2410results about "Graphite" patented technology

A graphite composite material and a preparation method therefor, a negative electrode active material, a secondary battery, and an electric device. The graphite composite material comprises an inner core and a coating layer located on the surface of the inner core, wherein the material of the inner core comprises graphite, and the material of the coating layer comprises a nitrogen-doped porous aluminum oxide-carbon composite material. The provided graphite composite material improves the initial efficiency of the graphite material, and improves the rate capability of a battery.

The invention discloses a graphite-doped negative electrode material as well as a preparation method and application thereof, and belongs to the technical field of rechargeable secondary battery negative electrode materials. The doped graphite negative electrode material comprises an inner core and a shell on the outer layer of the inner core, the inner core is an element-doped graphite-doped secondary particle; the doping mode of the doped graphite secondary particles is solid phase doping or liquid phase doping; the shell comprises an element-doped carbon coating layer formed by vapor deposition; and the total mass of the doped elements accounts for 0.5-10% of the mass of the doped graphite negative electrode material. According to the doped graphite negative electrode material provided by the invention, the graphite secondary particle core and the carbon coating layer are subjected to element doping treatment, the microstructure of graphite is improved by element doping, and active site defects are formed, so that the diffusion of a charge carrier is facilitated, and the dynamic performance of the material is improved; meanwhile, the graphite layer spacing is enlarged; the carbon coating layer isolates the graphite secondary particle inner core from being in direct contact with the electrolyte, so that the fast charging performance of the doped graphite negative electrode is comprehensively improved in an omnibearing and multi-angle manner.

The invention discloses a lithium ion battery modified graphite negative electrode material and a preparation method and application thereof, and belongs to the technical field of batteries, the negative electrode material is of a core-shell structure, an internal core is graphite particles, an external shell is a high electronegativity nonmetal / metal heteroatom co-doped carbon material of N, O, F and the like, the weight ratio of carbon doped in the shell part to graphite is X, and 2% < = X < = 20%. Compared with the prior art, the negative electrode material can form an SEI film which is more stable, compact and continuous and is rich in fluoride with high ionic conductivity, so that the SEI film can be effectively prevented from being broken and lost in the later charging and discharging process, and the service life of the negative electrode material is prolonged while the first-round coulombic efficiency of the negative electrode material is remarkably improved. And the cycle life and the high-current charge-discharge performance of the negative electrode material can be remarkably improved.

The invention discloses a modified resin coated double-doped microcrystalline graphite negative electrode material as well as a preparation method and application thereof. The modified resin coated double-doped microcrystalline graphite negative electrode material has a core-shell structure, wherein an inner core is a three-dimensional network porous structure formed by metal salt and sulfur double-doped microcrystalline graphite; metal salt in the inner core forms a chemical bond between sulfur and microcrystalline graphite to provide a bridge for bonding of microcrystalline graphite and sodium; the shell is a coating layer formed by coating the surface of the inner core with modified resin and carbonizing the modified resin, and has a three-dimensional porous conductive network structure. According to the invention, through the activation process, increase of interlamellar spacing and active sites of microcrystalline graphite, and double doping of sulfur element and metal salt, the doping amount of sulfur and metal salt in microcrystalline graphite is improved, meanwhile, the metal salt forms chemical bonds between sulfur and microcrystalline graphite, sodium ion loss in the charge and discharge process is reduced, and the material stability is improved; and the rate cycle performance of the sodium ion battery is improved.

The invention discloses a nanometer silicon filled microcrystalline graphite negative electrode material and a preparation method and application thereof. The preparation method of the nano-silicon filled microcrystalline graphite negative electrode material comprises the following steps: by taking microcrystalline graphite as a base material, depositing silane between sheet layers of the microcrystalline graphite by adopting a gradient heating method to obtain a nano-silicon filled microcrystalline graphite composite material; and finally, forming the nano-silicon filled microcrystalline graphite negative electrode material with a porous structure on the surface of the nano-silicon filled microcrystalline graphite composite material through carbon source coating carbonization. According to the nano-silicon-filled microcrystalline graphite negative electrode material with the core-shell structure provided by the invention, an inner core is a silicon-graphite composite material formed by nano-silicon-filled microcrystalline graphite, nano-silicon particles are filled in the surfaces and gaps of crystalline grains of the microcrystalline graphite, volume expansion of the nano-silicon in the charging and discharging process is inhibited by a microcrystalline graphite matrix material, and particularly, the volume expansion of the nano-silicon in the charging and discharging process is inhibited by the microcrystalline graphite matrix material. And due to different structural orientations of the microcrystalline graphite, the stress effect can be counteracted, and the volume expansion of the material is further inhibited.

