Software-driven design of non-aqueous electrolyte options by quantification of interfacial reactions in lithium steel batteries

Preparation of the electrolyte options and SLS pouch cells

LiFSI (99.99%, Kaixin), DME (99.95%, Guotai), TTE (99.5%, Aladdin), BTFE (99%, Aladdin) and BZ (99.9%, Aladdin) have been used for the preparation of electrolyte options. All chemical compounds have been used as obtained and the water content material was decided to be <20 ppm by Karl Fischer titration. All options have been gravimetrically ready and magnetically stirred in glass scintillation vials in a dry room (4 m × 5 m) with relative humidity <1% at 25 °C utilizing Pasteur pipets (for liquids) and a 4-digit analytical steadiness. Graphite||NMC811, Cu||NMC811 and Li||NMC811 SLS pouch cells have been fabricated in a CATL pilot line (technical specs of the electrode formulations can’t be disclosed as they’re coated by an industrial non-disclosure settlement) and used for biking after electrolyte injection. NMC811-based optimistic electrodes are 42 mm × 49.5 mm and double-side coated, with an lively materials loading of 17.1 mg cm⁻² and an areal capability of three.53 mAh cm⁻² for a 0.2 C (28 mA) present on either side. Cell meeting was carried out in the identical dry room talked about above. Electrolyte injection was achieved gravimetrically after sealing three sides of the pouch cell; the ultimate aspect was heat-sealed beneath vacuum (−90 kPa) instantly thereafter. Parameters for the pouch cell are proven in Supplementary Desk 8. All of the cells have been set at 0.21 MPa (30 psi) preliminary strain and cycled beneath a fixed-gap situation (that’s, securing the pouch cell between two aluminium plates with an preliminary 0.21 MPa strain utilizing 4 screws, such that the clamped cell maintains a set thickness) utilizing a Neware CT-4008Tn-5V6A-S1 testing system in a temperature-controlled room set to 25 °C. All cells have been cycled at 0.2 C (28 mA)–1 C (140 mA) between 2.8 V and 4.3 V with none prior formation cycles, and the charging adopted a continuing present–fixed potential (CC–CP) protocol with a cut-off present of 0.1 C (14 mA). For simplicity, we abbreviate this biking course of as ‘0.2–1 C’.

T-DEMS

Preparation of cycled electrode samples

The Cu||NMC811 pouch cells have been first cycled for 1 cycle, 20 cycles, 40 cycles, 60 cycles, 80 cycles and 100 cycles beneath 0.2–1 C. A deep discharge process was then utilized on every cycled Cu||NMC811 pouch cell. The deep discharge process refers back to the repeated discharging of the cell to 2.8 V utilizing successively smaller currents (7 mA, 3.5 mA and 1 mA) to totally strip the lively Li from the damaging electrode such that it’s going to not be mistaken as ‘useless’ Li. The deep discharge process normally extracts a further 5–20 mAh of discharge capability. After deep discharge, the cell was disassembled in an argon-filled glove field (H₂O <0.1 ppm, O₂ <0.1 ppm). Both the Cu electrode or the NMC811-based electrode was then positioned right into a titration vessel for subsequent assessments (Supplementary Fig. 1).

Quantification of ‘useless’ Li, LiH and Li₂CO₃

The quantification of ‘useless’ Li and LiH was carried out with deuterated ethanol (CD₃CD₂OD) because the titrant. The quantification of Li₂CO₃ was carried out with 10 M H₂SO₄ because the titrant. The titration was carried out in an in-house developed Teflon container. The fuel generated was collected and measured utilizing a differential electrochemical mass spectrometry system (DEMS, Shanghai LingLu Devices; Supplementary Fig. 1).

