Activating method for an all-solid-state battery comprising halide catholyte

Abstract

The present invention relates to a method for activating an all-solid-state battery comprising a cathode and an electrolyte, the cathode comprising an active material, and a halide catholyte, wherein the halide catholyte has the formula: Li[(x-y)+a+b+c+p]NayZr(1-a-b-c)EraYbSccCl[(4+x)-m-n-o-p]ImBrnFoOp in which: 0.2 ≤ x ≤ 6; 0 ≤ y ≤ 6; 0 ≤ a ≤ 1; 0 ≤ b ≤ 1; 0 ≤ c ≤ 1; 0 ≤ m ≤ 1; 0 ≤ n ≤ 1; 0 ≤ o ≤ 1; 0 ≤ p ≤ 2; with 0 ≤ a+b+c ≤ 1, with (4+x) > (m+n+o+p), wherein the active material of the cathode is selected from LiFePO4, LiFe1-zMnzPO4with 0 < z ≤ 1, LiMn2O4, Li3V2(PO4)3, LiVOPO4 and Li2VOPO4F, wherein the battery is activated by charging it at a voltage greater than 4.5 V vs Li+ / Li.

Description

ACTIVATING METHOD FOR AN ALL-SOLID-STATE BATTERY COMPRISING HALIDE CATHOLYTE.

[0001] The present invention relates to a method for activating an all-solid-state battery comprising halide catholyte.

[0002] All-Solid-State Batteries (ASSBs) stand poised to surpass the energy densities of Li-ion batteries and alleviate safety concerns. Among diverse solid-state electrolytes (SEs), halides, notably Li2ZrCl6(LZC), exhibit stability window up to 4 V vs Li+ / Li0when used as the electrolyte of a cathode (therefore referred to as catholyte and noted SC). Y-doped LZC showed a reversible electrochemical activity in this potential region. Yet, the untapped potential of halides SCs for enhancing overall ASSB performance remains unexplored, diverging from their conventional use solely for ionic conduction.

[0003] It has been discovered that halide catholytes under certain activation conditions allow remarkable enhancements in the specific capacity of all solid-state cells driven by combined effects that concurrently address major issues in silicon and anode-less chemistry. Notably, such activation of the battery yields outstanding performance of industry-relevant, highly loaded electrodes, showcasing significant advancements in ASSB technology. Furthermore, the tunability of these effects by adjusting the initial Li, Cl, I and F contents of the solid catholyte (SC) is demonstrated.

[0004] Thus, the invention relates to a method for activating an all-solid-state battery comprising a cathode and an electrolyte, the cathode comprising an active material and a halide catholyte, wherein the halide catholyte has the formula:

[0005] Li[(x-y)+a+b+c+p]NayZr(1-a-b-c)EraYbSccCl[(4+x)-m-n-o-p]ImBrnFoOp

[0006] in which:0.2 ≤ x ≤ 6;0 ≤ y ≤ 6;0 ≤ a ≤ 1;0 ≤ b ≤ 1;0 ≤ c ≤ 1;0 ≤ m ≤ 1;0 ≤ n ≤ 1;0 ≤ o ≤ 1;0 ≤ p ≤ 2;with 0 ≤ a+b+c ≤ 1,with (4+x) > (m+n+o+p),

[0007] wherein the active material of the cathode is selected from LiFePO4, LiFe1-zMnzPO4with 0 < z ≤ 1, LiMn2O4, Li3V2(PO4)3, LiVOPO4and Li2VOPO4F,

[0008] wherein the battery is activated by charging it at a voltage greater than 4.5 V vs Li+ / Li.

[0009] A catholyte is the part of an electrolyte which is mixed with the cathode active material and, if needed, an electronic conductor.

[0010] In one particular embodiment, the battery is activated by charging it at a voltage greater than or equal to 5.0 V vs Li+ / Li.

[0011] The halide catholyte can be selected from: LixZrX4+xOp, wherein X is selected from Cl, F, I and their mixtures, wherein x is a number from 0.4 to 6 and p is a number from 0 to 0.5, being in particular Li0.4ZrCl4.4, Li0.59ZrCl4.59, Li0.8ZrCl4.8, LiZrCl5, Li2ZrCl6, Li2ZrCl5I, Li2ZrCl5.75I0.25, Li2ZrCl5.5I0.5, Li2ZrCl5F, Li3ZrCl7, Li4ZrCl8,Li5ZrCl9, Li6ZrCl10and Li5ZrCl8I.

