72results about How to "Improve mass energy density" patented technology

The invention discloses a current collector, and an application of the current collector in a lithium ion battery, and concretely relates to a composite current collector, and a lithium ion secondary battery applying the current collector. The composite current collector comprises an upper metal layer, a lower metal layer and a nonmetal layer arranged between the upper metal layer and the lower metal layer, vacuum electroplating, electrolytic electroplating or composite bonding compounding is carried out between the upper metal layer and the nonmetal layer and between the nonmetal layer and the lower metal layer, and the thickness of the nonmetal layer is controlled to be 2-20 [mu]m; and the thickness of each of the upper metal layer and the lower metal layer is controlled to be 1-10 [mu]m. The above structure reduces the weight of the current collector and guarantees that the composite current collector have excellent tensile strength and excellent flexibility; the outer layer of the current collector is the metal layer, and has a conductive effect; and the above reasonable structure design substantially improves the mass energy density of the produced lithium ion secondary battery and effectively prolongs the cycle life of the battery.

The invention discloses a flexible current collector, an electrode containing the flexible current collector, and a battery. The flexible current collector comprises a textile fabric base and a metal conductive coating; the fiber of the textile fabric is coated with the metal conductive coating; the thickness of the metal conductive coating is 200 nm to 5 microns. An electrode active material of the electrode containing the flexible current collector is loaded on the surface and / or in the hole of the flexible current collector. By adoption of the battery prepared from the electrode provided by the invention, the interface resistance of the battery can be effectively reduced, the electrode mass of unit area is reduced, and the mass energy density is improved; the flexible current collector provided by the invention has higher machining property relative to that of the traditional metal foil, so the production efficiency of the battery can be improved, and the production cost of the battery can be reduced; the current collector base is a macromolecular material and can be shrunk and fused at high temperature, so the safety performance of the battery is improved.

The invention relates to a soft current collector and a lithium-ion battery made of a soft current collector, which is characterized in that the manufacturing method is as follows: first, the positive electrode is prepared: the positive electrode slurry is coated on the aluminum layer with a thickness of 0.1-10.0 μm, and the thickness of the plastic is 5.0~30.0μm aluminized plastic, the coating thickness is 0.08~0.20mm, after drying in a vacuum oven at 80~120oC, the positive electrode sheet is obtained; the negative electrode is prepared and the negative electrode slurry is coated on the copper layer with a thickness of 0.2~8.0μm , On the copper-plated plastic with a plastic thickness of 5.0~30.0μm, the coating thickness is 0.06~0.15mm, and the negative electrode sheet is obtained after drying in a vacuum oven at 80~120oC; the positive electrode sheet, PP or PE separator, and the negative electrode are sequentially The pole pieces are stacked and packed with aluminum-plastic film, and an appropriate amount of electrolyte solution 1MLiPF6+EC:DMC (1:1) is injected into the glove box; the aluminum-plastic film is hot-pressed and packaged to obtain a flexible lithium-ion battery. It effectively improves the mass energy density of the battery cell. The cost of the battery monomer is reduced; it has the advantages of low price, because the shape of the lithium-ion battery prepared by it can be arbitrary, ultra-thin, and the mass energy density is high.

The invention discloses a low-temperature lithium-ion battery. The low-temperature lithium-ion battery comprises a positive plate, a membrane, a negative plate and an electrolytic solution, wherein the positive plate comprises a ternary lithium nickel-cobalt manganate material, the ternary lithium nickel-cobalt manganate material is a composite material of an aggregate material and a quasi-monocrystalline material, and the median particle diameter of the aggregate material is smaller than the median particle diameter of the quasi-monocrystalline material; the negative plate comprises a carbonmaterial, the carbon material comprises synthetic graphite and natural graphite, and the synthetic graphite and the natural graphite are both carbon-coated secondary particles; and the electrolytic solution comprises a solvent, lithium salt and an additive, the solvent comprises EC, DEC, EMC and an auxiliary solvent, the solvent is a quaternary or above compound, the lithium salt comprises LiPF<6>, LiFSI and LiPO<2>F<2>, and the additive comprises VEC, DTD and GBL. The low-temperature lithium-ion battery has good charge / discharge properties, high safety and high energy density under low temperature and can be well suitable for a low-temperature environment.

