Lithium Superionic Conductor Li10GeP2S12 with a Practical Conductivity of 12 mS cm−1
2011 · paper · Materials
Reports a new lithium solid electrolyte, Li10GeP2S12, with a three-dimensional framework structure. It shows a lithium ionic conductivity of 12 mS/cm at room temperature, which the authors say is the highest for a solid electrolyte and exceeds organic liquid electrolytes.
5 findings
Substance p.1 names the ref. 5 superionic conductor as "Li7PS6 (ref. 5)", but the introduction cites the same ref. 5 for "glass ceramics (Li7P3S11; refs 5,6)", and Fig. 3 plots the glass-ceramic as Li7P3S11.
- p. 1 Right column, synthesis paragraph
Li7PS6 (ref. 5)
- p. 1 Left column
glass ceramics (Li7P3S11; refs 5,6)
- p. 1 paragraph on synthesis
thio-LISICON (ref. 4) and Li7PS6 (ref. 5)
Only the authors can say what is right here.
Judge's note: Rests on outside knowledge: that Mizuno et al. 2005 (ref. 5) reports Li7P3S11 and not Li7PS6. The crop shows 'Li7PS6 (ref. 5)'. Inside the paper, the left column of p.1 cites refs 5,6 for Li7P3S11, the ref. 5 title is about crystals precipitated from Li2S–P2S5 glasses, and the Fig. 3 legend reads 'Glass-ceramic electrolyte Li7P3S11'. Li7PS6 appears nowhere else in the paper. The two formulas given for the same citation do not agree.
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Substance p.2: "The Ge/P ratio is then 4.06:1.94, which is very close to the stoichiometric ratio of 2:1". The stated occupancies (4d: Ge 0.515, P 0.485; 2b: P 1.00) give Ge:P = 2.06:3.94, about 1:2, in line with the formula GeP2 and with the ICP result P/Ge = 2.
- p. 2 Text below Fig. 2, left column
The Ge/P ratio is then 4.06:1.94, which is very close to the stoichiometric ratio of 2:1
- p. 1 Right column, ICP result
ratio of P/Ge = 2
- p. 2 Text below Fig. 2, left column
with occupancy parameters of 0.515(5) and 0.485(5), respectively
- p. 2 Crystal structure text
The Ge/P ratio is then 4.06:1.94, which
Judge's note: The page image confirms the occupancies 0.515(5) and 0.485(5) on 4d and 1.00(15) for P on 2b, and the printed ratio 4.06:1.94 with '2:1'. Taking multiplicity 4 for 4d and 2 for 2b gives Ge = 2.06 and P = 3.94 per cell. Neither 4.06 nor 1.94 is the total for either element, and Ge/P = 2:1 contradicts Li10GeP2S12 and the p.1 statement 'P/Ge = 2'. As a check on the multiplicities, the lithium count works out: 16(0.691) + 4(1.000) + 8(0.643) = 20.2, as printed.
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Reference or label The Fig. 3 caption cites conductivity sources as "3–8,13–16,20,22". Ref. 22 is Boultif & Louer, 'Indexing of powder diffraction patterns…' (DICVOL, cited in Methods for indexing). Ref. 21, which the text cites for the plotted 1 M LiBF4/EMIBF4 ionic liquid, is missing from the list.
- p. 3 Figure 3 caption
ionic liquids and gel electrolytes3–8,13–16,20,22
- p. 5 Reference 22
Boultif, A. & Louer, D. Indexing of powder diffraction patterns
- p. 5 Reference 22
Boultif, A. & Louer, D. Indexing of powder diffraction patterns for low-symmetry lattice by the successive dichotomy method
- p. 4 text on ionic liquid
tetrafluoroborate21
Judge's note: The caption superscript '3–8,13–16,20,22' is checked on the page image. In the reference list, ref. 22 is a powder-indexing method paper and is cited in Methods only for DICVOL. On p.4 the ionic liquid shown in Fig. 3 is cited as ref. 21. A conductivity-data list that includes 22 and omits 21 points to 21 being intended.
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Wording The Fig. 2 caption says "thermal vibration of lithium ions in three tetrahedral sites gives rise to 1D conduction pathways", but the same caption and the p.3 text name only two tetrahedral Li sites (LiS4 at 16h and 8f); the third Li site (4d) is the LiS6 octahedron.
- p. 2 Figure 2 caption, last sentence
lithium ions in three tetrahedral sites gives rise to 1D conduction pathways
- p. 3 Right column
the thermal vibration of lithium at the 16h and 8f sites is highly anisotropic
- p. 2 Figure 2 caption, last sentence
thermal vibration of lithium ions in three tetrahedral sites gives rise to 1D conduction pathways
Judge's note: The caption says conduction is through LiS4 tetrahedra at 16h and 8f. The p.3 text says 'the thermal vibration of lithium at the 16h and 8f sites is highly anisotropic', and Fig. 2c labels Li(4d) within LiS6. 'Three tetrahedral sites' therefore contradicts the paper's own structural description; 'two' appears intended. The caption miscounts the sites, but the result it supports still holds.
