【綜述背景與內(nèi)容簡介】

由于電動汽車的普及化，當前鋰電池的需求產(chǎn)能正在急劇增長，預計將在2030年達到2500 GWh。當前，鋰電制造業(yè)的支柱工藝為濕法電極加工， 該技術(shù)不僅能耗高、成本高（水系與非水系溶劑均有高沸點，另外非水系溶劑由于高毒性需要進行額外的回收處理），而且其生產(chǎn)的電極在電化學性能方面也尚有不足（如熱烘干過程中的粘合劑遷移會導致因材料分部不均造成電化學性能和機械性能降低），因此該工藝無法很好地適配于當前發(fā)展趨勢。為了更好地滿足鋰電池的產(chǎn)量缺口，鋰電制造業(yè)需要開發(fā)采用新一代電極制備工藝以實現(xiàn)高性能電極的加工處理并達到綠色、高產(chǎn)、低成本的生產(chǎn)技術(shù)要求。

【創(chuàng)新成果】

近日，位于美國的阿貢國家實驗室、橡樹嶺國家實驗室、凱斯西儲大學聯(lián)合在國際知名期刊Nature Reviews Clean Technology 上發(fā)表了題為“Advanced Electrode Processing for Lithium-Ion Battery Manufacturing”的最新綜述。該綜述系統(tǒng)性地介紹了不同先進電極加工技術(shù)的工藝（包括濕法、干法、3D打印、輻照固化），深入地討論了實際生產(chǎn)應用和回收領域的現(xiàn)狀，并指出當前各鋰電池電極加工技術(shù)的發(fā)展仍然不足，優(yōu)勢與挑戰(zhàn)并存，強調(diào)科研人員要著眼于工業(yè)化發(fā)展，進一步深化各技術(shù)方向研發(fā)。該文回顧了鋰電池電極產(chǎn)業(yè)加工發(fā)展，為促進鋰電池制造業(yè)的技術(shù)革新提出了戰(zhàn)略性的新思維。

【綜述亮點】

1、傳統(tǒng)的鋰離子電池電極加工主要依賴于濕法加工，既耗時又耗能。所得電極電化學性能有限。

2、與傳統(tǒng)濕法工藝相比，先進電極加工技術(shù)不僅更經(jīng)濟實惠而且能有著更低能耗和更環(huán)保的特點。另外利用laser ablation、co-extrusion、freeze casting (ice templating)、additive manufacturing來改進電極結(jié)構(gòu)從而提高鋰離子擴散動力學效率，但生產(chǎn)成本會有相應的提高。

3、干法電極加工技術(shù)已經(jīng)展現(xiàn)出劃時代的作用。它不僅可簡化電極制造流程而且可以降低制造成本（約～11.5%）和能耗（>46%）。其中Maxwell型工藝作為目前最先進成熟的工藝正在工業(yè)界內(nèi)逐漸取代濕法加工。

4、輻照固化電極加工技術(shù)具有最高的電極制備能力，而3D打印電極加工技術(shù)則可以制造出不同幾何形狀和結(jié)構(gòu)的電極。

【圖文解讀】

Fig. 1: Electrode processing techniques.

Electrode processing techniques usually comprise three main steps: mixing (panels 1), electrode fabrication (panels 2) and calendering (panels 3). a, Conventional slurry-based processing. b, Dry processing. c, Radiation curing processing. d, 3D-printing processing.

Fig. 2: Modified electrodes manufactured by conventional slurry-based processing.

Conventional slurry-based processed electrodes with various modifications. a, Conventional slurry-based processing with a slot-die coater. b–d, Grid (panel b), line (panel c) and hole (panel d) patterns from laser ablation. e, Electrodes with ridges (regular coating) and valleys (thinner or no coating) from co-extrusion.

Fig. 3: Properties and performance of dry-processed electrodes.

Dry-processed electrode morphological properties affect their electrochemical performance. a, Tortuosity comparison between conventional electrodes and dry-processed electrodes at comparable electrode porosity, thickness and active material loading. b, Material distribution in conventional (left) and dry-processed electrodes (right). c, Cross-sectional scanning electron microscopy image of a Maxwell-type graphite dry-processed electrode. d, Improved cyclic performance of dry-processed lithium nickel manganese cobalt oxide (LNMO) electrodes. e, Electrochemical performance of a lithium-ion battery full cell, incorporating a graphite anode with (NM75/TE-Graphite cell 1 and cell 2) and without (NM75/E-Graphite cell 1 and cell 2) a polymer-based protective coating. Dry processing exhibits various advantages for manufacturing and can deliver electrodes with enhanced electrochemical performance. C, carbon; F, fluorine.

Fig. 4: Dry processing methods.

Mechanism of various dry processing methods. a, Ball milling-based dry mixing. b, Double-blade blender-based dry mixing. c, Maxwell type. d, Hot pressing and melting extrusion. e, Dry spraying deposition.

Fig. 5: Beam curing electrode processing.

Radiation curing processing working principles. a, Mechanism for ultraviolet (UV) curing processing. b, Size of lithium-ion battery electrode processing equipment for beam curing processing (blue) and conventional wet processing (red).

Fig. 6: 3D-priting electrode processing.

3D-printed electrodes have different structural features. a, Microgrid. b, Digit. c, Line. d, Cross-sectional view of the line structure. e, Spiral. f, Hierarchical. g, Fibre. h, Flexible direct ink writing processed electrode. i, Stereolithography printed and pyrolysed hard carbon electrode for sodium-ion batteries. j, Template-assisted electrodeposition porous electrode.

Table 1: Comparison of electrode manufacturing technologies.

【總結(jié)與展望】

由于人類社會對鋰電池日益增長的需求，鋰電池制造業(yè)需要在電極加工技術(shù)方面進行技術(shù)升級革新來取代有著諸多不足的傳統(tǒng)濕法電機加工工藝。作為干法電極加工技術(shù)的代表，Maxwell型工藝以高實用性已經(jīng)在鋰電批量化工業(yè)生產(chǎn)方面拔得頭籌，與此同時該技術(shù)也在固態(tài)電極和固態(tài)電解質(zhì)的加工制備方面初露頭角。輻照固化電極加工技術(shù)展現(xiàn)出極高的電極制備能力也在商業(yè)化方面有了小規(guī)模展示。3D打印電極加工技術(shù)因其可以制造多樣幾何形狀和結(jié)構(gòu)的能力正處于學術(shù)研究探索階段。另外綜述也對人工智能/機器學習技術(shù)和先進電極回收領域提出建設性的討論與建議，強調(diào)了兩者在促進未來鋰電池制造業(yè)升級革新的作用。

轉(zhuǎn)載自：材料人