The invention relates to a lithium ion battery anode lithium supplement pole piece and a preparation method thereof. The lithium ion battery anode lithium supplementary pole piece comprises a currentcollector (1), active material coating layers (2) which are attached on upper and lower surfaces of the current collector (1), microstructure grooves (3) which are set on a single side or double sidesof the surfaces of the active material coating layers (2), and lithium supplement layers (4) which cover the surfaces of the microstructure grooves (3). According to the lithium ion battery anode lithium supplement pole piece and the preparation method, consumption of lithium in an application process of the battery can be effectively supplemented, a first effect is improved, relatively much space and many channels for soaking of electrolyte are provided, and circulation service life and stability of the battery are greatly improved.

The invention discloses solid gravity flow carrying equipment, gravity energy storage elements and an energy storage system. The solid gravity flow carrying equipment comprises a transfer track, wherein the transfer track is provided with a low-altitude section, a high-altitude section opposite to the low-altitude section and an inclined section, and the transfer track is used for enabling the gravity energy storage elements to directionally move; a plurality of pushing mechanisms are arranged side by side along the inclined section of the transfer track; electric and kinetic energy conversion mechanisms are connected with the pushing mechanisms; the plurality of pushing mechanisms are driven by the corresponding electric and kinetic energy conversion mechanisms to move and drive the plurality of gravity energy storage elements to be continuously pushed to the high-altitude section from the low-altitude section along the inclined section; or the plurality of pushing mechanisms move through the gravity action of the plurality of gravity energy storage elements and drive the corresponding electric and kinetic energy conversion mechanisms to convert the mechanical kinetic energy into the electric energy, and the gravity action is formed in the mode that the gravity energy storage elements are continuously pushed from the high-altitude section to the low-altitude section along the inclined section to slide downwards. The problems that in the prior art, the terrain requirement is high, and the applicability is not high are solved.

The invention provides a rechargeable zinc-manganese battery and a preparation method thereof. A positive electrode adopts a linear alpha-MnO2 material to replace a traditional amorphous manganese dioxide material, and the linear alpha-MnO2 material has a uniform structure. The large tunnels and vacancies in MnO2 increase the contact between the active material and the electrode, reduce the internal resistance of the battery, and improve the diffusivity of protons. The larger aspect ratio of MnO2 can make the preferred orientation degree of the material higher, thus improving the rate performance of the battery. Stable structure, not easy to collapse, the activity can be maintained at a high level, the decay rate is slow, more conducive to the battery cycle performance. In accordance withthat present invention, the preparation method of the alpha-MnO2 material is simple and feasible, the experimental reproducibility is good, the raw materials used are cheap and easy to obtain, the linear alpha-MnO2 material has a uniform structure, large aspect ratio, and stable structure, and is not easy to collapse and slow in attenuation rate.

The invention provides a lithium-rich cathode material doped with lithium manganate at a Mn site, and a preparation method of the lithium-rich cathode material. The preparation method of the lithium-rich cathode material doped with the lithium manganate at the Mn site comprises the following steps: evenly mixing a lithium source, a manganese source, doped metal salt and a metal complexing agent, carrying out ultrasonic gas atomization on the obtained mixture, and calcining to obtain spherical lithium manganate powder; mixing the obtained spherical lithium manganate powder with a spherical cathode material, coating and calcining. The lithium-rich cathode material provided by the invention is prepared by doping the lithium manganate at the Mn site, thus effectively inhibiting oxygen evolution and solving the problem of voltage drop in a circulating process; the tap density of powder can be improved by mixing, so that the energy density of the material is further improved; due to the stepof coating, the loss of oxygen vacancies and the migration of transition metal ions are reduced; after the lithium-rich cathode material is adopted, the first time efficiency is increased, the safetyperformance of batteries is improved, and the energy density of the material is improved.

