Search

EP-4736245-A1 - ELECTROCHEMICAL ELEMENT WITH ADDITIVES IN THE ELECTROLYTE AND LITHIUM PHOSPHATE-BASED ELECTRODE

EP4736245A1EP 4736245 A1EP4736245 A1EP 4736245A1EP-4736245-A1

Abstract

The invention relates to an electrochemical element comprising: - at least one positive electrode comprising, as positive active material, at least one lithium phosphate compound of formula LixMn1-y-zFeyMzPO4 with 0.8 ≤ x ≤ 1.2; 0 ≤ 1-y-z < 1; 0 < y ≤ 1; 0 ≤ z ≤ 0.6; and M selected from the group consisting of: B, Mg, Al, Si, Ca, Ti, V, Cr, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, W, S, K, Pb and mixtures thereof; - at least one negative electrode; - at least one electrolyte comprising at least one additive chosen from: tris(trimethylsilyl) phosphite (TMSP), hexanetricarbonitrile (HTCN) and any mixture thereof.

Inventors

  • GAJAN, Antonin
  • CARRIQUIRY, Michael
  • BOISSON, Mathieu

Assignees

  • SAFT

Dates

Publication Date
20260506
Application Date
20240617

Claims (15)

  1. 1. Electrochemical element comprising: - at least one positive electrode comprising, as positive active material, at least one lithium phosphate compound of formula Li x Mni. yz Fe y MzPO4 with 0.8<x<1.2;0<1-y-z<1;0<y<1;0<z<0.6; and M selected from the group consisting of: B, Mg, Al, Si, Ca, Ti, V, Cr, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, W, S, K, Pb and mixtures thereof; - at least one negative electrode; - at least one electrolyte comprising at least one additive chosen from: tris(trimethylsilyl)phosphite (TMSP), hexanetricarbonitrile (HTCN) and any of their mixtures.
  2. 2. Electrochemical element according to claim 1, in which 1 > 1 -y-z > 0.5; 0 < y < 0.5; 0 < z < 0.2.
  3. 3. An electrochemical element according to claim 1 or claim 2, wherein the positive electrode comprises one or more additional lithium compounds selected from: i) lithium nickel, manganese and cobalt oxide (NMC) compounds of formula Li w (Ni x Mn y Co z M t )02 with 0.9<w<1.1;0<x;0<y;0<z;0<t; and M selected from the group consisting of Al, B, Mg, Si, Ca, Ti, V, Cr, Fe, Cu, Zn, Y, Zr, Nb, W, Mo, S, Sr, Ce, Ta, Ga, Nd, Pr, La and mixtures thereof, ii) lithium nickel, cobalt and aluminium oxide (NCA) compounds of formula Li w (Ni x Co y Al z M t )02 with 0.9<w<1.1;0<x;0<y;0<z;0<t; and M selected from the group consisting of B, Mg, Si, Ca, Ti, V, Cr, Mn, Fe, Cu, Zn, Y, Zr, Nb, W, Mo, Sr, Ce, Ga, Ta, Nd, Pr, La and mixtures thereof, iii) compounds of formula Lii +x Mi- x O2- y F y of cubic structure where M represents at least one element selected from the group consisting of Na, K, Mg, Ca, B, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Y, Zr, Nb, Mo, Ru, Ag, Sn, Sb, Ta, W, Bi, La, Pr, Eu, Nd, Sm and mixtures thereof; where 0 < x < 0.5 and 0 < y <1; (iv) lithium nickel manganese oxide (NMX) compounds of formula Li a (Nii. xyz Mn x Co y Mz)02 with 0.9<a<1.1;0.60<1-xyz<0.80;0<x;0<y<0.02;0<z; and M selected from the group consisting of Al, B, Mg, Si, Ca, Ti, V, Cr, Fe, Cu, Zn, Y, Zr, Nb, W, Mo, S, Sr, Ce, Ga, Ta, Nd, Pr, La and mixtures thereof; (v) lithium nickel manganese oxide compounds of formula Li w (Ni x Mn y Co z Mt)02 with 1.1<w<1.6;0<x;0.50<y<0.80;0<z<0.02;0<t and M selected from the group consisting of Al, B, Mg, Si, Ca, Ti, V, Cr, Fe, Cu, Zn, Y, Zr, Nb, W, Mo, S, Sr, Ce, Ta, Ga, Nd, Pr, La and mixtures thereof; (vi) mixtures thereof.
