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All-solid-state Li–S batteries with fast solid–solid sulfur reaction

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Huimin Song
Huimin Song
Huimin Song
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Konrad Münch
Konrad Münch
Konrad Münch
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Xu Liu
Xu Liu
Xu Liu
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Kaier Shen
Kaier Shen
Kaier Shen
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Abstract and Figures

With promises for high specific energy, high safety and low cost, the all-solid-state lithium–sulfur battery (ASSLSB) is ideal for next-generation energy storage1, 2, 3, 4–5. However, the poor rate performance and short cycle life caused by the sluggish solid–solid sulfur redox reaction (SSSRR) at the three-phase boundaries remain to be solved. Here we demonstrate a fast SSSRR enabled by lithium thioborophosphate iodide (LBPSI) glass-phase solid electrolytes (GSEs). On the basis of the reversible redox between I⁻ and I2/I3⁻, the solid electrolyte (SE)—as well as serving as a superionic conductor—functions as a surficial redox mediator that facilitates the sluggish reactions at the solid–solid two-phase boundaries, thereby substantially increasing the density of active sites. Through this mechanism, the ASSLSB exhibits ultrafast charging capability, showing a high specific capacity of 1,497 mAh g⁻¹sulfur on charging at 2C (30 °C), while still maintaining 784 mAh g⁻¹sulfur at 20C. Notably, a specific capacity of 432 mAh g⁻¹sulfur is achieved on charging at an extreme rate of 150C at 60 °C. Furthermore, the cell demonstrates superior cycling stability over 25,000 cycles with 80.2% capacity retention at 5C (25 °C). We expect that our work on redox-mediated SSSRR will pave the way for developing advanced ASSLSBs that are high energy and safe.
Fundamental concept and characterization of the LBPSI GSEs a, Schematic showing the design principle for the fast-charging mechanism of ASSLSBs. The redox-mediating SE shown in blue is moderately redox active and generates surficial I2/I3⁻ to mediate the sulfur reaction on fast charge; this revitalizes reactions at the SE|active material two-phase boundary that is otherwise inactive and much more populated than the conventionally required SE|C|active material three-phase boundary. b, The variation of ionic conductivity with increasing P2S5 ratio, which is defined as n(P2S5)/n(P2S5 + B2S3). With the addition of P2S5, the ionic conductivity increases and reaches a maximum at n(P2S5)/n(P2S5 + B2S3) = 0.17 and then it decreases at higher ratios. c, Arrhenius plots of ionic conductivity between −40 °C and 60 °C with the corresponding activation energy (Ea) for the three electrolytes with n(P2S5)/n(P2S5 + B2S3) ratios of 0, 0.17 and 0.29. d,e, Local structural analysis of the three electrolytes using ¹¹B (d) and ⁷Li (e) MAS NMR. The ball-and-stick models in d show the different [BS4] coordination environments; the mono-bridged [BS4] means [BS4] that is bridged with each other, with only one B–S–B bond (forming chain-like structure), whereas the multi-bridged [BS4] means that each [BS4] is bridged with several B–S–B bonds (forming a network structure). The B, S and Li atoms are shown in blue, yellow and red, respectively, solid lines represent the covalent bonds between B and S and dashed lines represent the ionic bonds between S and Li. The peaks in e at 0.17–0.50 ppm correspond to Li⁺ that is solvated by non-bridging sulfur, as shown in the inset of d, whereas the peak around −4.4 ppm corresponds to iodine-bound Li⁺. a.u., arbitrary units.