The invention provides a Li-O site lithium manganate doped lithium-enriched positive electrode material and a preparation method thereof. The Li-O site lithium manganate doped lithium-enriched positive electrode material is prepared through mixing a manganese source, a lithium source and an element lithium doped compound and then carrying out a process including solid-phase sintering, wet-processcladding, material mixing and calcination. The prepared positive electrode material realizes doping on a Li site and an O site of lithium manganate and the aims of effectively inhibiting oxygen evolution, improving the rate performance, keeping an oxygen vacancy in a charging process, improving the initial efficiency, improving the safety performance of a battery and improving the energy density of the material are realized.

The invention relates to the technical field of battery production, in particular to a battery pack. The battery pack comprises a box body, a wiring harness plate and a plurality of battery cells. The box body comprises a box bottom and a box wall. The box wall is connected to the box bottom. A plurality of first grooves are formed in the box bottom. The wiring harness plate is opposite to the box bottom and connected to the box body. The side, close to the box bottom, of the wiring harness plate is provided with a plurality of second grooves. The number of the second grooves is equal to the number of the first grooves. The second grooves correspond to the first grooves one to one. The openings of the second grooves face the box bottom. The openings of the first grooves face the wiring harness plate. In the corresponding set of the first groove and the second groove, one end of the corresponding battery cell is placed in the first groove, and the other end of the battery cell is installed in the second groove. A module frame is omitted, the structural layer outside the battery cells is omitted, the weight of the battery pack is reduced, and the mass and energy density of the battery pack can be improved.

The invention discloses preparation and application of a positive electrode-interlayer integrated membrane electrode material for a lithium-sulfur battery. According to the integrated membrane material provided by the invention, a polyacrylonitrile / carbon nanotube composite membrane solution is subjected to solvent phase conversion and carbonization to form a carbon membrane, and then the surfaceof the carbon membrane is coated with an organic membrane solution to prepare the integrated membrane electrode material of which the surface of a porous carbon membrane is covered with an organic membrane. The integrated membrane material has double functions of a positive electrode and an interlayer, and is beneficial to ion transfer. The organic membrane has a battery diaphragm function, and the carbon membrane can be used as a lithium-sulfur battery positive electrode by loading sulfur; nano-particles can be added into the carbon film to adsorb polysulfide, so that the shuttle effect of the lithium-sulfur battery is relieved, and the cycling stability, the rate capability and the coulombic efficiency of the battery are improved. The lithium-sulfur battery prepared from the integrated membrane electrode material has excellent energy storage performance, the specific capacity is 890mA hg<-1> after circulation for 100 circles under 0.2 C current density, the capacity loss rate of eachcircle is 0.21%, and the coulombic efficiency is close to 100%.

The invention provides a composite current collector which comprises at least two composite layers and a splicing fixing layer, the two composite layers are respectively a conductive layer containing a carbon material and a carrier layer containing a non-metallic material with holes, the conductive layer is connected with the carrier layer, and the edges of the conductive layer and the carrier layer are spliced and fixed through the splicing fixing layer. The weight of the current collector is reduced, so that the mass energy density of a battery is improved, the cycle life of the battery is prolonged, the overall structural stability of the current collector is improved, the cost is low, the lithium ion battery comprises a shell and a battery cell, the battery cell is arranged in the shell, and the battery cell comprises a positive electrode, a negative electrode and an isolating membrane between the positive electrode and the negative electrode; the positive electrode and the negative electrode of the lithium battery comprise the composite current collectors, the positive electrode and the negative electrode of the lithium battery are made of the composite current collectors, the mass energy density of the lithium battery is improved, the cycle life of the lithium battery is prolonged, and the production cost is reduced.