Dedication of calibration equations

To assemble the calibration equations (equations (7) and (8)) used to quantify ‘useless’ Li, Li steel with totally different recognized plenty was positioned right into a titration vessel related to DEMS. After the argon (99.999%, Fuzhou Zhongming Qiti) influx stabilized, ethanol-d₆ (CD₃CD₂OD, 99%, Aladdin) was injected into the vessel, and the generated fuel was flushed into DEMS for evaluation. A number of-ion mode was used to file the ion present of mass/cost ratios: m/z = 3 for hydrogen deuteride (HD) and m/z = 4 for deuterium (D₂) fuel. Afterwards, calibration equations have been obtained by linear regressions of the areas of HD and D₂ indicators towards the Li steel plenty (with the origin included; Supplementary Fig. 2a,b). Equally, calibration equations of LiH have been obtained by CD₃CD₂OD titration on LiH (97%, Macklin) samples (Supplementary Fig. 2c,d).

The reactions of CD₃CD₂OD with Li steel and LiH occur as follows:

Nevertheless, weak but observable indicators of HD and D₂ have been detected for Li steel and LiH, respectively. We attribute this to the non-ideal deuterium abundance within the CD₃CD₂OD titrant and the random recombination of hydrogen and deuterium radicals through the titration experiments. For the accuracy of subsequent quantifications, we carried out linear regressions on each HD and D₂ indicators for Li steel and LiH (Supplementary Fig. 2a–d).

A calibration equation of Li₂CO₃ (equation (9)) was obtained by 10 M H₂SO₄ titration on Li₂CO₃ (99.5%, Macklin) samples with CO₂ because the generated fuel⁴² (Supplementary Fig. 2e).

The response of 10 M H₂SO₄ with Li₂CO₃ occurs as follows:

Quantification of ‘useless’ Li, LiH and Li₂CO₃ on a pattern

To quantify ‘useless’ Li and LiH, a cycled Cu electrode pattern was positioned right into a titration vessel related to DEMS. After the argon influx stabilized, CD₃CD₂OD was injected into the vessel, and the generated fuel was flushed into DEMS for measurements. The plenty of ‘useless’ Li and LiH on the cycled electrode have been set as x and y, respectively, and the areas of peaks attributed to HD and D₂ from the DEMS end result was set to be A and B, respectively. The values of x and y have been decided by the next equations:

To quantify Li₂CO₃, the same course of was utilized with 10 M H₂SO₄ because the titrant. The mass of Li₂CO₃ on the pattern was set to be z, and the realm of the height attributed to CO₂ from the DEMS end result was set to be C. The worth of z was decided by the next equation:

Right here ({ok}_{mathrm{HD}-{mathrm{Li}}; {rm{steel}}}), ({ok}_{mathrm{HD}-mathrm{LiH}}), ({ok}_{mathrm{D}_{2}-{mathrm{Li}}; {rm{steel}}}), ({ok}_{mathrm{D}_{2}-mathrm{LiH}}) and ({ok}_{{mathrm{CO}}_{2}}) are the slopes of the calibration curves (Supplementary Fig. 2a–e).

On this work, we additional standardized the plenty of ‘useless’ Li, LiH and Li₂CO₃ into equal Li capacities (C_Li) by the next calculations:

In equations (11) and (12), the plenty of LiH and Li₂CO₃ (y and z, respectively) are transformed into mole-equivalent plenty of Li by their corresponding molar plenty. These, together with the mass of ‘useless’ Li (x) in equation (10), are then transformed into equal Li capability utilizing the precise capability of Li (3,860 mAh g⁻¹).

E-G&IC

E-G&IC was carried out on Cu||NMC811 and 50 μm Li||NMC811 cells with 0.3 g of electrolyte after biking for a set variety of cycles (for instance, 1 cycle, 50 cycles, 100 cycles, …, 300 cycles for 50 μm Li||NMC811 cells) beneath 0.2–1 C.

Preparation of the extraction agent

1,2-Diethoxyethane (DEE, 99.9%, Aladdin, <20 ppm H₂O) was used as the inner normal. Diethylene glycol dimethyl ether (diglyme, 99.9%, Aladdin, <20 ppm H₂O) was used because the extracting solvent. An extraction agent was ready by mixing 4 g of DEE with diglyme in a 200 ml volumetric flask at 25 °C in a dry room. The extraction agent was then sealed with parafilm in a scintillation vial and saved beneath the identical circumstances for later use.

