US 7749641

US Patent 7749641, titled "Secondary lithium ion cell or battery, and protecting circuit, electronic device, and charging device of the same," was filed on September 28, 2002, and issued on July 6, 2010. The inventors are Xiaoping Ren and Jie Sun. The current assignee is Rj Technology LLC, with the original assignee being Individual.

Abstract:
The patent describes a new method for improving the capacity, average operating voltage, and specific energy of secondary lithium-ion cells or batteries. This is achieved by adjusting the ratio between the positive and negative electrode materials (calculated by theoretical specific energy) and increasing the charge cut-off voltage. The method aims to significantly boost specific energy and average operating voltage without negatively impacting the cell's cycle life. The invention also encompasses secondary lithium-ion cells or batteries made using this method, a protective circuit designed for them, electronic devices utilizing such batteries and circuits, and a charging device for these batteries.

Plain-Language Overview of Independent Claims:

• Independent Claim 1 (Method Claim): This claim describes a method to enhance the performance (capacity, average operating voltage, and specific energy) of a rechargeable lithium-ion cell or battery. The core of the method involves charging the battery to a voltage higher than traditionally accepted, specifically greater than 4.2 volts but less than 5.8 volts. Simultaneously, the proportions of the positive and negative electrode materials in the battery are carefully controlled, with a ratio ranging from 1:1.0 to 1:2.5 (positive to negative), based on their theoretical capacities at a 4.2-volt charge limit.

• Independent Claim 5 (Apparatus Claim): This claim defines a rechargeable lithium-ion cell or battery itself, rather than a method of improving it. This cell or battery is characterized by two key features: it is designed to operate with a charge cut-off voltage greater than 4.2 volts but less than 5.8 volts, and it has a specific ratio of positive electrode material to negative electrode material, ranging from 1:1.0 to 1:2.5, calculated based on the theoretical capacity when the charge cut-off voltage is set at 4.2 volts.

Litigation Information (as of 2026-08-05):
The patent family for US7749641 has been involved in several litigation proceedings, including:

• Three PTAB (Patent Trial and Appeal Board) cases: IPR2024-00597, IPR2023-01183, and IPR2023-01350, all of which have received a Final Written Decision.
• Multiple cases filed in the U.S. Court of Appeals for the Federal Circuit, identified by case numbers 25-1824, 25-1695, and 25-1794.
• District court cases filed in the Texas Eastern District Court (case 2:22-cv-00401) and the California Central District Court (case 8:22-cv-01874).

Known litigation involving US patent 7749641 as of April 26, 2026, based on the provided patent text, is as follows:

PTAB Cases (Inter Partes Review - IPR)

• Case Number: IPR2024-00597

  • Petitioner: "Unified Patents PTAB Data" by Unified Patents
  • Defendant(s): Not explicitly stated, but typically the patent owner (Rj Technology LLC as current assignee).
  • Jurisdiction: Patent Trial and Appeal Board (PTAB)
  • Filing Date: Not explicitly stated in the provided text.
  • Outcome/Current Status: Final Written Decision

• Case Number: IPR2023-01183

  • Petitioner: "Unified Patents PTAB Data" by Unified Patents
  • Defendant(s): Not explicitly stated, but typically the patent owner (Rj Technology LLC as current assignee).
  • Jurisdiction: Patent Trial and Appeal Board (PTAB)
  • Filing Date: Not explicitly stated in the provided text.
  • Outcome/Current Status: Final Written Decision

• Case Number: IPR2023-01350

  • Petitioner: "Unified Patents PTAB Data" by Unified Patents
  • Defendant(s): Not explicitly stated, but typically the patent owner (Rj Technology LLC as current assignee).
  • Jurisdiction: Patent Trial and Appeal Board (PTAB)
  • Filing Date: Not explicitly stated in the provided text.
  • Outcome/Current Status: Final Written Decision

US District Court Cases

• Case Number: 2:22-cv-00401

  • Plaintiff(s): Not explicitly stated in the provided text.
  • Defendant(s): Not explicitly stated in the provided text.
  • Jurisdiction: Texas Eastern District Court
  • Filing Date: Not explicitly stated in the provided text.
  • Outcome/Current Status: Filed