The invention provides an ultrathin lithium-silver alloy strip for a lithium ion battery anode and a preparation method thereof. The method comprises the steps of: heating lithium to a predetermined temperature in a first predetermined environment to completely melt the lithium into liquid lithium; adding silver to the liquid lithium according to a predetermined mass ratio in the first predetermined environment at the predetermined temperature, stirring the mixture for a predetermined time in order that the silver is liquefied to be completely uniformly mixed with the liquid lithium to form a lithium-silver solid solution; stopping heating, cooling the lithium-silver solid solution in the first predetermined environment to the room temperature so as to obtain a lithium-silver solid solution block in a solid state; and in a second predetermined environment, rolling the lithium-silver solid solution block in a roller press to a predetermined thickness to obtain a lithium-silver alloy strip of a predetermined thickness, wherein the predetermined temperature is greater than 180 degrees centigrade, and the second predetermined environment is an environment with a relative humidity of less than 10%. The lithium-silver alloy strip prepared by the method has a thickness of 4[mu]m to 200 [mu]m, a uniform thickness, good continuity, and excellent ductility.

The invention discloses a current collector and a lithium ion battery containing the current collector. The current collector comprises a conductive layer, an insulating layer and a reinforcing layer,wherein the number of the conducting layers is two, an insulating layer is arranged between the two conducting layers, and a reinforcing layer used for reinforcing conductivity is further arranged between the conducting layers and the insulating layer. The conductive layer, the enhancement layer and the insulating layer are compounded by adopting vacuum electroplating or electrolytic electroplating; the conductive layer is made of a metal material, wherein the thickness of the conductive layer is 0.1-1 [mu]m; the insulating layer is made of an organic polymer insulating material, wherein thethickness of the insulating layer is 2-8 microns; the enhancement layer is made of at least one of a carbon-based conductive material and a nano conductive ceramic material, wherein the thickness of the enhancement layer is 0.1-1 micron. The insulating layer is arranged between the two conductive layers, and the reinforcing layer is arranged between the conductive layers and the insulating layer,so the weight of the current collector is reduced, the conductivity of the current collector is ensured, the toughness of the current collector can be improved, and the consistency and safety of products are improved.

The invention provides a composite solid-state electrolyte, a preparation method thereof and a lithium secondary solid-state battery comprising the composite solid-state electrolyte. The composite solid electrolyte comprises a polymer matrix, an inorganic solid electrolyte filler, a lithium salt and an ionic liquid, wherein based on the total mass of the composite solid electrolyte, the mass content of the polymer matrix is 10%-40%; wherein the mass content of the lithium salt is 15%-60%; the mass content of the inorganic solid electrolyte filler is 2%-10%; wherein the mass content of the ionic liquid is 20-50%, the thickness of the composite solid electrolyte is 80-200 [mu] m, and the thickness of the assembled battery is pressed to 20-50 [mu] m under the pressure of 20-50 MPa. Both the positive electrode and the negative electrode of the lithium secondary solid-state battery do not contain a current collector.

Provided is a method for preparing a high-energy-density negative pole piece and a lithium ion battery comprising the high-energy-density negative pole piece. By weight, the preparation method comprises the following steps of 1 preparation of negative pole high-viscosity slurry, 2 preparation of modified nickel foam and 3 rolling. According to the high-energy-density negative pole piece and the preparation method of the lithium ion battery of the high-energy-density negative pole piece, the contact internal resistance of electrode active matter and a current collector is effectively reduced, and the comprehensive performance of an electrode is improved. Meanwhile, the surface of the nickel foam is plated with lithium ion containing matter, and therefore the transmission rate of lithium ions in the charging and discharging process can be increased. The advantages of being high in energy density, high in liquid absorption capacity, high in adhesive power and the like are achieved, and the high-energy-density negative pole piece is especially suitable for the lithium ion batteries used in the digital field.

