondary battery of the present application, as a second essential component, the total stoichiometrically with respect to divalent tin ions, etc. One or two or more acids or complexing agents that form a water-soluble salt or complex with a divalent tin ion in an amount or more are used.
The suitable concentration is preferably 1.05 times or more and 30 times or less with respect to divalent tin ions in terms of gram equivalent. More preferably, 1.3 times or more and 10 times or less are used.
[0012]
As acids or complexing agents that form water-soluble salts with divalent tin ions contained as essential components in the plating bath, the acids or (and) complexing agents shown in (i) to (c) below. Are preferably used alone or in combination. Acids and complexing agents may be added in the form of salts such as their alkali metal salts or ammonium salts.
That is,
(Ii): one or more acids selected from sulfuric acid, hydrochloric acid, borohydrofluoric acid, silicofluoric acid, sulfamic acid, acetic acid, 1-hydroxyethane-1,1-diphosphonic acid, phosphoric acid and / or condensed phosphoric acid or 2 or more,
(Ii): One or more sulfonic acids selected from the aliphatic sulfonic acids represented by the following general formula (I) or (II) or the aromatic sulfonic acids represented by the general formula (III),
Formula (I)
[Chemical 8]

[Where R ₁ Is C ₁ ~ C ₅ Represents an alkyl group of X ₁ Represents hydrogen, a hydroxyl group, an alkyl group, an aryl group, an alkylaryl group, a carboxyl group, or a sulfonic acid group, and may be at any position of the alkyl group, and n is an integer of 0 to 3. ]
Formula (II)
[Chemical 9]

[Where R ₂ Is C ₁ ~ C ₅ Alkyl group or C ₁ ~ C ₃ And an alkylene group may have a hydroxyl group at any position, and X ₂ Represents a halogen of chlorine or (and) fluorine, and the number of substitutions of chlorine or (and) fluorine substituted with hydrogen of the alkyl group or alkylene group is from 1 to all hydrogens coordinated to the alkyl group or alkylene group The substituted halogen species may be one or two, and the chlorine or fluorine substituent may be at any position. Y represents hydrogen or a sulfonic acid group, and the number of substitution of the sulfonic acid group represented by Y is in the range of 0 to 2. General formula (III)
[Chemical Formula 10]

[Where X ₃ Represents a hydroxyl group, an alkyl group, an aryl group, an alkylaryl group, an aldehyde group, a carboxyl group, a nitro group, a mercapto group, a sulfonic acid group or an ammono group, or two X3 together with a benzene ring are a naphthalene ring M is an integer of 0-3. ]
(Reference): At least one carboxyl group and carboxy
1 type or 2 types or more of aliphatic carboxylic acid ions having one or more types selected from 1 group, 2 types or more of groups selected from a ru group, hydroxyl group, sulfonic acid group, amino group, and thiol group,
Is used.
[0013]
As the condensed phosphoric acid, both linear polyphosphoric acid and cyclic metaphosphoric acid are used, and diphosphoric acid (pyrophosphoric acid) is particularly preferably used.
As the above sulfonic acid, methanesulfonic acid, methanedisulfonic acid, methanetrisulfonic acid, trifluoromethanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, 2-propanesulfonic acid, butanesulfonic acid, 2-butanesulfonic acid, pentanesulfonic acid Hexane sulfonic acid, decane sulfonic acid, dodecane sulfonic acid, 2-hydroxyethane-1-sulfonic acid, 1-hydroxypropane-2-sulfonic acid, 3-hydroxypropane-1-sulfonic acid, 2-hydroxypropane-1- Sulfonic acid, 2-hydroxybutanesulfonic acid, 2-hydroxypentanesulfonic acid, 2-hydroxyhexane-1-sulfonic acid, 2-hydroxydecanesulfonic acid, 2-hydroxydodecanesulfonic acid, 1-carboxyethanesulfonic acid, 2- Karboki Ethanesulfonic acid, 1,3-propanedisulfonic acid, allylsulfonic acid, 2-sulfoacetic acid, 2- or 3-sulfopropionic acid, sulfosuccinic acid, sulfomaleic acid, sulfofumaric acid, monochloromethanesulfonic acid, perchloroethanesulfonic acid, Trichlorodifluoropropanesulfonic acid, perfluoroethanesulfonic acid, monochlorodifluoromethanesulfonic acid, trifluoromethanesulfonic acid, trifluoroethanesulfonic acid, tetrachloropropanesulfonic acid, trichlorodifluoroethanesulfonic acid, monochloroethanolsulfonic acid, dichloropropanolsulfonic acid, monochloro Difluorohydroxypropane sulfonic acid, benzene sulfonic acid, toluene sulfonic acid, xylene sulfonic acid, nitrobenzene sulfonic acid, sulfo Benzoic acid, sulfosalicylic acid, benzaldehyde sulfonic acid, p-phenolsulfonic acid, phenol-2,4-disulfonic acid, 2-sulfoacetic acid, 2-sulfopropionic acid, 3-sulfopropionic acid, sulfosuccinic acid, sulfomethylsuccinic acid , Sulfofumaric acid, sulfomaleic acid, 2-sulfobenzoic acid, 3-sulfobenzoic acid, 4-sulfobenzoic acid, 5-sulfosalicylic acid, 4-sulfophthalic acid, 5-sulfoisophthalic acid, 2-sulfoterephthalic acid, etc. Are preferably used.
In particular, methanesulfonic acid, 2-hydroxyethane-1-sulfonic acid, 2-hydroxypropane-1-sulfonic acid, phenolsulfonic acid, cresolsulfonic acid, or trifluoromethanesulfonic acid is particularly preferably used.
[0014]
As the above aliphatic carboxylic acids, oxalic acid, malonic acid, succinic acid, glycolic acid, lactic acid, tartaric acid, citric acid, tartronic acid, malic acid, ascorbic acid, glycine, alanine, valine, leucine, isoleucine, lysine, serine, threonine , Phenylalanine, aspartic acid, glutamic acid, methionine, mercaptosuccinic acid, cystine, sulfosuccinic acid, ethylenediaminetetraacetic acid, iminodiacetic acid, nitrilotriacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraminehexaacetic acid, ethylenedioxybis (ethylamine) -N, N N ′, N′-tetraacetic acid, glycol ethylenediaminetetraacetic acid, N-hydroxyethylethylenediaminetetraacetic acid and the like are preferably used. Of these, sulfosuccinic acid, glycolic acid, lactic acid, tartaric acid, citric acid, ethylenediaminetetraacetic acid, nitrilotriacetic acid and the like are more preferably used.
[0015]
As will be described later, the tin or tin alloy plating bath for producing the electrode material of the present invention is not an essential component, but it is desirable to contain some tetravalent tin. On the other hand, since the tetravalent tin has an adverse effect if it exists beyond the limit, the concentration of the tetravalent tin compound or ion is not increased beyond the limit, and the concentration of the divalent tin ion is not increased. In order to keep the constant, it is necessary to contain one or two or more antioxidants having a total concentration of at least 1 ppm as the third essential component. Although there is no strict upper limit, it is usually used at a concentration of 50 g / L or less. More preferably, it is used at 5 mg / L or more and 2 g / L or less, and most preferably 10 mg / L or more and 1 g / L or less.
[0016]
Specific examples of the antioxidant include those selected from substituted or unsubstituted aromatic mono-, di- or triphenols selected from the following general formula (ii), or (ro) aliphatic polyhydroxy compounds 1 One species or two or more species may be used alone or in combination. General formula (I)
Embedded image