[0012] The halide catholyte noted as LiXZrCl4+xcan also be referred to as xLiCl-ZrCl4. In order to prepare one mole of LiXZrCl4+x, x mole of LiCl and one mole of ZrCl4are used. When there is a mixture of halogens, synthesis is conducted by using stoichiometric amounts of LiI or LiF.

[0013] The cathode can further comprise a carbon-material chosen from single walled carbon nanotubes, multi-walled carbon nanotubes, vapor grown carbon fibers, acetylene black, kejen black, graphene, graphite, porous carbon, disordered mesoporous carbon, ordered mesoporous carbon and activated carbon.

[0014] The cathode can be prepared via mixing together the halide catholyte, the active material of the cathode and carbon-material using a ball milling machine at a speed of 100 rpm to 400 rpm during 0.5 to 3 hours. The halide catholyte, the active material of the cathode and carbon-material can be present in the cathode at a mass ratio of 20-72 : 25-75 : 3-10. The mass ratio between halide catholyte and carbon-material can be 97:3-70:30 and the mass ratio between catholyte and cathode active material can be 20:80-80:20.

[0015] In one particular embodiment, the battery is anode less.

[0016] In the anode-less case, the oxidation process immediately results in the plating of metallic lithium at the anode and therefore the potential is correctly defined vs Li+ / Li0.

[0017] In one particular embodiment, the battery has an anode, the active material of which is selected from lithium metal, lithium-indium alloy, silicon, tin or carbon intercalation materials. The lithium-indium alloy can be LiInx’’with 0 < x’’ ≤ 3. The carbon intercalation materials can be selected from graphite and hard carbon.

[0018] In the case of Li-In system as an anode, the potential that is measured is translated to a Li+ / Li0reference by adding 0.62 V (A. L. Santhosha, L. Medenbach, J. R. Buchheim, and P. Adelhelm, Batteries and Supercaps, 414, 359 (2019)). Therefore the 4.5 V vs Li+ / Li0potential should be translated to 3.88 V vs Li0.33In.

[0019] In the case of Si system as an anode, the oxidation process immediately results in the alloying of Si by lithium at a potential of about 0.2 V vs Li+ / Li0(B. Jerliu , E. Hüger, L. Dörrer, B. K. Seidlhofer, R. Steitz, M. Horisberger and H. SchmidtPhys. Chem. Chem. Phys., 2018, 20, 23480-23491). Therefore, the potential that is measured using a Si / LCPL system as an anode should be translated to a Li+ / Li0reference by adding 0.2 V. Therefore the 4.5 V vs Li+ / Li0potential should be translated to 4.3 V vs Si.

[0020] In one particular embodiment, the electrolyte is an halide electrolyte having the formula:

[0021] Li[(x’-y’)+a’+b’+c’+p’]Nay’Zr(1-a’-b’-c’)Era’Yb’Scc’Cl[(4+x’)-m’-n’-o’-p’]Im’Brn’Fo’Op’

[0022] in which:0.2 ≤ x’ ≤ 6;0 ≤ y’ ≤ 6;0 ≤ a’ ≤ 1;0 ≤ b’ ≤ 1;0 ≤ c’ ≤ 1;0 ≤ m’ ≤ 1;0 ≤ n’ ≤ 1;0 ≤ o’ ≤ 1;0 ≤ p’ ≤ 2;with 0 ≤ a’+b’+c’ ≤ 1,with (4+x’) > (m’+n’+o’+p’).

[0023] The halide electrolyte can be selected from Lix’ZrX4+x’Op’, wherein X is selected from Cl, F, I and their mixtures, wherein x’ is a number from 0.4 to 6 and p’ is a number from 0 to 0.5, being in particular Li0.4ZrCl4.4, Li0.59ZrCl4.59, Li0.8ZrCl4.8, LiZrCl5, Li2ZrCl6, Li2ZrCl5I, Li2ZrCl5.75I0.25, Li2ZrCl5.5I0.5, Li2ZrCl5F, Li3ZrCl7, Li4ZrCl8,Li5ZrCl9, Li6ZrCl10and Li5ZrCl8I. The halide electrolyte can be under the form of a layer in contact with the cathode.

[0024] The battery can further comprise a second electrolyte layer comprised of sulfide electrolyte, such as Li6PS5Cl.

