电子科技大学：《物理与化学电源基础 Fundamental of Physical and Chemical Power Sources》课程教学资源（课件讲稿，第二部分）Lecture 07 Anode material for LIBs（Lithium）

Lecture 7 196 Anode material for LIBs: Lithium Chen Junsong School of Materials and Energy 2018.10

Anode material for LIBs: Lithium Chen Junsong School of Materials and Energy 2018.10 Lecture 7

Content /986 ·Introduction of Li Advantage and disadvantage of Li Modification methods One literature example 2

2 Content • Introduction of Li • Advantage and disadvantage of Li • Modification methods • One literature example

Lithium 956 Periodi Atomic weight: 18 2 H 6.94 g/mol He 与m 16016- Lightest alkali metal 16 17 403 10 Li (0.54g/cm3) 0 F Ne en 64941 012 1R0用 11 Silvery,metallic solid 16 18 Na Mg Theoretical capacity: Ar Salfar 24305 6 > 35453 94 19 32 23 24 25 34 35 36 Ca Sc Cr Mn 3.86 Ah/g Se Br Kr Chroealam Nasganese 4007日 44956 50942 5196 5493细 E。=-3.04VsHE 2 7897 79904 37 39 40 41 43 52 53 Rb Sr Zr Nb Mo Tc Ru Ca m Sn Te Xe N比行n Rhodiam a向 Caduftm 4a 航2 995 9907 101.67 162 1078d 112.410 1101 11711 12170 12690 11224 55 57-71 72 73 74 75 76 78 79 80 83 84 85 86 Cs Ba Hf Ta Re r Pt Au Hg T Pb Bi At Rn ristes Pmith 1290 13n32 178.49 180.9号 1884 18207 190.23 19221 15 1696 200592 2043☒ 2072 2e980 289 2099 2218 87 89-103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 Fr Ra Rf Db g Bh Hs Mt Ds Rg Cn Uut Lv Uus Uuo 0tt当端用 htn 222 226025 261 2 小w B9 57 58 60 61 62 63 64 65 66 67 68 69 70 71 a Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Sanarien Terbiam Hon当s Tbein T月a3un Lotetam 1905 140.116 140.90 1442日 144913 150.36 151964 15723 1925 160 164930 1629 16934 1725g 174967 89 90 93 94 95 96 98 99 100 101 102 103 AC. Th Np Am Cm Bk CE Es Fm Md No r Tortn a忙aem nengio Criin Beriellum Prlum 4otl柱与 2228 26 229 270梯 244064 243661 24070 207 2514 2的第 281 2511 lkal Metal Metal Batie Metal emimeta国 Nonmetal 3

3 Lithium - Atomic weight: 6.94 g/mol - Lightest alkali metal (0.54 g/cm3 ) - Silvery, metallic solid - Theoretical capacity: 3.86 Ah/g - Eo = -3.04 VSHE

Advantage of Li /986 Li←→Lit+e The molecular weight of lithium is 6.94 g/mol,so its theoretical capacity is:96500:6.94-:3.6 3862.5 mA-h/g >Eo=-3.04 VsHE-high operating voltage of battery cells 4

4 Advantage of Li  The molecular weight of lithium is 6.94 g/mol, so its theoretical capacity is: 96500÷6.94÷3.6 = 3862.5 mA·h/g  Eo = -3.04 VSHE → high operating voltage of battery cells Li ↔ Li+ + e─ 1 2

Disadvantage of Li Formation of Li dendrite Solid electrolyte interphase(SEl) o LiLit@negative potential-electrolyte reduced at Li surface-passivation layer (SEl) Electrolyte:1 M LiPF6 in ethylene carbonate/diethyl carbonate (EC/DEC;1/1) Formation process: b Li dendrites Step 1 Step 2 Step3 Isolated Li Step 4 Cracks ]Dead Li Thick SEI SEl on Li Porous Li plating Further Li stripping electrode Continuous plating cycle Step 1:Li plating Step 2:further plating Step 3:Li stripping Step 4:Continuous cycling causes volume causes Li dendrites to produces isolated Li which causes steps 1-3 to occur expansion,which shoot out through the becomes part of the 'dead' repeatedly,and this finally cracks the SEl film. cracks. Li,while volume results in accumulated dead Li, contraction results in thick SEl and porous Li further SEl fracture. electrode 5 DO:10.1038/NNANO.2017.16