[However, X represents hydrogen or a hydroxyl group, and may be the same or different, and n represents an integer of 1 to 3. At least one of X is a hydroxyl group. Y is one or more selected from hydrogen, methyl group, ethyl group, methoxy group, ethoxy group, carboxyl group, sulfonic acid group or amino group, and may be the same or different, and m is 6- It is an integer of n. The bonding position on the benzene ring of X and Y is not limited. However, the compound which can take the said structure by tautomerism is included. ]
A substituted or unsubstituted aromatic mono-, di- or triphenol represented by the formula:
(B) Aliphatic polyhydroxy compounds.
[0017]
Specific examples of the phenols represented by the general formula (ii) include hydroquinone, catechol, resorcin, pyrogallol, oxyhydroquinone, phloroglysin, gallic acid, catechol sulfonic acid, guaiacol, hydroquinone sulfonic acid, and 3,4-dihydroxy. One or more selected from benzoic acid, 3,4,5-trihydroxybenzoic acid, p-phenolsulfonic acid, cresolsulfonic acid, hydroquinonesulfonic acid, β-naphthol and the like are particularly preferably used.
As the aliphatic polyhydroxy compound (ro), sorbic acid, sorbitol, budo sugar, ascorbic acid, isoascorbic acid and the like are preferably used.
[0018]
The above plating bath has a concentration of 0.5 g / L or more and 200 g / L or less and a carbon number of 6 or less as the fourth essential component in order to refine the plating particles and improve the stability of the plating bath. Or one or more of aliphatic branched or unbranched alcohols having 6 or less carbon atoms are used. More preferably, a concentration of 1 g / L or more and 200 g / L or less is used.
Since it depends on the concentration of other additives, etc., the absolute concentration cannot be limited. However, if the alcohol concentration becomes too high, there is an adverse effect on the stabilizing effect of the bath, especially if it exceeds 300 g / L. large. Therefore, the upper limit concentration of the aliphatic alcohol or ketone is strictly regulated to 200 g / L or less. Further, when the concentration is high, the odor becomes remarkable, which is not preferable from the work environment.
[0019]
As the aliphatic branched or unbranched alcohol having 6 or less carbon atoms, alcohols represented by the following general formulas (A) to (C) are used.
General formula (b)
Embedded image

[However, n is an integer greater than m and 6 or less, and m represents an integer of 1 or 2. X is hydrogen or a hydroxyl group, and may be the same or different, and at least one of X is a hydroxyl group. The position of the carbon to which X is bonded is not limited, and the carbon chain may be linear or branched. ]
A linear saturated aliphatic mono- or dialcohol represented by:
General formula (b)
Embedded image

[However, n is an integer greater than m and 6 or less, and m represents an integer of 1 or 2. X is hydrogen or a hydroxyl group, and may be the same or different, and at least one of X is a hydroxyl group. The carbon chain to which X is bonded is not limited, and the carbon chain may be branched. ]
A cyclic saturated aliphatic mono- or dialcohol represented by:
General formula (c)
Embedded image

