本發明係關於用於將鋰離子電池且尤其撓性軟包型電池中之電極及隔板黏著在一起之官能連結層黏合劑。該黏合劑係含有均勻分佈於共聚物中之低含量黏著促進單體單元的共聚物或藉由低分子量官能聚合物鏈轉移劑改質之聚亞乙烯基均聚物或共聚物。 「共聚物」用於指具有兩個或更多個不同單體單元之聚合物。「聚合物」用於指均聚物及共聚物二者。聚合物可為直鏈、具支鏈、星形梳狀、嵌段或任何其他結構。聚合物可為均質、異質的，且可具有共單體單元之梯度分佈。所引用之所有參考文獻均以引用的方式併入本文中。如本文所用，除非另外闡述，否則百分比將意指重量%。除非另外陳述，否則分子量係重量平均分子量，如藉由GPC使用聚甲基丙烯酸甲酯標準物量測。在其中聚合物含有一些交聯且由於不溶性聚合物分數而不能應用GPC之情形中，使用可溶性部分/凝膠部分或自凝膠萃取後之可溶性部分分子量。結晶度及熔融溫度係藉由DSC如ASTM D3418中所述在10℃/min之加熱速率下量測。熔融黏度係根據ASTM D3835在230℃下量測，以在100 Sec^(-1)下之千泊(k Poise)表示。共聚物
本發明之連結層主要係由80至99莫耳%且較佳85至98.8莫耳%之一或多種氟單體構成之氟共聚物，該等氟單體包括(但不限於)二氟亞乙烯(VDF)、四氟乙烯(TFE)、乙烯-四氟乙烯(ETFE)及/或氯三氟乙烯(CTFE)。與非氟聚合物相比，氟聚合物之化學惰性提供長電池壽命。在較佳實施例中，共聚物含有80至99莫耳% VDF單體單元。 共聚物亦包括一或多種基於共聚物計自0.2至20莫耳%、較佳0.5至15莫耳%且最佳1至10莫耳%之低含量的「黏著」共聚單體。更低之含量不會導致超過均聚物之黏著改良。具有較高含量共聚單體之共聚物會太軟且黏，此使得其更有可能在電池環境中溶解。黏著共聚單體之存在提供具有較氟均聚物更好之黏著的共聚物。 隨機共聚物係最有用的，此乃因此提供黏著劑基團之更佳分佈，導致更佳之黏著、低膨脹及低可提取性(極少或不溶於電解質中)。本發明亦涵蓋接枝共聚物。 有用共聚單體通常含有極性基團，或具有高表面能。有用共聚單體之實例包括(但不限於)以下中之一或多者：乙酸乙烯酯、2,3,3,3-四氟丙烯(HFO-1234yf)、2,3,3 三氟丙烯、六氟丙烯(HFP)及2-氯-1,1-二氟乙烯(R-1122)。HFP提供良好黏著，但會具有降低之耐溶劑性。磷酸酯(甲基)丙烯酸酯、(甲基)丙烯酸及羥基官能基(甲基)丙烯酸共聚單體亦可用作共聚單體。 可與一或多種氟單體組合使用之其他有用黏著共聚單體包括(但不限於)以下中之一或多種： A) 乙烯基烷基酸，其具有共聚單體(M1)：其中R1、R2及R3係氫或鹵素(F、Cl、Br、I)。 其中R4係C1至C16直鏈烷基、具支鏈烷基、芳基或環烷基、C1至C16氟化直鏈烷基、具支鏈烷基、芳基或環烷基、六氟環氧丙烷之寡聚物或四氟環氧乙烷之寡聚物。 其中R5係羧酸(C(O)OH)、鹼金屬羧酸鹽(COO-
M+
)、銨羧酸鹽(COO-
NH4 +
)、烷基銨羧酸鹽(COO-
N(Alk)4 +
)、醇(OH)、醯胺(C(O)NH2
)、二烷基醯胺(C(O)NAlk2
)、磺酸(S(O)(O)OH)、鹼金屬磺酸鹽(S(O)(O)O-
M+
)、銨磺酸鹽(S(O)(O)O-
NH4 +
)、烷基銨磺酸鹽(S(O)(O)O-
N(Alk)4 +
)。 B) 乙烯基烷基酸，其具有以下式M2：其中：R1、R2及R3係氫或鹵素(F、Cl、Br、I)； 其中：R4及R5單獨地係氫、C1至C16直鏈烷基、具支鏈烷基、芳基或環烷基、C1至C16氟化直鏈烷基、具支鏈烷基、芳基或環烷基、六氟環氧丙烷之寡聚物或四氟環氧乙烷之寡聚物、鹼金屬離子(Li+
、Na+
、K+
、Rb+
、Cs+
)、銨離子(NH4 +
)或烷基銨(NAlk4 +
) C) 官能丙烯酸酯，其具有共聚單體(M3)：其中R1、R2及R3係氫或鹵素(F、Cl、Br、I)； 其中R4係鍵、C1至C16直鏈烷基、具支鏈烷基、芳基或環烷基、C1至C16氟化直鏈烷基、具支鏈烷基、芳基或環烷基、六氟環氧丙烷之寡聚物或四氟環氧乙烷之寡聚物。 其中R5係羧酸(C(O)OH)、鹼金屬羧酸鹽(COO-
M+
)、銨羧酸鹽(COO-
NH4 +
)、烷基銨羧酸鹽(COO-
N(Alk)4 +
)、醇(OH)、醯胺(C(O)NH2
)、二烷基醯胺(C(O)NAlk2
)、磺酸(S(O)(O)OH)、鹼金屬磺酸鹽(S(O)(O)O-
M+
)、銨磺酸鹽(S(O)(O)O-
NH4 +
)、烷基銨磺酸鹽(S(O)(O)O-
N(Alk)4 +
)、環氧化物、碳酸C1至C16烷基酯或環烷基酯。 在一個實施例中，發現兩種或更多種不同的官能丙烯酸酯提供增加的黏著。儘管不欲受任何具體理論約束，但據信不同官能基(例如醇及酸官能基)可反應或交聯以形成酯基團。該兩種或更多種不同的官能基較佳存在於相同三元共聚物中，但亦可為兩種或更多種不同共聚物之摻合物。 D) 官能丙烯醯胺，其具有共聚單體(M4)：其中：R1、R2及R3係氫或鹵素(F、Cl、Br、I)。 其中：R4及R5單獨地係氫、C1至C16直鏈烷基、具支鏈烷基、芳基或環烷基、C1至C16氟化直鏈烷基、具支鏈烷基、芳基或環烷基、六氟環氧丙烷之寡聚物或四氟環氧乙烷之寡聚物。 其中：R5及R6單獨地係羧酸(C(O)OH)、鹼金屬羧酸鹽(COO-
M+
)、銨羧酸鹽(COO-
NH4 +
)、烷基銨羧酸鹽(COO-
N(Alk)4 +
)、醇(OH)、醯胺(C(O)NH2
)、二烷基醯胺(C(O)NAlk2
)、磺酸(S(O)(O)OH)、鹼金屬磺酸鹽(S(O)(O)O-
M+
)、銨磺酸鹽(S(O)(O)O-
NH4 +
)、烷基銨磺酸鹽(S(O)(O)O-
N(Alk)4 +
)、酮(C(O))、或乙醯丙酮酸鹽(C(O)-CH2-C(O))或膦酸鹽(P(O)(OH)2)、鹼金屬或銨膦酸鹽 E) 碳酸酯，其含有共聚單體M5：其中：R1、R2及R3係氫或鹵素(F、Cl、Br、I)。 其中：R4係鍵、C1至C16直鏈烷基、具支鏈烷基、芳基或環烷基、C1至C16氟化直鏈烷基、具支鏈烷基、芳基或環烷基。 其中：R5係C1至C16環烷基、C1至C16氟化環烷基，其含有碳酸酯基作為環狀基團之一部分。 F) 乙烯基醚，其具有共聚單體(M6)：其中：R1、R2及R3係氫或鹵素(F、Cl、Br、I)。 其中：R4係C1至C16直鏈烷基、具支鏈烷基、芳基或環烷基、C1至C16氟化直鏈烷基、具支鏈烷基、芳基或環烷基、六氟環氧丙烷之寡聚物或四氟環氧乙烷之寡聚物。 其中：R5係羧酸(C(O)OH)、鹼金屬羧酸鹽(COO-
M+
)、銨羧酸鹽(COO-
NH4 +
)、烷基銨羧酸鹽(COO-
N(Alk)4 +
)、醇(OH)、醯胺(C(O)NH2
)、二烷基醯胺(C(O)NAlk2
)、磺酸(S(O)(O)OH)、鹼金屬磺酸鹽(S(O)(O)O-
M+
)、銨磺酸鹽(S(O)(O)O-
NH4 +
)、烷基銨磺酸鹽(S(O)(O)O-
N(Alk)4 +
)、酮(C(O))、乙醯丙酮酸鹽(C(O)-CH2-C(O)) G) 烯丙基氧基化合物，其具有共聚單體(M7)：其中：R1、R2及R3係氫或鹵素(F、Cl、Br、I)。 其中：R4係C1至C16直鏈烷基、具支鏈烷基、芳基或環烷基、C1至C16氟化直鏈烷基、具支鏈烷基、芳基或環烷基、六氟環氧丙烷之寡聚物或四氟環氧乙烷之寡聚物。 其中：R5係羧酸(C(O)OH)、鹼金屬羧酸鹽(COO-
M+
)、銨羧酸鹽(COO-
NH4 +
)、烷基銨羧酸鹽(COO-
N(Alk)4 +
)、醇(OH)、醯胺(C(O)NH2
)、二烷基醯胺(C(O)NAlk2
)、磺酸(S(O)(O)OH)、鹼金屬磺酸鹽(S(O)(O)O-
M+
)、銨磺酸鹽(S(O)(O)O-
NH4 +
)、烷基銨磺酸鹽(S(O)(O)O-
N(Alk)4 +
)、酮(C(O))、或乙醯丙酮酸鹽(C(O)-CH2-C(O))、或膦酸鹽(P(O)(OH)2)、鹼金屬或銨膦酸鹽。官能鏈轉移劑
本發明之官能鏈轉移劑係低分子量官能聚合物。低分子量意指聚合物具有小於或等於1,000且較佳小於800之聚合度。在較佳實施例中，如藉由GPC所量測，聚合鏈轉移劑之重量平均分子量為20,000 g/莫耳或以下、更佳15,000 g/莫耳且更佳小於10,000 g/莫耳。在一個實施例中，重量平均分子量小於5,000 g/莫耳。低分子量官能鏈轉移劑係具有兩個或更多個單體單元且較佳三個或更多個單體單元之聚合物或寡聚物。 如發明所用之官能聚合鏈轉移劑意指含有一或多個不同官能基之低分子量聚合物鏈轉移劑。鏈轉移劑具有式-(CH2-CH2)y-X-R， 其中y係介於2至1000之間之整數，X係鏈接基團，其包括(但不限於)共價或離子鍵、烷基、烯烴、炔烴、經取代烷基、經取代烯烴、芳基、酯、醚、酮、胺、醯亞胺、醯胺、有機矽烷，且R係官能基。 官能基(R)提供官能性，且可藉由官能單體(作為唯一單體或作為共聚單體)之聚合來提供。官能性亦可藉由後聚合反應或接枝來添加。有用官能基包括(但不限於)羧酸基、羥基、矽氧烷基、醚基、酯基、磺酸基、磷酸基、膦酸基、硫酸基、醯胺基及環氧基、或其混合物。 除本發明之低分子量官能鏈轉移劑以外，亦可以低含量添加通常用於氟聚合物聚合之其他鏈轉移劑以提供期望分子量。 一般而言，將一部分或所有鏈轉移劑添加至初始裝料，以防止形成不溶於極性溶劑且作為凝膠存在之極高分子量聚合物。然後可在剩餘之聚合期間連續或以小份添加剩餘鏈轉移劑。 本發明之官能氟聚合物可視情況與相容氟聚合物及非氟聚合物摻和以形成最終連結層組合物。 現將關於本發明之特定較佳實施例一般地闡述實踐本發明之方式，即，在水性乳化聚合中使用非氟化乳化劑作為主要乳化劑製備基於聚二氟亞乙烯之共聚物。儘管已關於PVDF共聚物一般地說明本發明，但熟習此項技術者應認識到，類似的聚合及應用技術可應用於氟化單體之其他共聚物的製備。儘管非氟化表面活性劑係較佳的，但本發明亦預期氟表面活性劑之使用。聚合製程