Extraction of electrolytes in LMBs

Inside an argon-filled glove field (H₂O <0.1 ppm, O₂ <0.1 ppm), an incision was made on the fringe of a cycled LMB pouch cell, by which 5 ml of the extraction agent was injected. The cell was then re-sealed by heat-sealing the pouch alongside the lower edge. The contents of the sealed cell have been completely blended by first permitting the liquid to diffuse throughout storage at 25 °C for 3.5 days after which vertically inverting and storing the cell for one more 3.5 days. After 7 days, the liquid combination contained within the pouch cell was extracted through a syringe and syringe-filtered (0.22 μm) for subsequent measurements.

IC and quantification of LiFSI

Dedication of calibration equation

LiFSI (20 mg, 40 mg, 60 mg, 80 mg and 100 mg) was dissolved in 1,000 ml of deionized H₂O (18.5 MΩ cm at 25 °C, Milli-Q IQ 7000) to type 5 normal options. Every normal answer (5 ml) was measured with IC (Dionex Aquion RFIC, Thermo Scientific) and the realm of peaks attributed to the FSI⁻ anion was calculated. Afterwards, a linear regression was carried out between the height space and the LiFSI focus, serving because the calibration equation (equation (13) and Supplementary Fig. 2f).

Quantification of LiFSI

The extracted liquid of a cycled LMB cell was diluted 200-fold with deionized H₂O. The diluted answer (5 ml) was measured with IC. The focus of LiFSI within the diluted answer was set to be c_LiFSI, and the realm of the FSI⁻ anion peak from the IC end result was set to be S_LiFSI. The worth of c_LiFSI was decided making use of the next equation:

Right here ({ok}_{mathrm{LiFSI}}) is the slope of the calibration curve (Supplementary Fig. 2f). Absolutely the mass of residual LiFSI within the cycled cell m_LiFSI was additional calculated as follows:

the place 200 is the dilution issue and 5.25 ml comes from 5 ml of extraction agent and 0.25 ml from 0.3 g of the electrolyte used on this work.

GC and quantification of DME and TTE

Dedication of response components

The freshly ready (uncycled) electrolyte (0.3 g) was blended into 5 ml of extraction agent. The combination was additional diluted fivefold with diglyme to acquire a normal answer. The usual answer (1.5 ml) was measured with GC (Nexis GC-2030, Shimadzu). The plenty of DME, TTE and DEE in the usual answer have been recognized (m_DME = 32.7 mg, m_TTE = 210.6 mg and m_DEE = 100.0 mg). The areas of peaks attributed to DME, TTE and DEE have been collected from the GC outcomes (S_DME, S_TTE and S_DEE). The response components for DME (f_DME) and TTE (f_TTE) have been calculated as follows:

Quantification of DME and TTE

The extracted liquid of a cycled LMB cell was diluted fivefold with diglyme. The diluted answer (1.5 ml) was measured with GC. The areas of peaks attributed to DME, TTE and DEE have been collected from the GC outcomes (S_DME-exp, S_TTE-exp and S_DEE-exp). Absolutely the plenty of residual DME (m_DME-exp) and TTE (m_TTE-exp) within the cycled cell have been calculated as follows:

Further physicochemical characterizations

NMR measurements have been carried out utilizing a Bruker AVANCE NEO 500 MHz digital FT-NMR spectrometer. After Cu||NMC811 was cycled beneath 0.2–1 C for 100 cycles, 5 ml of diglyme was added into the cell. The cell was sealed and saved for 7 days at 25 °C, after which the combination of cycled electrolyte and diglyme was extracted for the NMR check. The entire sampling process was carried out in a dry room.

Electrolyte options for Raman measurements have been ready in a dry room and sealed in glass scintillation vials for switch to a separate laboratory for pattern loading. The liquid pattern was drawn through capillary motion by submerging one finish of a quartz capillary tube into the liquid pattern beneath atmospheric circumstances. The 2 ends of the capillary have been then sealed with ultra-light clay to stop pattern evaporation and contamination. The sealed capillary was then loaded right into a Renishaw InVia Qontor Raman spectrometer. Spectra have been acquired at 25 °C utilizing an excitation wavelength of 785 nm.