[However, n is an integer greater than m and 6 or less, and m represents an integer of 1 or 2. l represents an integer of n-2 or less. X is hydrogen or a hydroxyl group, and may be the same or different, and at least one of X is a hydroxyl group. The carbon chain to which X is bonded is not limited, and the carbon chain may be branched. O represents etheric oxygen and is located between two carbons, but the position is not limited. ]
A linear saturated aliphatic mono- or dialcohol having an ether bond represented by the formula:
[0020]
Specific examples of the aliphatic ketone having 6 or less carbon atoms or the aliphatic branched or unbranched alcohol having 6 or less carbon atoms include methanol, ethanol, (n- and i-) propanol, (n -, I- and t-) butanol, 1,2,6-hexanetriol, thiodiglycol, pentanediol, hexanediol, 1,3-propanediol, 1,4-butanediol, ethylene glycol, propylene glycol, acetone One or two or more selected from methyl ethyl ketone and the like are preferably used, i-propanol and acetone are more preferably used, and i-propanol is most preferably used.
[0021]
The tin or tin alloy plating bath for depositing the plating film of the electrode material for the secondary battery of the present application includes the organic additive as a fifth essential component in order to obtain a plating film of fine crystal particles. 1 type (s) or 2 or more types are contained. Organic additives include surfactants, smoothing additives, semi-brighteners, brighteners, and the like.
In general, it is suitably used in the range of 0.001 g / L to 50 g / L, but the concentration used depends on the type and combination of the compounds.
[0022]
As the surfactant, known surfactants can be used, and any of nonionic, anionic, amphoteric, and cationic surfactants are preferably used, and are used alone or in combination as appropriate. Nonionic, anionic and amphoteric systems are more preferably used.
[0023]
Examples of suitable nonionic surfactants include polyoxyalkylene alkyl ether (or ester), polyoxyalkylene phenyl (or alkylphenyl) ether, polyoxyalkylene naphthyl (or alkylnaphthyl) ether, polyoxyalkylene Styrenated phenyl ether (or a polyoxyalkylene chain added to the phenyl group), polyoxyalkylene bisphenol ether, polyoxyethylene polyoxypropylene block polymer, polyoxyalkylene sorbitan fatty acid ester, polyoxyalkylene sorbite fatty acid ester, Polyethylene glycol fatty acid ester, polyoxyalkylene glycerin fatty acid ester, polyoxyalkylene alkylamine, ethylene diamine Polyoxyalkylene condensate adduct, polyoxyalkylene fatty acid amide, polyoxyalkylene castor (or / and hydrogenated castor oil) oil, polyoxyalkylene alkylphenyl formalin condensate, glycerin (or polyglycerin) fatty acid ester surfactant And pentaerythritol fatty acid esters, sorbitan mono (sesqui, tri) fatty acid ester surfactants, higher fatty acid mono (di) ethanolamides, alkyl / alkylroadamides, and oxyethylene alkylamines.
[0024]
Examples of suitable anionic surfactants include alkyl (or formalin condensate) -β-naphthalene sulfonic acid (or salt thereof), fatty acid soap, alkyl sulfonate, α-olefin sulfonate, alkyl benzene Sulfonate, alkyl (or alkoxy) naphthalene sulfonate, alkyl diphenyl ether disulfonate, alkyl ether sulfonate, alkyl sulfate ester salt, polyoxyethylene alkyl ether sulfate ester salt, polyoxyethylene alkyl phenol ether sulfate ester salt, Higher alcohol phosphate monoester salt, polyoxyalkylene alkyl ether phosphate (salt), polyoxyalkylene alkyl phenyl ether phosphate, polyoxyalkylene phenyl ether phosphate, Reoxyethylene alkyl ether acetate, alkyl ylsarcosine, alkyl yl sarcosine, alkyl yl methyl alanine, N acyl sulfocarboxylate, alkyl sulfoacetate, acyl methyl taurate sodium, alkyl fatty acid glycerine sulfate, Hardened coconut oil fatty acid sodium glyceryl sulfate, alkylsulfocarboxylic acid ester salt system, alkylsulfosuccinate, dialkylsulfosuccinate, alkylpolyoxyethylenesulfosuccinate, sulfosuccinic acid monooleylamide sodium salt (or ammonium, TEA salt), etc. be able to.
[0025]
Examples of amphoteric surfactants preferably used include 2-alkyl-N-carboxymethyl (or ethyl) -N-hydroxyethyl (or methyl) imidazolinium betaine, 2-alkyl-N-carboxymethyl (or Ethyl) -N-carboxymethyloxyethylimidazolinium betaine, dimethylalkylbetaine, N-alkyl-β-aminopropionic acid (or its sodium salt), alkyl (poly) aminoethylglycine, N-alkyl-N-methyl- Examples include β-alanine (or its sodium salt), fatty acid amidopropyldimethylaminoacetic acid betaine, and the like.
[0026]
Suitable surfactants include tetra-lower alkylammonium halide, alkyltrimethylammonium halide, hydroxyethylalkylimidazoline, polyoxyethylene alkylmethylammonium halide, alkylbenzalkonium halide, dialkyldimethylammonium halide. , Alkyldimethylbenzylammonium halide, alkylamine hydrochloride, alkylamine acetate, alkylamine oleate, alkylaminoethylglycine, alkylpyridinium halide, and the like.
[0027]
As the smoothing additive, semi-brightening agent or brightening agent, known ones can be used. Specifically, the following compounds are used alone or in combination.
Further, additives such as a smoothing agent, semi-brightening agent, brightening agent and the like that can be used in the tin or tin alloy plating bath used in the preparation of the electrode material for the secondary battery of the present invention are used in tin or tin alloy plating. Known materials used can be used, and examples of particularly effective among them include polymer compounds, sulfanilic acid and derivatives thereof, salts thereof, quinolines, triazole and derivatives thereof, benzothiazole and derivatives thereof. , Imines, triazines, guanamines, esters of aromatic oxycarboxylic acids, compounds having a double bond at the position conjugated with C = O, aldehydes, diketones, aniline and derivatives thereof, nitro compounds or the compounds thereof Sodium, potassium or ammonium salts, mercaptocarboxylic acids, heterocyclic compounds, acetophenones, Min alcohols, condensates of aliphatic primary or secondary amine and an aldehyde, and the like other.
These compounds can be used alone or in combination. The amount used is suitably 0.5 to 50 g / L, preferably 1 to 20 g / L when the following polymer substance is used. For other additives, 0.001 to 50 g / L is appropriate, and 0.02 to 20 g / L is more preferably added.
[0028]
Examples of the polymer substance include gelatin, peptone, polyethylene glycol, polyacrylamide, polyethyleneimine, and polyvinylpyrrolidone. Examples of sulfanilic acid derivatives and salts thereof include N-butylidenesulfanilic acid, N- (3-hydroxybutylidene) -p-sulfanilic acid, aldol, and the like. An example of quinolines is a product obtained by adding 5 mol of propylene oxide to 8-hydroxyquinoline. Examples of triazole and its derivatives include benzotriazole, 4-methylbenzotriazole, 4-hydroxybenzotriazole, 4-carboxybenzotriazole and the like. Examples of benzothiazole and its derivatives include benzothiazole, 2-methylbenzothiazole, 2-mercaptobenzothiazole, 2-amino-4-chlorobenzothiazole, 2-amino-6-methoxybenzothiazole, 2-hydroxybenzothiazole, 2-chlorobenzothiazole, 2-methyl-5-chlorobenzothiazole, 2,5-dimethylbenzothiazole, 5-hydroxy-2-methylbenzothiazole, 6-chloro-2-methyl-4-methoxybenzothiazole, 2- (N-butyl) mercapto-6-aminobenzothiazole, 2-benzothiazolethioacetic acid, 2-benzothiazoleoxyacetic acid, 6-ethoxy-2-mercaptobenzothiazole and the like. Examples of imines include N, N′diiso-butylidene-o-phenylenediamine. Examples of triazines include 2,4-diamino-6- [2′-methylimidazolyl (1 ′) ethyl-1,3,5-triazine, 2,4-diamino-6- [2′-ethylimidazolyl (1 ') Ethyl-1,3,5-triazine, 2,4-diamino-6- [2'-undecylimidazolyl (1') ethyl-1,3,5-triazine and the like. Examples of guanamines include β-N-dodecylaminopropioguanamine, β-N-hexylaminopropioguanamine, piperidinepropioguanamine, cyclohexylaminopropioguanamine, morpholine propioguanamine, β-N- (2-ethyl Hexyloxypropylamino) propioguanamine, β-N- (lauryloxypropylamino) propioguanamine and the like. Examples of aromatic oxycarboxylic acid esters include methyl o- (or m- or p-) benzoate, phenyl salicylate, and the like. As an example of a compound having a double bond at a position conjugated with C═O, itaconic acid, propylene-1,3-dicarboxylic acid, acrylic acid, crotonic acid, cinnamic acid, methyl acrylate, ethyl acrylate, methacrylic acid, Methyl methacrylate, butyl methacrylate, ethacrylic acid, acrylamide, diacetone acrylamide, t-butyl acrylamide, N-methoxydimethylacrylamide, curcumin (1,7-bis (4-hydroxy-3-methoxyferral) -1,6- (Heptadiene-3,5-dione), isophorone (3,5,5-trimethyl-2-cyclohexenone), mesityl oxide, vinyl phenyl ketone, phenyl propenyl ketone, phenyl isobutenyl ketone, phenyl-1-methylpropenyl ketone Benzylideneacetophenone charcone), 2- (ω-benzoyl) vinyl furan, p-fluorophenyl propenyl ketone, p-chlorophenyl propenyl ketone, p-hydroxyphenyl propenyl ketone, m-nitrophenyl propenyl ketone, p-methylphenyl propenyl ketone, 2,4 , 6-trimethylphenyl propenyl ketone, p-methoxyphenyl propenyl ketone, p-methoxyphenyl butenyl ketone, p-methylthiophenyl propenyl ketone, p-isobutylphenyl propenyl ketone, α-naphthyl-1-methylpropenyl ketone, 4-methoxy Naphthyl propenyl ketone, 2-thienyl propenyl ketone, 2-furyl propenyl ketone, 1-methylpyrrole propenyl ketone, benzylidene methyl ethyl ketone, benzylidene aceto Alcohol, p-toluideneacetone, anisalacetone (anisylideneacetone), p-hydroxybenzylideneacetone, benzylidenemethylisobutylketone, 3-chlorobenzylideneacetone, benzalacetone (benzylideneacetone), benzylideneacetylacetone, 4- (1- Naphthyl) -3-buten-2-one, pyridideneacetone, furfuridineacetone, 4- (2-thiophenyl) -3-buten-2-one, 4- (2-furyl) -3-buten-2- ON, acrolein (acrylaldehyde, propenal), allyl aldehyde, crotonaldehyde, cinnamaldehyde, benzylcrotonaldehyde, tenylideneacetone and the like. Examples of aldehydes include formaldehyde, acetaldehyde, propionaldehyde, n-butyraldehyde, isobutyraldehyde, n-valeraldehyde (valeral, pentanal), isovaleraldehyde, n-capronaldehyde (hexanal, hexylaldehyde), succinaldehyde ( Succindialdehyde), glutaraldehyde (1,5-pentanediar, glutardialdehyde), aldol (3-hydroxybutyraldehyde, acetoaldol), crotonaldehyde, cinnamic aldehyde, propargylaldehyde, benzaldehyde, o-phthalaldehyde, Salicylaldehyde (o-hydroxybenzaldehyde), p-hydroxybenzaldehyde, p-nitrobenzaldehyde, o- (or p-) Toxibenzaldehyde (anisaldehyde), 3-methoxybenzaldehyde, vanillin, o-vanillin, veratraldehyde (3,4-dimethoxybenzaldehyde), 2,5-dimethoxybenzaldehyde, (2,4-, 2,6-) dichlorobenzaldehyde 1- (or 2-) naphthaldehyde, 2- (or 4-) chloro-1-naphthaldehyde, 2- (or 4-) hydroxy-1-naphthaldehyde, 5 (or 2) -methoxynaphthaldehyde, 2 -Furaldehyde (2-furaldehyde = furfural), 3-furaldehyde, 2 (3) -thiophene carboxaldehyde, picoline aldehyde, 3-acenaphthaldehyde, 3-indole carboxaldehyde and the like. Examples of diketones include glyoxal (ethanedial, oxalaldehyde, diformyl, biformyl), diacetyl (biacetyl, dimethylglyoxal, butanedione), hexanedione-3,4, acetylacetone (2,4-pentanedione), hexanedione-3 , 4-acetylacetone and the like. Examples of aniline derivatives include aniline, o- (or m- or p-) toluidine, o- (or p-) aminoaniline, o- (or p-) chloroaniline, 2,5- (or 3,4- ) Chlormethylaniline, N-monomethylaniline, 4,4′diaminodiphenylmethane, N-phenyl- (α- or β-) naphthylamine, dithizone and the like. Examples of the nitro compound or its sodium, potassium or ammonium salts include p-nitrophenol, nitrobenzenesulfonic acid, 2,4-dinitrobenzenesulfonic acid, m-nitrobenzoic acid and the like. Examples of mercaptocarboxylic acids include mercaptoacetic acid (thioglycolic acid), mercaptosuccinic acid, and the like. Examples of heterocyclic compounds include 1,10-phenanthroline, 2-vinylpyridine, quinoline, indole, imidazole, 2-mercaptobenzimidazole, 1,2,3- (or 1,2,4- or 1,3 , 5-) triazine, 1,2,3-benzotriazine, 2-mercaptobenzoxazole, 2-cinnamylthiophene and the like. Acetophenone and halogenated acetophenone. Examples of amine alcohols include triethanolamine, diethanolamine, monoethanolamine, N-methylethanolamine condensate, and the like. Examples of aliphatic primary or secondary amine and aldehyde condensates include amine-aldehyde condensates such as piperazine, biperidine, morpholine, cyclopropylamine, cyclohexylamine, cyclooctylamine, ethylenediamine, monoethanolamine, diethanolamine, etc. And the condensates of aliphatic primary or secondary amines or aromatic amines with the aldehydes.
[0029]