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Wording p.4 says the Li2S–P2S5 glass, the ionic liquid (1 M LiBF4/EMIBF4) and the polymer electrolyte "have conductivities that are several orders of magnitude lower than those of organic liquid electrolytes", but in Fig. 3 the ionic-liquid line at 27 °C sits near log σ ≈ −2, about the same as the 1 M LiPF6/EC–PC organic electrolyte.
- p. 4 Left column, top paragraph
These electrolytes have conductivities that are several orders of mag-
- p. 3 Figure 3
Ionic liquid electrolyte 1 M LiBF4/EMIBF4
- p. 4 Left column, top paragraph
These electrolytes have conductivities that are several orders of magnitude lower than those of organic liquid electrolytes.
Only the authors can say what is right here.
Judge's note: Reading Fig. 3 at the 27 °C tick (10^3/T ≈ 3.33), the blue ionic-liquid line is at about log σ −2.0 to −2.1. The green organic-electrolyte line begins at about −2.0. The ionic liquid lies above the gel and organic curves at higher temperature. The 'several orders of magnitude' statement fits the polymer and the Li2S–P2S5 glass but not the ionic liquid named in the same sentence.
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6 minor (typos and the like; most checked by the judge only)
Wording The introduction says Li10GeP2S12 "exhibits an extremely high bulk conductivity of over 10−2 S cm−1", but the reported value is described as "obtained from the sum of the grain boundary and bulk resistances" (Fig. 1 caption: sum of grain boundary and bulk conductivities).
- p. 1 Right column, introduction
exhibits an extremely high bulk conductivity of over 10−2 S cm−1 at room temperature (27 ◦C)
- p. 3 Left column
The conductivity was obtained from the sum of the grain boundary and bulk resistances.
Judge's note: The p.3 text and the Fig. 1 caption both say the 12 mS cm−1 value is a total (bulk plus grain boundary). Bulk conductivity is at least as high as the total, so 'over 10−2' is not false for bulk. However, the paper reports no separate bulk value, so the label 'bulk' does not match the quantity actually measured. This is a wording point only.
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Wording The text gives the activation energy of 24 kJ mol−1 "for the temperature range of −110 to 110 ◦C", but the Arrhenius data in Fig. 1a end at about 10^3/T ≈ 5.8 (≈ −100 °C), and the axis stops at 6.0, short of −110 °C (≈ 6.13).
- p. 3 Left column, conductivity paragraph
for the temperature range of −110 to 110 ◦C
- p. 2 Figure 1a, Arrhenius plot
−100
Only the authors can say what is right here.
Judge's note: In Fig. 1a the lowest-temperature points sit at about 5.8 on the 10^3/T axis, near the −100 °C top-axis tick. −110 °C would plot at about 6.13, beyond the 6.0 axis limit. Methods say impedance was measured between −110 and 110 °C, so −110 °C data may exist but are not plotted. Only the authors can say which range the fit covers.
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Typo p.3: "such as Li3N and Li1/3−xLi3xNbO3 have low electrochemical stabilities". The next sentence and ref. 18 give the compound as La1/3−xLi3xNbO3.
- p. 3 Left column, electrochemical stability paragraph
Li1/3−xLi3xNbO3 have low electrochemical stabilities
- p. 3 Left column, electrochemical stability paragraph
Li3N and Li1/3−xLi3xNbO3 have low electrochemical stabilities
- p. 3 Electrochemical stability paragraph
Li3N and Li1/3−xLi3xNbO3 have low
- p. 3 Electrochemical stability paragraph
such as Li3N and Li1/3−xLi3xNbO3 have low electrochemical stabilities
Judge's note: The page image clearly shows 'Li1/3−xLi3xNbO3' (Li as the first element). Two lines later the same perovskite is written 'La1/3−xLi3xNbO3 perovskite18', which matches the title of ref. 18. This is a formula typo, and the context makes the intended compound clear.
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Typo The Fig. 3 caption prints the unit with a space inside it: "(12 m S cm−1 at 27 ◦C)"; elsewhere the paper writes "mS".
- p. 3 Figure 3 caption
12 m S cm−1 at 27 ◦C
Judge's note: The page image shows 'm S' with a visible space; this is not a line break. It is a cosmetic inconsistency.
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Typo p.3: "containing 1 M LiPF6(ref. 16)" has no space before the parenthetical reference.
- p. 3 Fig. 3 paragraph
1 M LiPF6(ref. 16)
Judge's note: The image shows 'LiPF6(ref. 16)' with no space, unlike the other '(ref. n)' citations. This is cosmetic.
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Typo The Acknowledgements write "proposal No 2010A1584" and "proposal No 2009B0039" but "No. 2010A0060", so the abbreviation is punctuated inconsistently.
- p. 5 Acknowledgements
proposal No 2010A1584
Judge's note: The crop of the Acknowledgements shows 'No' without a period twice and 'No.' once. This is purely cosmetic.
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