For dynamic viscosity and ionic conductivity measurements, electrolyte options have been ready in a dry room and sealed in glass scintillation vials for switch to a separate laboratory for measurements. Dynamic viscosities have been measured with a Brookfield DV2T viscometer utilizing the SC4-18 spindle at 25 °C beneath ambient atmospheric circumstances. After levelling and autozeroing the gear, an 8 ml aliquot of the answer (sufficient liquid to totally submerge the spindle) was transferred to the instrument pattern holder and equilibrated at 25 °C for 10 min. Measurements have been carried out with periodic stirring. Ionic conductivities have been measured with a Shanghai Leici DDSJ-318 conductivity meter at 25 °C beneath ambient atmospheric circumstances. An ~10 ml aliquot of the answer was transferred to and sealed in a 50 ml Falcon tube, after which equilibrated at 25 °C for 10 min in a water bathtub. The calibration of the meter was verified utilizing high and low ionic conductivity normal samples. The probe head was cleaned with ethanol and DI water in between makes use of.

XPS measurements have been carried out utilizing a Shimadzu Axis Supra+ imaging X-ray photoelectron spectrometer. An Al Kα X-ray (1,486.7 eV) was used because the excitation supply, and the information have been collected in an space of 700 × 300 µm through the use of a hemispherical electron vitality analyser at an emission energy of 195 W. Sputtering was carried out on a 3 × 3 cm area with a 5 keV argon ion supply and an incident angle of 45°. The electrode samples have been washed with DME solvent and dried inside an Ar glove field, after which transferred inside an hermetic vessel from the glove field to the XPS pattern chamber. The sputtering time increments have been 0 s, 60 s, 120 s, 180 s and 300 s.

For the ICP-OES measurement, a Cu||NMC811 cell was cycled beneath 0.2–1 C for 100 cycles, adopted by a deep discharge course of. Afterwards, the cell was disassembled inside an argon-filled glove field (H₂O <0.1 ppm, O₂ <0.1 ppm). The stable rSEI shaped on the Cu electrodes was collected utilizing a scraper right into a glass vial. The collected powder was then soaked in DME for 60–120 min. After eradicating the supernatant, the powder pattern was dried in a vacuum chamber at 25 °C. The soaking and drying process was repeated 5 occasions in dry room earlier than the pattern was measured with a ThermoFisher iCAP PRO ICP-OES. These preparation procedures ensured full elimination of lively Li and residual electrolyte elements from the pattern.

For FT-IR measurements, the FT-IR spectra for the cycled Cu electrode have been collected with a Thermo Scientific Nicolet iS50 spectrometer. A Cu||NMC811 cell with LiFSI–1.2DME–3TTE was cycled beneath 0.2–1 C for 100 cycles and deep discharged (deep discharge refers back to the repeated discharging of the cell to 2.8 V utilizing successively smaller currents (7 mA, 3.5 mA and 1 mA) to totally strip the lively Li from the damaging electrode such that it’s going to not be mistaken as ‘useless’ Li). Afterwards, the cell was disassembled inside an argon-filled glove field (H₂O <0.1 ppm, O₂ <0.1 ppm). The Cu electrode was sealed with tape to stop corrosion in ambient air and was transferred instantly for FT-IR measurement.