The invention provides a natural graphite composite negative electrode material and a preparation method thereof, and a lithium ion battery, the natural graphite composite negative electrode material comprises natural graphite, a fluffy net-shaped three-dimensional carbon network coated outside the natural graphite, and an amorphous carbon coating layer arranged outside the fluffy net-shaped three-dimensional carbon network; wherein magnesium ions and / or aluminum ions are dispersed in the fluffy three-dimensional carbon network, and copper particles and / or silver particles are doped in the amorphous carbon coating layer. The natural graphite composite negative electrode material provided by the invention has a three-dimensional conductive network, is doped with metal, and has good conductivity and excellent electrochemical cycle performance.

The invention discloses a lithium salt doped porous carbon coated graphite composite material for an energy storage battery and a preparation method thereof, the composite material has a core-shell structure, the core is graphite, and the shell is a lithium salt doped porous carbon complex. The preparation method comprises the following steps: uniformly mixing amino resin, a pore-forming agent and a heteroatom compound of the pore-forming agent, curing, activating to obtain porous carbon, adding the porous carbon into an inorganic lithium salt, uniformly mixing, and carrying out spray drying to obtain lithium salt doped porous carbon; the preparation method comprises the following steps: adding lithium salt doped porous carbon into a carboxymethyl cellulose lithium solution, uniformly dispersing, then adding into a graphite material, uniformly dispersing, spray-drying, and carbonizing to obtain the lithium salt doped porous carbon coated graphite composite material. According to the obtained material, the coating layer lithium salt is doped with porous carbon, so that the liquid absorption and retention capacity of the material is improved, the diffusion rate of lithium ions is increased, and the rate capability is improved; meanwhile, the expansion of the composite material in the charging and discharging process is reduced by utilizing the low expansion of the porous carbon, and the cycle performance is improved.

The invention relates to the technical field of lithium ion battery negative electrode materials, in particular to a graphite composite material and a preparation method and application thereof. The preparation method comprises the following steps: heating metal lithium to obtain lithium steam, and depositing the lithium steam into a metal organic framework material to obtain a lithium-doped metal organic framework material; a chemical vapor deposition method is adopted, carbon source gas and oxygen are introduced, amorphous carbon is deposited in the lithium-doped metal organic framework material, and an amorphous carbon and lithium co-doped metal organic framework material is obtained; and mixing the amorphous carbon and lithium co-doped metal organic framework material, a metal salt solution and a graphite material to obtain a mixture, heating, carrying out solid-liquid separation, taking solid components, introducing carbon source gas, and reacting to generate carbon nanotubes, thereby obtaining the graphite composite material. When the prepared graphite composite material is applied to a lithium ion battery as a negative electrode material, the battery has the advantages of high first efficiency, good liquid retention performance, low expansion, fast charge, good cycle performance and the like.

The present invention discloses a modified silicon-carbon negative electrode material and a preparation method thereof, comprising the following steps: mixing modifier 2 with asphalt and stirring evenly, then carbonizing, cooling, crushing and screening to obtain modified asphalt A; dynamically adding modified asphalt A to a solution of modifier 1, dispersing by high-speed shearing in an emulsifier, heating, drying and crushing to obtain modified asphalt B; mixing a silicon source with a base carbon material to obtain a composite material C, and fully mixing the composite material C with the modified asphalt B at room temperature to obtain a silicon-carbon coated precursor material; calcining the silicon-carbon coated precursor material under inert atmosphere protection to obtain a Si / Gr@C composite material, and crushing and screening to obtain a modified silicon-carbon negative electrode material. The negative electrode material can improve the capacity and initial efficiency of the silicon-carbon negative electrode.