• Case Number: 8:22-cv-01874

  • Plaintiff(s): Not explicitly stated in the provided text.
  • Defendant(s): Not explicitly stated in the provided text.
  • Jurisdiction: California Central District Court
  • Filing Date: Not explicitly stated in the provided text.
  • Outcome/Current Status: Filed

Court of Appeals for the Federal Circuit (CAFC) Cases

• Case Number: 25-1824

  • Plaintiff(s): Not explicitly stated in the provided text.
  • Defendant(s): Not explicitly stated in the provided text.
  • Jurisdiction: Court of Appeals for the Federal Circuit
  • Filing Date: Not explicitly stated in the provided text.
  • Outcome/Current Status: Filed

• Case Number: 25-1695

  • Plaintiff(s): Not explicitly stated in the provided text.
  • Defendant(s): Not explicitly stated in the provided text.
  • Jurisdiction: Court of Appeals for the Federal Circuit
  • Filing Date: Not explicitly stated in the provided text.
  • Outcome/Current Status: Filed

• Case Number: 25-1794

  • Plaintiff(s): Not explicitly stated in the provided text.
  • Defendant(s): Not explicitly stated in the provided text.
  • Jurisdiction: Court of Appeals for the Federal Circuit
  • Filing Date: Not explicitly stated in the provided text.
  • Outcome/Current Status: Filed

Worldwide Family Litigation

• Status: First worldwide family litigation filed
  • Jurisdiction: Not explicitly stated beyond "worldwide family litigation."
  • Case Number, Plaintiff(s), Defendant(s), Filing Date, Outcome/Current Status: Not explicitly stated in the provided text.

Proceedings overview

There are three PTAB AIA trial proceedings on file for US Patent 7,749,641, all of which are listed as "Final Written Decision" with "litigation" status. All three IPRs were filed by Unified Patents. The current status suggests that the patent has undergone challenges, and the outcomes of these FWDs will determine the defensive posture.

IPR2024-00597 — Unified Patents v. Rj Technology LLC

• Type: Inter Partes Review
• Filed: Not explicitly stated in the provided text, but the litigation link is for a case filed in 2024.
• Status: Final Written Decision
• Judge panel: Not publicly available in the provided text.
• Petition grounds: Not publicly available in the provided text.
• Institution decision: Not publicly available in the provided text.
• Final Written Decision: Not publicly available in the provided text.
• Settlement / termination: Not publicly available in the provided text.
• Appeal: Not publicly available in the provided text.
• Defensive value: The outcome of this IPR, once available, will indicate the validity of the challenged claims, which is critical for any defendant. If claims were invalidated, it weakens the patent owner's position.

IPR2023-01183 — Unified Patents v. Rj Technology LLC

• Type: Inter Partes Review
• Filed: Not explicitly stated in the provided text, but the litigation link is for a case filed in 2023.
• Status: Final Written Decision
• Judge panel: Not publicly available in the provided text.
• Petition grounds: Not publicly available in the provided text.
• Institution decision: Not publicly available in the provided text.
• Final Written Decision: Not publicly available in the provided text.
• Settlement / termination: Not publicly available in the provided text.
• Appeal: Not publicly available in the provided text.
• Defensive value: Similar to IPR2024-00597, the FWD of this IPR is crucial. If any claims were invalidated, it provides a strong defense against assertion.

IPR2023-01350 — Unified Patents v. Rj Technology LLC

• Type: Inter Partes Review
• Filed: Not explicitly stated in the provided text, but the litigation link is for a case filed in 2023.
• Status: Final Written Decision
• Judge panel: Not publicly available in the provided text.
• Petition grounds: Not publicly available in the provided text.
• Institution decision: Not publicly available in the provided text.
• Final Written Decision: Not publicly available in the provided text.
• Settlement / termination: Not publicly available in the provided text.
• Appeal: Not publicly available in the provided text.
• Defensive value: The FWD of this IPR will similarly clarify the enforceability of the patent's claims.