The invention provides a coating material for a light-weight lithium ion battery diaphragm, a preparation method of the coating material and a light-weight lithium ion battery composite diaphragm. The coating material takes water as a liquid phase component, the coating material also comprises a solid phase component, and the solid phase component comprises nanocellulose and porous inorganic nanofiber. According to the coating material for the light-weight lithium ion battery diaphragm, the porous inorganic nanofibers and the nanocellulose are combined, the coating material modifies the microporous polyolefin diaphragm, the electrolyte wettability and stability of the diaphragm can be improved on the premise that the air permeability is not sacrificed, the binding force between the obtained coating and a base membrane is high, and the coating is light and thin, thereby facilitating the transmission of lithium ions and improvement of properties such as mass energy density of the battery; therefore, the coating has a very good application prospect.

The invention relates to an asymmetric super capacitor with cobalt hydroxide and active carbon as the anode and the cathode respectively and a preparation method thereof. The anode adopts a carbon material / cobalt hydroxide electrode, the cathode adopts a carbon material or a foamed nickel / active carbon electrode, the anode and the cathode are separated by a diaphragm such as a polypropylene sulfonic acid membrane, an electrolyte is an alkaline aqueous solution, and a single super capacitor or super capacitor set is assembled. The cobalt hydroxide of the anode provides a pseudocapacitor and the active carbon of the cathode provides an electrical double-layer capacitor, so that the specific capacitance is effectively improved, and the electric potential working window of the capacitor is widened, thereby improving the energy density of the super capacitor. The cobalt hydroxide material of the anode takes quasi-reversible oxidation reduction reaction, and the active carbon of the cathode performs static physical absorption, so that the asymmetric super capacitor is good in cyclic stability and has a long service life. The super capacitor set adopts a flexible package form, so that the mass energy density of a super capacitor overall device is greatly improved.

The invention provides a negative pole piece for a solid-state battery as well as a preparation method and application of the negative pole piece. The negative pole piece comprises a copper foil, a lithium metal layer, a lithium nitride layer and an organic-inorganic composite layer which are sequentially stacked. Ultrathin uniformly-electroplated lithium metal is used as a base material, and surface modification is carried out on the surface of the base material through nitrogen, so that the lithium metal is uniformly deposited, short circuit is prevented, and loss of a lithium source in the circulation process is reduced; and then the organic-inorganic composite coating layer is compounded on the surface of the treated lithium metal, so that the charged and deposited lithium metal is deposited more uniformly and compactly, the short circuit is effectively inhibited, and the interface reaction promotion cycle generated by direct contact between the lithium metal and an electrolyte is inhibited, so that the technical problem that the lithium metal is difficult to apply to an all-solid-state battery is solved.

The invention provides an electrode plate and an application thereof. A first functional surface of a current collector in the electrode plate comprises a first active layer area and a first tab area, and a second functional surface of the current collector comprises a second active layer area opposite to the first active layer area and a second tab area opposite to the first tab area. The active layer is arranged in the first active layer area and / or the second active layer area; n through holes penetrating to the second tab area are formed in the first tab area, a T-shaped tab passes through the through holes, one end of a first section of the T-shaped tab is connected with the first tab area to form a first connecting area, and the other end of the first section of the T-shaped tab is connected with the first tab area to form a second connecting area; the second section of the T-shaped tab is connected with the second tab area to form a third connecting area, and N is greater than or equal to 1; and the current collector comprises a first conductive layer, an insulating layer and a second conductive layer which are stacked. The lithium ion battery prepared from the electrode plate has relatively high mass energy density and safety performance.

The self-supporting lithium-sulfur battery positive plate comprises a carbon carrier, lithium sulfide and transition metal sulfide, and the lithium sulfide and the transition metal sulfide are locatedon the surface of the carbon carrier and / or in the carbon carrier; and the lithium sulfide is in contact with the transition metal sulfide in microstructure. The invention also provides a preparationmethod of the self-supporting lithium-sulfur battery positive plate, and a lithium-sulfur battery comprising the self-supporting lithium-sulfur battery positive plate.