The invention relates to a graphite negative electrode material and a preparation method thereof, a negative electrode plate and an electrochemical device. The graphite negative electrode material comprises secondary particles formed by granulating and carbonizing 20%-90% of a doped porous graphite precursor, 5%-30% of hard carbon particles and 5%-50% of a coating agent, in the secondary particles, the hard carbon particles are at least partially filled in holes of the doped porous graphite precursor, and the coating agent is at least partially filled in the holes of the doped porous graphite precursor. And after the coating agent is carbonized, at least part of the coating agent forms amorphous carbon to coat the outer layer of the doped porous graphite precursor. According to the scheme provided by the invention, the doped porous graphite precursor can be compounded with the hard carbon particles and the coating agent to obtain the graphite negative electrode material with high capacity and fast charging performance.

The invention provides a graphite negative electrode active material and a preparation method thereof, and a negative electrode plate, a secondary battery and an electric device containing the graphite negative electrode active material. A particle body of the graphite negative electrode active material comprises an internal region and a surface layer region at least partially surrounding the internal region, the surface layer region is a region formed by extending the surface of the particle body of the graphite negative electrode active material to the interior of the particle by a distance of 30nm, and the mass percentage content of crystalline carbon in the internal region is marked as eta 1, the mass percentage content of the crystalline carbon in the surface layer region is recorded as eta 2, and 10% < = eta 1-eta 2 < = 35%. The graphite negative electrode active material can improve the cycle performance of the battery.

The invention relates to the technical field of artificial graphite production, and particularly discloses a method for preparing artificial graphite from waste coke powder. According to the preparation method of the artificial graphite provided by the invention, by-product micro powder generated in a raw material coke grinding stage is used as a raw material, an asphalt substance is used as a binder, the asphalt substance is subjected to aerobic baking, part of the asphalt substance is oxidized in the baking process, the asphalt substance and waste coke powder are mixed and granulated, and the artificial graphite is obtained. In the subsequent carbonization process, the oxidized substances can form special holes in the surface of the graphite, the special carbon coating layers with the holes enable the artificial graphite to have good porosity, and the problem that the tap density is low after the waste coke powder is granulated is solved. When the artificial graphite is applied to the lithium ion battery, the electrochemical performance of an electrochemical device comprising the negative electrode material is favorably improved. The invention provides a low-cost and high-performance negative electrode material for the lithium ion battery, and has very important significance for the development of the lithium ion battery.

The invention provides a polycrystalline diamond material with a double-peak structure and a preparation method of the polycrystalline diamond material, and relates to the technical field of superhard materials. The polycrystalline diamond material comprises the following raw materials: nano onion carbon and micron graphite, and the preparation method comprises the following steps: weighing the nano onion carbon and the micron graphite, carrying out mechanical grinding treatment, fully mixing to obtain mixed powder, pressing the mixed powder with a mold, and wrapping with boron nitride to obtain a green body; and the blank is loaded into a high-temperature and high-pressure synthesis cavity for high-temperature and high-pressure synthesis treatment, then heat preservation and pressure maintaining treatment is carried out, cooling and pressure relief treatment are carried out, and the polycrystalline diamond material with the double-peak structure is obtained. According to the method disclosed by the invention, the grain size with a'double-peak structure 'is constructed in the polycrystalline diamond, so that the fracture toughness of the polycrystalline diamond is improved by more than two times while high hardness is maintained, the extremely-hard and high-toughness polycrystalline diamond is successfully synthesized, and a reference is provided for toughening of other ceramic materials.

The invention discloses a negative electrode material, a negative electrode plate and a secondary battery, and relates to the technical field of secondary batteries. The negative electrode material comprises natural graphite and amorphous carbon filled in pores of the natural graphite; the particle hardness of the negative electrode material is 0.28 GPa to 0.4 GPa, and the elastic modulus of the negative electrode material is 7.0 GPa to 8.0 GPa; when the compaction density of the tablet of the negative electrode material is 1.5-2.0 g / cm < 3 >, the orientation OI value of the tablet of the negative electrode material is y, and y is more than 4 and less than or equal to 11. When the negative electrode material is applied to the secondary battery, the first coulombic efficiency and the cycling stability can be remarkably improved.

