BYD's Strategy for Enhancing Lithium-Ion Battery Efficiency

Dispersant for lithium-ion battery slurries that improves dispersion of active material, conductive agent, and binder in the slurry without requiring high amounts of dispersant. The dispersant is prepared by polymerizing monomers and then hydrogenating the polymer to reduce double bonds. This dispersant allows higher solid content slurries with better dispersion stability compared to conventional dispersants like PVP.

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Lithium battery with lithium supplementation during cycling to improve energy density and cycle life. The battery has a lithium-supplementing pole piece with a protective layer that deforms under pressure to expose the lithium-containing active layer to the electrode. This allows lithium replenishment when needed during cycling without increasing the initial NP ratio. The protective layer prevents premature lithium reaction during manufacturing. The lithium supplementation fills vacancies in the electrodes to utilize more capacity and reduce lithium ion loss compared to fixed NP ratio batteries.

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Lithium-ion battery design with internal liquid injection and isolation features for high capacity and safety. The battery has multiple accommodation cavities separated by separators. Each cavity contains a connected set of pole shanks forming the battery core. The separators have injection holes connecting adjacent cavities. A block mechanism closes the holes to isolate the cavities. During manufacturing, the mechanism is open for injection. Afterwards, it closes to isolate the cavities. This allows injecting electrolyte into all cavities simultaneously. The mechanism can switch between open and closed positions. This enables injection, then closure to block direct connections between cavities. This prevents electrolyte leakage or mixing. The mechanism can also be a magnetic substance.

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Self-heating method, device, and system for lithium-ion batteries in electric vehicles that avoids battery polarization effects during heating. The method involves adaptively adjusting the heating frequency based on the phase difference between battery current and voltage signals. If the phase difference is less than a threshold, the heating frequency is increased to avoid lithium plating. If the phase difference doesn't change after frequency increase, it indicates a malfunction and stops heating. This allows effective heating without degradation compared to fixed frequency heating.

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Ternary cathode material for lithium-ion batteries with improved performance compared to conventional ternary cathode materials with secondary spherical structure. The new material is a single-crystalline ternary cathode material with a unique particle structure that has a central area with higher nickel content surrounded by a surface layer with lower nickel content. This composition and structure provides higher capacity and rate performance compared to traditional ternary cathode materials. It also has advantages like improved cycle life, reduced side reactions, and lower expansion due to the smooth surface and uniform composition. The single-crystalline particle structure is prepared by co-precipitation and solid-state sintering techniques.

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Lithium-ion battery with improved cycle life and reduced expansion by using a unique nanostructured positive electrode material with multiple nested cores. The material has a first core with multiple nested second cores, each with an optional cladding layer. The nested core structure prevents particle reorientation during rolling that can hinder lithium ion movement and expansion. The nested cores also provide more surface area for intercalation while reducing stress concentration during cycling compared to monolithic particles.

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A lithium ion battery with improved capacity and cycle life by optimizing the ratio of lithium iron phosphate (LFP) to ternary materials like nickel-rich cathode materials in the positive electrode. It also involves using the ternary materials to consume excess lithium ions formed during charging to help form a protective SEI film on the graphite negative electrode. The ratio of LFP to ternary capacity should be between 0.49 and 1.15, and the total LFP capacity should be at least 135 mAh/g. This balance prevents excessive lithium loss from the LFP while allowing the ternary material to contribute. It also improves cycle life by reducing dissolution of LFP elements like Fe and Mn. The ternary material residual alkali, electrolyte injection coefficient, and residual hydrogen

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Lithium iron phosphate (LiFePO4) anode material for lithium-ion batteries with higher density to improve specific capacity and energy density compared to conventional LiFePO4 materials. The higher density LiFePO4 is made by optimizing the sintering conditions when mixing two LiFePO4 powders. The method involves controlling the sintering temperature and time to obtain a LiFePO4 composite with higher compressed density. This enables LiFePO4 batteries with higher specific capacity and energy density. The higher density LiFePO4 anode material can be used in Li-ion batteries along with conventional LiFePO4 cathodes.

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Pole piece design for lithium-ion batteries that allows controlled replenishment of lithium ions during battery cycling to improve capacity retention. The pole piece has a current collector, a semiconductor layer, and a lithium replenishment layer sandwiched between them. The semiconductor layer can be turned on or off to selectively allow electron transfer between the current collector and replenishment layer. When the semiconductor layer is off, it blocks electron exchange and prevents lithium loss from the replenishment layer. When the semiconductor layer is on, it allows electron transfer between the current collector and replenishment layer to replenish lithium ions during battery cycling. This controlled replenishment improves capacity retention compared to one-time lithium supplementing methods.