The tin or tin alloy plating bath for depositing the plating film of the secondary battery electrode material of the present application preferably further contains a tetravalent tin ion or compound of 0.1 g / L or more and 20 g / L or less. . More preferably, the concentration is 0.1 g / L or more and 10 g / L or less.
In tin or tin alloy plating from divalent tin ions, tetravalent tin ions should not be directly involved in tin precipitation, but according to the study by the present inventors, the concentration range depends on the bath type. Although it is not necessarily strictly constant, the concentration exceeding 20 g / L certainly inhibits the uniformity of the plating film and adversely affects it. However, in the concentration region of 0.1 g / L to 10 g / L, the crystal It has been found that a plating film having good cycle characteristics is provided as an electrode of a lithium battery.
The tetravalent tin compound or ion can be contained in the bath by oxidizing the divalent tin ion in the bath by a forced method such as air stirring or preliminary electrolysis, or a stannate. It can be contained in the bath also by adding a compound such as tin tetrachloride.
The concentration of tetravalent tin can be analyzed and controlled by measuring the total tin concentration by ICP analysis or atomic absorption analysis and subtracting the analytical value of divalent tin obtained by the oxidation-reduction titration method. If instrumental analysis is not available, the total tin concentration can be analyzed by oxidation-reduction titration after dissolving metal aluminum under acidic conditions to reduce tetravalent tin to divalent.
[0030]
In the tin or tin alloy plating bath for depositing the plating film of the electrode material for the secondary battery of the present application, in order to further improve the discharge capacity and / or cycle characteristics, the atomic number is 26 to 33, tin is further added. One or more alloying metals selected from 44 to 51 or 75 to 82 excluding mercury can be contained.
At present, the mechanism for improving electrode characteristics has not been fully elucidated.
However, since it is known that when different metals are contained in electroplating, the crystal is known to be refined, and it is assumed that such refinement of the crystal further improves the charge / discharge characteristics.
The alloying metal indicated by the atomic number is specifically exemplified by iron, cobalt, nickel, zinc, gallium, germanium, arsenic, ruthenium, rhodium, palladium, silver, cadmium, indium, antimony, osmium, iridium, Platinum, gold, mercury, thallium, lead, bismuth. Among these, iron, cobalt, nickel, copper, zinc, gallium, germanium, arsenic, silver, cadmium, indium, antimony, thallium, lead, and bismuth are more preferably used.
These alloying metals have an effect of refining crystal grains when the total content in the plating bath is 20 ppm or more with respect to tin. More preferably, 0.5% or more of tin is used.
If the metal component other than tin in the plating film is more than what percentage, it is tin alloy plating,
There is no clear definition of what percentage or less is considered to be tin (single) plating. In the present application, for the sake of convenience, any of non-destructive methods such as EPMA and X-ray diffraction or destructive methods such as ICP and atomic absorption may be used. In the case of including tin, all are defined as a tin alloy plating film, and those below are defined as a tin (single) plating film.
Of the above metals, metals other than mercury, group IIB, IIIB, IVB, and VB are particularly effective.
The tin alloy plating film containing one or more of the metals in total and containing 20 ppm or more with respect to tin exhibits good charge / discharge characteristics. Here, the expressions IIB, IIIB, IVB, and VB are based on the IUPAC periodic table, specifically zinc, gallium, germanium, arsenic, cadmium, indium, antimony, thallium, lead, and bismuth. is there. Among these, lead, antimony, arsenic, and cadmium are more preferably used.
[0031]
The electrode material which is a fine crystal tin or tin alloy plating film of the present invention has an extremely high energy density per unit weight and unit volume as compared with the current mainstream carbon material negative electrode. Can be made thinner than when the current carbon material is used. In particular, for a very small battery such as a micro battery, it is preferably used in a thickness of 0.01 μm or more and less than 5 μm. A thicker plating film of 5 μm or more and 500 μm or less can be suitably used for a battery having a size larger than that of a normal button battery.
[0032]
When tin or a tin alloy is used as a negative electrode, expansion and contraction occur due to charge and discharge, so it has been conventionally considered that the tin or tin alloy is not high in density and should have a certain amount of voids. However, the inventors have found by the research of the present invention that rather good charge / discharge cycle characteristics can be obtained by using a tin or tin alloy plating film having a density close to that of tin prepared by ordinary melting. That is, the density of the tin or tin alloy plating film as the secondary battery electrode is 6.6 g / cm. ³ Over 8.5 g / cm ³ The following are preferably used.
[0033]
For the reasons described above, it is not necessary for the tin or tin alloy plating to further reduce the density. Therefore, it is desirable that the organic matter occlusion amount in the coating does not exceed approximately 10%. That is, the battery electrode material can be preferably produced by maintaining the carbon content within the range of 0.0001% to 10%. As a result, the density of the tin or tin alloy plating film is adjusted to the above-mentioned 6.6 g / cm. ³ Can be kept above the value.
[0034]
In the step of depositing the plating film from the tin or tin alloy plating bath, (a) an insoluble anode, (b) 3N or more, so that an unintended metal component accumulates in the plating bath and does not precipitate in the plating film. Plating is carried out using one or more of a tin anode having a purity of (c), or (c) a tin alloy anode prepared by melting 3N or higher purity tin and the alloyed metal having a purity of 3N or higher. A plating method is preferably used.
An insoluble anode is preferable from the viewpoint of preventing the contamination of impurities, but (b) or (c) is more preferably used because the bath may be deteriorated by an oxidation reaction on the anode surface.
In order to obtain a tin or tin alloy plating film having stable electrode characteristics over a long period of time, it is particularly preferable to use a tin anode or alloying metal having a purity of 4N or higher and a purity of 4N or higher. A method is used in which tin or tin alloy plating is performed using one or more tin alloy anodes prepared by melting tin.
[0035]
In producing a secondary battery electrode material by depositing a plating film from the tin or tin alloy plating bath of the present application, 0.1 A / dm ² 100 A / dm or more ² The following cathode current densities are preferably used. More preferably, 5 A / dm ² Over 100A / dm ² The following cathode current density is used. Especially when plating is performed in the continuous plating method, 5 A / dm. ² A current density exceeding 1 is preferably used.
[0036]
Moreover, when performing those plating, the 1 type (s) or 2 or more types of processes chosen from electrolytic degreasing, pickling, or activation are used suitably prior to performing plating.
Furthermore, after performing tin or tin alloy plating on them, a temporal change prevention treatment can be used. As the temporal change prevention treatment, phosphate treatment is preferably used.
[0037]
In the step of depositing a plating film from a tin or tin alloy plating bath, an aqueous solution in which one or more of acid, complexing agent, tin salt, antioxidant, or alloyed metal salt is dissolved in advance is plated. A plating bath construction method and / or concentration control method used for bath construction or (and) component replenishment is preferably used.
[0038]
The tin or tin alloy plating film used for the secondary battery electrode needs to be managed with extremely strict characteristics, and requires stricter management than general plating. To make concentration control easier, it is easier to reconstitute each component into the plating bath by adjusting the concentration to the expected concentration and replenishing the solution form. Can be implemented. For this reason, in the preparation of an electrode using the plating film of the present invention, a method in which an acid, a complexing agent, a tin salt, an antioxidant, a salt of an alloying metal, or the like is prepared in advance and replenished Is used. In particular, in the concentration control of alloyed metals, a method can be used in which the metal-forming anode is placed in a plating bath and the metal is dissolved with the progress of electrolysis, but in order to keep the concentration strictly constant. Rather, a method that is performed from other than the anode, that is, a method in which a solution in which the soluble salt or soluble complex of the metal element is dissolved in advance is appropriately added to the plating bath is more preferably used.
[0039]
Moreover, the antioxidant which is the 3rd essential component of the plating bath in the process of depositing a plating film from a tin or (and) tin alloy plating bath of this invention, or the organic additive which is the (5) essential component In addition, a solution that has been dissolved in a predetermined concentration in an aliphatic ketone having 6 or less carbon atoms or an aliphatic branched or unbranched alcohol having 6 or less carbon atoms, which is the fourth essential component, is added. The management method by doing is used suitably.
[0040]
In order to apply the plating of the above-mentioned tin or tin alloy or plating of the underlying copper, copper alloy, nickel or nickel alloy to the plate-like body, a known method, that is, a barrel plating method, a rack plating method or a continuous plating method is preferably used. Of these, the continuous plating method is more preferably used. The continuous plating method refers to a plating method in which the plate-like body wound in a roll shape is continuously unwound and supplied to a plating line including a front-back treatment and wound up.
[0041]
For the current collector of the secondary battery electrode of the present invention, copper, nickel, or iron is preferably used as the type of metal. Copper, nickel or iron includes those known alloys defined in JIS and the like which are usually used industrially and those coated with these metals by plating.
[0042]
The current collector may be subjected to base plating of copper or nickel according to a normal plating technique. Depending on the components of the plating solution, when the current collector is immersed in the plating solution, substitutional precipitation may occur on the current collector. To prevent this, it is recommended to apply a base plating of copper or nickel. Is done.
[0043]
As the current collector for the secondary battery electrode of the present invention, all the current collectors that are usually used in secondary batteries are used, but generally plate-shaped ones are used. In the expression “plate-like body”, in addition to a flat plate-like body, a sheet-like porous body, foam, screen, net, expanded body, punched body, non-woven fabric, sintered body, etc. Those showing a plate-like shape are included.
[0044]
The electrode material for a secondary battery composed of the tin or (and) tin alloy plating film of the present invention is suitably used particularly as an electrode for a lithium battery, particularly as a negative electrode material.
[0045]
【Example】
EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited to these Examples, It can change suitably in the range as described in a claim.
[0046]
Example 1
Using copper foil as the negative electrode current collector, 1 A / dm in alkaline electrolytic degreasing solution ² Electrolytic degreasing was performed for 1 minute, washed with water, and then immersed in a 5% aqueous methanesulfonic acid solution for 30 seconds for activation. After washing it with water, the following plating solution (a):