[0025] METHODS:

[0026] Electrolytes / catholytes synthesis:

[0027] LixZrCl4+x(x = 0. 4, 0. 59, 0. 8, 1, 2, 3, 4, 5) (LZC) electrolytes were synthesized using starting materials: LiCl (>99%, Sigma Aldrich), dried overnight at 160°C under vacuum, and ZrCl4(98%, anhydrous, Sigma Aldrich).

[0028] The stoichiometric amount of LiCl was first crushed in a mortar with pestle in dry argon glove box, to reduce the particle size. After that, the stoichiometric amount of ZrCl4was added to the mortar and mixed for 10 minutes with LiCl. The mixture was then placed in a 25ml ZrO2ball-milling jars along with 10 ZrO2balls of 10 mm diameter. The LixZrCl4+xelectrolytes or catholytes used in this work were synthesized over 50h at 600 rpm, with 15 minutes break between each 1 hour cycle. XRD diagrams of xLiCl-ZrCl4composition (x = 0.4, 0.59, 0.8, 1, 2, 3, 4, and 5) compounds along with Rietveld refinements are reported in Figure 1 a-h. For x > 2, all samples contain various ratio of two phases, Li2ZrCl5.7O0.15and a LiCl-rich phase (LixZrCl4+x) of variable composition but with x in the vicinity of 5 according to Rietveld refinements. For 0.4 < x < 2, all samples contain various ratio of phases, the Li2ZrCl6core phase and a LiCl-poor phase (LixZrCl4+x) and an amorphous component. The composition x = 0.4 is quite unique as it does not contain the Li2ZrCl6core phase in addition to the main Li0.4ZrCl4.4poor LiCl phase and an amorphous component. Summary of the metrics and reliability factors in xLiCl-ZrCl4series (0.4 ≤ x ≤ 5) derived from synchrotron XRD are reported in Table 1.

[0029] Sample CompositionPhase CompositionPhaseSpace Groupa (Å)b (Å)c (Å)β (°)V (Å3)RBragg (%)GOFRp (%)Rwp (%)0.4LiCl-ZrCl4Li0.4ZrCl3.90O0.25C2 / m126.335(3)11.035(4)6.336(2)109.17(3)418.4(3)2.982.432.383.050.59LiCl-ZrCl4Li2ZrCl6P-3m116410.985(4)5.950(4)621.9(5)3.25Li0.5ZrCl4.5C2 / m126.329(2)11.019(4)6.327(2)109.17(2)416.8(2)2.683.502.362.940.8LiCl-ZrCl4Li2ZrCl6P-3m116410.9684(9)5.9499(8)619.90(11)2.01Li0.35ZrCl4.35C2 / m126.339(2)11.008(5)6.336(2)109.11(4)417.8(3)1.653.232.202.711LiCl-ZrCl4Li2ZrCl6P-3m116410.9772(5)5.9548(6)621.41(7)1.79Li0.6ZrCl4.2O0.2C2 / m126.099(7)11.293(13)6.344(6)107.95(7)415.7(8) 1.002.662.383.272LiCl-ZrCl4Li2ZrCl6P-3m116410.9717(7)5.9374(6)618.98(9)3.741.382.322.923LiCl-ZrCl4Li2ZrCl6P-3m116410.9583(5)5.9342(5)617.14(7)1.43Li4.7ZrCl8.7C2 / m126.301(3)11.046(4)6.302(3)109.01(2)414.7(3)1.203.412.282.874LiCl-ZrCl4Li2ZrCl5.6O0.2P-3m116410.9783(8)5.9466(8)620.69(10)2.14Li5.0ZrCl9.0C2 / m126.321(2)10.993(3)6.330(2)108.883(19)416.2(2)1.692.282.242.845LiCl-ZrCl4Li2ZrCl5.7O0.15P-3m116411.026(4) 5.915(3) 622.8(4)2.45Li5.7ZrCl9.7C2 / m126.316(2)11.011(4)6.331(2)108.96(3)416.4(3)2.082.032.142.72

[0030] Variations of the xLiCl-ZrCl4conductivities vs x has been characterized by impedance spectroscopy ().

[0031] Electrode preparation:

[0032] Cathodes

[0033] The cathodes used for the evaluation of the electrolyte redox activity, that is the ones consisting of LixZrCl4+xcatholyte and single wall carbon nanotubes (P2SWNT), as well as the electrodes with LiFePO4(LFP), or LiFe0.5Mn0.5PO4 or LiMn2O4 (LMO) as the electrochemically active material and vapor grown carbon fibers (VGCFs), used for galvanostatic cycling, are prepared by mixing the materials in their respective weight ratios by ball milling at 300 rpm for 2 hours. The ball milling was done in the same system described for the case of electrolytes synthesis for 2 hours at 300 rpm.