關於製備本發明氟聚合物之較佳方法，初始將去離子水、至少一種表面活性劑(通常基於單體之量以0.01至小於2.0重量%之含量)、較佳非氟化表面活性劑及一部分鏈轉移劑引入至反應器中，隨後脫氧。反應器達到期望溫度後，將二氟亞乙烯(VDF)單體及可選共聚單體添加至反應器。端視共聚單體之反應性而定，不將共聚單體添加至初始裝料，將一部分或所有共聚單體添加至初始裝料。然後可在剩餘之聚合期間連續或以小份添加剩餘共聚單體，以在最終聚合物中與VDF達到預定比率。實施添加共聚單體之方式以提供共聚單體單元於共聚物中之相當均勻分佈。然後，將自由基起始劑以適宜流速引入至反應器以維持適當聚合速率。一旦反應已開始或在反應開始的同時，既將低分子量官能聚合物鏈轉移劑及氟單體以期望比率連續進給至反應器中。達到期望聚合物固體含量後，可停止單體之進料，同時較佳維持起始劑之裝料以消耗反應器中之任何殘餘單體。然後可停止起始劑裝料，反應器壓力下降且使反應器冷卻。可將未反應單體排出並藉助排放口或其他收集構件收集氟聚合物分散液。然後可使用標準分離技術(例如烘箱乾燥、噴霧乾燥、剪切或酸凝固隨後乾燥等)分離氟聚合物分散液，或官能氟聚合物可保持乳液形式用於後續應用。所形成之一次官能氟聚合物粒子具有小於500 nm、較佳在20至400 nm範圍內且最佳在50至300 nm範圍內之平均粒徑。添加劑
本發明之連結層組合物可視情況包括基於共聚物計0至15重量%且較佳0.1至10重量%添加劑，添加劑包括(但不限於)增稠劑、pH調節劑、防沉劑、表面活性劑、潤濕劑、填充劑、消泡劑及短效黏著促進劑。金屬氧化物(例如氧化鋁、二氧化矽、氧化鋅、氧化鋇及氧化鈦)係較佳添加劑。製程
本發明之鋰離子電池連結層可藉由若干方式添加至電池堆疊中。在一個實施例中，藉由乳化聚合產生PVDF共聚物，如上所述。然後將添加劑(若有)添加至乳液中，或將乳液乾燥並將添加劑乾摻和於PVDF共聚物中以形成連結層組合物。 所得共聚物連結層組合物可藉由此項技術已知之任何方法(例如藉由吹氣模製、溶液澆鑄或薄膜擠出製程)轉換為自支撐膜。該膜之厚度小於10微米、較佳小於7微米且最佳約5微米或甚至更小。共聚物連結層組合物亦可在載體膜上形成為膜。自支撐薄膜連結層可放置於隔板與電極之間，隨後熱層壓。載體膜上之連結層膜可轉移至電極或隔板上，去除載體膜，然後將隔板或電極置於連結層膜頂部，然後將堆疊熱層壓。 或者，多狹縫式模頭澆鑄可與隔板、陽極或陰極之表面上之連結層一起使用以降低生產成本。 在另一實施例中，使用此項技術中已知之方法(包括(但不限於)凹版、浸漬或輥塗佈及噴墨印刷)將連結層組合物作為溶劑或較佳水性塗料塗佈於隔板或電極中之任一者上，乾燥並抵靠電極放置。為了最佳性能，如此形成之塗層將為多孔塗層。自水性分散液形成之連結層塗層產生粒徑小於500 nm之離散、官能氟聚合物粒子之層。 在較佳實施例中，連結層置於陰極上。 熱層壓係將堆疊(陽極/連結層/隔板/連結層/陰極)黏著在一起之較佳方式。在50至90℃且較佳60-80℃下施加熱可幫助黏著。在組裝期間用電解質潤濕經塗佈隔板亦可幫助良好黏著。 在此說明書內，已經以能夠寫出清楚且簡潔之說明書的方式闡述實施例，但期望且應瞭解，實施例可以各種方式組合或分開而不脫離本發明。舉例而言，應瞭解，本文所述之所有較佳特徵可適用於本文所述之本發明之所有態樣。 本發明之態樣包括： 1. 一種鋰離子電池，其包含： a) 陽極； b) 陰極； c) 隔板； 其中該隔板藉由官能聚二氟亞乙烯連結層黏著至該陰極、該陽極或該陽極與該陰極二者，該官能聚二氟亞乙烯係選自：a) 共聚物，其包含0.2至20重量%、較佳0.5至15重量%且更佳1至10重量%之至少一種黏著促進共聚單體，b) 經改質氟聚合物，其包含0.1至25重量%、較佳1.0至15重量%、更佳2.2至10重量%之來自一或多種低分子量聚合官能鏈轉移劑之殘餘官能基，及c) a)與b)之混合物。 2. 如態樣1之鋰離子電池，其中該連結層具有0.5至10微米、較佳0.7至小於5微米且最佳1至4微米之厚度。 3. 如態樣1或2之鋰離子電池，其中該鋰離子電池係軟包型電池。 4. 如態樣1至3中任一者之鋰離子電池，其中該共聚單體包含至少一種選自由以下組成之群之共聚單體：乙酸乙烯酯、HFO-1234yf、HFP、2-氯-1,1-二氟乙烯(R-1122)及磷酸酯(甲基)丙烯酸酯。 5. 如態樣1至4中任一者之鋰離子電池，其中該共聚物係隨機共聚物或接枝共聚物。 6. 如態樣1至5中任一者之鋰離子電池，其中該隔板經水性聚二氟亞乙烯黏合劑組合物塗佈。 7. 如態樣1至6中任一者之鋰離子電池，其中該陽極及/或該陰極經水性聚二氟亞乙烯黏合劑塗佈。 8. 如態樣1至7中任一者之經改質氟聚合物，其中該經改質氟聚合物包含2.2至10重量%之該等殘餘官能基。 9. 如態樣1至8中任一者之經改質氟聚合物，其中該經改質氟聚合物包含一或多個氟聚合物嵌段及一或多個來自一或多種低分子量聚合官能鏈轉移劑之該等殘餘官能基之嵌段。10. 如態樣1至9中任一者之經改質氟聚合物，其中該等殘餘官能基選自由以下組成之群：羧酸基、羥基、矽氧烷基、醚基、酯基、磺酸基、磷酸基、膦酸基、硫酸基、醯胺基、環氧基及其混合物。 11. 一種產生鋰離子電池之方法，其包含使用聚二氟亞乙烯共聚物連結層將隔板黏著至電極的步驟，其中該聚亞乙烯基共聚物包含0.2至20重量%、較佳0.5至15重量%且更佳1至10重量%之至少一種黏著促進共聚單體。 12. 如態樣11之方法，其中該連結層係作為塗層施加至該隔板、該電極或二者，且該電極及隔板係直接接觸放置，其中該聚二氟亞乙烯共聚物連結層經固化。 13. 如態樣11或12之方法，其中該聚二氟亞乙烯共聚物係呈薄連結層片材之形式，該片材直接置於該隔板與該電極之間，隨後熱層壓。 14. 如態樣11至13中任一者之方法，其中該熱層壓係在50至100℃、較佳60至80℃之溫度下發生。 15. 如態樣11至14中任一者之方法，其中該連結層個別地黏著至該電極、該隔板或二者，隨後放置連結層/電極、及/或連結層/隔板直接與相應電極或隔板接觸，之後係熱層壓步驟。 16. 如態樣11至15中任一者之方法，其中該隔板在組裝之前用電解質潤濕。 實例實例 -A
向2加侖不銹鋼反應器中裝填：4000克去離子水及4.0克PLURONIC 31R1 (非氟化非離子表面活性劑，來自BASF)。以72 rpm開始攪拌並將反應器加熱。反應器溫度達到100℃之期望設定點後，將VDF及HFP單體以36之VDF/HFP比率引入至反應器。然後藉由裝填大約400克總單體至反應器中使反應器壓力升至650 psi。反應器壓力穩定後，將75.0克由2.0 wt%過硫酸鉀及6.0 wt % SOKALAN cp-10 (低分子量聚丙烯酸，來自BASF)製得之起始劑溶液添加至反應器以起始聚合。在起始時，HFP與VDF之比率經調整以在進料中達到10% HFP對總單體。進一步添加起始劑溶液之速率亦經調整以獲得並維持大約600克/小時之最終組合VDF及HFP聚合速率。VDF及HPF共聚繼續進行，直至將大約1800克VDF引入反應物質中為止。停止HFP進料，但繼續VDF進料，直至大約2000克VDF進給至反應器為止。停止VDF進料且使批料在反應溫度下反應以在降低之壓力下消耗殘餘單體。20分鐘後，停止起始劑進料及攪拌並使反應器冷卻，排放並回收膠狀物。藉由重量技術測定所回收膠狀物中之固體且係約34重量%，且根據ASTM方法D-3835在450 °F及100 sec-1
下所量測，熔融黏度為約72 kp。樹脂之熔融溫度係根據ASTMD3418量測且發現為約135℃。重量平均粒徑係藉由NICOMP雷射光散射儀量測且發現為約160 nm。實例 - B
向2加侖不銹鋼反應器中裝填：4000克去離子水及4.0克PLURONIC 31R1 (非氟化非離子表面活性劑，來自BASF)。以72 rpm開始攪拌並將反應器加熱。反應器溫度達到100℃之期望設定點後，將VDF單體引入至反應器，直至藉由裝填大約400克單體至反應器中使反應器壓力達到650 psi為止。反應器壓力穩定後，將75.0克由2.0 wt%過硫酸鉀及6.0 wt % SOKALAN cp-10 (低分子量聚丙烯酸，來自BASF)製得之起始劑溶液添加至反應器以起始聚合。在起始時，HFO-1234yf與VDF之比率經調整以使得在進料中達到2% HFO-1234yf對總單體。進一步添加起始劑溶液之速率亦經調整以獲得維持大約600克/小時之最終VDF聚合速率。VDF及HFO-1234yf共聚繼續進行，直至將大約2000克VDF引入反應物質中為止。停止HFO-1234yf進料，但繼續VDF進料，直至大約2200克VDF進給至反應器為止。停止VDF進料且使批料在反應溫度下反應以在降低之壓力下消耗殘餘單體。20分鐘後，停止起始劑進料及攪拌並使反應器冷卻，排放並回收膠狀物。藉由重量技術測定所回收膠狀物中之固體且係約33重量%，且根據ASTM方法D-3835在450 °F及100 sec-1
下所量測，熔融黏度為約66 kp。樹脂之熔融溫度係根據ASTMD3418量測且發現為約160℃。重量平均粒徑係藉由NICOMP雷射光散射儀量測且發現為約160 nm。應用實例