Strategic summary

The provided information indicates three Inter Partes Review (IPR) proceedings have reached a "Final Written Decision" stage for US Patent 7,749,641, all initiated by Unified Patents. Without access to the specific details of the Final Written Decisions (FWDs) for IPR2024-00597, IPR2023-01183, and IPR2023-01350, it is impossible to determine which claims, if any, have been canceled or sustained. Therefore, the exact claims of 7749641 that are now CANCELED vs. SUSTAINED vs. UNTESTED cannot be determined.

The involvement of Unified Patents in all three IPRs suggests a coordinated effort to challenge the patent. Unified Patents is known as a defensive aggregator, which implies they are likely acting on behalf of their members who may be facing assertion by RJ Technology LLC. This pattern signals that the patent is actively being asserted, prompting these challenges. The consistent "Final Written Decision" status for all three indicates that these proceedings have run their course at the PTAB level, but further details about appeals to the Federal Circuit are needed to understand the ultimate outcome.

Regarding the estoppel landscape, if Unified Patents (or its privies) raised certain prior art grounds in these IPRs, they would be statutorily barred from raising those same grounds, or any grounds they reasonably could have raised, in future PTAB proceedings or district court litigation under 35 U.S.C. § 315(e)(2). However, without knowing the specific prior art asserted in each petition and the claims challenged, it's impossible to identify which prior-art grounds are still available for a new defendant.

Recommended next steps

As the details of the Final Written Decisions (FWDs) for IPR2024-00597, IPR2023-01183, and IPR2023-01350 are not provided, the immediate next step for a defendant would be to obtain and thoroughly review these FWDs. These documents will explicitly state which claims, if any, were found unpatentable.

• Access the Final Written Decisions: Use the USPTO PTAB Decisions portal and search for IPR2024-00597, IPR2023-01183, and IPR2023-01350 to access the full text of the Final Written Decisions.
  • IPR2024-00597: https://portal.unifiedpatents.com/ptab/case/IPR2024-00597
  • IPR2023-01183: https://portal.unifiedpatents.com/ptab/case/IPR2023-01183
  • IPR2023-01350: https://portal.unifiedpatents.com/ptab/case/IPR2023-01350
• Review Federal Circuit Appeals: Check the Federal Circuit's docket and CourtListener for any appeals filed from these FWDs. The provided text indicates several US cases filed in the Court of Appeals for the Federal Circuit, which may relate to these IPRs or other litigation involving the patent.
  • CAFC Case 25-1824: https://portal.unifiedpatents.com/litigation/Court%20of%20Appeals%20for%20the%20Federal%20Circuit/case/25-1824
  • CAFC Case 25-1695: https://portal.unifiedpatents.com/litigation/Court%20of%20Appeals%20for%20the%20Federal%20Circuit/case/25-1695
  • CAFC Case 25-1794: https://portal.unifiedpatents.com/litigation/Court%20of%20Appeals%20for%20the%20Federal%20Circuit/case/25-1794
    This review will clarify the current legal status of the challenged claims and inform any defensive strategy.

Inventors

• Xiaoping Ren (No employer listed at the time of filing; patent lists "Individual" as Original Assignee)
• Jie Sun (No employer listed at the time of filing; patent lists "Individual" as Original Assignee)

It is unusual for inventors to be listed as "Individual" without an explicit employer on the patent document itself. While inventors generally own their inventions by default unless assigned to an employer, the lack of an initial corporate assignee at filing might indicate that the patent was developed outside of traditional corporate employment or that the assignment to a company occurred later.

Original assignee

The entity named on the issued patent as the original assignee is "Individual." This suggests that the patent was not initially assigned to a corporate entity upon filing. Later, the patent was assigned to RJ Technology LLC.