For the in situ DEMS measurement of fuel era at 25 °C, an hermetic electrochemical vessel was used to accommodate a pouch cell. The electrodes of the pouch cell have been related to 2 binding posts on the electrochemical vessel in order that the cell could possibly be cycled. The sting of the pouch cell was incised earlier than being sealed into the vessel. The vessel was related to a provider fuel system, and the fuel generated from the pouch cell was directed right into a mass spectrometer for quantitative evaluation. The provider fuel system consisted of a provider fuel (Ar, 99.999%, Fuzhou Zhongming Qiti), a 2.0 μm filter (Swagelok), a digital mass flowmeter (Bronkhorst, EL-FLOW Choose) and an in-house developed chilly entice with a temperature controller. The Ar fuel, regulated by a strain regulator (set to 0.1 MPa), was directed sequentially by a 2.0 μm filter, a quantitative ring within the pulse inlet system, and the chilly entice earlier than getting into the mass spectrometer for fuel evaluation. The filter serves to guard the mass move controller and the mass spectrometer from small particles within the steel tubing and the pattern itself. The move charge of Ar was maintained at 0.6 ml min⁻¹ to make sure excessive sensitivity for hint fuel evaluation contained in the pouch cell. The chilly entice temperature was set to −90 °C to seize the risky natural species contained within the provider fuel to guard the mass spectrometer and improve sensitivity.

Scanning electron microscope (SEM) pictures have been captured utilizing a ThermoFisher Helios G4 CX dual-beam targeted ion beam (FIB)–SEM and ZEISS GeminiSEM 360. Cross-sectional samples have been ready by reducing a small piece of the pattern of curiosity and sprucing with a Hitachi ArBlade 5000 beneath cryogenic circumstances in an argon ambiance. Samples have been transferred in an air-free pattern holder.

All of the STEM characterizations have been carried out utilizing an aberration-corrected FEI Themis Z electron microscope geared up with a Gatan GIF Quantum 1065 for EELS operated at 300 kV. For STEM HAADF imaging on the NMC811-based optimistic electrode, site-specific TEM lamellae have been ready by FIB. The Helios FIB–SEM was used for trenching, in situ lift-out and thinning. To scale back the potential floor injury brought on by FIB milling, an additional low-energy cleansing at 2 kV was carried out. HAADF imaging was then carried out with a convergence angle of 26.5 mrad and an angular assortment angle between 60 mrad and 120 mrad. For cryo-TEM, STEM, EDS and EELS characterizations on the rSEI pattern, a pure Cu TEM grid was mounted on the Cu damaging electrode of a Cu||NMC811 pouch cell, which was cycled beneath 0.2–1 C. The cell was deep discharged after 10 cycles, after which dissembled inside an argon-filled glove field. The TEM grid was transferred to the microscope utilizing a Fischione 2550 Cryo Switch Holder. The TEM, STEM, EDS and EELS experiments have been carried out beneath a temperature of −170 °C. The probe present used for EELS mapping is ~30 pA, and the dose charge is round 7.5 × 10⁴ e/(Ų s).

CO₂ solubility was measured with an Preliminary Vitality Science and Expertise (IEST) GVM2200 in situ cell quantity analyser. For the fuel solubility check, 10 g of LiFSI–1.2DME–3TTE electrolyte was vacuum sealed in an empty pouch in a dry room. CO₂ fuel (40 ml) was injected into the electrolyte-containing pouch with a syringe, and the pouch was sealed once more with duct tape. The shrinkage of the pouch because of the CO₂ dissolved within the electrolyte answer was measured with the in situ cell quantity analyser. The pouch was submerged in silicone oil (at 25 °C), and quantity adjustments have been measured in actual time by making use of the Archimedes precept⁴³.

In keeping with the Archimedes precept, when an object is partially or absolutely submerged in a fluid, it experiences an upward buoyant drive equal to the burden of the fluid displaced by the thing.

The quantity of the cell could possibly be obtained as follows:

the place V is the amount of the cell, (Delta m) is the mass of water displaced by the cell, (rho) is the density of water at 25 °C and (g) is the gravitational acceleration.