4N purity tin anode and current density 8A / dm ² Was plated to obtain a 2 μm thick plating film.
After plating, the boundary of the plated particles could not be identified as a result of observation with a scanning electron microscope at a magnification of 5000 times.
Separately, the thickness of the plating film thickened on a 10 cm square sample under the same conditions was calculated from the volume of the plating film calculated using the average film thickness obtained from the microscopic observation of the cross section and the film calculated from the weight difference before and after plating. It was 7.3 when the density was calculated | required from the weight.
[0047]
Comparative Example 1
The plating solution is as follows (b):
Plating solution (b)
Stannous sulfate 40g / L
Sulfuric acid 60g / L
Gelatin 2g / L
And the cathode current density during plating is 1 A / dm. ² A plating film having a thickness of 2 μm was obtained by performing the same operation as in Example 1 except that.
After plating, it was observed with a scanning electron microscope at an enlargement magnification of 3000. As a result, the boundaries of the plated particles could be clearly identified, and the average particle size was about 25 μm.
[0048]
Example 2
The plating solution is as follows (c):

The plating film of 2 micrometers thickness was obtained by performing the same operation as Example 1 except having changed to. After plating, the boundary of the plated particles could not be identified as a result of observation with a scanning electron microscope at a magnification of 5000 times.
Separately, the thickness of the plating film thickened on a 10 cm square sample under the same conditions was calculated from the volume of the plating film calculated using the average film thickness obtained from the microscopic observation of the cross section and the film calculated from the weight difference before and after plating. It was 7.3 when the density was calculated | required from the weight.
[0049]
Example 3
The plating solution is as follows (d):

A plating film having a thickness of 2 μm was obtained by performing the same operation as in Examples 1 and 2, except that
After plating, the boundary of the plated particles could not be identified as a result of observation with a scanning electron microscope at a magnification of 5000 times.
Separately, the thickness of the plating film thickened on a 10 cm square sample under the same conditions was calculated from the volume of the plating film calculated using the average film thickness obtained from the microscopic observation of the cross section and the film calculated from the weight difference before and after plating. It was 7.3 when the density was calculated | required from the weight.
[0050]
Example 4
The plating solution is as follows (e):

A plating film having a thickness of 2 μm was obtained by performing the same operation as in Examples 1, 2 and 3, except that
After plating, the boundary of the plated particles could not be identified as a result of observation with a scanning electron microscope at a magnification of 5000 times.
[0051]
Example 5
Using copper foil as the negative electrode current collector, 1 A / dm in alkaline electrolytic degreasing solution ² Electrolytic degreasing was performed for 1 minute, washed with water, and then immersed in a 5% aqueous methanesulfonic acid solution for 30 seconds for activation. After washing it with water, the following plating solution (f):