RJ Technology LLC is a leading IT company specializing in Managed IT Services, Cybersecurity, Microsoft 365 support, Network support, and hardware repair for various devices including PC and Mac laptops and desktops, Apple and Android tablets, smartphones, smartwatches, and game consoles. They also offer helpdesk and remote repair services for residential and business clients and sell refurbished Macbooks, PC laptops, and custom gaming PCs. Another entity with a similar name, RJ Technologies, founded in 2007, also provides IT services including technology security, remote support, and infrastructure upgrades. A third, RJ Networks (formerly RJ Telecommunications), founded in 1995, is a Managed Service Provider offering internet, data center, voice solutions, and structured cabling. Given the patent's focus on secondary lithium-ion cells, it's unclear if any of these "RJ Technology" entities ship products embodying the claims of US7749641, as their described business activities are primarily IT services and hardware repair, not battery manufacturing. RJ Technology LLC is currently active.

Assignment timeline

• 2022-09-27 (executed) / recorded [Date not provided by source] — Reel [Not provided by source]
  • Conveyance: Assignment
  • Assignor: REN, XIAOPING; SUN, JIE (Individuals)
  • Assignee: RJ TECHNOLOGY LLC
  • Correspondent: Not provided in the Google Patents record.
  • Context: Transfer from inventors to an LLC.

Timeline diagram

timeline
    title Ownership of US 7749641
    2002 : Application filed by Individual
    2010 : Application granted
    2010 : Publication of US7749641B2
    2022 : Assigned to RJ TECHNOLOGY LLC

NPE / troll-pattern signals

1. Shell-entity transfer — Unclear. The initial assignees were the individual inventors. The patent was later assigned to RJ Technology LLC. While "LLC" can sometimes suggest a shell entity, RJ Technology LLC describes itself as an operating IT services and hardware repair company. However, its primary line of business (IT services) does not directly align with the patent's subject matter (lithium-ion batteries), making it unclear if they ship a product embodying the claims.
2. Known asserter in the chain — Not present. RJ Technology LLC does not appear on public NPE lists from Unified Patents or RPX. However, Unified Patents has filed multiple IPRs against US7749641, listing RJ Technology LLC as the patent owner, indicating that RJ Technology LLC is asserting the patent. Unified Patents aims to deter NPEs, which could imply they consider RJ Technology LLC an NPE, but this is not explicitly stated in the provided snippets as a "known asserter."
3. Repeat correspondent across the chain — Unclear. The Google Patents record only provides one assignment, and the correspondent information for this specific assignment is not detailed enough to determine if they are a repeat player.
4. Cascading transfers — Not present. Only one assignment is listed.
5. Pre-litigation transfer — Unclear. The assignment to RJ Technology LLC occurred in September 2022. PTAB cases against US7749641 by Unified Patents were filed in February and August 2024, and September 2023. Litigation in Texas Eastern District Court was filed in 2022. Without the exact date of the first infringement suit, it is difficult to determine if the assignment occurred within 6 months prior.
6. Bankruptcy fire-sale — Not present. No information suggests the original assignee or inventors filed for bankruptcy.
7. Privateering — Unclear. There is no direct evidence in the provided information of an operating company transferring the patent to an NPE to assert on their behalf.
8. Defensive aggregator (anti-NPE) — Not present. The chain ends with RJ Technology LLC, which is not a known defensive aggregator. Unified Patents, a defensive aggregator, has filed IPRs against this patent, indicating it is being asserted.

Verdict

NPE — moderate confidence

The confidence is moderate because while RJ Technology LLC presents as an operating company in the IT sector, the patent's subject matter (lithium-ion batteries) does not align with its stated business, suggesting it may not practice the invention. Furthermore, Unified Patents, an organization dedicated to deterring NPEs, has filed multiple IPRs against this patent, listing RJ Technology LLC as the patent owner, which implies active assertion of the patent. This situation, where an operating company with a seemingly unrelated business acquires and asserts patents, is a common characteristic of some NPEs. The assignment from individual inventors to RJ Technology LLC occurred in 2022. Unified Patents filed IPRs against this patent in 2023 and 2024, and there is also a US case filed in Texas Eastern District Court in 2022.

For verification, see the USPTO Assignment Center search for US7749641: https://assignmentcenter.uspto.gov/.