[0034] Anodes

[0035] Li0.33In composite anode was prepared by folding Li metal foil into an In metal foil in 2:98 weight ratio, until the resulting Li0.33In alloy became brittle. After that the foil was crushed and mixed using mortar and pestle with argyrodite Li6PS5Cl (LPSC) electrolyte (NEI Corporation) in 60:40 wt% ratio.

[0036] To make Si composite anode, (LPSC) and Si powder having grain size in the micrometer range (referred to as micro-Si) were mixed in the ball milling jar in 50:50 under the same conditions as for the cathode.

[0037] Electrochemical impedance spectroscopy:

[0038] To measure the conductivity of electrolytes, 120 mg of electrolyte powder was pressed under 375 MPa for 3 minutes, between two titanium plungers in an in-house built system comprised of 2 Ti plungers and a PEEK insulating cylinder. Then, the cell was taken into a pressure holder that exerted 100 MPa of stack pressure onto it.

[0039] To measure the impedance of the full cell with different composite cathodes, the EIS measurements were taken after each cycle or after each charge or discharge sequence at the same pressure used during the cycling of the cells.

[0040] The sinusoidal voltage of 10mV amplitude was applied in the frequency range 100 mHz – 100 kHz to the cell. The corresponding signal is plotted in the form of Nyquist diagram, typically showing a straight line. The resistance of the electrolyte was found by the intersect of the interpolated straight line with the real axis. The conductivity was calculated based on the equation:

[0041] σ = l / A * 1 / R, where l is the thickness of the electrolyte pellet (measured individually for each pellet: usually in the 500-700 µm range) and A is the surface area of the pellet (0.785 cm2)

[0042] Cells assembly:

[0043] Each cell was made in the in-house made system comprised of 2 Ti plungers and a PEEK insulating cylinder. By compressing 40mg layer of Li6PS5Cl (NEI Corporation) at 125MPa for 10 seconds, the first layer (LPSC layer) of separator is formed. Second layer of the bi-layer separator is made by compressing 40mg LixZrCl4+x(x = 0. 4, 0. 59, 0. 8, 1, 2 and 3) (LZC layer) on top of the first layer at 375 MPa for 1 minute. Then, appropriate amount of specific composite cathode powder was placed on top the LZC layer, and corresponding amount of composite anode, when present, was placed on top of the LPSC layer. Finally, the whole stack was pressed at 375MPa for 3 minutes. Each cell would, then, be placed in an in-house designed holder, and the pressure of either 100 MPa or 75 MPa was applied.

[0044] The three cell schematics are depicted in Figure 3. Each of the cell integrates a positive electrode resulting from the ball milled mixture (300 rpm, 2 hours) of LZC, LFP and VGCF, a LZC (2LiCl-ZrCl4) / LPSC bilayer electrolyte and Li0.33In anode in cell (a), anode-less in cell (b) and Si anode in cell (c).

[0045] Cyclic voltammetry:

[0046] Around 12 mg of composite cathode composed of LixZrCl4+x(x = 0.4, 0.59, 0.8, 1, 2, 3, 4 and 5) balled milled (300 rpm, 2 hours) with single wall carbon nanotubes referred to as P2SWNT (Carbon solution inc.) in 85:15 wt% was used for each measurement. The voltage was linearly increased / decreased in the range 2.5V – 5V vs Li+ / Li, while the current was measured. Each experiment was repeated 6 times. To evaluate the capacity the area under current (mA / g) – time (h) was integrated using Origin software or EC-Lab software.

[0047] Full cell cycling:

[0048] Full cell with Li0.33In alloy composite anode was made using 18 mg of composite cathode made out of LZC, LFP and vapor grown carbon fibers (VGCFs) in a 59.7:33.3:7 weight ratio as described previously, and 30 mg of the composite anode.

[0049] Cell was cycled galvanostatically at C / 10 for 2 cycles: during the first cycle the voltage range was 2.5V – 3.8 V vs Li+ / Li in order to extract the capacity coming purely from LFP cathode active material; on the second cycle the voltage range of 2.5V – 5V vs Li+ / Li was applied in order to utilize the capacity of LFP and oxidation of LZC catholyte. This was followed by 5 cycles at C / 5, and C / 2, after which 100 cycles at 1C were performed in the voltage range 2.5 V – 5 V vs Li+ / Li. Finally, the capacity retention of both LFP and LZC oxidation after 100 cycles is demonstrated by performing the same cycling conditions as in the initial 2 cycles.