And using a platinum-plated titanium insoluble anode and a current density of 6 A / dm. ² Was plated to obtain a 2 μm thick plating film.
After plating, the boundary of the plated particles could not be identified as a result of observation with a scanning electron microscope at a magnification of 3000 times.
Separately, the thickness of the plating film thickened on a 10 cm square sample under the same conditions was calculated from the volume of the plating film calculated using the average film thickness obtained from the microscopic observation of the cross section and the film calculated from the weight difference before and after plating. It was 7.3 when the density was calculated | required from the weight.
[0052]
Comparative Example 2
The following plating solution (g):
Plating solution (g)
Potassium pyrophosphate 178g / l
Potassium iodide 332 g / l
Stannous chloride (as divalent tin) 23g / L
Silver iodide (as silver) 0.5g / L
pH (adjusted with KOH) 8.9
And the cathode current density during plating is 1 A / dm. ² A plating film having a thickness of 2 μm was obtained by performing the same operation as in Example 1 except that.
After plating, observation with a scanning electron microscope at an enlargement magnification of 3000 shows that the boundaries of the plated particles can be clearly identified, and particles with a diameter of approximately 2 μm and particles with a diameter of approximately 1 μm coexisting with volcanic holes. Was.
[0053]
Example 6
Using copper foil as the negative electrode current collector, 1 A / dm in alkaline electrolytic degreasing solution ² Electrolytic degreasing was performed for 1 minute, washed with water, and then immersed in a 5% aqueous methanesulfonic acid solution for 30 seconds for activation. After washing it with water, according to a conventional method, a nickel base plating of 3 μm was applied from a watt bath, followed by washing with water, and the following plating solution (h):
Plating solution (h)
Sulfosuccin tin (as divalent tin) 40g / L
Zinc sulfosuccinate (as zinc) 10g / L
Lead sulfosuccinate (as lead) 5mg / L
Cadmium sulfate (as cadmium) 10mg / L
Arsenous acid (as arsenic) 5mg / L
Sulfosuccinic acid 100g / L
Sodium gluconate 20g / L
Hydroquinone 8g / L
Ethanol 10g / L
Surfactant (alkyroyl sarcosinate) 1g / L
The anode was immersed in 4N purity tin and zinc and alloyed, and the current density was 20 A / dm. ² Was plated to obtain a 2 μm thick plating film.
After plating, the boundary of the plated particles could not be identified as a result of observation with a scanning electron microscope at a magnification of 5000 times.
[0054]
Example 7
Using a copper net as a negative electrode current collector, 1 A / dm in an alkaline electrolytic degreasing solution ² Electrolytic degreasing was performed for 1 minute, washed with water, and then immersed in a 5% aqueous methanesulfonic acid solution for 30 seconds for activation. After washing it with water, the following plating solution (i):
Plating solution (i)
Tin methanesulfonate (as divalent tin) 30g / l
Indium sulfamate (as indium) 2g / L
Methanesulfonic acid 80g / L
Gallic acid 5mg / L
Ethanol 5g / L
Surfactant (polyoxyethylene alkylamine) 10g / L
A current density of 50 A / dm using an anode which is immersed in 4N purity tin and indium and alloyed. ² Thus, a plating film having a thickness of 2 μm was obtained.
After plating, the boundary of the plated particles could not be identified as a result of observation with a scanning electron microscope at a magnification of 5000 times.
[0055]
Example 8
A nickel porous body is used as a negative electrode current collector, and 1 A / dm in an alkaline electrolytic degreasing solution. ² Electrolytic degreasing was performed for 1 minute, washed with water, and then immersed in a 5% aqueous methanesulfonic acid solution for 30 seconds for activation. After washing it with water, the following plating solution (j):
Plating solution (j)
Phenol sulfonate tin (as divalent tin) 20g / L
Lead phenol sulfonate (as lead) 10g / L
Phenolsulfonic acid 100g / L
3,4,5-trihydroxybenzoic acid 0.1 g / L
Ethanol 5g / L
Surfactant (2-alkyl-N-carboxymethyl-N-hydroxyethyl
Imidazolinium betaine) 5g / L
2-mercaptobenzothiazole 0.01 g / L
Formalin 3g / L
A current density of 8 A / dm using an anode made by melting and alloying 3N purity tin and lead. ² Was plated to obtain a 2 μm thick plating film.
After plating, the boundary of the plated particles could not be identified as a result of observation with a scanning electron microscope at a magnification of 5000 times.
Separately, the thickness of the plating film thickened under the same conditions on a 10 cm square sample was calculated from the volume of the plating film calculated using the average film thickness obtained from the cross-sectional observation of the cross section, and the film calculated from the weight difference before and after plating. The density obtained from the weight was 8.1.
[0056]
Example 9
Using copper punching metal as the negative electrode current collector, 1 A / dm in alkaline electrolytic degreasing solution ² Electrolytic degreasing was performed for 1 minute, washed with water, and then immersed in a 5% aqueous methanesulfonic acid solution for 30 seconds for activation. After washing it with water, the following plating solution (k):

And using a platinum-plated titanium insoluble anode and a current density of 10 A / dm. ² Was plated to obtain a 2 μm thick plating film.
After plating, it was observed with a scanning electron microscope at a magnification of 5000. As a result, the average particle size of the plated particles was about 0.3 μm.
[0057]
Example 10
A copper nonwoven fabric is used as the negative electrode current collector, and 1 A / dm in an alkaline electrolytic degreasing solution. ² Electrolytic degreasing was performed for 1 minute, washed with water, and then immersed in a 5% aqueous methanesulfonic acid solution for 30 seconds for activation. After washing it with water, the following plating solution (l):

And using a platinum-plated titanium insoluble anode and a current density of 6 A / dm. ² Was plated to obtain a 2 μm thick plating film.
After plating, the boundary of the plated particles could not be identified as a result of observation with a scanning electron microscope at a magnification of 5000 times.
[0058]
Example 11
Using copper foil as the negative electrode current collector, 1 A / dm in alkaline electrolytic degreasing solution ² Electrolytic degreasing was performed for 1 minute, washed with water, and then immersed in a 5% aqueous methanesulfonic acid solution for 30 seconds for activation. After washing it with water, the following plating solution (m):

And using a platinum-plated titanium insoluble anode and a current density of 15 A / dm. ² Was plated to obtain a 2 μm thick plating film.
After plating, the boundary of the plated particles could not be identified as a result of observation with a scanning electron microscope at a magnification of 5000 times.
[0059]
Example 12
Using copper foil as the negative electrode current collector, 1 A / dm in alkaline electrolytic degreasing solution ² Electrolytic degreasing was performed for 1 minute, washed with water, and then immersed in a 5% aqueous methanesulfonic acid solution for 30 seconds for activation. After washing it with water, the following plating solution (n):

And using a platinum-plated titanium insoluble anode and a current density of 12 A / dm. ² Was plated to obtain a 2 μm thick plating film.
After plating, it was observed with a scanning electron microscope at a magnification of 5000. As a result, the average particle size of the plated particles was about 0.3 μm.
Separately, the thickness of the plating film thickened on a 10 cm square sample under the same conditions was calculated from the volume of the plating film calculated using the average film thickness obtained from the microscopic observation of the cross section and the film calculated from the weight difference before and after plating. It was 7.3 when the density was calculated | required from the weight.
[0060]
Example 13
Using copper foil as the negative electrode current collector, 1 A / dm in alkaline electrolytic degreasing solution ² The electrode was degreased for 1 minute, washed with water, and immersed in 5% sulfuric acid for 30 seconds for activation. After washing it with water, the following plating solution (o):
Plating solution (o)
Tin sulfate (as divalent tin) 33g / L
Copper sulfate (pentahydrate) 15g / L
Sulfuric acid 98g / L
Cresol sulfonic acid 10g / L
Catechol 3g / L
Ethylene glycol 50g / L
Surfactant (Emulgen B66 (Kao Soap)) 2g / L
Benzalacetone 0.3g / L
And using a platinum-plated titanium insoluble anode and a current density of 6 A / dm. ² Was plated to obtain a 2 μm thick plating film.
After plating, it was observed with a scanning electron microscope at a magnification of 5000. As a result, the average particle size of the plated particles was about 0.3 μm.
[0061]
Example 14
1 A / dm in an alkaline electrolytic degreasing solution using iron foil as a negative electrode current collector ² Electrolytic degreasing was performed for 1 minute, washed with water, and then immersed in a 5% aqueous methanesulfonic acid solution for 30 seconds for activation. After washing with water, according to a conventional method, after applying a copper base plating of 3 μm from a copper sulfate bath, it is washed with water and the following plating solution (p):