First-principles simulations

All floor calculations have been carried out using the density useful concept (DFT) as carried out within the Vienna Ab initio Simulation Bundle (VASP)^44,45. The electron exchange-correlation energies have been decided utilizing the generalized gradient approximation and Perdew–Burke–Ernzerhof useful throughout the DFT framework⁴⁶. Transition metals have been handled utilizing the DFT + U augmented method with U values of 4 eV, 4.4 eV and 5 eV for Mn, Co and Ni, respectively. The DFT + D3 technique, which included dispersion correction, was used to account for weak interactions within the programs beneath investigation⁴⁷. All calculations have been spin-polarized, and a plane-wave cut-off vitality of 520 eV was utilized. All floor calculations have been carried out utilizing a 2 × 2 × 1 ok-point throughout the Monkhorst–Pack scheme, and a 15 Å vacuum layer was added to keep away from the interactions between repeated periodic slabs. A five-layer slab of the (110) floor of Li was utilized to analyze the discount decomposition course of, whereas the charged NCM811 slab, by taking the Li atoms out, was used to review the DME oxidation course of. Geometric construction optimizations have been carried out till the drive on all atoms was lower than 0.02 eV Å⁻¹, with vitality convergence standards set to be smaller than 10⁻⁵ eV per atom. The climbing picture nudged elastic band⁴⁸ and dimer strategies⁴⁹ have been mixed to find the transition states alongside the response pathways, with all transition states verified to have just one imaginary vibrational frequency alongside the response coordinate.

The energies of the best occupied molecular orbital and lowest unoccupied molecular orbital have been calculated utilizing the DFT technique on the B3LYP/6-311G+(d, p) stage⁵⁰ carried out within the Gaussian 09 (ref. ⁵¹) software program bundle. The SMD (solvation mannequin primarily based on density)⁵² was chosen to account for the solvent impact.

The conductor-like screening mannequin for actual solvents (COSMO-RS) technique^53,54 was used to get macroscopic fuel solubility knowledge. The BP useful and TZVP foundation set from the Turbomole programme⁵⁵ have been used for COSMO calculations. The ensuing COSMO information have been subsequently imported within the COSMOtherm programme⁵⁶ to find out the solubility of fuel⁵⁷.

MD simulation

MD simulations have been carried out with large-scale atomic/molecular massively parallel simulator (LAMMPS)⁵⁸. As visualized with OVITO⁵⁹ (Supplementary Fig. 12a), the simulation field encompasses two Li steel electrodes separated by a distance of 144 Å and a area of electrolyte. Every Li steel electrode floor is represented by the (100) side and has a dimension of 37 Å × 37 Å × 10 Å with 500 atoms. About 130 LiFSI, 157 DME and 472 TTE molecules have been positioned between the 2 electrodes, and the configuration was obtained by a preliminary MD simulation of the majority electrolyte beneath the NPT ensemble at 298 Ok.

The OPLS-AA drive subject⁶⁰ was used to deal with the interactions between the atoms within the liquid section. Power subject parameters have been generated by the LigParGen internet server⁶¹. Parameters for Li within the electrode have been obtained from Nichol et al.⁶². Interactions between electrode and electrolyte atoms have been modelled by the Lennard-Jones potentials primarily based on geometric mixing guidelines, along with the long-range Coulomb forces. Electrode atoms have been mounted through the simulation, and solely electrolyte atoms have been allowed to maneuver throughout the area confined by the 2 electrodes. Beneath the NVT ensemble, the system was simulated utilizing the Nosé–Hoover thermostat⁶³ at 313 Ok.

To precisely depict the fees held by the electrode atoms, we carried out a continuing potential technique^64,65,66,67. This concerned dynamically assigning a cost to every electrode atom in a approach that ensured that each one atoms in a single electrode have been at a single Poisson potential, whereas all atoms within the different electrode have been at a special Poisson potential. The 2 potentials have been then set to vary by a predetermined worth, ΔU. The 2 electrodes bore costs of equal magnitude however reverse indicators, leading to a charge-neutral system total. On the premise of the fixed potential technique, the cost held by every atom within the electrodes may be decided by the next equation⁶⁷:

the place Q is a vector containing the cost for every electrode atom, A is the elastance matrix representing the interactions between electrode atoms, b is an electrolyte vector representing the electrostatic potential brought on by the electrolyte atoms, which is a operate of the electrolyte atom positions⁶⁷, and v is a vector containing the utilized potential (U) for every electrode atom, which depends upon ΔU. On this examine, one pair of ΔU have been used: {−5 V, 5 V}. This corresponds to {backside electrode potential, high electrode potential} in Supplementary Fig. 12.