[0050] Anode-less cell was utilizing 11.5 mg of composite cathode made out of LZC, LFP and VGCF in 53.7: 33.3:10 weight ratio in order to extract more capacity from LZC oxidation and improve the performance of the anode-less cell. Galvanostatic cycling was performed at C / 10 for 11 cycles.

[0051] Full cell using a composite silicon anode was composed of 43.5 mg of composite cathode consisting of LZC, LFP and VGCF in 44.7:50:5.3 weight ratio and composite anode made of the mixture of LPSC and micro-Si as previously described, while having the nominal capacity of the anode set to be 3 times larger than that of the cathode. This was done to insure most of the capacity fade is a result of interphase (referred to as SEI) formation between micro-Si and LPSC electrolyte. The full cell was, then, galvanostatically cycled in 2.5 V – 3.8 V vs Li+ / Li voltage ratio at C / 10 (C being the theoretical capacity of the cathode). After that, the cell undergoes 1 cycle in the voltage range 2.5 V – 5V in order to extract the capacity from the LZC oxidation, followed by 3 cycles in lower voltage range, to unveil if this additional capacity could increase the Li+ion storage in the LFP cathode material.

[0052] RESULTS

[0053] The cells integrating positive electrode resulting from the mixture of LZC (2LiCl-ZrCl4), LFP and VGCF, a LZC (2LiCl-ZrCl4) / Li6PS5Cl bilayer electrolyte and Li0.33In, anode-less or micro-Si negative electrode as represented in Figure 3 have been tested. These cells were charged either to 4V, which is typical when cycling LFP active material, or 5V to purposely oxidize the halide catholyte.

[0054] For the Li0.33In half-cell, under a 4 V charge, the typical LFP profile delivers nearly 150 mAh / gLFP, (50 mAh / gcathode) under 0.12 mA / cm2(). However, when the charge is extended to 5V, the LZC (2LiCl-ZrCl4) electroactivity occurs from 4 V vs Li+ / Li, dramatically enhancing the overall electrode discharge capacity by 35%, to 68 mAh / gcathode(205 mAh / gLFP) (). Moreover, although the reduction of LZC (2LiCl-ZrCl4) is characterized by a germination-growth like response, the LFP discharge plateau at 3.4 V exhibited no signs of additional polarization. This demonstrates that although LZC (2LiCl-ZrCl4) can be advantageously used as a second active material it appears to maintain its electrolyte properties.

[0055] The combined electroactivity of LZC (2LiCl-ZrCl4) and LFP consistently surpassed that of LFP alone by 22% even after 110 cycles (). Furthermore, the 94% capacity retention of LFP confirms the enduring conduction property of this redox electrolyte.

[0056] Notably, increasing the LFP loading from 33 to 50 wt% and areal capacity from 1.4 to 4.1 mAh / cm2, yielded competitive gains (+17%) in specific capacity per mass of LZC (2LiCl-ZrCl4). In fact, triggering the LZC (2LiCl-ZrCl4) redox activity allows to reach the same capacity at five times higher C-rate (Figure 6 representing the capacity normalized by: a) total mass of cathode; b) area of the electrodes in function of the cycle number).

[0057] Interestingly, the initial oxidation process is characterized by an irreversible decrease in cell pressure despite Li alloying occurring at the negative electrode along with a significant increase in cell impedance (showing the variation of a half-cell stack pressure bearing LZC (2LiCl-ZrCl4) / P2SWNT composite cathode during cycling andshowing the EIS of half-cell with LZC (2LiCl-ZrCl4) / P2SWNT composite cathode at open-circuit voltage (OCV), the first charge being at 5V vs Li+ / Li and subsequent discharge to 2.5 V vs Li+ / Li). These results are likely indicative of substantial structural and morphological changes. However, strikingly, electrochemical impedance spectroscopy measurements of the reduced sample (showing the EIS of half-cell with LZC (2LiCl-ZrCl4) / P2SWNT composite cathode in the discharged state (at 2.5V vs Li+ / Li) after 1st, 2ndand 10thcycle) indicates that cell impedance reverts to a value close to the pristine state. This unexpected property is a factor enabling LFP-based electrode to operate without additional polarization, regardless of whether the electrochemical activity of LZC (2LiCl-ZrCl4) is triggered ().