The invention relates to the field of battery materials, in particular to a preparation method and application of a high-rate silicon-carbon negative electrode material. The preparation method of the high-rate silicon-carbon negative electrode material comprises the steps of silicon powder pretreatment, silicon-carbon powder composite ball milling, phosphoric acid treatment, high-temperature carbonization and the like. The preparation method of the high-magnification silicon-carbon negative electrode material is simple in process and high in success rate, the cycle stability of a negative electrode is effectively improved, the silicon-carbon negative electrode material has the characteristics of low expansion volume and long cycle life, the phenomenon that a surface oxide layer hinders lithium ion diffusion is avoided, and the service life of the silicon-carbon negative electrode material is prolonged. The comprehensive performance requirement of the existing lithium ion battery on the negative electrode material is met, and the application potential is very wide.

The invention relates to a low-temperature graphite negative electrode material and a preparation method thereof, and belongs to the technical field of high polymer materials. According to the prepared low-temperature graphite negative electrode material, firstly, the surface of graphite is pre-oxidized through potassium persulfate, phosphorus pentoxide and concentrated sulfuric acid, and then under the action of sodium nitrate, potassium permanganate and hydrogen peroxide, graphite oxide is prepared; then, ammonium molybdate hydrate and thioacetamide are used as a molybdenum source and a sulfur source, graphite oxide is used as a supporting material, a molybdenum disulfide-graphite compound is synthesized, and the conductivity and the cycling stability are improved; secondly, the surface of the negative electrode is coated with amorphous resin carbon / nickel oxide, so that the ion diffusion efficiency of the low-temperature graphite negative electrode material is enhanced, and the electrochemical lithium storage performance is improved in a low-temperature environment; and finally, the surface of the amorphous resin carbon / nickel oxide is coated with a layer of polythiophene film, so that the rate capability of the negative electrode material is improved due to large surface area and high pores.

The invention discloses an anthracite-based fast-charging carbon negative electrode material and a preparation method thereof.The preparation method comprises the steps that firstly, component separation is conducted on anthracite, meanwhile, the dual effects of reducing ash content and separating maceral components are achieved, then grading treatment is conducted by means of the density and hardness difference of vitrinite and inertinite, small-particle-size vitrinite is further sufficiently enriched, and the carbon negative electrode material is obtained. The content of vitrinite in the auxiliary material B is larger than or equal to 96 wt%, and then the auxiliary material B is subjected to hot air oxidation treatment to be subjected to a cross-linking reaction, so that the auxiliary material B is promoted to form a hard-carbon-like structure in the high-temperature carbonization process; meanwhile, collecting a mixed material containing 50-70wt% of vitrinite and 30-40wt% of inertinite as a main material A, and graphitizing the main material A; the graphitized main material A, the oxidized auxiliary material B and a binder are heated, fused and carbonized to form a graphite / hard-like carbon hybrid structure, and the anthracite-based fast-charging carbon negative electrode material with excellent electrochemical performance is obtained.

The invention provides a graphite negative electrode active material and a preparation method thereof, a secondary battery and an electric device, the graphitization degree of the graphite negative electrode active material is 88-93%, and the oil absorption value of the graphite negative electrode active material is not more than 50ml / 100g. The graphite negative electrode active material can improve the cycle performance of the battery and prolong the service life of the battery.

The invention belongs to the field of waste artificial graphite regeneration, and particularly relates to a waste artificial graphite regeneration method, a regenerated material and application thereof, the regeneration method comprises the following steps: carrying out normal pressure liquid phase modification on waste artificial graphite in an organic acid solution in advance, and then putting the modified waste artificial graphite in an inorganic acid solution for positive pressure liquid phase modification to prepare a modified material; mixing the modified material with a Mn source, a metal N source, a first carbon source and a binder to obtain a mixture, then performing heat treatment on the mixture in a hydrogen-containing atmosphere, and then performing negative-pressure annealing treatment to obtain a heat-treated material; the metal N source comprises a compound of at least one of iron, cobalt and nickel; and mixing the heat-treated material with lithium salt and a second carbon source, and carrying out roasting treatment to obtain the graphite regenerated material. The regeneration method disclosed by the invention is particularly suitable for repairing the artificial graphite waste which is difficult to treat, so that the artificial graphite waste can be repaired to obtain a material with excellent capacity, long circulation and particularly low-temperature stability.

