Lithium–Graphite Paste: An Interface Compatible Anode for Solid‐State Batteries

Abstract

cathodes, [10][11][12] silicon-based anodes, [13][14][15][16] and optimizing organic liquid electrolytes. [17,18] However, the safety challenges related to the electrolyte are serious because operation of LIBs is exothermic and organic liquid electrolytes mostly with ester carbonates are highly flammable, generating massive heat. [19,20] Dendritic lithium in LIB represents a further challenge considering internal short circuit would occur if the dendrite punctures the separator. [21,22] Therefore, solutions for safety of LIBs are urgently required.Inorganic ceramic solid-state electrolyte (SSE) provides an ideal alternative to liquid flammable electrolytes for the design of safe ASSBs, since ceramic SSE is nonflammable and it has adequate fracture toughness to prevent internal short circuit from lithium dendrite. [23][24][25] Furthermore, lithium metal anode, the ultimate anode with the highest specific capacity and lowest electrochemical potential has been demonstrated in ASSBs, which exhibited intrinsic safety under rigorous conditions. [26][27][28][29][30] In the search for SSEs, while most of the superionic conductors with conductivity >1 mS cm −1 are based on sulfides, such as Li 10 GeP 2 S 12 , [31,32] Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 , [33] and Li 9.6 P 3 S 12 , [34] it has shown that garnet-type oxides are the most stable SSEs with lithium metal anode. [35][36][37][38][39] However, the lithium/garnet interface appeared to have a remarkably large impedance due to the poor interfacial contact. [40] This motivates a variety of studies to turn garnet from lithiophobic to lithiophilic by coating garnet with metal, [41][42][43][44] metal oxides, [45,46] semi-conductors, [47,48] polymer interlayers, [49,50] and graphite. [51] Although these approaches have shown great progress, they mainly addressed the interface issue from garnet side. As a result, ample opportunities remain on lithium metal side.Here we introduce a new strategy to synthesize a ceramic compatible lithium anode by using graphite additives. Our scheme to implement a lithium/garnet interface experiment is sketched in Figure 1. We find that pure lithium is not compatible with garnet, which is consistent with that expected for lithiophobic garnet surface and previous reports (Figure 1a). [52] On the other side, lithium-graphite (Li-C) composite presents lower fluidity and higher viscosity compared to pure Li. So the Li-C composite, like a paste, can be casted onto garnet and exhibits an intimate contact (Figure 1b). As expected, All-solid-state batteries (ASSBs) with ceramic-based solid-state electrolytes (SSEs) enable high safety that is inaccessible with conventional lithium-ion batteries. Lithium metal, the ultimate anode with the highest specific capacity, also becomes available with nonflammable SSEs in ASSBs, which offers promising energy density. The rapid development of ASSBs, however, is significantly hampered by the large interfacial resistance as a matched lithium/ ceramic interface that is not easy to pursue. Here, a lithium-graphite...

Enhanced Rate Capability of Ion‐Accessible Ti3C2Tx‐NbN Hybrid Electrodes

“…[ 7–12 ] SCs can provide power density in excess of 10 kW kg −1 since charges are stored through highly reversible ion adsorption or fast redox reactions (in the case of pseudocapacitors), which is at least ten times higher than commercially available lithium‐ion batteries. [ 13–16 ] This meets the requirements of the applications where high‐rate charge/discharge is demanded, which include but are not limited to energy harvesting/recapturing and delivery in electric vehicles, elevators, trains, smart grids, and backup power for electronics, electric utilities, and factories. [ 17–19 ]…”

Li/Garnet Interface Stabilization by Thermal‐Decomposition Vapor Deposition of an Amorphous Carbon Layer

“…The lack of physical contact not only brings large ASR but also promotes uneven Li plating and stripping, which causes the formation of Li dendrites. Many studies have focused on interfacial modifications by introducing interlayers or alloy anodes, [11][12][13][14][15][16][17][18][19] but there is still a lack of strategies that deal with contaminants elimination. Furthermore, consistent volume changes of the alloy can be harmful for the solid physical contact of the Li/garnet interface, which creates Griffith cracks and carves out paths for Li dendrites to penetrate through.…”

Toward safer solid-state lithium metal batteries: a review

“…The poor solid-solid contact greatly increases the internal impendence of the battery, which not only deteriorates the structure of the interface, but also causes the battery to overheat during rapid charging. Except for the methods mentioned above (building exible intercalation or using interface wetting agents) used to achieve good interface contact, some other approaches are also useful, such as using a lithiophilic intercalation layer, 90 reducing the surface tension of molten lithium, 61 or constructing an electrode with a 3D structure. 92,93 In particular, in situ polymerization should be given more attention.…”