And using a platinum-plated titanium insoluble anode and a current density of 6 A / dm. ² Was plated to obtain a 2 μm thick plating film.
After plating, the boundary of the plated particles could not be identified as a result of observation with a scanning electron microscope at a magnification of 5000 times.
[0062]
Battery evaluation
In order to see the performance of the negative electrodes of Examples and Comparative Examples as a single electrode, a coin-type cell having a lithium electrode as a counter electrode was prepared and evaluated. 1 mol / L LiPF ₆ A polypropylene separator impregnated with a 1: 1 mixed electrolyte of propylene carbonate and dimethyl carbonate in which was dissolved was sandwiched between the negative electrode and lithium foil, and this was set in a coin-type cell. The charge / discharge test has a voltage range of 0 to 1 V, 1 mA / cm. ² The current density was.
The table shows the discharge capacity at the first cycle (here, the reaction in which the inserted lithium is desorbed is called discharge) and the discharge capacity maintenance rate at the first cycle at the 100th cycle.
Examples 1 to 14 are examples in which an electrode was prepared using a plating film composed of particles having a particle size of 0.5 μm or less. On the other hand, Comparative Example 1 is a plating film of tin alone as in Example 1, but an example of a plating film having a particle diameter of about 25 μm. Comparative Example 2 is a tin-silver alloy plating as in Example 5. Although it is a film | membrane, it is an example of the plating film | membrane in which the particle | grains about 1 micrometer and 2 micrometers coexisted. In any of the Examples and Comparative Examples, the discharge capacity at the first cycle was higher than that of the current carbon-based material, and it was shown that tin and tin alloy plating are high-capacity negative electrodes.
However, the crystal grain size of the plating film has a great influence on the discharge capacity and cycle characteristics. In the case of a tin-only plating film, the particle diameter is so small that the particle boundary cannot be identified by observation with a scanning electron microscope at a magnification of 5000 times. In Example 1, both the discharge capacity and capacity retention rate at the first cycle showed good values, whereas in Comparative Example 1 where the average particle diameter of the plating film was 25 μm, the discharge at the first cycle It can be seen that both the capacity and the capacity retention ratio are lower than those of Example 1, particularly the capacity retention ratio is remarkably low, and the charge / discharge characteristics do not depend only on the kind of element called tin but greatly depend on the particle diameter.
In Examples 2, 3, and 4 in which trace amounts of lead, antimony, cadmium, arsenic, and thallium were added to the plating bath, the first cycle discharge was more than in Example 1 prepared under the same conditions except for the presence or absence of these trace amount added metals Both the capacity and the capacity retention ratio show good values, and even if these metals are added in a small amount to the plating bath, they contribute to the refinement of crystals and improve the charge / discharge characteristics.
As an example using an alloy plating film, Example 5 shows an example of a tin-silver alloy plating film. In Example 5 which is a film having a small particle diameter, in Comparative Example 2 in which particles of about 1 and 2 μm coexist, although both the discharge capacity at the first cycle and the capacity retention rate showed good values, The discharge capacity at the first cycle was low, and the capacity retention rate was remarkably low.
[0063]
Plating bath life test
In order to industrially produce tin and a tin alloy as a battery negative electrode by a plating method, considering the cost and workability, it is essential that the life of the plating bath is long. Newly constructed plating bath with current density of 1 A / dm ² 50 Ahr / L of continuous plating was performed, and the appearance of the plating bath after 10 Ahr / L of electrolysis was evaluated. Example 1 containing all of stoichiometrically equivalent or higher amount of acid or complexing agent, antioxidant, alcohol or ketone as an essential component contributing to stabilization of the plating bath In -14, the plating bath was stable even after electrolysis of 50 Ahr / L, and a plating film equivalent to the initial stage of the bath was obtained, but in Comparative Examples 1 and 2 lacking those components, after electrolysis of 10 Ahr / L, Precipitation and turbidity occurred, the appearance of the plating generated dendrites, and the particles became rough.
[0064]
[Table 1]
table

[0065]
【The invention's effect】
As described above, according to the present invention, by using a fine tin or tin alloy plating film of crystals deposited from a tin or tin alloy plating bath having a limited bath composition as an electrode material for a secondary battery, A secondary battery electrode having excellent charge / discharge characteristics can be manufactured, and a secondary battery having excellent charge / discharge characteristics can be manufactured and provided.

Claims (27)

An electrode material for a secondary battery in which a tin or tin alloy plating film deposited from a tin or tin alloy plating bath is formed on one side or both sides of a current collector, the plating film having an average particle size of less than 0.5 μm The plating particles having a diameter form a substantially continuous film, and the plating film has at least the following components (i) to (v):
(I) a divalent tin ion of 5 g / L or more and 200 g / L or less,
(Ii) One or more acids or complexing agents that form a water-soluble salt or complex with a divalent tin ion in a total stoichiometric equivalent or more with respect to the divalent tin ion ,
(Iii) one or more antioxidants having a total concentration of at least 1 ppm or more,
(Iv) 0.5 g / L or more and 200 g / L or less of an aliphatic ketone having 6 or less carbon atoms or one or more of aliphatic branched or unbranched alcohols having 6 or less carbon atoms,
(V) Deposited from a tin or tin alloy plating bath containing one or more organic additives selected from surfactants, smoothing additives, semi-brightening agents and brightening agents as essential components There is an electrode material for a secondary battery. The plated particles having an average particle size of less than 0.5 μm are small enough that the boundaries of the particles cannot be substantially identified when observed from the surface direction at a magnification of 3000 to 5000 with a scanning electron microscope. The electrode material for a secondary battery according to claim 1, wherein Acids or complexing agents that form water-soluble salts or complexes with divalent tin ions in the tin or tin alloy plating bath are the following (ii) to (reference):
(Ii): One or more sulfonic acids selected from sulfuric acid, hydrochloric acid, borohydrofluoric acid, silicofluoric acid, sulfamic acid, acetic acid, 1-hydroxyethane-1,1-diphosphonic acid, phosphoric acid and condensed phosphoric acid ,
(Ii): One or more sulfonic acids selected from the aliphatic sulfonic acids represented by the general formula (I) or (II) or the aromatic sulfonic acids represented by the general formula (III),
Formula (I)

[Wherein R ₁ represents a C ₁ -C ₅ alkyl group, X ₁ represents hydrogen, a hydroxyl group, an alkyl group, an aryl group, an alkylaryl group, a carboxyl group, or a sulfonic acid group, and any alkyl group] N may be an integer from 0 to 3. General formula (II)

[Wherein R ₂ represents a C _{1 to} C ₅ alkyl group or a C _{1 to} C ₃ alkylene group, and an alkylene group may have a hydroxyl group at any position, and X ₂ represents chlorine or (and) fluorine. Represents halogen, the number of substitutions of chlorine or (and) fluorine substituted with hydrogen of the alkyl group or alkylene group represents from 1 to all hydrogens coordinated to the alkyl group or alkylene group and saturated substitution The halogen species selected can be one or two, and the chlorine or fluorine substituent can be in any position. Y represents hydrogen or a sulfonic acid group, and the number of substitution of the sulfonic acid group represented by Y is in the range of 0-2. ]
General formula (III)