5 Disadvantage of Li  Formation of Li dendrite • Solid electrolyte interphase (SEI) o Li↔Li+ @ negative potential → electrolyte reduced at Li surface → passivation layer (SEI) o Electrolyte: 1 M LiPF6 in ethylene carbonate/diethyl carbonate (EC/DEC; 1/1) Step 1: Li plating causes volume expansion, which cracks the SEI film. DOI: 10.1038/NNANO.2017.16 Step 2: further plating causes Li dendrites to shoot out through the cracks. Step 3: Li stripping produces isolated Li which becomes part of the ‘dead’ Li, while volume contraction results in further SEI fracture. Step 4: Continuous cycling causes steps 1–3 to occur repeatedly, and this finally results in accumulated dead Li, thick SEI and porous Li electrode Formation process:

Observing the dendrites and SEl BATTERIES Atomic structure of sensitive battery materials and interfaces revealed by cryo-electron microscopy Yuzhang Li,*Yanbin Li,1*Allen Pei,Kai Yan,Yongming Sun,1 Chun-Lan Wu,1 Lydia-Marie Joubert,2 Richard Chin,Ai Leen Koh,Yi Yu,*John Perrino,2 Benjamin Butz,15 Steven Chu,6.7 Yi Cuils Yi CUI Li et al.,Science 358,506-510(2017) Whereas standard transmission electron microscopy studies are unable to preserve the native state of chemically reactive and beam-sensitive battery materials after operation,such materials remain pristine at cryogenic conditions.It is then possible to atomically resolve individual lithium metal atoms and their interface with the solid electrolyte interphase (SEI).We observe that dendrites in carbonate-based electrolytes grow along the (preferred).,or directions as faceted,single-crystalline nanowires.These growth directions can change at kinks with no observable crystallographic defect.Furthermore,we reveal distinct SEl nanostructures formed in different electrolytes. 6

6 Observing the dendrites and SEI Yi CUI

Preparation of cryo sample /98 A Cu TEM B Liquid N2 -grid Shutter control Li deposition Cryo TEM holder Li dendrite Plunge freeze under Ar Sample in Electron liquid N. beam Load sample Transfer at Liquid N2 Close shutter -170C Li deposition: working electrode:Cu grid Counter/reference electrode:Li metal Electrolyte:1M LiPF in EC/DEC or 10%FEC in EC/DEC Condition:1 mA cm-2 for 30 min 7

7 Preparation of cryo sample Li deposition: working electrode: Cu grid Counter/reference electrode: Li metal Electrolyte: 1M LiPF6 in EC/DEC or 10% FEC in EC/DEC Condition: 1 mA cm-2 for 30 min

Cryo vs.Standard /986 医M EM Cu TTM subsirate Standard Cryo SEM Li dendrite 2 um 1μm um After attempting high-resolution Cu TEM substrate Star Standard 2 nm TEM Beam damage Li dendrite Corroded 1μm 500nm Li dendrite 500nm 8

8 Cryo vs. Standard SEM TEM Standard Cryo Standard

Morphology observation /986 Cryo-TEM Time-lapse images of the dendrite from Fig. 2A(boxed in green)under constant electron- Li dendrite beam irradiation.No damage in dendrite morphology is detected even after 10 min. Lacey carbon ↓ Better structural stability under Cryo-TEM um 5 10 min 250nm 250nm 250nm 9

9 Morphology observation Time-lapse images of the dendrite from Fig. 2A (boxed in green) under constant electron￾beam irradiation. No damage in dendrite morphology is detected even after 10 min. Better structural stability under Cryo-TEM

Effect of temperature 196 -178C -1000C -50C 200nm 200nm 200m 0oC 24oC 200m 200m 10

10 -178 oC -100 oC -50 oC 0 oC 24 oC Effect of temperature