  4. 4. Electrochemical element according to any one of the preceding claims, in which the tris(trimethylsilyl)phosphite (TMSP) content is from 0% to 2% by mass, relative to the total mass of the electrolyte, preferably from 0.5% to 1.5% by mass, more preferably from 0.7% to 1.2% by mass.
  5. 5. Electrochemical element according to any one of the preceding claims, in which the content of hexanetricarbonitrile (HTCN) is from 0% to 5% by mass, relative to the total mass of the electrolyte, preferably from 0.5% to 2% by mass, more preferably from 0.7% to 1.2% by mass.
  6. 6. Electrochemical element according to any one of claims 1 to 3, in which the electrolyte further comprises at least one lithium salt chosen from lithium hexafluorophosphate LiPFe, lithium bis(fluorosulfonyl)imide Li(FSC>2)2N (LiFSI) and mixtures thereof.
  7. 7. Electrochemical element according to the preceding claim, in which said at least one lithium salt is lithium hexafluorophosphate LiPFe, optionally mixed with lithium bis(fluorosulfonyl)imide Li(FSC>2)2N (LiFSI).
  8. 8. Electrochemical element according to claim 6, in which the lithium salt is lithium bis(fluorosulfonyl)imide Li(FSC>2)2N (LiFSI), and in which said additive is hexanetricarbonitrile (HTCN), alone or in admixture with tris(trimethylsilyl)phosphite (TMSP).
  9. 9. An electrochemical element according to any preceding claim, wherein the electrolyte comprises both tris(trimethylsilyl)phosphite (TMSP) and hexanetricarbonitrile (HTCN).
  10. 10. Electrochemical element according to claim 9, in which the tris(trimethylsilyl)phosphite (TMSP) and the hexanetricarbonitrile (HTCN) are present in a mass ratio ranging from 10:1 to 1:10, preferably from 5:1 to 1:5, more preferably in a mass ratio of 1:1.
  11. 11. Electrochemical element according to any one of the preceding claims, in which the electrolyte comprises at least one organic solvent, said solvent comprising: at least one cyclic carbonate, preferably chosen from ethylene carbonate (EC), propylene carbonate (PC) and any of their mixtures, and - at least one linear carbonate, preferably chosen from dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC) and any of their mixtures.
  12. 12. Electrochemical element according to any one of the preceding claims, in which the electrolyte further comprises at least one additive chosen from the group consisting of: vinylene carbonate (VC), ethylene sulfate (ESA), fluoroethylene carbonate (FEC), lithium difluorophosphate UPO2F2 and any of their mixtures.
  13. 13. Electrochemical element according to claim 12, comprising: - from 0% to 5% by mass of vinylene carbonate (VC), - from 0% to 3% by mass of ethylene sulfate (ESA), - from 0% to 5% by mass of fluoroethylene carbonate (FEC), - from 0% to 2% by mass of lithium difluorophosphate UPO2F2, relative to the total mass of the electrolyte.
  14. 14. Electrochemical module comprising a stack of at least two electrochemical elements according to any one of the preceding claims, each electrochemical element being electrically connected with one or more other electrochemical element(s).
  15. 15. Use of an electrochemical element according to any one of claims 1 to 13 or of an electrochemical module according to claim 14, in storage, charging or discharging at a temperature ranging from -15°C to 85°C.