The invention provides a graphite negative electrode material for a lithium battery and a preparation method of the graphite negative electrode material. The preparation method comprises the following steps: (1) preparing modified phenolic resin; (2) adding natural graphite and the modified phenolic resin into a reaction kettle, continuously adding the modified graphene, and stirring, heating and coating in a nitrogen atmosphere, specifically, heating to 150-200 DEG C at a speed of 1-2 DEG C / min, preserving heat for 100-120 minutes, heating to 550-600 DEG C at a speed of 4-6 DEG C / min, preserving heat for 180-200 minutes, and cooling to obtain coated graphite; and (3) carbonizing the coated graphite in an atmosphere furnace, and sieving to obtain the graphite negative electrode material for the lithium battery. When the negative electrode material is used for preparing a lithium battery, the capacity retention ratio is high, the rate capability is good, the impedance is low, and the lithium precipitation point of fast charge is high.

The invention relates to a graphite silicon carbon composite negative electrode material, a negative electrode plate and a lithium ion battery, and belongs to the technical field of battery negative electrode materials. The graphite silicon carbon composite negative electrode material comprises a graphite inner core and a composite shell layer, the composite shell layer coats the surface of the inner core, the composite shell layer comprises a continuous carbon layer, the carbon layer is of a porous structure, and the porous structure is filled with nano silicon particles. According to the core-shell structure, through a three-stage synergistic mechanism of graphite inner core conductive supporting, porous carbon layer expansion buffering and nanometer silicon capacity contribution, the cycling stability of the negative electrode material is remarkably improved while the high specific capacity is maintained.

The present invention relates to a silicon-carbon (Si / C) composite that is prepared by combining silicon with a porous carbon-based material, which is obtained by removing iron impurities from solid carbon produced during pyrolysis for converting a methane-containing feedstock into hydrogen in the presence of an iron-based catalyst. The present invention further relates to a method for making the silicon-carbon (Si / C) composite and a use thereof as electrode material.

A negative active material, a method of preparing the negative active material, and a rechargeable lithium battery including the negative active material are disclosed. The negative active material may include a crystalline carbon core and a magnesium (Mg)-included coating layer on a surface of the core, wherein the Mg-included coating layer may include MgO and MgxSiOy (1≤x≤2 and 3≤y≤4).

A method for producing carbon foam boards from starch for use as an insulation material or a filter is disclosed. The method is suitable for producing fine-pored carbon foam boards having a mainly homogeneous structure. This is achieved by sprinkling at least one very thin layer of foamable starch powder onto a temperature-resistant boardlike substrate, introducing the starch-powder-coated substrate into a furnace, introducing air, argon or nitrogen into the furnace until an internal pressure of ≈720 mbar to ≈1000 mbar has been established, heating the furnace to a foaming temperature of 180° C.-450° C. to foam the starch powder, maintaining the temperature over a prolonged duration of up to 10 hours to stabilize the foamed starch into a foam board.

The invention relates to the field of battery material recovery, and discloses regenerated graphite and a preparation method thereof.The preparation method includes the steps that in protective gas, waste graphite, inorganic fused salt and a fused salt auxiliary are mixed and roasted to obtain the regenerated graphite, the inorganic fused salt comprises sodium chloride and potassium chloride, and the fused salt auxiliary comprises acid phosphate. Binary inorganic fused salt is combined with a fused salt auxiliary agent to form a fused salt system, regeneration treatment including impurity removal and molecular structure reforming can be carried out on waste graphite at a low heat treatment temperature, and doping treatment on a graphite material is completed through the same process. Meanwhile, the method does not need to carry out additional pretreatment on the waste graphite. Therefore, the method provided by the invention has relatively high heat energy utilization rate and relatively low treatment temperature, can be used for directly treating the waste graphite, reduces the requirements on equipment and process in the treatment process of preparing the regenerated graphite, and can be used for preparing the regenerated graphite with relatively high electrochemical performance.