： 將實例A及B中所形成之官能氟聚合物藉由以下方式施加至陽極或陰極作為連結層： 實例A或B之官能氟聚合物可吹氣模製成2-6微米厚度之自支撐膜。該膜然後在陰極與隔板之間熱層壓。 在替代實施例中，實例A或B之官能氟聚合物可塗佈於電極(陰極或陽極)上，以形成厚度為0.1至5微米、較佳1至3微米之連結層。然後將經塗佈電極置於堆疊中靠近隔板隔膜，並層壓就位。The present invention relates to a functional bonding layer adhesive for adhering electrodes and separators in a lithium-ion battery, especially a flexible soft-pack battery. The adhesive is a copolymer containing a low content of adhesion-promoting monomer units uniformly distributed in the copolymer or a polyvinylidene homopolymer or copolymer modified by a low molecular weight functional polymer chain transfer agent. "Copolymer" is used to refer to polymers having two or more different monomer units. "Polymer" is used to refer to both homopolymers and copolymers. The polymer may be linear, branched, star comb, block, or any other structure. The polymer may be homogeneous, heterogeneous, and may have a gradient distribution of comonomer units. All references cited are incorporated herein by reference. As used herein, unless stated otherwise, percentages will mean% by weight. Unless stated otherwise, molecular weights are weight average molecular weights, as measured by GPC using polymethylmethacrylate standards. In cases where the polymer contains some cross-linking and GPC cannot be applied due to the insoluble polymer fraction, the molecular weight of the soluble fraction / gel fraction or soluble fraction after gel extraction is used. Crystallinity and melting temperature were measured by DSC as described in ASTM D3418 at a heating rate of 10 ° C / min. Melt viscosity is measured according to ASTM D3835 at 230 ° C and expressed in kilopoises at 100 Sec ^ (-1). Copolymer The bonding layer of the present invention is mainly a fluorocopolymer composed of one or more fluoromonomers of 80 to 99 mole% and preferably 85 to 98.8 mole%. These fluorine monomers include (but are not limited to) two Vinylidene fluoride (VDF), tetrafluoroethylene (TFE), ethylene-tetrafluoroethylene (ETFE) and / or chlorotrifluoroethylene (CTFE). Compared to non-fluoropolymers, the chemical inertness of fluoropolymers provides long battery life. In a preferred embodiment, the copolymer contains 80 to 99 mole% VDF monomer units. Copolymers also include one or more low levels of "adhesive" comonomers based on the copolymer from 0.2 to 20 mole%, preferably 0.5 to 15 mole%, and most preferably 1 to 10 mole%. Lower levels will not result in improved adhesion over homopolymers. Copolymers with higher comonomer content will be too soft and sticky, which makes them more likely to dissolve in the battery environment. The presence of cohesive comonomers provides copolymers with better adhesion than fluoro homopolymers. Random copolymers are the most useful, which is therefore to provide a better distribution of the adhesive groups, leading to better adhesion, low swelling and low extractability (little or insoluble in the electrolyte). The invention also encompasses graft copolymers. Useful comonomers often contain polar groups or have high surface energy. Examples of useful comonomers include, but are not limited to, one or more of the following: vinyl acetate, 2,3,3,3-tetrafluoropropene (HFO-1234yf), 2,3,3 trifluoropropene, Hexafluoropropylene (HFP) and 2-chloro-1,1-difluoroethylene (R-1122). HFP provides good adhesion but will have reduced solvent resistance. Phosphate (meth) acrylate, (meth) acrylic, and hydroxy-functional (meth) acrylic comonomers can also be used as comonomers. Other useful cohesive comonomers that can be used in combination with one or more fluoromonomers include, but are not limited to, one or more of the following: A) Vinyl alkyl acid having a comonomer (M1): Among them, R1, R2 and R3 are hydrogen or halogen (F, Cl, Br, I). Among them, R4 is C1 to C16 straight chain alkyl, branched alkyl, aryl or cycloalkyl, C1 to C16 fluorinated straight alkyl, branched alkyl, aryl or cycloalkyl, hexafluoro ring An oligomer of propylene oxide or an oligomer of tetrafluoroethylene oxide. Among them, R5 series carboxylic acid (C (O) OH), alkali metal carboxylate (COO - M + ), ammonium carboxylate (COO - NH 4 + ), alkylammonium carboxylate (COO - N (Alk) 4 + ), alcohol (OH), ammonium (C (O) NH 2 ), dialkyl ammonium (C (O) NAlk 2 ), sulfonic acid (S (O) (O) OH), alkali metal sulfonate Acid salt (S (O) (O) O - M + ), ammonium sulfonate (S (O) (O) O - NH 4 + ), alkylammonium sulfonate (S (O) (O) O - N (Alk) 4 +) . B) a vinyl alkyl acid having the formula M2: Among them: R1, R2 and R3 are hydrogen or halogen (F, Cl, Br, I); Among them: R4 and R5 are independently hydrogen, C1 to C16 linear alkyl, branched alkyl, aryl or naphthenic Group, C1 to C16 fluorinated linear alkyl group, branched alkyl group, aryl or cycloalkyl group, oligomer of hexafluoropropylene oxide or oligomer of tetrafluoroethylene oxide, alkali metal ion ( Li + , Na + , K + , Rb + , Cs + ), ammonium ion (NH 4 + ) or alkylammonium (NAlk 4 + ) C) functional acrylate with comonomer (M3): Where R1, R2, and R3 are hydrogen or halogen (F, Cl, Br, I); where R4 is a bond, C1 to C16 linear alkyl, branched alkyl, aryl or cycloalkyl, C1 to C16 fluorine Straight-chain alkyl, branched-chain alkyl, aryl or cycloalkyl, oligomers of hexafluoropropylene oxide or oligomers of tetrafluoroethylene oxide. Among them, R5 series carboxylic acid (C (O) OH), alkali metal carboxylate (COO - M + ), ammonium carboxylate (COO - NH 4 + ), alkylammonium carboxylate (COO - N (Alk) 4 + ), alcohol (OH), ammonium (C (O) NH 2 ), dialkyl ammonium (C (O) NAlk 2 ), sulfonic acid (S (O) (O) OH), alkali metal sulfonate Acid salt (S (O) (O) O - M + ), ammonium sulfonate (S (O) (O) O - NH 4 + ), alkylammonium sulfonate (S (O) (O) O - N (Alk) 4 +) , epoxide, carbonate, C1 to C16 alkyl esters or cycloalkyl esters. In one embodiment, two or more different functional acrylates were found to provide increased adhesion. Although not wishing to be bound by any particular theory, it is believed that different functional groups, such as alcohol and acid functions, can react or crosslink to form ester groups. The two or more different functional groups are preferably present in the same terpolymer, but may also be a blend of two or more different copolymers. D) Functional acrylamide with comonomer (M4): Among them: R1, R2 and R3 are hydrogen or halogen (F, Cl, Br, I). Among them: R4 and R5 are independently hydrogen, C1 to C16 linear alkyl, branched alkyl, aryl or cycloalkyl, C1 to C16 fluorinated linear alkyl, branched alkyl, aryl or Oligomers of cycloalkyl, hexafluoropropylene oxide or oligomers of tetrafluoroethylene oxide. Among them: R5 and R6 are independently carboxylic acid (C (O) OH), alkali metal carboxylate (COO - M + ), ammonium carboxylate (COO - NH 4 + ), alkylammonium carboxylate (COO - N (Alk) 4 +) , alcohols (OH), Amides (C (O) NH 2) , dialkyl Amides (C (O) NAlk 2) , sulfonic acid (S (O) (O) OH ), Alkali metal sulfonate (S (O) (O) O - M + ), ammonium sulfonate (S (O) (O) O - NH 4 + ), alkylammonium sulfonate (S (O ) (O) O - N (Alk) 4 + ), ketone (C (O)), or acetamidine pyruvate (C (O) -CH2-C (O)) or phosphonate (P (O) (OH) 2), alkali metal or ammonium phosphonate E) carbonate, which contains comonomer M5: Among them: R1, R2 and R3 are hydrogen or halogen (F, Cl, Br, I). Among them: R4 series bond, C1 to C16 straight chain alkyl, branched alkyl, aryl or cycloalkyl, C1 to C16 fluorinated straight alkyl, branched alkyl, aryl or cycloalkyl. Among them: R5 is a C1 to C16 cycloalkyl group and a C1 to C16 fluorinated cycloalkyl group, which contains a carbonate group as a part of the cyclic group. F) Vinyl ether with comonomer (M6): Among them: R1, R2 and R3 are hydrogen or halogen (F, Cl, Br, I). Among them: R4 is C1 to C16 straight chain alkyl, branched alkyl, aryl or cycloalkyl, C1 to C16 fluorinated straight alkyl, branched alkyl, aryl or cycloalkyl, hexafluoro Oligomers of propylene oxide or oligomers of tetrafluoroethylene oxide. Among them: R5 series carboxylic acid (C (O) OH), alkali metal carboxylate (COO - M + ), ammonium carboxylate (COO - NH 4 + ), alkylammonium carboxylate (COO - N (Alk ) 4 + ), alcohol (OH), ammonium (C (O) NH 2 ), dialkyl ammonium (C (O) NAlk 2 ), sulfonic acid (S (O) (O) OH), alkali metal Sulfonate (S (O) (O) O - M + ), ammonium sulfonate (S (O) (O) O - NH 4 + ), alkylammonium sulfonate (S (O) (O) O - N (Alk) 4 + ), ketone (C (O)), acetam pyruvate (C (O) -CH2-C (O)) G) allyloxy compound having comonomer (M7): Among them: R1, R2 and R3 are hydrogen or halogen (F, Cl, Br, I). Among them: R4 is C1 to C16 straight chain alkyl, branched alkyl, aryl or cycloalkyl, C1 to C16 fluorinated straight alkyl, branched alkyl, aryl or cycloalkyl, hexafluoro Oligomers of propylene oxide or oligomers of tetrafluoroethylene oxide. Among them: R5 series carboxylic acid (C (O) OH), alkali metal carboxylate (COO - M + ), ammonium carboxylate (COO - NH 4 + ), alkylammonium carboxylate (COO - N (Alk ) 4 + ), alcohol (OH), ammonium (C (O) NH 2 ), dialkyl ammonium (C (O) NAlk 2 ), sulfonic acid (S (O) (O) OH), alkali metal Sulfonate (S (O) (O) O - M + ), ammonium sulfonate (S (O) (O) O - NH 4 + ), alkylammonium sulfonate (S (O) (O) O - N (Alk) 4 + ), ketone (C (O)), or acetamidine pyruvate (C (O) -CH2-C (O)), or phosphonate (P (O) (OH) 2). Alkali metal or ammonium phosphonate. Functional chain transfer agent The functional chain transfer agent of the present invention is a low molecular weight functional polymer. Low molecular weight means that the polymer has a degree of polymerization of less than or equal to 1,000 and preferably less than 800. In a preferred embodiment, as measured by GPC, the weight average molecular weight of the polymeric chain transfer agent is 20,000 g / mole or less, more preferably 15,000 g / mole and more preferably less than 10,000 g / mole. In one embodiment, the weight average molecular weight is less than 5,000 g / mole. The low molecular weight functional chain transfer agent is a polymer or oligomer having two or more monomer units and preferably three or more monomer units. The functional polymeric chain transfer agent as used in the present invention means a low molecular weight polymer chain transfer agent containing one or more different functional groups. Chain transfer agents have the formula-(CH2-CH2) yXR, where y is an integer between 2 and 1000, and X is a linking group, which includes (but is not limited to) covalent or ionic bonds, alkyl, olefins, Alkynes, substituted alkyls, substituted olefins, aryls, esters, ethers, ketones, amines, amines, amines, organosilanes, and R is a functional group. The functional group (R) provides functionality and can be provided by polymerization of a functional monomer (as the sole monomer or as a comonomer). Functionality can also be added by post-polymerization or grafting. Useful functional groups include, but are not limited to, carboxylic acid, hydroxyl, siloxy, ether, ester, sulfonic, phosphate, phosphonic, sulfate, amido, and epoxy groups, or mixture. In addition to the low molecular weight functional chain transfer agent of the present invention, other chain transfer agents commonly used in fluoropolymer polymerization can also be added at low levels to provide a desired molecular weight. Generally, some or all of the chain transfer agent is added to the initial charge to prevent the formation of very high molecular weight polymers that are insoluble in polar solvents and exist as gels. The remaining chain transfer agent can then be added continuously or in small portions during the remaining polymerization. The functional fluoropolymer of the present invention may be optionally blended with compatible fluoropolymers and non-fluoropolymers to form a final tie layer composition. A specific preferred embodiment of the present invention will now be described generally in a manner of practicing the present invention, that is, a non-fluorinated emulsifier is used as the main emulsifier in the aqueous emulsion polymerization to prepare a polydifluoroethylene-based copolymer. Although the present invention has been generally described with respect to PVDF copolymers, those skilled in the art will recognize that similar polymerization and application techniques can be applied to the preparation of other copolymers of fluorinated monomers. Although non-fluorinated surfactants are preferred, the present invention also contemplates the use of fluorosurfactants. Polymerization Process Regarding the preferred method of preparing the fluoropolymer of the present invention, initially, deionized water, at least one surfactant (usually based on the amount of monomers in the range of 0.01 to less than 2.0% by weight), and preferably non-fluorinated surface The agent and a portion of the chain transfer agent are introduced into the reactor and subsequently deoxygenated. After the reactor reaches the desired temperature, difluoroethylene vinylene (VDF) monomer and optional comonomer are added to the reactor. Depending on the reactivity of the comonomer, no comonomer is added to the initial charge, and some or all of the comonomer is added to the initial charge. The remaining comonomer can then be added continuously or in small portions during the remaining polymerization to achieve a predetermined ratio to VDF in the final polymer. The comonomer addition is implemented to provide a fairly uniform distribution of comonomer units in the copolymer. Then, a free radical initiator is introduced into