The simulation was run for no less than 20 ns with a step of 1 fs to permit for equilibration of the solvation construction close to the electrode interface. Throughout this time, the initially uncharged electrode progressively acquired cost, and ions with reverse costs approached the electrode to type electrical double layers. Following the equilibrium interval, samples have been taken at 2,000 fs intervals for the ultimate 5 ns, then averaged and analysed. To acquire the distribution of electrolyte species, the area occupied by the electrolyte was segmented into bins with widths of 0.1 Å. Numbers of electrolyte species in every bin have been tallied and quantity densities (Supplementary Fig. 12b) have been calculated, which is also normalized by the corresponding quantity density (Supplementary Desk 2).

Faradic currents between the electrodes and (electro)chemical reactions weren’t allowed to occur throughout this simulation.

Electrochemical simulation

Li||NMC811 cell’s discharge potential profiles (Fig. 3j) and electrolyte focus distributions (Fig. 3k) have been simulated by COMSOL Multiphysics model 6.0. A Li steel electrode was handled as a great planar electrode and its floor morphology change throughout discharging was not thought-about. Due to this fact, x = 0 in Fig. 3k represents the interface between Li steel electrode and separator. Parameters of the simulation are listed as follows.

Electrolyte

Diffusion coefficient is 1 × 10⁻¹⁰ m² s⁻¹. The transference quantity is 0.363. Static molar focus and ionic conductivity are extracted from Fig. 3h.

Separator

The thickness is 15 μm. The porosity is 0.39. Tortuosity is correlated with porosity following the Bruggeman relationship⁶⁸ with a Bruggeman coefficient of two.

NMC811 optimistic electrode

The thickness is 49.6 μm. The porosity is 0.25. Tortuosity is correlated with porosity following the Bruggeman relationship with a Bruggeman coefficient of two.2. The open circuit potential is experimentally measured for a Li||NMC811 cell (Supplementary Fig. 28). The solid-state diffusion coefficient is 4 × 10⁻¹⁵ m² s⁻¹. The electrochemical response charge fixed is 8 × 10⁻¹² m s⁻¹.

Li steel damaging electrode

The electrochemical response charge fixed is 6 × 10⁻¹¹ m s⁻¹.

Calculation of lifetime CE for LMBs

Dedication of the general CE through the cycle lifetime of an LMB (hereinto known as lifetime CE) was modified primarily based on our beforehand reported method³¹. After a Cu||NMC811 or Li||NMC811 cell capability retention decayed to 50–80%, the cell was stopped from biking and a deep discharge was carried out to strip away all of the remaining lively Li on the damaging electrode. We outline the ith cycle cost capability as C_i-c, the final cycle quantity as n_EOL, the overall discharge capability of the final cycle, together with that through the deep discharge as C_EOL-dc, and the Li capability of the pristine Li foil as C_{Li foil} (for a Cu||NMC811 cell, C_{Li foil} = 0 mAh). The lifetime Li steel CE is given by

Notice that two key experimental operations are obligatory:

1. 1.

   The electrolyte quantity must be extreme.

   This ensures that the cell failure is because of lively Li loss as an alternative of electrolyte consumption.

2. 2.

   Deep discharge must be carried out on the final cycle.

Though capability tendencies may differ between replicate cells, C_EOL-dc outcomes remained constant (Fig. 4a). This indicated the excessive repeatability of CE and the influence of rSEIs on Li stripping polarization improve, which led to the discharge capability variation between replicate cells, particularly close to EOL. The truth is, C_EOL-dc outcomes elevated together with Li foil thicknesses and cycle life (Fig. 4a). This was as a result of a thicker layer of rSEIs accumulates after longer biking, resulting in a better polarization throughout Li stripping. Nonetheless, C_EOL-dc remains to be decrease than C_1-c for all of the cells in Fig. 4a. This ensures the entire stripping of all lively Li on the damaging electrode and the accuracy of the CE calculations.