The invention provides a preparation method of a nanocrystalline aluminum material, which belongs to the field of air fuel batteries. The nanocrystalline aluminum material is obtained by twisting purealuminum or an aluminum-alloy raw material at a high pressure; and the high-pressure twisting condition comprises: the number of revolutions is 3 to 11, the pressure is 4 to 6 GPa, and the twisting rate is 1 to 2 turns per minute; and a diameter of the pure aluminum or aluminum-alloy raw material is 10 to 20 mm. By adopting the high-pressure twisting technology, a micro structure of the pure aluminum or aluminum-alloy sample is changed to be a nanocrystalline structure, so that the size of the crystal particle is reduced, the tiny and uniform crystal particle tissue can generally improve theuniformity of the micro tissues, the galvanic corrosion among the crystal particles can be reduced, the hydrogen precipitation rate is reduced, the discharging efficiency is improved, and the mass energy density of the nanocrystalline aluminum material as a negative material can be greatly improved.

The invention provides a lithium ion battery module and a battery pack. The lithium ion battery module comprises a plurality of battery module units which are connected in series, wherein each moduleunit comprises a plurality of single batteries and a current collection bar, the single batteries are connected in parallel by the current collection bar, the current collection bar comprises positivewelding sheets, an elastic sheet structure and a support structure, the positive welding sheets are welded with positive electrodes of the single batteries, negative electrodes of the single batteries are crimped by the elastic sheet structure, and the support structure is used for positioning and supporting the single batteries. In the lithium ion battery module and the battery pack, provided bythe invention, the multi-functional current collection bar is employed, the lithium ion battery module is light in mass, and the mass energy density of the battery module is improved; each single battery is rapidly integrated by an elastic sheet crimping mode, the assembly efficiency is improved, and the disassembly and the recycling of the lithium ion battery are convenient; and a weak connection structure of a welding sink position of the positive electrode of the current collection bar has an effect of fuse protection when the single batteries are circuit-shorted, and the safety of the battery module and the battery pack are improved.

The invention provides a lithium ion power battery liquid cooling module. A battery module is formed through assembly of a plurality of battery module units, wherein clamping grooves where liquid cooling flat pipes are stored are formed in the upper surfaces of the lower surfaces of the battery module units; the clamping grooves are parallel to the length direction of the battery module; the liquid cooling flat pipes which are arranged back and forth are arranged in the lithium ion power battery liquid cooling module, the liquid cooling flat pipes extend in the length direction of the batterymodule, and bend at the end part of the battery module, and the liquid cooling flat pipes penetrate through the positions between adjacent battery module units. The integrated liquid cooling pipelinesare designed in the battery module, rapid cooling and heating of the module can be achieved under the premise that the temperature uniformity of the module is maintained, and the lithium ion power battery liquid cooling module has an excellent heat management property; parameter adjustment and matching design can be conducted according to the heat management requirements, and the lithium ion power battery liquid cooling module has an extremely high temperature adaptive capacity, and the gravimetric specific energy density and the volumetric specific energy density of the battery module can beeffectively improved; and the modularized design is adopted, the lithium ion power battery liquid cooling module is convenient, rapid and efficient to assemble.

The invention discloses a positive plate, a negative plate, a battery cell, a lithium battery and a preparation method of the lithium battery, and belongs to the technical field of batteries. Positiveand negative tabs on the positive and negative plates belong to embedded tabs; on the premise that the shape and size of the battery are kept the same, the mass energy density of the embedded tabs ishigher than that of the extended tabs; meanwhile, due to the fact that an area ratio of the positive and negative tabs is low, the internal space utilization rate of the battery is high, and the advantages of high compaction surface density of the positive and negative plates and larger battery capacity are achieved; and the positive and negative tabs are positioned at the two ends of the positive and negative plates respectively, so that the problem of non-uniform heating in the charging and discharging processes of the lithium battery can be effectively improved, and the safety and reliability of the lithium battery are improved.