the reactor at a suitable flow rate to maintain a suitable polymerization rate. Once the reaction has started or at the same time as the reaction, both the low molecular weight functional polymer chain transfer agent and the fluoromonomer are continuously fed into the reactor at the desired ratio. After reaching the desired polymer solids content, the monomer feed can be stopped, while the charge of the initiator is preferably maintained to consume any residual monomer in the reactor. The starter charge can then be stopped, the reactor pressure drops and the reactor is cooled. Unreacted monomers can be discharged and the fluoropolymer dispersion can be collected by means of a discharge port or other collection member. The fluoropolymer dispersion can then be separated using standard separation techniques (such as oven drying, spray drying, shearing or acid coagulation followed by drying, etc.) or the functional fluoropolymer can be kept in emulsion form for subsequent applications. The formed primary functional fluoropolymer particles have an average particle size of less than 500 nm, preferably in the range of 20 to 400 nm, and most preferably in the range of 50 to 300 nm. Additives The tie layer composition of the present invention may optionally include 0 to 15% by weight and preferably 0.1 to 10% by weight based on the copolymer. The additives include, but are not limited to, thickeners, pH adjusters, anti-settling agents, and surface Active agent, wetting agent, filler, defoamer and short-term adhesion promoter. Metal oxides (such as aluminum oxide, silicon dioxide, zinc oxide, barium oxide, and titanium oxide) are preferred additives. Process The lithium-ion battery connection layer of the present invention can be added to the battery stack in several ways. In one embodiment, the PVDF copolymer is produced by emulsion polymerization, as described above. Additives, if any, are then added to the emulsion, or the emulsion is dried and the additives are dry blended into the PVDF copolymer to form a tie layer composition. The resulting copolymer tie layer composition can be converted into a self-supporting film by any method known in the art, such as by blow molding, solution casting, or film extrusion processes. The thickness of the film is less than 10 microns, preferably less than 7 microns and most preferably about 5 microns or even smaller. The copolymer tie layer composition can also be formed as a film on a carrier film. A self-supporting thin film bonding layer can be placed between the separator and the electrode and then thermally laminated. The connecting layer film on the carrier film can be transferred to the electrode or the separator, the carrier film is removed, and then the separator or electrode is placed on top of the connecting layer film, and the stack is then thermally laminated. Alternatively, multi-slot die casting can be used with a tie layer on the surface of a separator, anode or cathode to reduce production costs. In another embodiment, the tie layer composition is applied as a solvent or, preferably, a water-based coating to the substrate using methods known in the art, including (but not limited to) gravure, dip or roll coating, and inkjet printing. On either the plate or the electrode, dry and place against the electrode. For best performance, the coating thus formed will be a porous coating. A tie layer coating formed from an aqueous dispersion produces a layer of discrete, functional fluoropolymer particles with a particle size of less than 500 nm. In a preferred embodiment, the bonding layer is placed on the cathode. Thermal lamination is a better way to adhere the stack (anode / link layer / separator / link layer / cathode) together. Applying heat at 50 to 90 ° C and preferably 60-80 ° C can help adhesion. Wetting the coated separator with an electrolyte during assembly can also help with good adhesion. In this specification, the embodiments have been described in such a way that a clear and concise description can be written, but it is expected and understood that the embodiments can be combined or separated in various ways without departing from the present invention. For example, it should be understood that all the preferred features described herein are applicable to all aspects of the invention