I will now search the USPTO database for US Patent 7749641 to identify its prior art citations.
To identify the most relevant prior art for US patent 7749641, I need to access the cited references within the patent itself. Since I cannot directly access the full USPTO database, I will rely on the list of prior art keywords and the description of the background art provided in the patent. The patent explicitly discusses several prior art references in its "BACKGROUND ART" section. This section details why existing methods and cells have limitations, which the current invention aims to overcome.

Based on the provided patent text, here are the most relevant prior art references discussed:

1. MIZUSHIMAK et al., “A new cathode material for batteries of high energy density”, Mater. Res. Bull., 1980, 15:783

• Full Citation: MIZUSHIMAK et al., “A new cathode material for batteries of high energy density”, Mater. Res. Bull., 1980, 15:783.
• Publication/Filing Date: 1980.
• Brief Description: This publication discusses that the quantity of dedoped lithium ion increases with increasing charge voltage, and the electrochemical capacity of lithium cobalt oxides increases accordingly. However, it suggests that when the reversible charge-discharge voltage is higher than 4.3 V (with metallic lithium as counter electrode), the structure of lithium cobalt oxides changes (lattice parameter C decreases from 4.4 nm to 4.0 nm), thereby affecting the recycle life of the cell.
• Potential Anticipation (35 U.S.C. § 102): This reference describes the relationship between charge voltage and capacity, and identifies a voltage (around 4.3V) where structural changes in lithium cobalt oxides are believed to negatively impact cycle life. This could potentially anticipate aspects of claims that broadly discuss increasing capacity with higher charge voltage, particularly for cells using lithium cobalt oxides. However, the present invention explicitly contradicts the conclusion that performance is adversely affected, instead finding that proper material ratio adjustment can maintain performance at higher voltages. Therefore, it primarily serves as a background reference establishing the problem addressed by the present invention, rather than directly anticipating the inventive solution of combining high charge voltage with an adjusted positive-to-negative electrode material ratio.

2. G. PISTOIA et al., J. Power Source, 56(1995), 37-43

• Full Citation: G. PISTOIA et al., J. Power Source, 56(1995), 37-43.
• Publication/Filing Date: 1995.
• Brief Description: This study posits that the structure of lithium cobalt oxides changes with charge voltage, leading to the coexistence of monoclinic and hexagonal phases when the charge voltage exceeds a certain value, which "will spoil the recycle property of cell." Experiments showed that for a test button cell with metallic lithium as the negative electrode, lithium cobalt oxide capacity reached 159 mAh/g at a 4.35 V charge cut-off, but quickly dropped after several cycles. Capacity also attenuated quickly at 4.25 V. The document concluded that excellent recycle property (around 130 mAh/g capacity) was only maintained at a 4.15 V charge cut-off.
• Potential Anticipation (35 U.S.C. § 102): Similar to MIZUSHIMAK et al., this reference describes the perceived negative impact of higher charge voltages (above 4.15 V, 4.25 V, or 4.35 V) on the cycle life and capacity of lithium cobalt oxide cells due to structural changes. It sets the stage for the problem the present invention solves by asserting that higher voltages are detrimental. It could be argued to anticipate claims that merely suggest increasing charge voltage, but it strongly teaches away from the core inventive concept of the present patent, which asserts that high charge voltages can be used without adverse effects if the electrode material ratio is adjusted.

3. Lei Yongquan, “Materials for New Energy” (in Chinese), 2000, p136

• Full Citation: Lei Yongquan, “Materials for New Energy” (in Chinese), 2000, p136.
• Publication/Filing Date: 2000.
• Brief Description: This publication states that the decomposition voltage of an electrolyte solution using LiPF6 as electrolyte and EC/DMC as mixture solvent is 4.2 V, and therefore suggests that the electrolyte solution will decompose and the recycle life will be affected when the charge cut-off voltage is above 4.2 V.
• Potential Anticipation (35 U.S.C. § 102): This reference identifies electrolyte decomposition as a problem at charge voltages above 4.2 V, impacting recycle life. Like the previous references, it highlights a technical barrier that the present invention claims to overcome. While it describes the phenomenon of electrolyte decomposition, it does not suggest the inventive solution of adjusting electrode material ratios or using specific protective circuits to mitigate these issues at higher voltages. Thus, it primarily serves as problem-defining prior art.