The invention discloses a silicon / graphite / carbon-aluminum oxide composite negative electrode material and a green preparation method thereof, and belongs to the technical field of lithium ion batteries. Aiming at the problems of high volume expansion rate and poor cycling stability of a silicon-based negative electrode and high cost of a traditional process, the invention innovatively provides the following scheme: 1) waste photovoltaic silicon wafer ball-milling liquid and waste graphite are taken as core raw materials, and resource recycling is realized; (2) phenolic resin and chitosan are adopted as double carbon sources, a nitrogen-doped carbon layer (the nitrogen content is 3-5 wt.%) is formed through pH-induced self-assembly, and the conductivity and the Li < + > diffusion rate are synchronously improved; and 3) aluminum nitrate is introduced for pyrolysis to generate 2-5nm aluminum oxide for doping, so that the side reaction of the electrolyte is inhibited, and the volume expansion of silicon is relieved (the expansion rate is less than or equal to 120%). The preparation process comprises the steps of silicon / graphite dispersion, double-carbon-source compounding, ammonia water regulation and control precipitation and gradient calcination. Experiments show that the specific capacity of the optimized material under the current of 0.5 A / g reaches more than 800mAh / g, the 100-time cycle capacity retention ratio is more than 98%, the 1000-time cycle capacity retention ratio is more than 80%, the reversible specific capacity under the multiplying power of 3A / g is more than 550mAh / g, and the raw material cost is reduced by 40%. The invention has the advantages of high capacity, long service life, environmental protection and economy, and provides an innovative solution for the fields of power batteries and energy storage.

The invention discloses a negative electrode material and a preparation method and application thereof. The negative electrode material comprises an inner core and a coating layer coated outside the inner core, the inner core is microcrystalline graphite with a porous structure, the coating layer is a carbonized material and comprises a cross-linking layer and a compact layer, the surface of the microcrystalline graphite is coated with the cross-linking layer, and the surface of the cross-linking layer is coated with the compact layer; wherein the cross-linking layer is formed by carbonizing heavy components in a coating agent on the surface of the microcrystalline graphite, the compact layer is formed by carbonizing weak polar groups in the coating agent, and the graphitization degree of the compact layer is greater than or equal to 94%. The negative electrode material disclosed by the invention can effectively reduce side reaction and structural breakage in the charge-discharge process, enhance the overall conductivity, and finally improve the first efficiency, the specific capacity and the cycling stability of the battery.

The invention belongs to the field of negative electrode materials, and particularly relates to a silicon-graphite composite material, a preparation method and application thereof and a lithium ion battery, the preparation method comprises the following steps: mixing and slurrying silicon powder, graphite and a composite functional additive, and then carrying out ball milling modification to obtain primary composite particles; the composite functional auxiliary agent comprises an auxiliary agent A, an auxiliary agent B and an auxiliary agent C; the primary composite particles and a carbon source liquid phase are compounded and then subjected to spray drying and heat treatment, or spray pyrolysis is directly carried out, and secondary composite particles are prepared; and carrying out modification treatment on the secondary composite particles prepared in the step 2 in a surface modification liquid, and then carrying out low-temperature annealing at 150-300 DEG C to prepare the silicon-graphite composite material. The surface modification liquid is an organic solution in which conductive lithium salt and an auxiliary agent D are dissolved. Based on the combined control of the preparation process and the structure, the silicon-based negative electrode material with ultra-long cycle life and excellent low-temperature fast charging performance can be obtained.

The invention provides a preparation method of a microcrystalline graphite intercalation compound, which comprises the following steps: mixing and ball-milling N-chlorosuccinimide, anhydrous aluminum chloride and microcrystalline graphite, washing and drying to obtain the microcrystalline graphite intercalation compound. Anhydrous AlCl3 is used as an intercalator to replace an acidic strong oxidant, so that the requirements of some fields on corrosion resistance of products are met, and the generation of harmful gas can be effectively reduced. The xAlCl3-yMGIC powder is prepared under relatively mild conditions by using microcrystalline graphite as an acceptor carbon source and N-chlorosuccinimide as a chlorinating agent and adopting a high-temperature mechanochemical method. And then the prepared xAlCl3-yMGIC powder is used as a raw material to prepare expanded microcrystalline graphite (EMG) which can be used for preparing an electromagnetic wave absorbing / shielding material.

The invention discloses a nitrogen-doped artificial graphite negative electrode material as well as a preparation method and application thereof. The preparation method comprises the following steps: pretreating and graphitizing raw material coke to obtain artificial graphite; and compounding the artificial graphite and a nitrogen source under an alkaline condition, and calcining to obtain the negative electrode material. According to the unique preparation method, the nitrogen element can be introduced into the artificial graphite, and the molecular structure of the ink sheet is changed due to the introduction, so that the connection between layers is enhanced. Compared with the conventional lithium ion battery, the lithium ion battery containing the nitrogen-doped artificial graphite negative electrode material has the advantages that the specific discharge capacity is improved, and the cycle life is remarkably prolonged.