described herein. Aspects of the present invention include: 1. A lithium-ion battery comprising: a) an anode; b) a cathode; c) a separator; wherein the separator is adhered to the cathode and the cathode through a functional polydifluoroethylene linking layer; The anode or both the anode and the cathode, the functional polydifluoroethylene is selected from: a) a copolymer comprising 0.2 to 20% by weight, preferably 0.5 to 15% by weight and more preferably 1 to 10% by weight At least one adhesion promoting comonomer, b) a modified fluoropolymer comprising from 0.1 to 25% by weight, preferably from 1.0 to 15% by weight, more preferably from 2.2 to 10% by weight from one or more low molecular weight polymeric functional chains Residual functional groups of the transfer agent, and c) a) and b) mixtures. 2. The lithium-ion battery according to aspect 1, wherein the connecting layer has a thickness of 0.5 to 10 microns, preferably 0.7 to less than 5 microns, and most preferably 1 to 4 microns. 3. The lithium-ion battery according to aspect 1 or 2, wherein the lithium-ion battery is a soft-pack battery. 4. The lithium ion battery according to any one of aspects 1 to 3, wherein the comonomer comprises at least one comonomer selected from the group consisting of vinyl acetate, HFO-1234yf, HFP, 2-chloro- 1,1-difluoroethylene (R-1122) and phosphate (meth) acrylate. 5. The lithium-ion battery according to any one of aspects 1 to 4, wherein the copolymer is a random copolymer or a graft copolymer. 6. The lithium-ion battery according to any one of aspects 1 to 5, wherein the separator is coated with an aqueous polydifluoroethylene adhesive composition. 7. The lithium ion battery according to any one of aspects 1 to 6, wherein the anode and / or the cathode are coated with an aqueous polydifluoroethylene adhesive. 8. The modified fluoropolymer according to any one of aspects 1 to 7, wherein the modified fluoropolymer comprises 2.2 to 10% by weight of the residual functional groups. 9. The modified fluoropolymer of any of aspects 1 to 8, wherein the modified fluoropolymer comprises one or more fluoropolymer blocks and one or more from one or more low molecular weight polymers Blocks of these residual functional groups of the functional chain transfer agent. 10. The modified fluoropolymer of any of aspects 1 to 9, wherein the residual functional groups are selected from the group consisting of a carboxylic acid group, a hydroxyl group, a siloxane group, an ether group, an ester group, Sulfonic, phosphate, phosphonic, sulfate, amido, epoxy and mixtures thereof. 11. A method for generating a lithium ion battery, comprising the step of adhering a separator to an electrode using a polydifluoroethylene copolymer bonding layer, wherein the polyvinylidene copolymer contains 0.2 to 20% by weight, preferably 0.5 to 15% by weight and more preferably 1 to 10% by weight of at least one adhesion promoting comonomer. 12. The method of aspect 11, wherein the bonding layer is applied as a coating to the separator, the electrode, or both, and the electrode and the separator are placed in direct contact with each other, wherein the polydifluoroethylene copolymer is bonded The layer is cured. 13. The method according to aspect 11 or 12, wherein the polydifluoroethylene copolymer is in the form of a thin connecting layer sheet, the sheet is directly placed between the separator and the electrode, followed by thermal lamination. 14. The method according to any one of aspects 11 to 13, wherein the thermal lamination occurs at a temperature of 50 to 100 ° C, preferably 60 to 80 ° C. 15. The method of any one of aspects 11 to 14, wherein the bonding layer is individually adhered to the electrode, the separator, or both, and then a bonding layer / electrode, and / or a bonding layer / separator is directly placed on The corresponding electrodes or separators are in contact, followed by a thermal lamination step. 16. The method of any one of aspects 11 to 15, wherein the separator is wetted with an electrolyte before assembly. Examples Example- A A 2 gallon stainless steel reactor was charged: 4000 grams of deionized water and 4.0 grams of PLURONIC 31R1 (non-fluorinated non-ionic surfactant from BASF). Start stirring at 72 rpm and heat the reactor. After the reactor temperature reached