[0058] For the anode-less cell, triggering LZC (2LiCl-ZrCl4) electroactivity resulted in an astounding 112% capacity increase after 10 cycles, accompanied by significantly improved Coulombic efficiencies (). Equally noteworthy is the effect on cell safety and longevity, as dendrite-related irregularities were deferred from the second discharge to the tenth cycle (Figures 10 showing the 1st(a), 2nd(b), 5th(c) and 10th(d) galvanostatic charge / discharge cycle of the anode-less cell in 2.5V – 4 V and 2.5 – 5 V voltage range).

[0059] These findings indicate the potential of halide electrochemistry forin situdeposition of a thin and uniform layer of lithium metal, offering a solution to common issues encountered in anode-less cell configurations.

[0060] Similarly, a micro-Si based full cell assembled at 4.1 mAh / cm2, shows a 37% capacity loss during the initial cycle, coupled with low Coulombic efficiency (). However, upon triggering LZC (2LiCl-ZrCl4) electroactivity, a remarkable 50% enhancement in discharge specific capacity was achieved. These improvements stem from two primary factors: the additional discharge capacity associated with LZC (2LiCl-ZrCl4) activity, and the heightened activity of LFP (,showing the increase in the discharge capacity upon triggering the oxidation of LZC (2LiCl-ZrCl4) on cycle 4 and resuming to cycling without oxidation of LZC (2LiCl-ZrCl4) on cycle 5). This underscores the reparative capability of halide electrolytes in Si-based full cells, suggesting that LZC (2LiCl-ZrCl4) can replenish the loss of active Li / e-.

[0061] Regardless of the LixZrCl4+x(xLiCl-ZrCl4) composition (x = 0.4, 0.59, 0.8, 1, 2, and 3), partially reversible faradic activity was observed at approximately 4V vs. Li+ / Li (cyclic voltammograms of the different xLiCl-ZrCl4) for cathode containing a ball milled mixture (300 rpm, 2 hours) of 2LiCl-ZrCl4 (85 wt%) and P2SWNT (15 wt%). This reversible capacity thus enables the enhancement of the cathode active materials (CAMs) electrode's capacity, while the irreversible capacity is transferred to the negative electrode, compensating for irreversible electron loss. By leveraging the chloride redox chemistry, the non-stoichiometric composition of the halide catholyte thus becomes a new and strong parameter for balancing the two electrodes. Indeed, reversible and irreversible capacities show linear and parabolic relationships with the xLiCl-ZrCl4composition, respectively and the ratio of these two capacities increases by nearly 200% from x=0.4 to x=3 (), showing the variations of reversible and total (reversible + irreversible) capacities referred to as “y” as well as the ratio of ytotal / yreversibleagainst the compositions of the halide xLiCl-ZrCl4solid catholytes. ytotaland yreversiblecorrespond to the average value over the 5 first cycles).

[0062] To demonstrate the effect of the catholyte composition x in xLiCl-ZrCl4, the electrochemical activity of cathode containing xLiCl-ZrCl4:LFP:VGCF (59.7:33.3:7) were evaluated in batterie described previously for (x = 0.4, 0.59, 0.8, 1, 2, 3, 4 and 5): LFP remains consistent in terms of potential (approx. 3.4 V) and capacity (161 mAh / g ± 1 mAh / g) (). We note that in these experiments with varying catholyte compositions, that of the electrolyte layer in contact with the cathode was always 2LiCl-ZrCl4. Thus, for all these compositions, the triggering of xLiCl-ZrCl4electrochemical activity by charging at 5 V does not significantly interfere with that of LFP. In contrast, the catholyte composition has a significant effect on the electrochemical behavior of xLiCl-ZrCl4. Indeed, after subtraction of the LFP capacity, the LZC first charge capacity increases by a factor of 12.6, from 7 mAh / gcathode for the composition x=0.4 to 88 mAh / gcathode for x=5 (). The effect is less pronounced on discharge, doubling from 5.5 mAh / g cathode (x=0.4) to 19 mAh / gcathode (x=5). It is also noteworthy that for x>2, the significant increase in charge capacity is associated with the appearance of an additional electrochemical step (potential plateau) at approximately 4.3V. Altogether, we demonstrate that among the new catholyte compositions, 5LiCl-ZrCl4achieves enhanced performance. Indeed, its higher reversible capacity boosts the capacity of LFP to nearly 220 mAh / gLFP. Moreover, subtracting the LFP capacity (161 mAh / g), the sacrificial capacity available for prelithiation (or healing of the negative electrode) steps up to 208 mAh / gLFP (69 mAh / gcathode), which represents an increase by a factor of 28 compared to the 0.4LiCl-ZrCl4composition. This capacity that represents a gain of around 80% compared to our results with x=2 may appear as an interesting alternative to the best sacrificial strategies and materials since it comes without mass adjunction. On the other side of the composition range, the 0.4LiCl-ZrCl4and 0.59LiCl-ZrCl4compositions are associated with a >95% reversibility on the first cycle. It is noted that as shown in Table 1 some catholyte compositions used for these electrochemical tests contains oxygen substituting chloride ions. This substitution is not detrimental to the electrochemical properties.