Fundamental concept and characterization of the LBPSI GSEs a, Schematic showing the design principle for the fast-charging mechanism of ASSLSBs. The redox-mediating SE shown in blue is moderately redox active and generates surficial I2/I3⁻ to mediate the sulfur reaction on fast charge; this revitalizes reactions at the SE|active material two-phase boundary that is otherwise inactive and much more populated than the conventionally required SE|C|active material three-phase boundary. b, The variation of ionic conductivity with increasing P2S5 ratio, which is defined as n(P2S5)/n(P2S5 + B2S3). With the addition of P2S5, the ionic conductivity increases and reaches a maximum at n(P2S5)/n(P2S5 + B2S3) = 0.17 and then it decreases at higher ratios. c, Arrhenius plots of ionic conductivity between −40 °C and 60 °C with the corresponding activation energy (Ea) for the three electrolytes with n(P2S5)/n(P2S5 + B2S3) ratios of 0, 0.17 and 0.29. d,e, Local structural analysis of the three electrolytes using ¹¹B (d) and ⁷Li (e) MAS NMR. The ball-and-stick models in d show the different [BS4] coordination environments; the mono-bridged [BS4] means [BS4] that is bridged with each other, with only one B–S–B bond (forming chain-like structure), whereas the multi-bridged [BS4] means that each [BS4] is bridged with several B–S–B bonds (forming a network structure). The B, S and Li atoms are shown in blue, yellow and red, respectively, solid lines represent the covalent bonds between B and S and dashed lines represent the ionic bonds between S and Li. The peaks in e at 0.17–0.50 ppm correspond to Li⁺ that is solvated by non-bridging sulfur, as shown in the inset of d, whereas the peak around −4.4 ppm corresponds to iodine-bound Li⁺. a.u., arbitrary units.
… 
Fast-charging performance of ASSLSBs a, Rate performance of cells using the different SEs at various charging rates (labelled) and a constant discharge rate of 1C at 30 °C. The cells were subjected to an activation process by charging at progressively increasing rates of 0.05–0.8C for six cycles before being charged at 2C (sulfur loading: 1.0 mg cm⁻²). The voltage profiles for the six cycles are shown in Extended Data Fig. 2b,c. b, Voltage profiles at different charging rates (as the focus of the study is on the cathode, for comparison between cells and with others reported in the literature, the cathode potential is hereafter shown with respect to Li⁺/Li, assuming the In/InLi potential to be 0.62 V versus Li⁺/Li). c, Cycling stability at a charging rate of 20C of the ASSLSB with LBPSI electrolyte. d, Rate performance of cells using the different SEs at various charging rates (labelled) and a constant discharge rate of 2C at 60 °C. The cells were subjected to an activation process by charging at progressively increasing rates of 0.1–1C for several cycles (sulfur loading: 1.05 mg cm⁻²). e,f, Voltage profiles with charging rates from 5C to 150C at 60 °C for ASSLSBs with LBPSI (e) and Li5.5PS4.5Cl1.5 electrolyte (f).
Fast-charging performance of ASSLSBs a, Rate performance of cells using the different SEs at various charging rates (labelled) and a constant discharge rate of 1C at 30 °C. The cells were subjected to an activation process by charging at progressively increasing rates of 0.05–0.8C for six cycles before being charged at 2C (sulfur loading: 1.0 mg cm⁻²). The voltage profiles for the six cycles are shown in Extended Data Fig. 2b,c. b, Voltage profiles at different charging rates (as the focus of the study is on the cathode, for comparison between cells and with others reported in the literature, the cathode potential is hereafter shown with respect to Li⁺/Li, assuming the In/InLi potential to be 0.62 V versus Li⁺/Li). c, Cycling stability at a charging rate of 20C of the ASSLSB with LBPSI electrolyte. d, Rate performance of cells using the different SEs at various charging rates (labelled) and a constant discharge rate of 2C at 60 °C. The cells were subjected to an activation process by charging at progressively increasing rates of 0.1–1C for several cycles (sulfur loading: 1.05 mg cm⁻²). e,f, Voltage profiles with charging rates from 5C to 150C at 60 °C for ASSLSBs with LBPSI (e) and Li5.5PS4.5Cl1.5 electrolyte (f).
… 
Electrochemical and spectroscopic studies of cells based on LBPSI at different states a,b, Voltage profiles of the cell with LBPSI (a) and Li5.5PS4.5Cl1.5 (b) as the active material at a current density of 0.25 mA cm⁻² (25 °C). The first cycle involves a discharge followed by charge, in which the initial discharge process delivers a small capacity. c,d, TOF-SIMS analysis results showing the I2⁻ (c) and I3⁻ (d) fragments for the LBPSI–C electrode at various states (pristine, 100% state of charge (SOC) and 100% depth of discharge (DOD)). e,f, TOF-SIMS analysis results showing the I2⁻ (e) and I3⁻ (f) fragments for the sulfur cathode with LBPSI. The data for box plots were obtained from five measurements at different spots on each sample. g, TOF-SIMS 3D representations of I2⁻ and I3⁻ in the fully charged sulfur cathode with LBPSI obtained by depth profiling. h, Scheme of the surficial I⁻–I2/I3⁻ redox-mediating mechanism for SSSRR that involves surface diffusion and redistribution of I2 and I⁻. i, In situ gas analysis of a cell configured as In/InLi|LPSCl|LBPSI–C at 45 °C. a.u., arbitrary units; IQR, interquartile range.