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Lithium iron manganese phosphate composite material for lithium-ion batteries with improved low-temperature and rate performance, reduced manganese dissolution, and enhanced structural stability. The composite consists of an inner core doped with strontium and an outer shell doped with zirconium. The strontium-doped inner core allows higher manganese content for higher voltage and capacity, while the zirconium-doped shell reduces manganese leaching and improves compaction density. The strontium and zirconium doping helps prevent cracking during cell assembly, reducing manganese dissolution and improving battery cycling.

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Lithium iron phosphate positive electrode material for batteries with higher energy density compared to conventional lithium iron phosphate. The material has a particle size distribution without peaks to allow closer packing. The particles inherit the morphology and size of the precursor anhydrous ferric phosphate. By dehydrating ferric phosphate at different temperatures and mixing according to a closest packing equation, the lithium iron phosphate has a continuously distributed granularity for higher compaction density.

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Flame-retardant electrolyte for lithium-ion batteries that improves safety by reducing the risk of combustion and explosion during abuse conditions. The electrolyte contains a specific flame retardant additive with high phosphorus and nitrogen content. The additive helps prevent thermal runaway by consuming oxygen and diluting it in the air, as well as combining with hydrogen radicals generated during battery operation. This reduces the likelihood of smoke, fire, and explosion in abusive scenarios. The additive has mass percentages of phosphorus >10% and nitrogen >5%.

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A lithium battery anode with a protective layer that prevents lithium dendrite growth and improves battery safety. The protective layer contains a carbon matrix doped with cobalt and nitrogen, as well as coated transition metal particles. The doped carbon matrix improves lithium ion deposition uniformity, while the coated particles provide additional lithium-philic sites. This prevents dendrites from growing through the anode and shorting the battery.

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Ternary lithium-ion battery anode material with improved cycling and safety over traditional agglomerated ternary materials. The new ternary precursor is made by agglomerating primary particles with a sheet structure. The sheet primary particles have lengths of 10-100nm and thicknesses of 10-20nm. The agglomerated secondary particles have diameters of 10-50 μm. This sheet primary particle structure reduces cracking and gaps between particles compared to agglomerated spherical particles. The sheet primary particles are prepared by a method involving dispersing precursor salts in water, adjusting pH, and evaporating the water. The resulting ternary precursor is used to make the ternary lithium-ion battery anode material.

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Polymer separator for lithium-ion batteries that prevents polymer solution penetration into the separator during coating and improves battery performance. The separator has a porous substrate, a hydrophilic blocking layer between it and the polymer coating, and porous polymer coating with node structures. The hydrophilic blocking layer prevents polymer solution invasion. It allows the porous substrate to absorb electrolyte and transmit ions while reducing shrinkage and swelling. The porous polymer coating improves adsorption and reduces bulk impedance.

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Lithium-ion battery electrolyte composition and battery with improved cycle performance at both normal and high temperatures. The electrolyte contains a blend of two film-forming additives, vinylene carbonate (VC) and 2-hydroxyethyl methacrylate (HEMA). This combination provides enhanced cycle stability and reduces polarization at both normal and elevated temperatures compared to using VC alone. The battery with this electrolyte has improved normal temperature cycling, low temperature cycling, high temperature cycling, and storage stability compared to conventional electrolytes.

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A conductive agent for lithium ion battery electrodes that improves conductivity and performance compared to traditional carbon black. The agent is a mix of conductive carbon black, two types of carbon nanotubes, and graphene. The nanotubes have different tube lengths. This combination provides better electrical connection between the electrode active material and current collector compared to just using carbon black. The shorter nanotubes form line-to-line connections while the longer nanotubes provide point-to-point connections. The graphene helps further. The mass ratios of the components are in a specific range.

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Electrode binder for lithium batteries with improved binding and ionic conductivity, preventing swelling and slurry separation. The binder is an ionic liquid polymer with imidazole cations on the main chain. The binder is prepared by dissolving the polymer in water for ion exchange, then drying. The water removes impurities and prevents solvent dissolution. The binder is used in lithium battery electrodes to bind the active material to the current collector without swelling or slurry separation.

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Lithium ion battery with controllable design and long service life for electric vehicles. The battery has a unique configuration with an independent lithium supplementing electrode that can be precisely controlled to compensate for lithium loss during cycling. This allows optimizing the battery's N/P ratio and lithium supplementing amount for improved capacity and cycle life compared to traditional lithium supplementing methods. The independent lithium electrode is either an additional lithium supplementing electrode or a lithium film on the negative electrode. This provides a controllable and optimized lithium supplementing amount without affecting the N/P ratio as much as other methods.

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Positive electrode material, preparation method, and battery for lithium-ion batteries with improved performance, cycle life, and reduced gas generation. The positive electrode material consists of secondary composite particles made of primary particles. The key is controlling the particle size distribution to meet certain relations. The secondary particle diameter, primary particle diameter, specific surface area, and number of primary particles per secondary particle should satisfy specific relations. This balances factors like lithium diffusion, capacity, impedance, gas generation, and side reactions. Coating the positive electrode further improves battery performance.

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