[0063] In, it is shown that following the same protocol as described above but using a cathode mixture with a Li2ZrCl5I:LFP:P2SWNT (59.7:33.3:7) composition and prepared as described previously, also allows to obtain substantial specific capacity gain after a charge to 5V with an overall capacity in discharge larger than 225 mAh / g (). The substitution of chloride by iodide induces a low voltage reversible step between 2.5 and 3V vs Li+ / Li0corresponding to the I3- / I-redox couple and a second reversible step between 3.5 V and 4V associated with the I3- / I2redox couple.

[0064] Regardless of the cathode active material (referred to as CAM) that is LiFePO4, LiMn0.5Fe0.5PO4or LiMn2O4, substantial specific capacity gains: three composite cathodes mixture having the of LZC(2LiCl-ZrCl4):CAM:VGCF = 59.7:33.3:7 composition and prepared as described previously for CAM= LiFePO4, LiMn0.5Fe0.5PO4or LiMn2O4have been prepared.shows that upon charge to 5 V vs Li+ / Li0, all three materials can be successively discharged with large reversible specific capacity.

[0065] Several mixed iodide chloride catholyte, namely Li2ZrCl5.75I0.25, Li2ZrCl5.5I0.5,Li2ZrCl5I andLi5ZrCl8Icompositions have been prepared by ball milling as described previously for pure chloride electrolytes but by substituting the appropriate amount of LiCl by LiI everything else being the same. X-Ray diffractograms show pure phases have been obtained with most XRD lines shifted to low angles as the iodide content increases. Then, cathodes integrating a ball milled mixture (300 rpm, 2 hours) of each of these four compositions with a carbon additive were prepared as previously described for xLiCl-ZrCl4catholytes. Galvanostatic cycling of these four compounds are shown inshowing increasing reversible contribution of the I3- / I-in the 2.5V-3V range and I2 / I3-redox processes in the 3.5-4V range with increasing substitution of Cl-by I-is observed. Moreover, an increasing reversible capacity vs irreversible (sacrificial) one is observed compared to the pure chloride compounds having the same Li content (namely Li2ZrCl6and Li5ZrCl9) as shown previously (). This shows that not only chloride but also iodide anions integrated in a halide electrolyte can be used to provide additional capacity to that of CAM in all solid state batteries such as demonstrated previously ().

[0066] The synthesis of Li2ZrCl5F has also been performed and verified by XRD to be a pure phase. The ionic conductivity of LIZrCl5F, are compared to that of LiZrCl6in Table 2 and.

[0067] ElectrolyteConductivity / mS*cm-1Li2ZrCl5F0.8Li2ZrCl60.4Li2ZrCl5I0.3

[0068] The cyclic voltammetry of Li2ZrCl5F integrated in a cathode with P2SWNT following the same protocol as described previously for LZC (mass ratio 85 :15, ball milled 300 rpm, 2 hours) has been evaluated between 2.5 and 6 V vs Li+ / L0(). It shows a behavior similar to that of Li2ZrCl6but with (i) a smaller extent of the oxidation process thanks to not oxidable fluoride anion within this potential window, (ii) a higher extent of the reduction process and therefore (iii) a higher reversible to irreversible capacity ratio vs Li2ZrCl6.