The invention provides a negative plate and a lithium ion battery comprising the same. The invention discloses a lithium ion battery negative plate. A porous copper foil filled with a binder is adopted as a negative current collector, the liquid retention amount of the negative plate is improved due to the existence of pores in the porous copper foil, the porous copper foil is lighter than commonlight foil, the overall mass specific energy of a battery cell can be improved, and the flexibility of the negative plate is also improved; the binder filled in the pores greatly improves the bindingpower between the active material layer and the negative electrode current collector, avoids stripping of the active material layer from the negative electrode current collector due to large volume expansion of the silicon-based material, and reduces the contact resistance between the silicon-based material and the negative electrode current collector; and the silicon-based material is used, so the overall capacity of the cell can be greatly improved.

The invention discloses a gluing structure battery cell with an embedded tab, a fabrication method of the gluing structure battery cell and a lithium battery, and belongs to the technical field of lithium batteries. The battery cell comprises a positive electrode plate, a negative electrode plate and a diaphragm and also comprises a positive electrode tab and a negative electrode tab, wherein thediaphragm is arranged between the positive electrode plate and the negative electrode plate, the positive electrode tab is arranged on each positive electrode plate, the negative electrode tab is arranged on each negative electrode plate, a tail-end edge of the positive electrode tab, a tail-end edge of the negative electrode tab and tail ends of the electrode plate are maintained at the same horizontal surface, one of the tabs in the positive electrode tabs is connected with a first nickel sheet, one of the tabs in the negative electrode tabs is connected with a second nickel sheet, and the first nickel sheet and the second nickel sheet extend out of the edges of the electrode plates and are used for leading out the tabs. By the battery cell, the mass energy density of the battery can beeffectively improved, moreover, malposition and loosening of the positive electrode plate and the negative electrode plate also can be effectively prevented, the contact between the electrode plates is improved, and the stability and the safety of the battery are favorably improved.

The invention belongs to the technical field of batteries, and particularly relates to a pole piece which comprises a first self-supporting layer, a first metal conductive layer, a second metal conductive layer and a second self-supporting layer which are sequentially laminated. The first self-supporting layer and the second self-supporting layer respectively comprise an active substance, a conductive agent and a binder. In addition, the invention also relates to a preparation method of the pole piece, a battery cell and a battery. Compared with the prior art, the battery provided by the invention has good safety performance while having high energy density.

The invention provides a current collector and application thereof. The current collector comprises an insulating layer, at least one functional surface of the insulating layer is provided with a conductive layer, and the conductive layer comprises a first part close to the insulating layer; based on the thickness of the conductive layer, the thickness of the first part is greater than or equal to 20%; the density D of the first part is larger than or equal to 50%; and the roughness of the surface, far away from the insulating layer, of the conductive layer is 50 nm to 2 microns. According to the current collector disclosed by the invention, the conductive layer with the thickness of at least 20% has relatively high density, so that the current collector has relatively low sheet resistance, and the lithium ion battery has relatively good electrical performance; and the surface, far away from the insulating layer, of the conductive layer is high in roughness, so that the adhesive force between the active layer and the conductive layer can be increased, the adhesion between the active layer and the current collector is increased, and the electrical performance of the lithium ion battery is further improved.

The invention provides a square lithium ion battery, the square lithium ion battery comprises a square shell and a cover plate, the square shell is internally provided with at least one roll core, the roll core comprises a positive plate and a negative plate which are arranged at two sides of a diaphragm, the positive plate comprises a positive current collector, and the negative plate comprises a negative current collector. The positive plate comprises a positive current collector and a positive active material coating area at least partially covering one surface of the positive current collector, and the negative plate comprises a negative current collector and a negative active material coating area at least partially covering one surface of the negative current collector; the square lithium ion battery meets the following conditions: (T / (30 * n)) 0.5 / V * Sc is greater than or equal to 3.0 and less than or equal to 5.0; according to the square lithium ion battery provided by the invention, the number of the roll cores and the coating area of the positive and negative active materials can be flexibly designed, the selection of the number of the roll cores and the coating area of the positive active materials and the size of the battery are limited, and the space utilization rate of the roll cores is improved, so that the mass energy density of the battery is improved; design is reasonable, operability is high, and popularization is facilitated.