the desired set point of 100 ° C, the VDF and HFP monomers were introduced into the reactor at a VDF / HFP ratio of 36. The reactor pressure was then raised to 650 psi by charging approximately 400 grams of total monomer into the reactor. After the reactor pressure was stabilized, 75.0 g of a starter solution prepared from 2.0 wt% potassium persulfate and 6.0 wt% SOKALAN cp-10 (low molecular weight polyacrylic acid, from BASF) was added to the reactor to initiate polymerization. At the beginning, the ratio of HFP to VDF was adjusted to reach 10% HFP to total monomer in the feed. The rate of further addition of the initiator solution was also adjusted to obtain and maintain a final combined VDF and HFP polymerization rate of approximately 600 grams / hour. VDF and HPF copolymerization continued until approximately 1800 grams of VDF was introduced into the reaction mass. The HFP feed was stopped, but the VDF feed was continued until approximately 2000 grams of VDF was fed to the reactor. The VDF feed was stopped and the batch was allowed to react at the reaction temperature to consume residual monomer under reduced pressure. After 20 minutes, the starter feed was stopped and stirred and the reactor was cooled, the gum was discharged and recovered. The solids in the recovered gum were determined by gravimetric techniques and were about 34% by weight, and were measured according to ASTM method D-3835 at 450 ° F and 100 sec -1 , and the melt viscosity was about 72 kp. The melting temperature of the resin was measured according to ASTM D3418 and found to be about 135 ° C. The weight average particle size was measured by a NICOMP laser light scattering instrument and found to be about 160 nm. Example - A 2 gallon stainless steel reactor was charged with B: 4000 grams of deionized water and 4.0 grams of PLURONIC 31R1 (non-fluorinated non-ionic surfactant from BASF). Start stirring at 72 rpm and heat the reactor. After the reactor temperature reached the desired set point of 100 ° C, the VDF monomer was introduced into the reactor until the reactor pressure reached 650 psi by loading approximately 400 grams of monomer into the reactor. After the reactor pressure was stabilized, 75.0 g of a starter solution prepared from 2.0 wt% potassium persulfate and 6.0 wt% SOKALAN cp-10 (low molecular weight polyacrylic acid, from BASF) was added to the reactor to initiate polymerization. At the beginning, the ratio of HFO-1234yf to VDF was adjusted to achieve 2% HFO-1234yf to total monomer in the feed. The rate of further addition of the initiator solution was also adjusted to obtain a final VDF polymerization rate that maintained approximately 600 grams / hour. VDF and HFO-1234yf copolymerization continued until approximately 2000 grams of VDF was introduced into the reaction mass. The HFO-1234yf feed was stopped, but the VDF feed was continued until approximately 2200 grams of VDF was fed to the reactor. The VDF feed was stopped and the batch was allowed to react at the reaction temperature to consume residual monomer under reduced pressure. After 20 minutes, the starter feed was stopped and stirred and the reactor was cooled, the gum was discharged and recovered. The solids in the recovered gum were determined by gravimetric techniques and were about 33% by weight, and measured according to ASTM method D-3835 at 450 ° F and 100 sec -1 , and the melt viscosity was about 66 kp. The melting temperature of the resin was measured according to ASTM D3418 and found to be about 160 ° C. The weight average particle size was measured by a NICOMP laser light scattering instrument and found to be about 160 nm. Application example : The functional fluoropolymer formed in Examples A and B is applied to the anode or cathode as a bonding layer by the following methods: The functional fluoropolymer of Example A or B can be blow-molded to a thickness of 2-6 microns. Self-supporting membrane. The film is then thermally laminated between the cathode and the separator. In an alternative embodiment, the functional fluoropolymer of Example A or B may be coated on an electrode (cathode or anode) to form a tie layer having a thickness of 0.1 to 5 microns, preferably 1 to 3 microns. The coated electrodes were then placed in a stack near the separator membrane and laminated in place.