Claims

– A method for activating an all-solid-state battery comprising a cathode and an electrolyte, the cathode comprising an active material and a halide catholyte, wherein the halide catholyte has the formula:Li[(x-y)+a+b+c+p]NayZr(1-a-b-c)EraYbSccCl[(4+x)-m-n-o-p]ImBrnFoOpin which:0.2 ≤ x ≤ 6;0 ≤ y ≤ 6;0 ≤ a ≤ 1;0 ≤ b ≤ 1;0 ≤ c ≤ 1;0 ≤ m ≤ 1;0 ≤ n ≤ 1;0 ≤ o ≤ 1;0 ≤ p ≤ 2;with 0 ≤ a+b+c ≤ 1,with (4+x) > (m+n+o+p),wherein the active material of the cathode is selected from LiFePO4, LiFe1-zMnzPO4with 0 < z ≤ 1, LiMn2O4, Li3V2(PO4)3, LiVOPO4and Li2VOPO4F,wherein the battery is activated by charging it at a voltage greater than 4.5 V vs Li+ / Li.- The method according to claim 1, wherein the battery is activated by charging it at a voltage greater than or equal to 5.0 V vs Li+ / Li.- The method according to one of claims 1 or 2, wherein the halide catholyte is selected from: LixZrX4+xOp, wherein X is selected from Cl, F, I and their mixtures, wherein x is a number from 0.4 to 6 and p is a number from 0 to 0.5, being in particular Li0.4ZrCl4.4, Li0.59ZrCl4.59, Li0.8ZrCl4.8, LiZrCl5, Li2ZrCl6, Li2ZrCl5I, Li2ZrCl5.75I0.25, Li2ZrCl5.5I0.5, Li2ZrCl5F, Li3ZrCl7, Li4ZrCl8,Li5ZrCl9, Li6ZrCl10and Li5ZrCl8I.– The method according to one of claims 1 to 3, wherein the cathode further comprises a carbon-material chosen from single walled carbon nanotubes, multi-walled carbon nanotubes, vapor grown carbon fibers, acetylene black, kejen black, graphene, graphite, porous carbon, disordered mesoporous carbon, ordered mesoporous carbon and activated carbon.– The method according to claim 4, wherein the cathode is prepared via mixing together the halide catholyte, the active material of the cathode and carbon-material using a ball milling machine at a speed of 100 rpm to 400 rpm during 0.5 to 3 hours.- The method according to one of claims 4 and 5, wherein the halide catholyte, the active material of the cathode and carbon-material are present in the cathode at a mass ratio of 20-72 : 25-75 : 3-10.– The method according to anyone of claims 1 to 6, wherein the battery is anode less.- The method according to anyone of claims 1 to 7, wherein the battery has an anode, the active material of which is selected from lithium metal, lithium-indium alloy, silicon, tin or carbon intercalation materials.- The method according to claim 8, wherein the lithium-indium alloy is LiInx’’with 0 < x’’ ≤ 3.- The method according to anyone of claims 8 and 9, wherein the carbon intercalation materials are selected from graphite and hard carbon.– The method according to anyone of claims 1 to 10, wherein the electrolyte is an halide electrolyte having the formula:Li[(x’-y’)+a’+b’+c’+p’]Nay’Zr(1-a’-b’-c’)Era’Yb’Scc’Cl[(4+x’)-m’-n’-o’-p’]Im’Brn’Fo’Op’in which:0.2 ≤ x’ ≤ 6;0 ≤ y’ ≤ 6;0 ≤ a’ ≤ 1;0 ≤ b’ ≤ 1;0 ≤ c’ ≤ 1;0 ≤ m’ ≤ 1;0 ≤ n’ ≤ 1;0 ≤ o’ ≤ 1;0 ≤ p’ ≤ 2;with 0 ≤ a’+b’+c’ ≤ 1,with (4+x’) > (m’+n’+o’+p’).- The method according to claim 11, wherein the halide electrolyte is selected from Lix’ZrX4+x’Op’, wherein X is selected from Cl, F, I and their mixtures, wherein x’ is a number from 0.4 to 6 and p’ is a number from 0 to 0.5, being in particular Li0.4ZrCl4.4, Li0.59ZrCl4.59, Li0.8ZrCl4.8, LiZrCl5, Li2ZrCl6, Li2ZrCl5I, Li2ZrCl5.75I0.25, Li2ZrCl5.5I0.5, Li2ZrCl5F, Li3ZrCl7, Li4ZrCl8,Li5ZrCl9, Li6ZrCl10and Li5ZrCl8I.- The method according to claim 12, wherein the halide electrolyte is under the form of a layer in contact with the cathode.- The method according to claim 13, wherein the battery further comprises a second electrolyte layer comprised of sulfide electrolyte, such as Li6PS5Cl.

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