Description

TITLE: ELECTROCHEMICAL ELEMENT WITH ADDITIVES IN THE ELECTROLYTE AND LITHIA PHOSPHATE BASED ELECTRODE The present invention relates to the field of energy storage and lithium batteries in particular. More specifically, the present application relates to electrochemical elements comprising a positive active material of the lithium phosphate type and usable over a wide temperature range, typically ranging from -15°C to 85°C. The invention is particularly useful in the field of rechargeable electrochemical elements of the lithium-ion (Li-ion) type. Rechargeable electrochemical cells of the lithium-ion type are known from the state of the art. Due to their high mass and volume energy density, they constitute a promising source of electrical energy. They comprise at least one positive electrode and at least one negative electrode, separated by an electrolyte layer. The electrodes consist of a metal current collector on which is coated a composition of active material and additives such as binder(s), dispersant(s), conductive element(s), etc. The electrodes are prepared from an ink comprising the composition, generally formulated in an organic solvent medium, coated on a current collector, from which the solvent is evaporated, before calendering so as to adjust the thickness of the ink layer on the collector. Lithium manganese-iron phosphates of the formula Li x Mni.y.zFe y MzPO4 (LMFP) with 0.8<x<1.2;0<1-yz<1;0<y<1;0<z< 0.6 are known for their use as cathode active material of lithium-ion cells. These phosphates contain manganese, iron and one or more substituent elements symbolized by the symbol M. These compounds are known to offer superior safety of use due to the fact that lithium transition metal phosphates are stable at high temperatures. The mixture of a lithium phosphate with a lithium nickel oxide has been proposed. The nickel of the lithium oxide can be associated with manganese, cobalt, and possibly one or more chemical elements (NMC type oxide), or can be associated with cobalt, aluminum and possibly one or more chemical elements (NCA type oxide). The mixture of a lithium phosphate and a lithium nickel oxide allows a good compromise between energy and safety. Thus, positive electrodes based on active material consisting of lithium manganese and iron phosphate compounds (LMFP), alone or mixed with lithium nickel oxides such as NMC and/or NCA have been described. These positive electrodes are typically used at operating temperatures close to room temperature, typically 25°C, where they are perfectly functional. However, we are seeking to improve their use at low and/or high temperatures. Indeed, at low temperatures (i.e. at negative operating temperatures typically down to -15°C), we are seeking to improve their dischargeability and their ability to be used for applications requiring high powers. Furthermore, at high temperatures typically up to 85°C, we are seeking to improve their lifetime and capacity retention. It is also known to integrate one or more additives into the electrolyte composition in order to improve certain properties of the final element. For example, the addition of tris(trimethylsilyl)phosphite (TMSP) and/or hexanetricarbonitrile (HTCN) is known in particular from CN 1 13140797 A1 and US 2022/0181690 A1. In particular, tris(trimethylsilyl)phosphite (TMSP) is known for its ability to trap water molecules (in English “Water scavenger”). Hexanetricarbonitrile (HTCN) is known to stabilize the interface between the positive electrode and the electrolyte by absorbing itself on the surface of the transition metals of the cathode materials. However, none of these documents specifically address electrochemical elements based on a positive active material of the lithium phosphate type. In particular, none of these documents seeks to broaden the temperature ranges of use of electrochemical elements based on a positive active material of the lithium phosphate type. It therefore remains to provide electrochemical elements, based on a positive active material of the lithium phosphate type, usable over wide temperature ranges. In particular, there remains the need for electrochemical elements comprising a positive electrode whose active material is of the lithium phosphate type and which are usable both at low temperatures, typically down to -15°C, and at high temperatures, typically up to 85°C. One aim of the invention is then to propose electrochemical elements, based on a positive active material of the lithium phosphate type, whose operating temperature range is significantly widened. The widening of the range of operating temperatures of an electrochemical element involves in particular an improvement in its dischargeability at low temperatures. temperature, typically down to -15°C, and/or by an extension of its service life, particularly at operating temperatures of up to 85°C. An aim of the invention is then to propose electrochemical elements, based on a positive active material of the