Electrochemical and spectroscopic studies of cells based on LBPSI at different states a,b, Voltage profiles of the cell with LBPSI (a) and Li5.5PS4.5Cl1.5 (b) as the active material at a current density of 0.25 mA cm⁻² (25 °C). The first cycle involves a discharge followed by charge, in which the initial discharge process delivers a small capacity. c,d, TOF-SIMS analysis results showing the I2⁻ (c) and I3⁻ (d) fragments for the LBPSI–C electrode at various states (pristine, 100% state of charge (SOC) and 100% depth of discharge (DOD)). e,f, TOF-SIMS analysis results showing the I2⁻ (e) and I3⁻ (f) fragments for the sulfur cathode with LBPSI. The data for box plots were obtained from five measurements at different spots on each sample. g, TOF-SIMS 3D representations of I2⁻ and I3⁻ in the fully charged sulfur cathode with LBPSI obtained by depth profiling. h, Scheme of the surficial I⁻–I2/I3⁻ redox-mediating mechanism for SSSRR that involves surface diffusion and redistribution of I2 and I⁻. i, In situ gas analysis of a cell configured as In/InLi|LPSCl|LBPSI–C at 45 °C. a.u., arbitrary units; IQR, interquartile range.
… 
Long-term cycling performance of ASSLSBs at 25 °C a, Cycling performance (charging capacity) of cells based on LBPSI and Li5.5PS4.5Cl1.5 at 0.2C (sulfur loading: 1.5 mg cm⁻²; experimentally achieved capacity: 2.1 mAh cm⁻²). b, Long-term cycling of the cell based on LBPSI at 2C (sulfur loading: 1.1 mg cm⁻²; experimentally achieved capacity: 1.2 mAh cm⁻²). The cell was subjected to an activation process by cycling at progressively increasing rates of 0.05–1C for several cycles. c, Cycling performance (the charging capacity) of the cells based on LBPSI and Li5.5PS4.5Cl1.5 at 5C (sulfur loading: 1.1 mg cm⁻²; experimentally achieved capacity: 0.91 mAh cm⁻² of the cell based on LBPSI). Cells were subjected to an activation process by cycling at progressively increasing rates of 0.05–4C for several cycles. d,e, Cycling performance of the cell based on LBPSI with a high sulfur loading of 3.0 mg cm⁻² (experimentally achieved capacity: 3.0 mAh cm⁻²; 301 mAh g⁻¹cathode) at 1C (d) and with a high sulfur fraction of 45 wt% in the cathode at 0.2C (e) (sulfur loading: 1.9 mg cm⁻²; experimentally achieved capacity: 2.0 mAh cm⁻²; 472 mAh g⁻¹cathode). The Coulomb efficiencies are calculated by dividing the discharge capacity by the charge capacity of the same cycle.
Long-term cycling performance of ASSLSBs at 25 °C a, Cycling performance (charging capacity) of cells based on LBPSI and Li5.5PS4.5Cl1.5 at 0.2C (sulfur loading: 1.5 mg cm⁻²; experimentally achieved capacity: 2.1 mAh cm⁻²). b, Long-term cycling of the cell based on LBPSI at 2C (sulfur loading: 1.1 mg cm⁻²; experimentally achieved capacity: 1.2 mAh cm⁻²). The cell was subjected to an activation process by cycling at progressively increasing rates of 0.05–1C for several cycles. c, Cycling performance (the charging capacity) of the cells based on LBPSI and Li5.5PS4.5Cl1.5 at 5C (sulfur loading: 1.1 mg cm⁻²; experimentally achieved capacity: 0.91 mAh cm⁻² of the cell based on LBPSI). Cells were subjected to an activation process by cycling at progressively increasing rates of 0.05–4C for several cycles. d,e, Cycling performance of the cell based on LBPSI with a high sulfur loading of 3.0 mg cm⁻² (experimentally achieved capacity: 3.0 mAh cm⁻²; 301 mAh g⁻¹cathode) at 1C (d) and with a high sulfur fraction of 45 wt% in the cathode at 0.2C (e) (sulfur loading: 1.9 mg cm⁻²; experimentally achieved capacity: 2.0 mAh cm⁻²; 472 mAh g⁻¹cathode). The Coulomb efficiencies are calculated by dividing the discharge capacity by the charge capacity of the same cycle.