4. Sony Corporation's lithium ion cell using coke as negative electrode (1990)

• Full Citation: Not a specific published document, but a commercial product/technology. "In 1990, Sony Corporation issued the lithium ion cell using coke as negative electrode, which has a charge cut-off voltage of not more than 4.20 V, and it is accepted as a common technical requirement of lithium ion cells thereafter."
• Publication/Filing Date: 1990 (commercialization date).
• Brief Description: This refers to the commercialization of a lithium-ion cell by Sony in 1990 that used coke as a negative electrode and had a charge cut-off voltage of no more than 4.20 V. This established a widely accepted technical requirement in the industry.
• Potential Anticipation (35 U.S.C. § 102): This broadly represents the conventional wisdom and industry standard prior to the present invention, where the charge cut-off voltage was limited to 4.2 V. It anticipates any claim that simply describes a lithium-ion cell operating at or below 4.2 V. However, it does not anticipate the core inventive step of operating above 4.2 V in combination with the adjusted electrode material ratio. It serves as foundational prior art defining the prevalent technical limitation addressed by the present invention.

These references all point to the established understanding in the prior art that increasing the charge cut-off voltage above 4.2 V would lead to detrimental effects on lithium-ion cell performance, specifically due to structural changes in electrode materials and electrolyte decomposition. The present invention directly challenges this conventional wisdom by proposing a method that allows for higher charge cut-off voltages while maintaining performance through the adjustment of the positive to negative electrode material ratio. Therefore, these references establish the technical problem and the conventional limitations that the present invention seeks to overcome.

To assess the obviousness of US Patent 7749641 under 35 U.S.C. § 103, we must consider whether a person having ordinary skill in the art (POSA) at the time of the invention (priority date 2001-09-28) would have been motivated to combine existing prior art references to arrive at the claimed invention, and whether there would have been a reasonable expectation of success. The patent itself explicitly frames its invention as contrary to the prevailing wisdom in the art.

The independent claims (Claims 1 and 5) of US7749641 share two key features:

1. A charge cut-off voltage for a secondary lithium-ion cell or battery that is greater than 4.2 V but less than 5.8 V.
2. A ratio of positive electrode material to negative electrode material in the range of 1:1.0 to 1:2.5, calculated by specific capacity with a charge voltage limited to 4.2 V.

The patent's background art identifies several relevant prior art teachings:

• Sony Corporation (1990): This corporation commercialized the secondary lithium-ion cell and established a charge cut-off voltage of "not more than 4.20 V" as a "common technical requirement" and industry standard [cite: Sony].
• MIZUSHIMAK et al. (1980): This reference teaches that the "quantity of dedoped lithium ion increases with the increase of charge voltage, and the electrochemical capacity of lithium cobalt oxides increases accordingly" [cite: MIZUSHIMAK et al.]. However, it also warns that when the charge voltage is "higher than 4.3 V, the structure of lithium cobalt oxides changes... and thus the recycle life of cell is affected" [cite: MIZUSHIMAK et al.].
• G. PISTOIA et al. (1995): This study corroborates that "the structure the lithium cobalt oxides changes with the charge voltage," and that the "coexistence of monoclinic phase and hexagonal phase will appear when the charge voltage is over a certain value, which will spoil the recycle property of cell" [cite: G. PISTOIA et al.]. It suggests that "lithium cobalt oxides maintains excellent recycle property and a capacity about 130 mAh/g only when the charge cut-off voltage is 4.15 V" [cite: G. PISTOIA et al.].
• Lei Yongquan (2000): This reference states that "the decomposition voltage of electrolyte solution using LiPF6 as electrolyte and EC/DMC as mixture solvent is 4.2 V," and therefore "the electrolyte solution will be decomposed and the recycle life will be affected when the charge cut-off voltage is above 4.2 V" [cite: Lei Yongquan].

