Rational Design of a Composite Electrode to Realize a High‐Performance All‐Solid‐State Battery

Abstract

A potential solid electrolyte for realizing all‐solid‐state battery (ASB) technology has been discovered in the form of Li10GeP2S12 (LGPS), a lithium superionic conductor with a high ionic conductivity (≈12 mS cm−1). Unfortunately, the achievable Li+ conductivity of LGPS is limited in a sheet‐type composite electrode owing to the porosity of this electrode structure. For the practical implementation of LGPS, it is crucial to control the pore structures of the composite electrode, as well as the interfaces between the active materials and solid‐ electrolyte particles. Herein, the addition of an ionic liquid, N‐methyl‐N‐butylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([Py14][TFSI]), is proposed as a pore filler for constructing a highly reliable electrode structure using LGPS. [Py14][TFSI] is coated onto the surface of LGPS powder through a wet process and a sheet‐type composite electrode is prepared using a conventional casting procedure. The [Py14][TFSI]‐embedded composite electrode exhibits significantly improved reversible capacity and power characteristics. It is suggested that pore‐filling with [Py14][TFSI] is effective for increasing contact areas and building robust interfaces between the active materials and solid‐electrolyte particles, leading to the generation of additional Li+ pathways in the composite electrode of ASBs.

Interface Issues and Challenges in All‐Solid‐State Batteries: Lithium, Sodium, and Beyond

“…[ 180 ] Recently, more studies have demonstrated that LiNbO 3 was a better choice due to the higher ion conductivity than that of Li 4 Ti 5 O 12 , [ 181 ] which can even suppress the SCL effects at high‐voltage LiNi 0.5 Mn 1.5 O 4 /LGPS interfaces. [ 182 ] In addition, some other oxides have also been employed as effective interlayers to suppress SCLs, such as the LiNb 0.5 Ta 0.5 O 3 or LiTaO 3 layer at LiCoO 2 /LGPS interface, [ 183 ] Li 3 PO 4 layer at LiCoO 2 /80Li 2 S·20P 2 S 5 interface, [ 184 ] ZrO 2 or LiAlO 2 layer at LiNi 1/3 Mn 1/3 Co 1/3 O 2 /Li 3 PS 4 interface, [ 185 ] [Py14][TFSI] ion liquid layer at LiNi 0.8 Mn 0.1 Co 0.1 O 2 /LGPS interface, [ 186 ] LGPS/LiNbO 3 double layer at LiCoO 2 /LGPS interface. [ 187 ]…”

Sulfide and Oxide Inorganic Solid Electrolytes for All-Solid-State Li Batteries: A Review

“…Zhang et al [ 285 ] prepared LGPS via planetary ball milling followed by heating. In addition, Kim et al [ 286 ] conducted studies on ionic liquids and LGPS composites. Few attempts were made to improve the structural stability of the LGPS lattice via Ba, Al, or Si doping.…”

Solid‐State Lithium Batteries: Bipolar Design, Fabrication, and Electrochemistry

“…Noteworthy advances have been made with regard to improving the contact between the SE and active electrode materials, and some selected approaches are summarized in Figure 4. [146][147][148] To ensure conformal solidsolid contacts, SEs could be coated on the surface of active materials via a solution-processable technique prior to electrode fabrication (Figure 4a). A one-step process was also proposed for making sheet-type, thick electrodes, which involved the mixing of SE precursors (e. g., Li 2 S and P 2 S 5 ) with active materials using nitrile butadiene rubber and tetrahydro- 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 furan to make the SE-electrode slurry.…”

“…Second, the interfacial resistance arises from the poor solid‐solid contact induced by the different mechanical properties of SEs and active materials. Noteworthy advances have been made with regard to improving the contact between the SE and active electrode materials, and some selected approaches are summarized in Figure . To ensure conformal solid‐solid contacts, SEs could be coated on the surface of active materials via a solution‐processable technique prior to electrode fabrication (Figure a).…”

“…In practice, a cell assembled with SE‐infiltrated LiCoO 2 and graphite electrodes exhibited high capacities of 141 and 364 mAh g −1 , respectively, at a current density of 0.1 C. Kim et al. proposed a rational design for a composite electrode in which the internal pores were completely filled with N ‐butyl‐ N ‐methylpyrrolidinium (Py14)‐TFSI . Filling the pores with an IL was effective for increasing contact areas and building robust interfaces between active materials and SEs, resulting in the formation of continuous Li + conduction pathways in the composite electrode.…”