… 
Long-term cycling performance of ASSLSBs at 60 °C a,b, Cycling performance of the cell based on LBPSI electrolyte at a charging/discharging rate of 10C and corresponding voltage profiles (sulfur loading: 1.0 mg cm⁻²; experimentally achieved capacity: 1.1 mAh cm⁻²). The cell was subjected to an activation process by cycling at progressively increasing rates of 0.05–8C for several cycles. c, Cycling performance (charging capacity) of the cells at 15C (sulfur loading: 1.0 mg cm⁻²; experimentally achieved capacity: about 1.1 mAh cm⁻²). The cells were subjected to an activation process by cycling at progressively increasing rates of 0.05–10C for several cycles.
Long-term cycling performance of ASSLSBs at 60 °C a,b, Cycling performance of the cell based on LBPSI electrolyte at a charging/discharging rate of 10C and corresponding voltage profiles (sulfur loading: 1.0 mg cm⁻²; experimentally achieved capacity: 1.1 mAh cm⁻²). The cell was subjected to an activation process by cycling at progressively increasing rates of 0.05–8C for several cycles. c, Cycling performance (charging capacity) of the cells at 15C (sulfur loading: 1.0 mg cm⁻²; experimentally achieved capacity: about 1.1 mAh cm⁻²). The cells were subjected to an activation process by cycling at progressively increasing rates of 0.05–10C for several cycles.
… 
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846 | Nature | Vol 637 | 23 January 2025
Article
All-solid-state Li–S batteries with fast solid–
solid sulfur reaction
Huimin Song1, Konrad Münch2,3, Xu Liu1, Kaier Shen1, Ruizhuo Zhang4, Timo Weintraut2,3,
Yuriy Yusim2,3, Dequan Jiang1, Xufeng Hong1, Jiashen Meng1, Yatao Liu1, Mengxue He1,
Yitao Li1, Philip Henkel4, Torsten Brezesinski4, Jürgen Janek2,3,4 & Quanquan Pang1 ✉
With promises for high specic energy, high safety and low cost, the all-solid-state
lithium–sulfur battery (ASSLSB) is ideal for next-generation energy storage1–5.
However, the poor rate performance and short cycle life caused by the sluggish
solid–solid sulfur redox reaction (SSSRR) at the three-phase boundaries remain to
be solved. Here we demonstrate a fast SSSRR enabled by lithium thioborophosphate
iodide (LBPSI) glass-phase solid electrolytes (GSEs). On the basis of the reversible
redox between I− and I2/I3−, the solid electrolyte (SE)—as well as serving as a superionic
conductor—functions as a surcial redox mediator that facilitates the sluggish
reactions at the solid–solid two-phase boundaries, thereby substantially increasing
the density of active sites. Through this mechanism, the ASSLSB exhibits ultrafast
charging capability, showing a high specic capacity of 1,497 mAh g−1sulfur on
charging at 2C (30 °C), while still maintaining 784 mAh g−1sulfur at 20C. Notably, a
specic capacity of 432 mAh g−1sulfur is achieved on charging at an extreme rate of
150C at 60 °C. Furthermore, the cell demonstrates superior cycling stability over
25,000 cycles with 80.2% capacity retention at 5C (25 °C). We expect that our work
on redox-mediated SSSRR will pave the way for developing advanced ASSLSBs that are
high energy and safe.