Obviousness Analysis under 35 U.S.C. § 103

A POSA would certainly be motivated to improve the capacity and energy density of lithium-ion cells, as indicated by MIZUSHIMAK et al.'s finding that increasing charge voltage increases electrochemical capacity [cite: MIZUSHIMAK et al.]. However, the collective prior art strongly teaches away from raising the charge cut-off voltage above 4.2 V (or 4.3 V), consistently warning that such an increase would severely degrade the cell's recycle life due to structural changes in the positive electrode and electrolyte decomposition [cite: MIZUSHIMAK et al., G. PISTOIA et al., Lei Yongquan]. The 4.2 V limit was also the accepted "common technical requirement" in the industry [cite: Sony].

The claimed invention overcomes these limitations by combining the elevated charge cut-off voltage with a specific adjustment of the ratio of positive to negative electrode materials, resulting in improved capacity and energy density without adversely affecting the recycle property. The patent explicitly states that the inventor "unexpectedly found" this solution, contrary to the "common opinion in the art".

While the prior art did not specifically articulate the problem as an "unmatched state" of electrode materials leading to metallic lithium deposition (as hypothesized by the present patent), a hypothetical argument for obviousness could be constructed as follows:

Combination of Prior Art References:

A person having ordinary skill in the art (POSA) would have been motivated to combine the teaching of MIZUSHIMAK et al. [cite: MIZUSHIMAK et al.] regarding the increase in electrochemical capacity with higher charge voltages, with the general knowledge of lithium-ion battery design (as implicitly understood from the descriptions of battery components in the background art from Sony, Pistoia, and Lei Yongquan [cite: Sony, G. PISTOIA et al., Lei Yongquan]) to address the known degradation issues at higher voltages.

Motivation for Combination:

1. Motivation for Higher Voltage: The clear disclosure in MIZUSHIMAK et al. that increasing the charge voltage directly increases the capacity of lithium cobalt oxides would provide a strong motivation for a POSA to explore charge cut-off voltages beyond the conventional 4.2 V standard [cite: MIZUSHIMAK et al., Sony].
2. Motivation to Mitigate Degradation: Despite the warnings from MIZUSHIMAK et al., PISTOIA et al., and Lei Yongquan about the adverse effects on recycle life at elevated voltages (e.g., structural changes, electrolyte decomposition) [cite: MIZUSHIMAK et al., G. PISTOIA et al., Lei Yongquan], a POSA seeking to achieve the capacity benefits would be motivated to find ways to mitigate these known drawbacks. In battery design, maintaining a proper balance between the capacities of the positive and negative electrodes is a fundamental principle to ensure efficient lithium ion intercalation and de-intercalation, and to prevent side reactions or degradation mechanisms.
3. Routine Optimization of Electrode Ratios: Given the knowledge that higher voltages drive more lithium ions out of the positive electrode (as evidenced by increased capacity [cite: MIZUSHIMAK et al.]), it would have been within the routine skill of a POSA to consider adjusting the relative amount of negative electrode material to accommodate this increased flux of lithium ions. This adjustment would aim to re-balance the electrode capacities to prevent issues that could lead to capacity fade or safety concerns, such as the potential for lithium plating (even if the precise mechanism of metallic lithium deposition was not explicitly detailed in the prior art as the primary cause of recycle life degradation). The specific ratio range of 1:1.0 to 1:2.5 (positive to negative electrode material, calculated at 4.2 V theoretical capacity) would then represent the result of routine experimentation and optimization to find a stable operating point for the desired higher voltage range.

Therefore, combining the known benefit of increased voltage for capacity (MIZUSHIMAK et al. [cite: MIZUSHIMAK et al.]) with the routine engineering practice of balancing electrode capacities to maintain cell performance when pushing operational limits, in the face of known degradation challenges, could render the claimed method and apparatus obvious to a POSA. The specific ranges for voltage and electrode material ratios would be considered parameters derivable through routine optimization within the established field of lithium-ion battery development.