CN1819321A - Lithium ion battery with high multiplying factor

In 2006, a commercial lithium-ion cell could typically sustain 1-3C continuous discharge. Power tools needed 5C. Flying models needed 7C. RC model aircraft needed 12C and above. That gap is why nickel-cadmium and nickel-metal-hydride packs - heavier, bulkier, burdened by memory effect - still dominated the high-drain market.

Patent application CN1819321A, filed on 6 March 2006, addressed that gap without exotic materials. It reached 12-15C using conventional LiCoO₂ and carbon chemistry, changing instead how the conductive agent is distributed before the slurry is ever mixed. Twenty years later, that same principle - dry-powder premixing under inert gas - underpins the dry electrode processing equipment TOB NEW ENERGY builds today.

Ⅰ. Patent Information

Ⅱ. Why This Mattered in 2006

Lithium-ion had won the portable electronics market by 1990s volume production, displacing lead-acid, Ni-MH and Ni-Cd across phones, laptops, PDAs, camcorders and digital cameras. But one segment resisted: high-drain power tools and model aircraft.

The physics were unforgiving. Above roughly 3C, a conventional 2006-era cell simply could not deliver - internal resistance rose, voltage collapsed under load, and usable capacity fell away. Manufacturers of cordless tools kept specifying Ni-Cd despite its weight, volume, environmental cost and memory effect, because nothing lithium-based could hold voltage at the currents they needed.

Two routes existed. The first - new cathode chemistries, new conductive frameworks - was slow, expensive, and years from production. CN1819321A took the second: keep the proven materials, and fix the electrode microstructure instead.

Ⅲ. The Core Insight: Dry-Powder Premixing

Conventional slurry preparation dissolves the binder in solvent, then adds active material and conductive agent together into the wet mix. The conductive carbon disperses through the liquid phase - but it disperses randomly. Some of it ends up bridging active particles; much of it does not.

CN1819321A inverts the sequence. Claim 10 specifies that active material and conductive agent are premixed as a dry powder before any solvent is introduced, under inert gas protection.

The described effect is direct: the conductive agent is driven onto and across the surface of each active particle first. When the binder solution is added afterwards, that conductive coating is already in place. The result is a continuous conductive network wrapping each particle, rather than a statistical scattering of carbon through a solvent.

Lower electronic resistance at the particle surface is precisely what governs whether a cell can sustain 12C or collapses at 3C.

The specification pairs this with three supporting measures:

• A polymer-coated separator - PVDF-HFP viscous particulate coated onto PP-PE-PP tri-layer or single-layer PE film, 0.016-0.025 mm thick, 40-55% porosity
• Controlled electrode compaction - 70-150 μm, applicable to both wound and stacked electrode groups
• A conductive electrolyte additive - a borate compound, written in the claims as [(CF₃)CHO]₃B, at 0.1-0.5% by weight in LiPF₆ or LiBF₄ carbonate electrolyte

Ⅳ. Technical Specification

Cathode - positive electrode (aluminium foil current collector)

• Active material: one or more lithium intercalation oxides - LiCoO₂, LiMn₂O₄, or LiCo1/3Ni1/3Mn1/3O₂
• Conductive agent: acetylene black, Super P, conductive graphite (KS-6), or vapour-grown carbon fibre (VGCF)
• Binder: PVDF homopolymer, or PVDF-HFP copolymer

Anode - negative electrode (copper foil current collector)

• Active material: modified natural spherical graphite, mesocarbon microbeads (CMS), or mesophase pitch-based carbon fibre (MCF)
• Conductive agent: Super P, conductive graphite (SFG-6 / SFG-15), or VGCF
• Binder: aqueous SBR + CMC, or oil-based PVDF

Worked example - Embodiment 1 (100-2500 mAh cell, wound)

• Cathode: LiCoO₂ : Super P : KS-6 : PVDF : NMP = 80 : 7 : 7 : 6 : 55
• Anode: CMS : Super P : SFG-6 : SBR : CMC : H₂O = 94 : 1 : 1 : 2 : 2 : 130
• Process: batching → coating → roll-pressing → sheet forming & winding → casing → electrolyte filling → formation → capacity grading

The specification further documents a laminated-stack variant (Embodiment 2), a LiCoO₂/LiMn₂O₄ blended cathode with MCF anode (Embodiment 3), and a VGCF-based conductive system (Embodiment 4).

Ⅴ. Measured Performance

Capacity retention relative to 1C discharge, as reported in the specification:

Holding 86% of nominal capacity at 15C - a full discharge in four minutes - placed this design well beyond the 1-3C ceiling of contemporary commercial cells, and above the 12C threshold that model aircraft applications demanded.

The published drawings include measured discharge curves at 7C (Fig. 6), 10C (Fig. 7) and 12C (Fig. 8), alongside cell construction schematics (Fig. 1), wound electrode geometry (Figs. 2-3) and stacked electrode geometry (Figs. 4-5).

Ⅵ. From a 2006 Patent to 2026 Production Equipment

The dry-premix principle in Claim 10 did not stay in 2006.

Distributing a conductive agent across active particles before solvent contact is the conceptual ancestor of what the industry now calls dry electrode processing - the solvent-reduced and solvent-free routes currently being scaled for high-energy and solid-state cells.

TOB NEW ENERGY builds equipment for exactly that process today:

• Dry Electrode Film Solution - dry-route electrode film forming
• Electrode Preparation - mixing, coating, calendering
• Solid State Battery Equipment - where dry processing is effectively mandatory

The engineer who co-invented the 2006 approach now leads the team specifying that equipment. That continuity - laboratory insight in 2006, production hardware in 2026 - is what our customers are buying when they choose TOB.

Explore the full record: all patents by the TOB technical team

Ⅶ. Frequently Asked Questions

Ⅷ. Official Record & Drawings

• Google Patents - CN1819321A (full text, claims, 11 forward citations)
• Official PDF with all drawings
• Espacenet record