Developing all-solid-state batteries is considered important for elec-
tric transportation, owing to their expected high safety and specific
energy
6–11
. All-solid-state batteries based on layered metal oxide (LMO)
cathodes are attractive
12,13
but irreversible parasitic reactions of LMOs
with the SE at high potentials and the chemo-mechanical degradation
of Ni-rich LMOs hinder long-term stability and rate capability
14–16
. The
ASSLSB with its high specific energy can, in principle, eliminate some of
these challenges, as the moderate potential does notcause notableoxi-
dation of the SEs
1–5
, nor does any release of reactive oxygen on charging
threaten the thermal safety
17,18
, therefore promising higher intrinsic
safety. The use of SEs would further eliminate the notorious polysulfide
shuttling present in liquid-electrolyte-based Li–S batteries19.
However, ASSLSBs have been plagued by poor rate performance and
cycle life because of the very slow SSSRR of both elemental sulfur and
Li
2
S. As both active materials are electron-insulating, the reaction can
only occur at the SE|active material|carbon three-phase boundary, which
is allsolid. As the density of three-phase boundary sites is typically much
lower than that of two-phase boundary sites, the reactions are spatially
highly confined, challenging effective solid–solid charge transfer. Nota-
ble efforts have been made by introducing functional additives to the
cathodes, such as Cu, LiVS
2
and modified carbon
20–23
, but the poor kinet-
ics caused by the‘all-solid three-phase boundary’ challenge is not fully
resolved (Supplementary Table1). Also, the use of Li2S as active material
may add technical challenges for electrode manufacturing4,19,24.
In this work, we demonstrate a fast SSSRR and high cycling stabil-
ity achieved with LBPSI GSEs. In contrast to using an extra electron-
mediating agent, the electrolyte itself is formulated with redox-active
iodine, such that it serves as surficial redox mediator to facilitate the
oxidation of Li2S particles. The iodine anions on the SE surface can be
electrochemically oxidized to I2 and I3− (denoted as I2/I3−) at the SE|C
boundary on charge, which subsequently chemically oxidizes the Li
2
S
in contact. Notably, such a SE surface-based redox-mediated process
enables the reaction at the SE|Li
2
S two-phase boundary that is other-
wise inactive but much more populated than the required SE|Li
2
S|C
three-phase boundary (Fig.1a). The tendency of the formulated elec-
trolytes to form a glass (as opposed to crystals) enables the reversible
iodine redox instead of persistent SE degradation. With this redox
mediation strategy
2,25–29
, we demonstrate ASSLSBs with excellent charg-
ing capability (up to 35C at 30 °C) and cycling stability.
Synthesis and characterization of GSEs
B2S3 is an excellent glass former and facilitates the formation of GSEs
of Li
2
S–B
2
S
3
(ref. 30), a low-mass-density family of sulfide electrolytes.
However, the pristine lithium thioborate glass shows very low ionic
conductivity30. As P2S5 is also known to form sulfide glasses31, we pro-
pose a new class of superionic LBPSI GSEs (Li
2
S–B
2
S
3
–P
2
S
5
–LiI) by tailor-
ing the ratio of the two glass formers and using LiI as a glass-network
https://doi.org/10.1038/s41586-024-08298-9
Received: 20 November 2023
Accepted: 29 October 2024
Published online: 15 January 2025
Check for updates
1Beijing Key Laboratory for Theory and Technology of Advanced Battery Materials, School of Materials Science and Engineering, Peking University, Beijing, China. 2Institute of Physical Chemistry,
Justus Liebig University Giessen, Giessen, Germany. 3Center for Materials Research, Justus Liebig University Giessen, Giessen, Germany. 4Battery and Electrochemistry Laboratory (BELLA),
Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany. ✉e-mail: qqpang@pku.edu.cn
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Enabling simple three-electrode (3E) setups for solid-state battery cells is important for allowing investigation of individual electrodes to shed more light on interface charge transfer and reactions occurring in solid-state battery cells. Two different 3E setups are compared, and their practical value is evaluated. A miniaturized reference electrode (μ-RE) is developed from lithium-plated gold wires with a tungsten core providing a stable potential. Cells with Li6PS5Cl as solid electrolyte, Li1-xNi0.85Co0.10Mn0.05O2 (NCM851005) as cathode active material, and Li4Ti5O12/Li7Ti5O12 (LTO) or In/InLi as anode are investigated. The reference electrode provides a stable potential of 0 V vs. Li+/Li, hence allowing the precise measurement of single electrode potentials. The setup leaves the usual cell geometry essentially unchanged and causes only minor additional work during cell assembly, allowing widespread application. Evidence is provided that 3E setups are needed to evaluate the rate capability of active materials correctly and that two-electrode setups can massively underestimate the rate capability of electrodes. The impedance of full cells is systematically analyzed based on separate anode and cathode impedances.