[Wherein X ₃ represents a hydroxyl group, an alkyl group, an aryl group, an alkylaryl group, an aldehyde group, a carboxyl group, a nitro group, a mercapto group, a sulfonic acid group or an amino group, or two X ₃ represent a benzene ring Together with n to form a naphthalene ring, m is an integer of 0-3. ]
(Reference): An acid or complexing agent having at least one carboxyl group and further selected from one or more groups selected from a carboxyl group, a hydroxyl group, a sulfonic acid group, an amino group, and a thiol group Or it is 2 or more types, The electrode material for secondary batteries of Claim 1 or 2. The aliphatic or aromatic sulfonic acid in the tin or tin alloy plating bath is one or more selected from methanesulfonic acid, 2-propanolsulfonic acid, phenolsulfonic acid, trifluoromethanesulfonic acid or cresolsulfonic acid The electrode material for a secondary battery according to claim 3 , wherein The antioxidant in the tin or tin alloy plating bath is one selected from substituted or unsubstituted aromatic mono-, di- or triphenols or (ro) aliphatic polyhydroxy compounds selected from the following general formula (ii) Or it is 2 or more types, The electrode material for secondary batteries in any one of Claims 1-4:
General formula (I)

[However, X represents hydrogen or a hydroxyl group, and may be the same or different, and n represents an integer of 1 to 3. At least one of X is a hydroxyl group. Y is one or more selected from hydrogen, methyl group, ethyl group, methoxy group, ethoxy group, carboxyl group, sulfonic acid group or amino group, and may be the same or different, and m is 6- It is an integer of n. The bonding position on the benzene ring of X and Y is not limited. However, the compound which can take the said structure by tautomerism is included. ]
A substituted or unsubstituted aromatic mono-, di- or triphenol represented by
(B) Aliphatic polyhydroxy compounds. The aliphatic branched or unbranched alcohol having 6 or less carbon atoms in the tin or tin alloy plating bath is represented by the following general formulas (A) to (C):
General formula (b)

[However, n is an integer greater than m and 6 or less, and m represents an integer of 1 or 2. X is hydrogen or a hydroxyl group, and may be the same or different, and at least one of X is a hydroxyl group. The position of the carbon to which X is bonded is not limited, and the carbon chain may be linear or branched. ]
A chain saturated aliphatic mono- or dialcohol represented by:
General formula (b)

[However, n is an integer greater than m and 6 or less, and m represents an integer of 1 or 2. X is hydrogen or a hydroxyl group, and may be the same or different, and at least one of X is a hydroxyl group. The carbon chain to which X is bonded is not limited, and the carbon chain may be branched. ]
A cyclic saturated aliphatic mono- or dialcohol represented by
General formula (c)

[However, n is an integer greater than m and 6 or less, and m represents an integer of 1 or 2. l represents an integer of n-2 or less. X is hydrogen or a hydroxyl group, and may be the same or different, and at least one of X is a hydroxyl group. The carbon chain to which X is bonded is not limited, and the carbon chain may be branched. O represents etheric oxygen and is located between two carbons, but the position is not limited. ]
The electrode material for secondary batteries according to any one of claims 1 to 5, which is an alcohol represented by a chain-like saturated aliphatic mono- or dialcohol having an ether bond represented by: The aliphatic ketone having 6 or less carbon atoms or the aliphatic alcohol having 6 or less carbon atoms in the tin or tin alloy plating bath is acetone, methyl ethyl ketone, methanol, ethanol, n-propanol, i-propanol, n-butanol and t. The electrode material for a secondary battery according to any one of claims 1 to 6, wherein the electrode material is one or more selected from butanol. The secondary battery according to any one of claims 1 to 7 , wherein the surfactant in the tin or tin alloy plating bath is one or more selected from nonionic, anionic, amphoteric and cationic systems. Electrode material. The tin or tin alloy plating bath further for a secondary battery according to any one of claims 1-8 containing 0.1 g / L or more 20 g / L or less of tetravalent tin ions or tetravalent tin compound Electrode material. The tin alloy plating bath is an alloy plating bath of tin with one or more alloying metals selected from atomic numbers 26 to 33, 44 to 51 excluding tin, or 75 to 82 excluding mercury. The electrode material for a secondary battery according to any one of claims 1 to 9 . Wherein the content of alloying the plating bath of metal, the electrode material for a secondary battery according to any one of claims 1 to 10 in a total of 20ppm or more to the tin. The said tin or tin alloy plating film is a total of one or more metals selected from the group IIB, IIIB, IVB and VB metals excluding mercury among the alloyed metals according to claim 10. The electrode material for a secondary battery according to any one of claims 1 to 11 , which is contained in an amount of 20 ppm or more. The tin or thickness of the tin alloy plating film, the electrode material for a secondary battery according to any one of claims 1 to 12, which is less than 0.01 [mu] m 5 [mu] m. The electrode material for a secondary battery according to any one of claims 1 to 12 , wherein a thickness of the tin or tin alloy plating film is 5 µm or more and 500 µm or less. The electrode material for a secondary battery according to any one of claims 1 to 14 , wherein a density of the tin or tin alloy plating film is more than 6.6 g / cm ³ and not more than 8.5 g / cm ³ . When depositing a plating film from the tin or tin alloy plating bath, the following (a) to (c):
(A) an insoluble anode,
(B) a tin anode having a purity of 3N or higher,
(C) any of claims 1 to 15, characterized in that the anode is used which is selected from any of the 3N or more purity tin and 3N or more purity tin alloy anode of the alloying metal is created by melting of An electrode material for a secondary battery as described above. The electrode material for a secondary battery according to claim 16 , wherein the tin having a purity of 3N or more is a tin having a purity of 4N or more. When precipitating the plated film from the tin or tin alloy plating bath, the cathode current density, claim 1-17, characterized in that a 0.1 A / dm ² or more 100A / dm ² or less in the range The electrode material for secondary batteries as described in 2. When precipitating the plated film from the tin or tin alloy plating bath, the cathode current density, to any one of claims 1 to 17, characterized in that a 5A / dm ² to more than 100A / dm ² or less in the range The electrode material for secondary batteries as described. The method of carrying out one or more of treatments selected from electrolytic degreasing, pickling or activation as a pretreatment when depositing a plating film from the tin or tin alloy plating bath. electrode material for a secondary battery according to any one of 1-19. When depositing a plating film from the tin or tin alloy plating bath, an aqueous solution in which one or more of an acid, a complexing agent, a tin salt, an antioxidant, or an alloyed metal salt is dissolved in advance is used in the plating bath. 21. The electrode material for a secondary battery according to any one of claims 1 to 20 , further comprising a bath preparation method and / or a concentration management method for a plating bath used for the bath preparation and / or component replenishment. When depositing a plating film from the tin or tin alloy plating bath, one or more of the antioxidant or the organic additive is preliminarily added to an aliphatic ketone having 6 or less carbon atoms or 6 or less carbon atoms. A plating bath erection method and / or a concentration control method using a solution of an aliphatic branched or unbranched alcohol or a solution dissolved in a solvent containing them as a basin for the plating bath or (and) replenishing components. The electrode material for a secondary battery according to any one of claims 1 to 21 , Rechargeable battery electrode produced by using the electrode material according to any one of claims 1 to 22. The secondary battery electrode according to claim 23 , wherein the current collector is copper, nickel, or iron. The secondary battery electrode according to claim 24 , wherein the current collector is a plate-like body, a porous body, a foam, a screen, a net, an expanded body, a punched body, a nonwoven fabric, or a sintered body. A secondary battery comprising at least a negative electrode, a positive electrode, and an electrolyte, wherein the electrode is a secondary battery electrode according to any one of claims 23 to 25 . The secondary battery according to claim 26 , wherein the secondary battery electrode is a negative electrode of a lithium secondary battery.