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A LaCl3-based lithium superionic conductor compatible with lithium metal
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Full-text available
  • Apr 2023
  • NATURE
Inorganic superionic conductors possess high ionic conductivity and excellent thermal stability but their poor interfacial compatibility with lithium metal electrodes precludes application in all-solid-state lithium metal batteries1,2. Here we report a LaCl3-based lithium superionic conductor possessing excellent interfacial compatibility with lithium metal electrodes. In contrast to a Li3MCl6 (M = Y, In, Sc and Ho) electrolyte lattice3–6, the UCl3-type LaCl3 lattice has large, one-dimensional channels for rapid Li⁺ conduction, interconnected by La vacancies via Ta doping and resulting in a three-dimensional Li⁺ migration network. The optimized Li0.388Ta0.238La0.475Cl3 electrolyte exhibits Li⁺ conductivity of 3.02 mS cm⁻¹ at 30 °C and a low activation energy of 0.197 eV. It also generates a gradient interfacial passivation layer to stabilize the Li metal electrode for long-term cycling of a Li–Li symmetric cell (1 mAh cm⁻²) for more than 5,000 h. When directly coupled with an uncoated LiNi0.5Co0.2Mn0.3O2 cathode and bare Li metal anode, the Li0.388Ta0.238La0.475Cl3 electrolyte enables a solid battery to run for more than 100 cycles with a cutoff voltage of 4.35 V and areal capacity of more than 1 mAh cm⁻². We also demonstrate rapid Li⁺ conduction in lanthanide metal chlorides (LnCl3; Ln = La, Ce, Nd, Sm and Gd), suggesting that the LnCl3 solid electrolyte system could provide further developments in conductivity and utility.
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Distinct thermal runaway mechanisms of sulfide-based all-solid-state batteries
Article
  • Jan 2023
All-solid-state batteries (ASSBs) are one of the most promising candidates for next-generation energy storage. In particular, ASSBs with sulfide solid-state electrolytes (SEs) offer high conductivity, rivaling those of liquid electrolytes...
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A lithium superionic conductor for millimeter-thick battery electrode
Article
  • Jul 2023
  • SCIENCE
No design rules have yet been established for producing solid electrolytes with a lithium-ion conductivity high enough to replace liquid electrolytes and expand the performance and battery configuration limits of current lithium ion batteries. Taking advantage of the properties of high-entropy materials, we have designed a highly ion-conductive solid electrolyte by increasing the compositional complexity of a known lithium superionic conductor to eliminate ion migration barriers while maintaining the structural framework for superionic conduction. The synthesized phase with a compositional complexity showed an improved ion conductivity. We showed that the highly conductive solid electrolyte enables charge and discharge of a thick lithium-ion battery cathode at room temperature and thus has potential to change conventional battery configurations.
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Stabilizing High-Temperature α-Li3PS4 by Rapidly Heating the Glass
Article
  • Jun 2023
  • J AM CHEM SOC
High-temperature metastable phases exhibit superior characteristics compared to those of thermodynamically stable phases at room temperature. Although optimization of the compositions and crystallizations from glasses contribute to the stabilization of metastable phases at room temperature, the stabilization of the high-temperature α-Li3PS4 phase is not yet reported. α-Li3PS4 was successfully stabilized at room temperature, instead of the middle-temperature β-Li3PS4 phase, via rapid heating to crystallize the Li3PS4 glass. The obtained electrolyte exhibited a high ionic conductivity of >10-3 S cm-1 at room temperature. The crystallization of the glass via rapid heating overcame the thermodynamic limitations in the preparation of the metastable crystals. Further development of materials via nonequilibrium states should contribute to the design of high-performance materials.
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